Movement disorders

Definition

Movement disorders are a group of diseases and syndromes affecting the ability to produce and control bodily movements.

Description

It seems simple and effortless, but normal movement requires an astonishingly complex system of control. Disruption of any portion of this system can cause a person to produce movements that are too weak, too forceful, too uncoordinated, or too poorly controlled for the task at hand. Unwanted movements may occur at rest. Intentional movement may become impossible. Such conditions are called movement disorders.

Abnormal movements are symptoms of underlying disorders. In some cases, the abnormal movements are the only symptoms. Childhood disorders or conditions that may cause abnormal movements include:

• cerebral palsy
• choreoasthetosis
• encephalopathies
• essential tremor
• inherited ataxias (Friedreich's ataxia , Machado-Joseph disease, and spinocerebellar ataxias)
• multiple sclerosis
• parkinsonism and juvenile Parkinson's disease
• poisoning by carbon monoxide, cyanide, methanol, or manganese
• psychogenic disorders
• restless legs syndrome
• spasticity
• stroke
• Tourette syndrome and other tic disorders
• Wilson disease

Demographics

The incidence rates and demographics vary for different types of movement disorders. Restless legs syndrome (RLS) affects approximately 12 million people in the United States. The disorder can affect males and females and can begin at any age, although it may become worse as a person gets older. The most common ataxia is Friedreich's ataxia; in the United States, it affects one in 50,000 people, both male and female.

Causes and symptoms

Causes

Movement is produced and coordinated by several interacting brain centers, including the motor cortex, the cerebellum, and a group of structures in the inner portions of the brain called the basal ganglia. Sensory information provides critical input on the current position and velocity of body parts, and spinal nerve cells (neurons) help prevent opposing muscle groups from contracting at the same time.

To understand how movement disorders occur, it is helpful to consider a normal voluntary movement, such as reaching to touch a nearby object with the right index finger. To accomplish the desired movement, the arm must be lifted and extended. The hand must be held out to align with the forearm, and the forefinger must be extended while the other fingers remain flexed.

the motor cortex Voluntary motor commands begin in the motor cortex, located on the outer wrinkled surface of the brain. Movement of the right arm is begun by the left motor cortex, which generates a large volley of signals to the involved muscles. These electrical signals pass along upper motor neurons through the midbrain to the spinal cord. Within the spinal cord, they connect to lower motor neurons, which convey the signals out of the spinal cord to the surface of the muscles involved. Electrical stimulation of the muscles causes contraction, and the force of contraction pulling on the skeleton causes movement of the arm, hand, and fingers.

Damage to or death of any of the neurons along this path causes weakness or paralysis of the affected muscles.

antagonistic muscle pairs The previous description of movement is too simple, however. One important refinement to it comes from considering the role of opposing, or antagonistic, muscle pairs. Contraction of the biceps muscle, located on the top of the upper arm, pulls on the forearm to flex the elbow and bend the arm. Contraction of the triceps, located on the opposite side, extends the elbow and straightens the arm. Within the spine, these muscles are normally wired so that willed (voluntary) contraction of one is automatically accompanied by blocking of the other. In other words, the command to contract the biceps provokes another command within the spine to prevent contraction of the triceps. In this way, these antagonist muscles are kept from resisting one another. Spinal cord or brain injury can damage this control system and cause involuntary simultaneous contraction and spasticity, an increase in resistance to movement during motion.

the cerebellum Once the movement of the arm is initiated, sensory information is needed to guide the finger to its precise destination. In addition to sight, the most important source of information comes from the "position sense" provided by the many sensory neurons located within the limbs (proprioception). Proprioception is what allows a person to touch a finger to his or her nose, even with eyes closed. The balance organs in the ears provide important information about posture. Both postural and proprioceptive information are processed by a structure at the rear of the brain called the cerebellum. The cerebellum sends out electrical signals to modify movements as they progress, "sculpting" the barrage of voluntary commands into a tightly controlled, constantly evolving pattern. Cerebellar disorders cause inability to control the force, fine positioning, and speed of movements (ataxia). Disorders of the cerebellum may also impair the ability to judge distance so that a person under- or over-reaches the target (dysmetria). Tremor during voluntary movements can also result from cerebellar damage.

the basal ganglia Both the cerebellum and the motor cortex send information to a set of structures deep within the brain that help control involuntary components of movement (basal ganglia). The basal ganglia send output messages to the motor cortex, helping to initiate movements, regulate repetitive or patterned movements, and control muscle tone.

Circuits within the basal ganglia are complex. Within this structure, some groups of cells begin the action of other basal ganglia components and some groups of cells block the action. These complicated feedback circuits are not entirely understood. Disruptions of these circuits are known to cause several distinct movement disorders. A portion of the basal ganglia called the substantia nigra sends electrical signals that block output from another structure called the subthalamic nucleus. The subthalamic nucleus sends signals to the globus pallidus, which in turn blocks the thalamic nuclei. Finally, the thalamic nuclei send signals to the motor cortex. The substantia nigra, then, begins movement and the globus pallidus blocks it. This complicated circuit can be disrupted at several points.

Disruptions in other portions of the basal ganglia are thought to cause tics , tremors, dystonia, and a variety of other movement disorders, although the exact mechanisms are not well understood.

Some movement disorders, including Huntington's disease and inherited ataxias, are caused by inherited genetic defects. Some diseases that cause sustained muscle contraction limited to a particular muscle group (focal dystonia) are inherited, but others are caused by trauma. The cause of most cases of Parkinson's disease is unknown, although genes have been found for some familial forms.

Symptoms

Abnormal movements are broadly classified as either hyperkinetic (too much movement) and hypokinetic (too little movement). Hyperkinetic movements include:

• Dystonia—sustained muscle contractions, often causing twisting or repetitive movements and abnormal postures. Dystonia may be limited to one area (focal) or may affect the whole body (general). Focal dystonias may affect the neck (cervical dystonia or torticollis); the face (one-sided or hemifacial spasm, contraction of the eyelid or blepharospasm, contraction of the mouth and jaw or oromandibular dystonia, simultaneous spasm of the chin and eyelid or Meige syndrome); the vocal cords (laryngeal dystonia); or the arms and legs (writer's cramp or occupational cramps). Dystonia may be painful as well as incapacitating.
• Tremor—uncontrollable (involuntary) shaking of a body part. Tremor may occur only when muscles are relaxed or only during an action or while holding an active posture.
• Tics—involuntary, rapid, non-rhythmic movement or sound. Tics can be controlled briefly.
• Myoclonus—a sudden, brief, jerky, shock-like involuntary muscle contraction. Myoclonic jerks may occur singly or repetitively. Unlike tics, myoclonus cannot be controlled even briefly.
• Spasticity—an abnormal increase in muscle tone. It may be associated with involuntary muscle spasms , sustained muscle contractions, and exaggerated deep tendon reflexes that make movement difficult or uncontrollable.
• Chorea—rapid, non-rhythmic, uncontrolled jerky movements, most often in the arms and legs. Chorea also may affect the hands, feet, trunk, neck, and face. Choreoathetosis is a syndrome of continuous random movements that usually occur at rest and may appear to be fidgety, dancing, or writhing.
• Ballism—like chorea, but the movements are much larger, more explosive and involve more of the arm or leg. This condition, also called ballismus, can occur on both sides of the body or on one side only (hemiballismus).
• Akathisia—restlessness and a desire to move to relieve uncomfortable sensations. Sensations may include a feeling of crawling, itching , stretching, or creeping, usually in the legs.
• Athetosis—slow, writhing, continuous, uncontrollable movement of the arms and legs.

Hypokinetic movements include:

• Bradykinesia—extreme slowness and stiffness of movement.
• Freezing—inability to begin a movement or involuntary stopping of a movement before it is completed.
• Rigidity—an increase in muscle tension when an arm or leg is moved by an outside force.
• Postural instability—loss of the ability to maintain upright posture caused by slow or absent righting reflexes.

Diagnosis

Diagnosis of movement disorders requires a careful medical history and a thorough physical and neurological examination.

The medical history helps the physician evaluate the presence of other conditions or disorders that might contribute to or cause the disorder. Records of previous diagnoses, surgeries, and treatments are reviewed. The child's family medical history is evaluated to determine if there is a history of muscular or neurological disorders. Genetic testing is available for some forms of movement disorders.

The physical and neurological exams may include an evaluation of the child's motor reflexes, including muscle tone, mobility, strength, balance, and endurance; heart and lung function; cranial nerve function; and an examination of the child's abdomen, spine, throat, and ears. The child's height, weight, and blood pressure also are checked and recorded. Routine blood and urine analyses are performed.

Brain imaging studies are usually performed. Imaging techniques include computed tomography scan (CT scan), positron emission tomography (PET), or magnetic resonance imaging (MRI) scans. A lumbar puncture (spinal tap) may be necessary. Video recording of the abnormal movement is often used to analyze movement patterns and track progress of the disorder and its treatment.

Other tests may include x rays of the spine and hips or diagnostic blocks with local anesthetics to provide information on the effectiveness of potential treatments.

To aid diagnosis, a multi-disciplinary team may be consulted so the proper treatment can be planned. Occupational and physical therapy evaluations may be helpful to determine upper and lower extremity movement patterns and passive range of motion.

In some cases, nerve conduction studies with electromyography of the affected muscles may be performed to evaluate the child's muscular activity and provide a comprehensive assessment of nerve and muscle function.

In both tests, the examiner uses a computer, monitor, amplifier, loudspeaker, stimulator, and high-tech filters to see and hear how the muscles and nerves are responding during the test. In the nerve conduction study, small electrodes are placed on the skin over the muscles to be examined. A stimulator delivers a very small electrical current (that does not cause damage to the body) through the electrodes, causing the nerves to fire. In the electromyogram, a very thin, sterilized needle is inserted into various muscles. The needle is attached by wires to a recording machine. The patient is asked to relax and contract the muscles being examined. The electrical signals produced by the nerves and muscles during these tests are measured and recorded by a computer and displayed as electrical waves on the monitor. The test results are interpreted by a specially trained physician.

An EEG (electroencephalogram ) may be performed to detect seizures, analyze general brain functioning, and measure brain activity associated with movement or sensation. This test measures the electrical signals from the brain. Surface electrodes attached to the scalp measure voltages in the brain. The electrical activity can be measured while the child is resting or, in some cases, when the child is moving. An evoked potentials study may be part of the EEG test. Evoked potentials record the response of the brain to a sensory, visual, or auditory stimulus.

Treatment

Treatment of a movement disorder begins with a proper diagnostic evaluation. Treatment options include physical and occupational therapies, medications, surgery, or a combination of these treatments.

The goals of treatment are to increase the child's comfort, decrease pain , ease mobility, help with activities of daily living such as hygiene, ease rehabilitation procedures, and prevent or decrease the risk of developing a joint contracture. The type of treatment recommended will depend upon the severity of the disorder; the child's overall health; the potential benefits, limitations, and side effects of the treatment; and the impact of the treatment on the child's quality of life.

Clinicians should work with the child and parents or caregivers to develop an individual treatment plan. Specific treatment goals will vary from one person to the next. Treatment should be provided by a movement disorders specialist or specially trained pediatric neurologist and a multi-disciplinary team of specialists that may include a physiatrist, physical therapist, occupational therapist, gait and movement specialists, social worker, and surgical specialists as applicable, such as a pediatric orthopedic surgeon or pediatric neurosurgeon.

In some cases, treatment is not recommended or desired, because it would actually interfere with the patient's current mobility and it would not improve function. For example, some people with multiple sclerosis who experience significant leg weakness find that spasticity makes their legs more rigid, helping them to stand, transfer to a chair or bed, or walk.

Physical and occupational therapies

Physical therapy includes stretching exercises, muscle group strengthening exercises, and range of motion exercises to prevent muscles from shortening (contracture), preserve flexibility and range of motion, and reduce the severity of symptoms. Exercises should be practiced daily, as recommended by the physical therapist. Prolonged stretching can lengthen muscles, and strengthening exercises can restore the proper strength to affected muscles. Aquatic therapy also may be recommended, since there is less stress on the body when in the water.

A physical therapist can instruct the patient on proper posture guidelines. Proper posture is critical, especially while sitting and sleeping, to maintain proper alignment of the hips and back. Balancing rest and exercise is also important.

Occupational therapy may include splints, casts, or braces on the affected arm or leg to enable proper limb positioning, and maintain flexibility and range of motion. The therapy may include training for proper limb positioning while seated in a wheelchair or lying in bed.

Physical and occupational therapists can provide guidelines on how to adapt the child's environment to ensure safety and comfort.

Medications

Medications can help compensate for some imbalances of the basal ganglionic circuit. Drugs to treat movement disorders include oral medications, injected medications, and continuous delivery medications. These medications work by preventing nerves from signaling the muscles to contract, thereby preventing muscle contractions.

If treatment with a single medicine fails to effectively treat the disorder, a different medicine may be tried or an additional medicine may be prescribed. The most important medication guidelines are to ensure that the child takes the medication exactly as prescribed, and to never discontinue any medication without first talking to the child's doctor, even if the medication does not seem to be working or is causing unwanted side effects.

oral medications Baclofen (Lioresal) is a muscle relaxant that works on nerves in the spinal cord to reduce spasticity. The benefits of baclofen include decreased stretch reflexes, improved passive range of motion, and reduced muscle spasms, pain, and tightness. Side effects include drowsiness and sedation, as well as weakness, decreased muscle tone, confusion, fatigue, nausea , and dizziness . Baclofen should not be taken with central nervous system depressants or alcohol.

Levodopa (L-dopa) is a medication that is converted to dopamine in the brain. Dopamine is a chemical that aids in the transmission of nerve signals. Sinemet is a combination medication containing levodopa and carbidopa. Carbidopa enables L-dopa to be converted to dopamine after the L-dopa enters the brain, thereby lowering the oral dose and decreasing side effects. Side effects include nausea, diarrhea , and low blood pressure.

Anticholinergics, including trihexyphenidyl (Artane) and benztropine (Benztrop MES, Cogentin), block acetylcholine receptors in the brain. Acetylcholine receptors are integral proteins that respond to the neurotransmitter acetylcholine by opening a pathway in the membrane for ion diffusion across the cell membrane. Side effects include dry mouth, blurred vision, constipation , urinary retention, and rapid heart rate. These side effects are usually much less frequent in children than adults; therefore, much higher doses are usually prescribed in children.

Benzodiazepines, such as diazepam (Valium), clonazepam (Klonopin, Rivotril), and lorazepam (Ativan) act on the central nervous system to improve passive range of motion, reduce muscle overactivity and painful spasms, and provide overall relaxation. These medications are often taken at night because they cause drowsiness, but they also can relieve muscle spasms that interrupt sleep . Side effects include unsteadiness, loss of strength, low blood pressure, gastrointestinal symptoms, memory problems, confusion, and behavioral problems.

Dantrolene sodium (Dantrium) acts on the muscles to directly interfere with the chemistry of the muscle contraction. It is generally used when other medications are not effective. Benefits may include improved passive movement, decreased muscle tone, and reduced muscle spasms, tightness, and pain. Side effects include generalized weakness—including weakness of the respiratory muscles—as well as drowsiness, fatigue, diarrhea, and sensitivity to the sun. Liver problems may occur with this medication, and frequent lab tests are performed to evaluate liver function.

Tizanidine (Zanaflex) acts on the central nervous system. It does not usually cause reduced muscle strength. The most common side effect is sedation, and other side effects include low blood pressure, dry mouth, dizziness, and hallucinations. Liver problems may occur with this medication, and frequent lab tests are performed to evaluate liver function.

A variety of other medications may be used to treat movement disorders, including antiepileptic drugs that stimulate GABA receptors in the brain's basal ganglia; neuroleptics that block dopamine D2-like receptors; Clonidine (Catapres) and selective serotonin reuptake inhibitors (SSRIs, such as fluoxetine, commonly known as Prozac) for the treatment of tics; and channel modulators that affect the behavior of channels that transport small molecules such as potassium, sodium, or calcium across cell membranes.

injected medications Botulinum-toxin type A (Botox, Dysport) or type B (Myobloc) is injected locally into the affected muscle group to relax the muscles in dystonia or spasticity. It works by preventing nerves from sending signals to the muscles that cause them to contract. Although the treatment takes one to two weeks to reach its full effectiveness, the beneficial effects last three to four months. Botulinum-toxin allows more normal limb positioning and improved mobility. In some patients, the injections also decrease pain. Injections may be used to make casting easier, ease the adjustment of a new brace, or delay surgery.

Botulinum-toxin is made by the bacteria that cause botulism . However, the amount of botulinum-toxin injected to treat spasticity is such a small amount that it would not cause botulism poisoning. This treatment is very safe, and the injections can be given in a doctor's office without the use of sedation or anesthesia. Injections can be repeated, but should be spaced from three to six months apart to avoid exceeding the recommended dose. Botulinum-toxin injections may be used in combination with other treatments.

Botulinum-toxin injections are typically expensive and may not be covered by insurance. A Reimbursement Hotline established by Allergan, the manufacturer of Botox, is a resource for reimbursement questions: (800) 530-6680 or online at <www.botox.com>. Elan, the manufacturer of Myobloc, also has resources available to answer questions about reimbursement. Interested persons may call (888) 461-2255 or go online at <www.elan.com>.

Alcohol and phenol are injected in combination, but are less common treatments. The medications are injected directly onto nerves that supply spastic muscles to destroy them. The injections cut off the signals to those muscles, allowing them to relax. This treatment may be used to treat spasticity in larger muscle groups closer to the trunk, such as the thigh muscles. Although this treatment is generally less expensive than botulinum-toxin injections, there are more serious side effects.

Short-term medications such as lidocaine, a local anesthetic, can be used to assess the potential benefit of botulinum-toxin or alcohol and phenol injections.

continuous delivery medications Baclofen usually is taken as an oral medication but also can be delivered directly into the spinal fluid when the oral medication does not effectively control symptoms. An intrathecal baclofen delivery system, surgically placed by a neurosurgeon, continuously releases prescribed amounts of baclofen in small doses directly into the spinal fluid via a small catheter and pump. This type of delivery system causes fewer and less severe side effects than the oral baclofen.

Pump refills and medication adjustments are generally made once every two to three months after the initial dosage is established. The pump system lasts from three to five years, at which time it needs to be replaced.

Surgery

Surgery is only recommended when all other treatments have been tried and have not effectively controlled the child's symptoms.

Selective dorsal rhizotomy surgery, also called selective posterior rhizotomy, involves a surgical resection of part of the spinal nerve. By cutting the sensory nerve rootlets that cause the spasticity, muscle stiffness is decreased while other functions are maintained. Potential benefits of this surgical procedure include pain relief, reduced spasticity to improve walking or aid sitting in a wheelchair, increased ability to bend at the waist, and improved use of the hands. Sometimes rhizotomy results in improved breathing and better control of the arms, legs, and head.

Thalamotomy is a surgical procedure used to destroy part of the thalamus, which is thought to produce abnormal brain activity that causes tremor. Pallidotomy is a surgical procedure used to destroy part of the globus pallidus, which is thought to become overactive with certain disorders, such as Parkinson's disease. Although effective, these surgeries have significant risks, including paralysis, loss of vision, or loss of speech if the precise location of the brain is not targeted during surgery. With the advent of a less invasive approach called deep brain stimulation, these surgeries have become less common.

Deep brain stimulation (DBS) is a way to inactivate the parts of the brain thought to cause overactivity or tremor in certain muscles, without destroying a part of the brain. It is currently a treatment option for adult patients with Parkinson's disease, but research is underway to determine if the procedure can benefit children with movement disorders.

During the DBS procedure, an electrode placed in a precise area of the brain delivers small, electrical shocks to interrupt the abnormal brain activity that leads to symptoms. The electrode has four metal contacts that can be used in different combinations. A few patients may have stimulators implanted on both sides of the brain, but this increases the risk for complications. The electrode is connected by a wire to a pacemaker-like device implanted under the skin in the chest. This device generates the electrical shocks. The electrical stimulation can be adjusted as the patient's condition progresses over time, and the stimulator can be turned off in the event that other beneficial therapies, such as brain cell transplantation, are performed.

Orthopedic surgery may be performed to correct a contracture. During contracture release surgery, the tendon of a contractured muscle is cut, the joint repositioned to a more normal angle, and a cast is applied. Regrowth of the tendon to this new length occurs over several weeks following surgery. After the cast is removed, physical therapy can help strengthen the muscles and improve range of motion. This procedure is most commonly performed on the Achilles tendon but may also be performed on the knees, hips, shoulders, elbows, and wrists. Tendon transfer surgery is another technique to treat contractures. During this procedure, the tendon attached to a spastic muscle is cut and transferred to a different site, preventing the muscle from being pulled into an abnormal position. The disadvantages of these orthopedic procedures are that they are irreversible and they may need to be repeated.

Other orthopedic surgeries that may accompany contracture release surgery include osteotomy, in which a small wedge is removed from a bone to allow repositioning. A cast is applied while the bone heals in a more natural position. Osteotomy is more commonly performed on the bones in the hips or feet. Arthrodesis is a fusing of bones that normally move independently, to limit the ability of a spastic muscle to pull the joint into an abnormal position. Arthrodesis is more commonly performed on the bones in the ankle.

Other treatments

Transplantation of fetal cells into the basal ganglia has produced mixed results in Parkinson's disease and is being researched for application in other movement disorders.

Brief application (about 10 minutes) of cold packs to spastic muscles may help ease pain and improve function for a short period of time.

Electrical stimulation may be used to stimulate a weak muscle to counteract the action of a stronger, spastic muscle.

Alternative treatment

Alternative and complementary therapies include approaches that are considered to be outside the mainstream of traditional health care. Among the therapies that may be helpful are acupuncture, homeopathy, touch therapies, postural alignment therapies, and biofeedback. The progress made will depend on the individual and his or her condition.

Biofeedback training may be used to teach the patient how to consciously reduce muscle tension. Biofeedback uses an electrical signal that indicates when a spastic muscle relaxes. The patient may be able to use biofeedback to learn how to consciously reduce muscle tension and possibly reduce symptoms.

Coenzyme Q10 supplements may be beneficial, as some people with movement disorders may have low levels of this substance. Coenzyme Q10 is a natural substance produced by the body that transports electrons during cellular respiration, or the process in which cells get their energy from oxygen.

Initial trials of cannabinoids, the active ingredient in marijuana, have shown promise in the treatment of muscle stiffness and limb straightening associated with multiple sclerosis. Further research is needed to determine the beneficial effects of marijuana-derived substances on neuromuscular symptoms associated with movement disorders. Researchers caution that smoking marijuana is dangerous, especially since there may be other harmful substances mixed in with the illegal drug.

Before learning or practicing any particular technique, it is important for the parent or caregiver and child to learn about the therapy, its safety and effectiveness, potential side effects, and the expertise and qualifications of the practitioner. Although some practices are beneficial, others may be harmful to certain patients. Alternative therapies should not be used as a substitute for medical therapies prescribed by a doctor. Parents should discuss these alternative treatments with the child's doctor to determine the techniques and remedies that may be beneficial for the child.

Nutritional concerns

Dietary guidelines are individualized, based on the child's age, diagnosis, overall health, severity of disability, and level of functioning. Specific nutritional problems, such as swallowing or feeding difficulties, may be a concern in some patients and should be managed by a team of specialists, including a speech therapist. Early identification, treatment, and correction of specific feeding problems will improve the health and nutritional status of the patient.

A well-balanced and carefully planned diet will help maintain general good health for people with movement disorders. Specialists recommend that people with multiple sclerosis and other movement disorders adhere to the same low-fat, high fiber diet that is recommended for the general population. A diet rich in fresh fruits and vegetables will ensure adequate intake of antioxidants, substances that help protect against free radical damage.

Children with movement disorders may have different energy needs, depending on their condition. One study indicated that ambulatory and non-ambulatory adolescents with cerebral palsy had decreased energy needs compared with a control group of normal adolescents. Therefore, a child's specific calorie needs should be evaluated by a registered dietitian who can work with the parents to develop an individualized meal plan. The child's weight should be obtained once a week or at least once a month to determine if caloric intake is adequate.

A child's self-feeding skills can impact his or her health outcome. One study indicated that 90 percent of children with good to fair motor and feeding skills reached adulthood. In contrast, a lack of self-feeding skills was associated with a six-fold increase in mortality (rate of death).

Maintaining a healthy weight is important to prevent the development of chronic diseases such as diabetes, high blood pressure (hypertension ), and heart disease.

Tube feedings may be required in some patients with failure to thrive , aspiration pneumonia , difficulty swallowing, or an inability to ingest adequate calories orally to maintain nutritional status or promote growth.

Prognosis

The prognosis for a patient with a movement disorder depends on the specific disorder. There is no cure for movement disorders. However, they can be well-managed with the proper combination of physical and occupational therapies, medication, and surgery. The long-term outlook depends on the severity of the disorder.

Prevention

Prevention depends on the specific disorder.

Parental concerns

Parents should work closely with the child's therapists and doctors to create an effective treatment plan. It is important for parents to communicate their treatment goals with the health care team. Parents should take an active role in the child's exercise program and help the child practice the exercises, as prescribed, every day.

There are many tips to make the home and school environments safer for a child with a movement disorder. An occupational therapist can work with parents to assess the home environment and provide resources for

KEY TERMS

Active motion —Spontaneous; produced by active efforts. Active range of motion exercises are those that are performed by the patient without assistance.

Activities of daily living (ADL) —The activities performed during the course of a normal day, for example, eating, bathing, dressing, toileting, etc.

Acupuncture —Based on the same traditional Chinese medical foundation as acupressure, acupuncture uses sterile needles inserted at specific points to treat certain conditions or relieve pain.

Anoxia —Lack of oxygen.

Ataxia —A condition marked by impaired muscular coordination, most frequently resulting from disorders in the brain or spinal cord.

Autonomic nervous system —The part of the nervous system that controls so-called involuntary functions, such as heart rate, salivary gland secretion, respiratory function, and pupil dilation.

Biofeedback —A training technique that enables an individual to gain some element of control over involuntary or automatic body functions.

Botulinum toxin —A potent bacterial toxin or poison made by Clostridium botulinum ; causes paralysis in high doses, but is used medically in small, localized doses to treat disorders associated with involuntary muscle contraction and spasms, in addition to strabismus. Commonly known as Botox.

Bradykinesia —Extremely slow movement.

Central nervous system —Part of the nervous system consisting of the brain, cranial nerves, and spinal cord. The brain is the center of higher processes, such as thought and emotion and is responsible for the coordination and control of bodily activities and the interpretation of information from the senses. The cranial nerves and spinal cord link the brain to the peripheral nervous system, that is the nerves present in the rest of body.

Cerebral palsy —A nonprogressive movement disability caused by abnormal development of or damage to motor control centers of the brain.

Chorea —Involuntary movements in which the arms or legs may jerk or flail uncontrollably.

Choreoathetosis —Involuntary rapid, irregular, jerky movements or slow, writhing movements that flow into one another.

Clonic —Referring to clonus, a series of muscle contractions and partial relaxations that alternate in some nervous diseases in the form of convulsive spasms.

Computed tomography (CT) —An imaging technique in which cross-sectional x rays of the body are compiled to create a three-dimensional image of the body's internal structures; also called computed axial tomography.

Contraction —A tightening of the uterus during pregnancy. Contractions may or may not be painful and may or may not indicate labor.

Contracture —A tightening or shortening of muscles that prevents normal movement of the associated limb or other body part.

Encephalopathy —Any abnormality in the structure or function of brain tissues.

Essential tremor —An uncontrollable (involuntary) shaking of the hands, head, and face. Also called familial tremor because it is sometimes inherited, it can begin in the teens or in middle age. The exact cause is not known.

Fasciculations —Small involuntary muscle contractions visible under the skin.

Fetal tissue transplantation —A method of treating Parkinson's and other neurological diseases by grafting brain cells from human fetuses onto the basal ganglia. Human adults cannot grow new brain cells but developing fetuses can. Grafting fetal tissue stimulates the growth of new brain cells in affected adult brains.

General anesthesia —Deep sleep induced by a combination of medicines that allows surgery to be performed.

Hereditary ataxia —One of a group of hereditary degenerative diseases of the spinal cord or cerebellum. These diseases cause tremor, spasm, and wasting of muscle.

Homeopathy —A holistic system of treatment developed in the eighteenth century. It is based on the idea that substances that produce symptoms of sickness in healthy people will have a curative effect when given in very dilute quantities to sick people who exhibit those same symptoms. Homeopathic remedies are believed to stimulate the body's own healing processes.

Huntington's disease —A rare hereditary disease that causes progressive chorea (jerky muscle movements) and mental deterioration that ends in dementia. Huntington's symptoms usually appear in patients in their 40s. Also called Huntington's chorea.

Hyperactive reflexes —Reflexes that persist too long and may be too strong. For example, a hyperactive grasp reflex may cause the hand to stay clenched in a tight fist.

Hypermobility —Unusual flexibility of the joints, allowing them to be bent or moved beyond their normal range of motion.

Hypertonia —Having excessive muscular tone or strength.

Levodopa (L-dopa) —A substance used in the treatment of Parkinson's disease. Levodopa can cross the blood-brain barrier that protects the brain. Once in the brain, it is converted to dopamine and thus can replace the dopamine lost in Parkinson's disease.

Local anesthesia —Pain-relieving medication used to numb an area while the patient remains awake. Also see general anesthesia.

Magnetic resonance imaging (MRI) —An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct detailed images of internal body structures and organs, including the brain.

Mask —An expressionless look, caused by reduced movements of the face.

Motor neuron —A nerve cell that specifically controls and stimulates voluntary muscles.

Multiple sclerosis —A progressive, autoimmune disease of the central nervous system characterized by damage to the myelin sheath that covers nerves. The disease, which causes progressive paralysis, is marked by periods of exacerbation and remission.

Muscle spasm —Localized muscle contraction that occurs when the brain signals the muscle to contract.

Myoclonus —Involuntary contractions of a muscle or an interrelated group of muscles. Also known as myoclonic seizures.

Neurologist —A doctor who specializes in disorders of the nervous system, including the brain, spinal cord, and nerves.

Neurosurgeon —Physician who performs surgery on the nervous system.

Nocturnal leg cramps —Cramps that may be related to exertion and awaken a person during sleep.

Occupational therapist —A healthcare provider who specializes in adapting the physical environment to meet a patient's needs. An occupational therapist also assists patients and caregivers with activities of daily living and provide instructions on wheelchair use or other adaptive equipment.

Orthopedist —A doctor specializing in treatment of the musculoskeletal system.

Parkinsonism —A set of symptoms originally associated with Parkinson disease that can occur as side effects of neuroleptic medications. The symptoms include trembling of the fingers or hands, a shuffling gait, and tight or rigid muscles.

Parkinson's disease —A slowly progressive disease that destroys nerve cells in the basal ganglia and thus causes loss of dopamine, a chemical that aids in transmission of nerve signals (neurotransmitter). Parkinson's is characterized by shaking in resting muscles, a stooping posture, slurred speech, muscular stiffness, and weakness.

Passive movement —Movement that occurs under the power of an outside source such as a clinician. There is no voluntary muscular contraction by the individual who is being passively moved.

Periodic limb movement disorder —A disorder characterized by involuntary flexion of leg muscles, causing twitching and leg extension or kicking during sleep.

Peripheral nerves —Nerves outside the brain and spinal cord that provide the link between the body and the central nervous system.

Physiatrist —A physician who specializes in physical medicine and rehabilitation.

Physical therapist —A healthcare provider who teaches patients how to perform therapeutic exercises to maintain maximum mobility and range of motion.

Positron emission tomography (PET) —A computerized diagnostic technique that uses radioactive substances to examine structures of the body. When used to assess the brain, it produces a three-dimensional image that shows anatomy and function, including such information as blood flow, oxygen consumption, glucose metabolism, and concentrations of various molecules in brain tissue.

Progressive supranuclear palsy —A rare disease that gradually destroys nerve cells in the parts of the brain that control eye movements, breathing, and muscle coordination. The loss of nerve cells causes palsy, or paralysis, that slowly gets worse as the disease progresses. The palsy affects ability to move the eyes, relax the muscles, and control balance. Also called Steele-Richardson-Olszewski syndrome.

Psychogenic disorders —A variety of unusual, involuntary movements that occur in children with psychiatric disorders or in response to anxiety, stress, depression, anger, or grief. Psychogenic movements are thought to represent the physical expression of an intolerable mental conflict.

Range of motion (ROM) —The range of motion of a joint from full extension to full flexion (bending) measured in degrees like a circle.

Restless legs syndrome (RLS) —A disorder in which the patient experiences crawling, aching, or other disagreeable sensations in the calves that can be relieved by movement. RLS is a frequent cause of difficulty falling asleep at night.

Rigidity —A constant resistance to passive motion.

Scissoring —Involuntary crossing of the legs.

Spinal cord injury —Injury to the spinal cord, via blunt or penetrating trauma.

Stroke —Interruption of blood flow to a part of the brain with consequent brain damage. A stroke may be caused by a blood clot or by hemorrhage due to a burst blood vessel. Also known as a cerebrovascular accident.

Tourette syndrome —A neurological disorder characterized by multiple involuntary movements and uncontrollable vocalizations called tics that come and go over years, usually beginning in childhood and becoming chronic. Sometimes the tics include inappropriate or obscene language (coprolalia).

Wilson disease —A rare, inherited disorder that causes excess copper to accumulate in the body. Steadily increasing amounts of copper circulating in the blood are deposited primarily in the brain, liver, kidneys, and the cornea of the eyes. It can cause psychiatric symptoms resembling schizophrenia.

adaptive equipment that may be helpful. Some of these tips include:

• All throw rugs should be removed unless they are firmly attached to the floor.
• There must be proper lighting. Nightlights should be placed along key pathways of the home.
• The top and bottom of stairs should be highlighted with a contrasting color or texture to distinguish them.
• The floor should be free of clutter, to prevent tripping or falling.
• Handrails should be installed, especially along stairways and in the bathroom.
• All electrical cords and other cords should be kept out of the way.

Raising a child with a movement disorder can be challenging. Support groups are available to provide information and assistance.

See also Tics; Tourette syndrome.

Resources

BOOKS

Jankovic, Joseph J., and Eduardo Tolosa. "A Guide to Movement Disorders." In Parkinson's Disease and Movement Disorders. 4th ed. Philadelphia: Lippincott, Williams, and Wilkins, 2002: 704.

Martini, Frederic. Fundamentals of Anatomy and Physiology. Englewood Cliffs, NJ: Prentice Hall, 1989.

Watts, Ray L., and William C. Koller, eds. Movement Disorders: Neurologic Principles and Practice. New York: McGraw-Hill, 1997.

PERIODICALS

"Position of the American Dietetic Association: Providing Nutrition Services for Infants, Children and Adults with Developmental Disabilities and Special Health Care Needs." Journal of the American Dietetic Association 104, no. 1 (2004): 97–107.

"Task Force on Childhood Motor Disorders Consensus Report of a Meeting at the National Institutes of Health." (2001): April 22–24. <www.ninds.nih.gov&gt;

ORGANIZATIONS

Brain Injury Association of America. 8201 Greensboro Dr., Ste. 611, McLean, VA 22102. (800) 444-6443 or (703) 761-0750. Web site: &;lt;http://www.biausa.org>.

Movement Disorders Society. 555 East Wells St., Suite 1100, Milwaukee, WI 53202-3823. (414) 276-2145. Web site: <www.movementdisorders.org>.

National Center on Birth Defects and Developmental Disabilities. Centers for Disease Control. 4770 Buford Highway., NE, Ste. F-35, Atlanta, GA 30341. (770) 488-7080. Web site: <http://cdc.gov/ncbddd/dh>.

National Institute on Disability and Rehabilitation Research. Office of Special Education and Rehabilitative Services. U.S. Department of Education, 400 Maryland Ave., SW, Washington, DC 20202-7100. (202) 245-7640. Web site: <www.ed.gov/about/offices/list/osers/nidrr>.

National Institute of Neurological Disorders and Stroke (NINDS). National Institutes of Health. P.O. Box 5801, Bethesda, MD 20824. (800) 352-9424 or (301) 496-5751. Web site: <www.ninds.nih.gov/about_ninds/>.

National Rehabilitation Information Center (NARIC). 4200 Forbes Blvd., Ste. 202, Lanham, MD 20700. (800) 346-2742 or (301) 459-5900. Web site: <www.naric.com>.

National Spinal Cord Injury Association. 6701 Democracy Blvd., #300-9, Bethesda, MD 20817. (800) 962-9629 or (301) 214-4006. info@spinalcord.org. Web site: <www.spinalcord.org>.

WE MOVE (Worldwide Education and Awareness for Movement Disorders). 204 W. 84th St. New York, NY 10024. (800) 437-MOVE. Web site: <www.wemove.org>.

WEB SITES

Spinal Cord Injury Information Network. Available online at: <www.spinalcord.uab.edu>.

Richard Robinson Angela M. Costello

Movement disorders

Definition

Movement disorders are a group of neurological diseases and syndromes that involve the motor and movement systems' ability to produce and control movement.

Description

Though it seems simple and effortless, normal movement actually requires an astonishingly complex system of control. Disruption of any portion of this system can cause a person to produce movements that are too weak, too forceful, too uncoordinated, or too poorly controlled for the task at hand. Unwanted movements may occur at rest. Intentional movement may become impossible. These conditions are examples of movement disorders.

Abnormal movements themselves are symptoms of underlying disorders. In some cases, the abnormal movements are the only symptoms. The more common diseases causing motor disorders include:

• spinal cord injury (SCI)
• stroke
• multiple sclerosis (MS)
• muscular dystrophy (MD)
• huntington's chorea (HC)
• cerebral palsy (CP)
• dystonias
• tremor
• myasthenia gravis (MG)
• parkinsonism (PD)
• Tourette syndrome

Other causes of motor disorders are Wilson's disease (WD), inherited ataxias (Friedreich's ataxia, Machado-Joseph disease, and spinocerebellar ataxias), and encephalopathies.

Causes and symptoms

Causes

Movement is produced and coordinated by several interacting brain centers, including the motor cortex, the cerebellum, and a group of structures in the inner potions of the brain called the basal ganglia. Sensory information provides critical input on the current position and velocity of body parts, and spinal nerve cells (neurons ) help prevent opposing muscle groups from contracting simultaneously.

To understand how movement disorders occur, it is helpful to consider a normal volunteer movements, such as reaching to touch a nearby object with the right index finger. To accomplish the desired movement, the arm must be lifted and extended. The hand must be held out to align with the forearm, and the forefinger must be extended while the other fingers remain flexed.

THE MOTOR CORTEX. Voluntary motor commands begin in the motor cortex located on the outer, wrinkled surface of the brain. Movement of the right arm is begun by the left motor cortex, which generates a large volley of signals to the involved muscles. These electrical signals pass along upper motor neurons, through the midbrain, to the spinal cord (SC). Within the SC, these signals connect to lower motor neurons, which convey the signals from the SC to the surface of the muscles involved. Neural activation of the muscles causes contraction, and the force of contraction pulling on the skeleton causes movement of the arm, hand, and fingers.

Damage to, or death of any of the neurons along this path, can cause weakness or paralysis of the affected muscles.

THE CEREBELLUM. Once the movement of the arm is initiated, sensory information is needed to guide the finger to its precise destination. In addition to sight, the most important source of information comes from the "position sense," provided by the many sensory receptors located within the limbs (proprioception). Proprioception allows a person to touch his or her nose with a finger even with the eyes closed. The balance organs in the ears provide important information about posture. Both postural and proprioceptive information are processed by a structure at the rear of the brain, called the cerebellum. The cerebellum sends out electrical signals to modify movements as they progress, "sculpting" the barrage of voluntary commands into a tightly controlled, constantly evolving pattern. Cerebellar disorders cause inability to control the force, fine positioning, and speed of movements (ataxia). Disorders of the cerebellum may also impair the ability to judge distance, so that a person under- or overreaches the target (dysmetria). Tremor during voluntary movements can also result from cerebellar damage.

THE BASAL GANGLIA. Both the cerebellum and the motor cortex send information to a set of structures deep within the brain that helps control involuntary components of movement (basal ganglia). The basal ganglia send output messages to the motor cortex, helping to initiate movements, regulate repetitive or patterned movements, and control muscle tone.

Circuits within the basal ganglia are complex. Within this structure, some groups of cells begin the action of other basal ganglia components, and some groups of cells block the action. These complicated feedback circuits are not entirely understood. Disruptions of these circuits are known to cause several distinct movement disorders. A portion of the basal ganglia, called the substantia nigra, sends electrical signals that block output from another structure, the subthalamic nucleus. The subthalamic nucleus sends signals to the globus pallidus, which in turn blocks the thalamic nuclei. Finally, the thalamic nuclei send signals to the motor cortex. The substantia nigra, then begins movement, and the globus pallidus blocks it.

This complicated circuit can be disrupted at several points. Loss of substantia nigra, cells increases blocking of the thalamic nuclei and prevents them from sending signals to the motor cortex. Degeneration of these nerve cells, as in PD, results in lower production of dopamine and fewer connections with other nerve cells and muscles, leading to a loss of movement (motor activity).

In contrast, cell loss in early HD decreases the blocking of signals from the thalamic nuclei, causing more cortex stimulation and stronger, but uncontrolled, movements.

Disruptions in other portions of the basal ganglia are thought to cause tics, tremors, dystonia, and a variety of other movement disorders, although the exact mechanisms are not well understood.

Some movement disorders, including HD, are caused by inherited genetic defects and inherited ataxias. Some diseases that cause sustained muscle contraction limited to a particular muscle group (focal dystonia) are inherited, but others are caused by trauma. The cause of most cases of PD is unknown, although genes have been identified for some familial forms.

ANTAGONISTIC MUSCLE PAIRS. This picture of movement, however, is too simple. One important refinement to it comes from considering the role of opposing, or antagonistic, muscle pairs. Contraction of the bicep muscle, located on the top of the upper arm, pulls on the forearm to flex the elbow and bend the arm. Contraction of the triceps, located on the opposite side, extends the elbow and straightens the arm. Within the spine, these muscles are normally wired so that willed (voluntary) contraction of one is automatically accompanied by blocking of the other. In other words, the command to contract the biceps provokes another command within the spine to prevent contraction of the triceps. In this way, these antagonist muscles are kept from resisting one another. Spinal cord or brain injury, can damage this control system and cause involuntary simultaneous contraction and spasticity, an increase in resistance to movement during motion.

While the peripheral mechanism, antagonistic muscle pairs, is certainly important, it is not the only one of concern with regard to movement disorders. Central pattern generators (CPGs) in the spinal cord are especially relevant because of their role in sensory processing. Filtration and processing of sensory input is accomplished locally, where the response of spinal pattern generator circuitry fits into continual movement, as necessary. Thus, although the brain receives much of the sensory input, the responses to spinal inputs are first the responsibility of the local spinal circuitry. Multi-segmental reflexes and anticipatory postural adjustments are as critical in the etiology of these syndromes.

Common conditions causing motor disorders

SPINAL CORD INJURY (SCI). Spinal cord injury (SCI) is very complex and can be very serious. An injury can affect the body in a multitude of ways depending on where the spinal cord (SC) is damaged. It is the largest nerve in the body and is composed of nerve fibers. These nerve fibers that manage the body's communication systems are responsible for its motor, sensory, and autonomic functions. They act as messenger between the brain and the rest of the body. The vertebral column—protective bone segments—surrounds the SC, perhaps because of its important in the nervous system. Approximately 18 inches (39 cm) long, the SC runs from the base of the brain, down the middle of the back, to the waist. Nerve fibers in the upper SC are upper motor neurons (UMNs). Spinal nerves branching off the SC that run up and down the neck and back are lower motor neurons (LMNs), and branch off between each vertebrae and go out to all parts of the body. The lower spinal nerve fibers continue down through the spinal canal to the sacram (tailbone) at the end of the SC.

Divided into four sections at the top of the spinal column is the cervical spine. It is composed of eight cervical nerves and seven cervical vertebrae. Further down is the thoracic sine, which includes the chest and twelve thoracic vertebrae. The lumbar spine is below that, and comprises five lumbar vertebrae. The bottom section is the sacral area, and there the bones fuse together into one bone.

When the SC is damaged by either a traumatic injury or from a disease, all nerves above the injury level still function normally. Those from the point of injury and below, however, are damaged, and messages between the brain and parts of the body that could once be sent are no longer are no longer possible. The patient must undergo physical examination by the doctor to earn the exact location of injury to the spinal cord. Frequently, the physician will use a "pin-prick" test," which evaluates the patient's level of feeling (sensory level). X rays are also frequently used to image the affected vertebrae. The patient's input is critical; he or she will be asked what parts of the body can be moved, and all major muscle groups will be tested (motor level) for strength. All of these tests are important, as they reveal what nerves and muscles are functioning. Each SCI is unique, and is defined by its type and level. Its level will be judged by the lowest level on the SC after which there is absence of feeling and/or movement (motor level).

Loss of feeling and/or movement in the head, neck, shoulder, arms, and/or upper chest is termed "tetraplegia," and is injury at level C1 to T1. The cervical spine is the highest part of the spinal cord and is designated by the letter "C." The thoracic spine is next to the highest, and is designated by the letter "T." T2 to S5 is paraplegia. The higher on the vertebral column , the closer the SCI is to the brain. Therefore, someone with a T-8 (thoracic spine; eight of 12 thoracic vertebrae) level injury would have more feeling and movement than someone with a C-5 (cervical spine; five of seven cervical vertebrae) level of injury.

STROKE. During a stroke, brain tissue is destroyed. This is cause by some malfunction of the brain's blood vessels . There are two major classifications of stroke: hemorrhagic and ischemic. The most common type of stroke is ischemic, caused by the same kind of vascular disease as heart attack. By "ischemic" it is meant that the blood flow to an area is insufficient; there is not enough oxygen to support the cells. The brain cells will cease to function if blood circulation is not restored quickly enough after a stroke. Cell death by lack of oxygen is termed "infarction." To be more specific, physicians often refer to this type of infarction as "cerebral." As of 2001, stroke is the third leading cause of disability and the fifth leading cause of death in the United States. Annually, 500,000 people suffer strokes; 150,000 die of them.

A hemorrhagic stroke happens with the rupture of a blood vessel. Bleeding occurs inside the skull . Usually, the cause is hypertension , or high blood pressure—but it can also be caused by trauma. An aneurysm (a sac formed by localized dilatation of the wall of an artery, a vein or the heart) may also cause a hemorrhagic stroke. Whatever the origin of the stroke, bleeding can rip through the tender connections within the brain, and ultimately compress brain cells until they die.

The extent of damage due to stroke depends on the severity of the stroke and where in the brain the blood supply was suspended. Each area of the brain is served by specific blood vessels; if a blood vessel in the area that controls muscle movements became blocked, those muscles will be weak, or paralyzed. The loss of function is greatest immediately after a stroke, but some usually some function is regained. Some brain cells do die, while some injured cells may recover. Bleeding on the brain, such as from a head injury or brain aneurysm, can also cause brain cell death from lack of oxygen. Symptoms may resemble those of a stroke. The best prevention for a stroke is for the patient to discuss risk factors with a physician.

MULTIPLE SCLEROSIS (MS). Multiple sclerosis (MS) is a demyelinating disease that is related to the inflammatory process. One feature of MS is multiple, separate, and harmful neurologic episodes caused by central nervous system (CNS) lesions. The result is multiple, clearly defined areas (plaque) of myelin (the protective sheath around nerves) in the brain's white matter SC known as perivenous distribution (i.e., not in the peripheral nervous system).

MS occurs early in the inflammatory phase, and disrupts the messages that are being transmitted within the body. The disease is called MS because the scar tissue (sclerosis) forms at various locations. Some of the diseased areas of the myelin may cause no obvious symptoms, while other areas may interfere with functions or sensations controlled by the brain or SC. For this reason, the symptoms and the severity of the disability varies greatly among persons with MS.

The cause of MS remains unknown, but many think that it may be an autoimmune disease. Normally, the immune system works by recognizing foreign invaders and producing its own cells to counteract or defend against attacks. In MS, the immune system is disrupted as the body incorrectly identifies itself as an invader and begins to attack its own cells. The body no longer recognizes myelin as its own and declares war on this nerve tissue. Further, linkage studies have noted significant genetic factors. A common first symptom is visual impairment, due to optic neuritis (inflammation of the optic nerve).

MUSCULAR DYSTOPHY (MD). The name "muscular dystrophy" (MD) encompasses a number of progressive hereditary diseases that makes muscles weaken and degenerate. Not a contagious disease, there are a multitude of variations. Each type has its own pattern of heredity, onset age, and speed with which muscle is lost. Alterations in specific genes causes different types of disease. There was no prevention or cure for MD as of 2001. However, because of research being done at this time, there is reason for hope for a cure.

HUNTINGTON'S CHOREA (HC). A genetically inherited disease, Huntington's chorea (HC) has neurological and psychotic characteristics. The forties or fifties are the usual ages of onset, but early and late onset are also possible. Either neurological or psychotic changes can mark the beginning of the disease. Symptoms of neurological changes may vary, but can begin with chorea—a series of movements that resemble dancing, with jerkiness and one part of the body moving to another. One might display clumsiness, jumpiness, and become fidgety. There may be movement in the face, particularly around the jaw, and walking may become difficult. It may be difficult to maintain posture. Paranoia, personality changes, and confusion may present, as well. It is also possible for dementia to occur.

Diagnosis of HC is dependent upon clinical symtomatology and MRI (magnetic brain imaging), as well as discovering family history of the disease. An MRI that reveals atrophy (shrinkage) of part of the basal ganglia, which is involved in movement and known as the caudate nucleus, is characteristic of HC.

CEREBRAL PALSY. In cerebral palsy (CP), abnormal development of or damage to motor areas in the brain disrupts the brain's ability to control movement and posture. The term CP is a term used to describe a group of chronic disorders impairing control of movement that appear in the first few years of life and generally do not worsen over time. Symptoms differ from person to person, and may change over time. Individuals with the disease may have difficulty with fine motor tasks (e.g., writing), and balance or walking. They may have involuntary movements. Cerebral palsy, which may be congenital (present at birth) or acquired after birth, results from brain injury that does not worsen over time. Possible causes of CP include developmental abnormalities of the brain, brain injury caused by low oxygen levels (asphyxia) or poor circulation, infection , and trauma to the fetus or newborn. Doctors encourage pregnant women to follow a program of regular prenatal care beginning early in pregnancy to help prevent CP.

DYSTONIAS. Dystonias are sustained muscle contractions that often cause twisting or repetitive movements and abnormal postures. Dystonias may be limited to one area (focal) or may affect the entire body (general). Focal dystonias may affect the neck (cervical dystonia or torticollis), the face (one-sided, or hemifacial spasm), contraction of the eyelid (blepharospasm), contraction of the mouth and jaw (oromandibular dystonia), simultaneous spasm of the chin and eyelid (Meige syndrome), the vocal cords (laryngeal dystonia), or the arms and legs (writer's and occupational cramps). Dystonia may be painful and incapacitating.

TREMORS. Uncontrollable (involuntary) shaking of body parts are known as tremors. Tremors may occur only when muscles are relaxed, during actions, or when holding active postures.

MYASTHENIA GRAVIS (MG). Myasthenia gravis (MG), a chronic autoimmune disease, is characterized by fluctuating degrees of weakness of the skeletal, or voluntary muscles. Muscle weakness of increasing severity is the key symptom of this disorder; it worsens with activity, and improves after periods of rest. It does not always include muscles that control facial expression, such as muscles of the eyes, talking, chewing, and swallowing, but can affect the muscles involved with breathing, the neck, and limb movements. A defect in the transmission of nerve impulses to muscles is responsible for MG. The symptoms of MG range in type and degree. It is not directly genetic, and it is not infectious. It can be controlled through medications that improve neuromuscular transmission, thereby improving muscle strength, or through medications that suppress the manufacture by the body of abnormal antibodies. Because of unpleasant, major side effects, these drugs must be used with caution and monitored carefully. Myasthenia gravis is caused by an autoimmune response attack on acetylcholine (neurotransmitter) receptors at muscular junctions.

PARKINSON'S DISEASE (PD). The possibility of developing Parkinson's disease , or parkinsonism, increases with age, with age of onset usually not less than 40 years of age. Approximately 500,000 people in the United States suffer from the disease, which affects both sexes equally. The cause of its most common form, PD (as well as related disorders) is not known—though genetic risk has been identified as a probable factor by the National Institutes of Health. Interestingly, the disorder is observed at the same rate in almost part of the globe, and is as common today as it was in late 1800s.

The two terms, Parkinson's disease (PD) and parkinsonism, are used interchangeably, as they both describe patients with the same symptoms. The four primary symptoms of PD are tremor or trembling, rigidity or stiffness of the limbs and trunk, bradykinesia (slowness of movement), and impaired balance and coordination.

There are a number of causes of parkinsonism, including degenerative neurologic disease, metabolic conditions, toxins, drugs, viral encephalitis (von Economo's disease), and related disorders result from the loss of dopamine, a chemical messenger responsible for transmitting signals within the brain. When certain nerve cells (neurons) that produce dopamine die or become impaired, dopamine is depleted. The result is nerve cells that fire out of control. Individuals with PD are then unable to direct or control their movements in a normal manner. The disease, which is usually not inherited, is both chronic and progressive, with subtle early symptoms and gradual progression.

Management of a movement disorder begins with determining its cause. Physical and occupational therapy may help to compensate for lost control and strength. Pharmacologic therapy can help to compensate for some imbalances of the basal ganglionic circuit. For instance, levodopa (L-dopa), or related compounds, can substitute for the loss of dopamine-producing cells in PD. Conversely, blocking normal dopamine action may be used to treat some hyperkinetic disorders, including tics. Oral medications can also help to reduce overall muscle tone. Local injections of botulinum toxin (BOTOX) can selectively weaken overactive muscles in dystonia and spasticity. Destruction of peripheral nerves through injection of phenol can reduce spasticity. It should be noted, however, that all of these treatments have some side effects.

Other movement disorders

Tic disorders are very quick, involuntary, rapid, non-rhythmic, and short-lived movements or sounds; tics can sometimes be controlled briefly. Tics are usually repeated movements. They commonly involve the motor systems and often involve the facial muscles, such as the eyelids or eyebrows. The most well-known tic disorder is Tourette syndrome. Tourette syndrome (TS) is an abnormal condition that causes uncontrollable facial grimaces and tics, and arm and shoulder movements. Tourette syndrome is best known, perhaps, for uncontrollable vocal tics that include grunts, shouts, and use of obscene language (coprolalia). It is also known as Gilles de la Tourette syndrome. Tics are more common among males than females. As with Tourette syndrome, tics may be associated with head injury, stroke, carbon monoxide poisoning , and mental retardation.

Myoclonus is a sudden, shock-like muscle contraction. Myoclonic jerks may occur singly or repetitively. Unlike tics, myoclonus cannot be controlled even briefly.

Postural instability is the loss of ability to maintain upright posture, caused by slow or absent righting reflexes (those that help to maintain balance).

Spasticity is a condition in which certain muscles are continuously contracted, causing stiffness or tightness of the muscles.

Flaccid paralysis is the loss of muscle tone of the paralyzed part and an accompanying absence of reflexes.

Diagnosis

A complete and thorough clinical examination should be performed. Diagnosis of movement disorders requires a careful medical history and a thorough physical and neurological examination. A thorough orthopedic exam may be important because patients with increased muscle tone may develop curvature of the spine (scoliosis ), hip dislocation, and tendon shortening. During the neurologic exam, the doctor will observe the individual's posture, tone, symmetry, and reflexes.

Certain symptoms may indicate a movement disorder disease. Doctors will pay special attention to the rate of development of children with CP, particularly with

KEY TERMS

Botulinum toxin (botox) —Any of a group of potent bacterial toxins or poisons produced by different strains of the bacterium Clostridium botulinum. The toxins cause muscle paralysis, and thus force the relaxation of a muscle in spasm.

Cerebral palsy (CJP) —A movement disorder caused by a permanent brain defect or an injury present at birth, or shortly after. It is frequently associated with premature birth. Cerebral palsy is not progressive.

Computed tomography (CT) —An imaging technique in which cross-sectional x rays of the body are compiled to create a three-dimensional image of the body's internal structures.

Encephalopathy —An abnormality in the structure or function of tissues of the brain.

Fetal tissue transplantation (FTT) —A method of treating PD and other neurological diseases by grafting brain cells from human fetuses onto the basal ganglia. Human adults cannot grow new brain cells, but developing fetuses can. Grafting fetal tissue stimulates the growth of new brain cells in affected adult brains.

Huntington's chorea (HC) disease (HD) —A rare, genetically inherited condition with both neurological and psychiatric manifestations that begins with either type of change. The chorea is progressive, and presents as jerky muscle movements and mental deterioration that ends in dementia. The symptoms of HC usually appear in patients in their 40s or 50s; however, early- or late-onset is possible. Huntington's chorea may also cause clumsiness, jumpiness, and fidgetiness, and facial movements—particularly around the jaw—may occur. It may become difficult to walk, and can affect posture. Paranoia, confusion, or personality changes may noted. A significant dementia develops as the disease progresses. There is no cure or effective treatment for the condition.

Levodopa (L-dopa) —A substance used in the treatment of PD. Levodopa can cross the blood-brain barrier that protects the brain. Once in the brain, it is converted to dopamine, and thus can replace the dopamine lost in PD.

Magnetic resonance imaging (MRI) —An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.

Paraplegia —Paralysis of the lower half of the body involving both legs and usually due to disease or injury to the spinal cord.

Parkinson's disease (PD) —A slowly progressive disease that destroys nerve cells in the basal ganglia and thus causes loss of dopamine, a chemical that aids in transmission of nerve signals (neurotransmitter). Parkinsonism is characterized by shaking in resting muscles, a stooping posture, slurred speech, muscular stiffness, and weakness.

Positron emission tomography (PET) —A diagnostic technique in which computer-assisted x rays are used to track a radioactive substance inside a patient's body. Biochemical activity of the brain can be studied using PET.

Progressive supranuclear palsy —A rare disease that shows some of the same features of PD, but differs in several ways. They usually do not develop tremors, but they have rigidity, bradykniesia (slow movements), and falls. The disorder gradually destroys nerve cells in the parts of the brain that control eye movements, breathing, and muscle coordination. The loss of nerve cells causes palsy (paralysis) that slowly gets worse as the disease progresses. The palsy affects the ability to move the eyes vertically (up and down) at first. Their eye movements then become even more restrictive (ophthalmoplegia). The ability to relax the muscles is lost, as is control over balance.

Tourette syndrome (TS) —An abnormal condition that causes uncontrollable facial grimaces and tics, and arm and shoulder movements. Tourette syndrome is best known, perhaps, for uncontrollable vocal tics that include grunts, shouts, and use of obscene language (coprolalia). Also known as Gilles de la Tourette syndrome.

Wilson's disease (WD) —An inborn defect of copper metabolism in which free copper may be deposited in a variety of areas of the body. Deposits in the brain can cause tremor and other symptoms of PD.

regard to head size and head growth, since abnormalities in these areas may point to a brain problem. Eye problems, such as blurred or double vision , red-green color distortion, or blindness in one eye, may occur. When combined with muscle weakness in extremities and paresthesias (transitory abnormal sensory feeling such as numbness or prickling), MS may be suspected.

Diagnostic tests should be conducted. These include brain imaging studies, such as computed tomography (CT) scan, positron emission tomography (PET ), or magnetic resonance imaging (MRI) scans. Routine blood and urine analyses are performed. A lumbar puncture (spinal tap) may be necessary. Video recording of the abnormal movement is often used to analyze movement patterns and to track progress of the disorder and its management. Genetic testing is available for some forms of movement disorders. If MS is suspected, physicians may study the patient's cerebrospinal fluid and the antibody, immunoglobulin G.

Treatment

Ongoing clinical studies indicate that estrogen may have beneficial effects on controlling movement disorders, such as PD, chorea, dystonia, tics, and myoclonus.

Deep brain stimulation, which inactivates the thalamus or globus pallidus through electrical shocks, may be useful to ease tremor of the arm in individuals with ET and tremor due to MS. In PD, the procedure may improve arm speed and dexterity, reduce tremor, and block the involuntary movements (dyskinesia) associated with the medications used to treat the disease.

Surgical destruction, or inactivation of basal ganglionic circuits, has proven effective for PD, and as of 2001 is being tested for other movement disorders. Transplantation of fetal cells into the basal ganglia has produced mixed results in PD.

Health care team roles

Nursing and allied health professionals play a key role in educating individuals with movement disorders about their conditions and appropriate treatment options. Physical, speech, and occupational therapy are often essential to the rehabilitation of individuals with movement disorders. Psychological counseling may be helpful to the individual and to family members and close friends.

The patient who has had a stroke may be treated by doctors, therapists, and nurses who work to keep the patient's muscles strong, prevent muscular contractions, avoid the bedsores that can result from being in one position for too long, and teach the patient to walk and talk again. With SCI, expert nursing care is important to prevent complications from weakness and paralysis, including bedsores. Physical and occupational therapy help to preserve muscle function and teach techniques to help the patient function despite lost functionality.

Prognosis

The prognosis for a patient with a movement disorder depends on the nature of the disorder. The age of onset has major implications in prognosis.

Prevention

Prevention depends on the specific disorder. With some diseases, certain preventive strategies can be particularly helpful. In the case of MS and stroke, for example, smoking cessation would drastically reduce the number of cases. Longtime smokers may face a much higher risk of both MS and stroke, according to researchers at Harvard University. In the case of MS, women who smoked at least one pack per day for at least 25 years had a greater chance of developing the disorder than nonsmokers.

A number of permanent cases of parkinsonism that presented in the early 1980s were caused by a contaminant found in some illicit street drugs. For the most part, cases of the disease induced by legal, prescribed drugs were only temporary: when the drug was stopped, the symptoms stopped, too. Permanent parkinsonism had only been the result of the contaminant found in the street drug.

In 1996, clinicians at the University of Hawaii found that patients with high blood levels of uric acid, a natural antioxidant, have a lower chance of developing Parkinsonism and gout (acute inflammatory arthritis) than people with lower levels. The study concluded that people with high levels of the antioxidant, uric acid, may be more resistant to developing parkinsonism. This was also shown in a pilot student in 1991, when investigator Stanley Fahn of Columbia University found that parkinsonism patients who were administered large doses of oral vitamin C and synthetic vitamin E supplements (3000 mg and 3200 iu daily, respectively) delayed the progression of the disease. He concluded that it was likely that it was the vitamin C alone, or in combination with vitamin E that actively worked.

• Parkinsonism (PD). Deprenyl (selegiline), administered early in the onset of the disorder, can slow progression of the disease. Antioxidants such as vitamin E and selenium may be of some benefit, as well.
• Spinal cord injury (SCI). Attention to following safety precautions may help to reduce the risk of SCI. The most frequent causes of SCI are motor vehicle crashes, falls , violence, and sports and recreation, especially diving. Proper protective equipment should be used if an injury is possible, and appropriate safety measures should be practiced. Depth of water should be checked and obstructions should be noted before diving. When in an automobile, seat belts should always be used.
• Stroke. Major risk factors include high blood pressure , high cholesterol level, smoking, and diabetes. Drugs, such as aspirin (half of an adult tablet or one children's tablet daily), can be taken to reduce the tendency of blood platelets (responsible for the clotting of blood) to form dangerous blood clots, a major cause of stroke. When stronger drugs are needed, a doctor may prescribe anticoagulants, such as heparin or warfarin (Coumadin). Research in the year 2001 suggests that paralysis and other symptoms may be prevented or reversed if certain drugs that break up clots are given within three hours of the onset of a stroke.

Resources

BOOKS

Adler, Charles H. and J. Eric Ahlskog, eds. Parkinson's Disease and Movement Disorders: Diagnosis and Treatment Guidelines for the Practicing Physician. Totowa, N.J.: Humana Press, 2000.

Cicala MD, Roger S. Brain Disorders Sourcebook. Lincolnwood, IL: Lowell House; NTC/Contemporary Publishing Group, Inc., 1999.

Floyd, R.T. and Clem W. Thompton. Manual of Structural Kinesiology. Dubuque, IA: McGraw-Hill, 2001.

Jankovic, Joseph and Eduardo Tolosa, ed. Parkinson's Disease and Movement Disorders. Baltimore: Williams & Wilkins, 1998.

Sawle, Guy, ed. Movement Disorders in Clinical Practice. Oxford: Isis Medical Media, 1999.

Vander, Arthur, James Sherman, and Dorothy Luciano. Human Physiology: The Mechanisms of Body Function. Boston: McGraw-Hill, 2001.

ORGANIZATIONS

American Association of Neuroscience Nurses, 4700 W. Lake Avenue, Glenview, IL 60025. (888) 557-2266. <http://www.aann.org>.

American Spinal Injury Association. 345 E. Superior Street, Chicago, IL 60611. (312)238-1242. <http:/www.asiaspinalinjury.org>.

Muscular Dystophy Association, 3300 East Sunrise Drive, Tucson, AZ 85718-3208, (520) 529-2000 or (800) 572-1717. <http://www.mdausa.org/>.

Myasthenia Gravis Foundation of America, Inc., 5841 Cedar Lake Road, Suite 204, Minneapolis, MN 55416, (952) 545-9438 or (800)541-5454. <http://www.myasthenia.org>.

National Institute of Neurological Disorders and Stroke. P.O. Box 5801, Bethesda, MD 20824, (800) 352-9424. <http://www.ninds.nih.gov>.

National Spinal Cord Injury Association, The Zalco Building, 8701 Georgia Avenue, Suite 500, 8701 Georgia Avenue, Silver Springs, MD 20910, (800) 962-9629 or (301) 588-6959. <http://www.spinalcord.org>.

National Spinal Cord Injury Statistical Center, UAB-Spain Rehabilitation Center, Rm 544, 619 19th Street South, SRC 544, Birmingham, AL 35249-7330, (205) 934-5359.

Paralyzed Veterans of America. 801 18th Street NW, Washington, DC 20006, (800) 424-8288 or infor@pva.org, <http://www.pva.org>.

The Movement Disorder Society. 611 East Wells Street, Milwaukee, WI 53202, (414) 276-2145. <http://www.movementdisorders.org>.

WE MOVE. 204 West 84th Street, New York, NY 10024. (800) 437-MOV2 or (212) 875-8389. <http://www.wemove.org>.

OTHER

"Smoking Risk Factor for Multiple Sclerosis: Study." National Library of Medicine. National Institutes of Health. Medline Plus. <http://www.nlm.nih.gov/medlineplus/news/fullstory_2440.html>.

"Spinal Cord Injury Information Network: Understanding Spinal Cord Injury and Functional Goals." University of Alabama at Birmingham. <http://www.spinalcord.uab.edu>.

Randi B. Jenkins

Movement Disorders

Definition

Movement disorders are a group of neurological diseases and syndromes that involve the motor and movement systems' ability to produce and control movement.

Description

Though it seems simple and effortless, normal movement actually requires an astonishingly complex system of control. Disruption of any portion of this system can cause a person to produce movements that are too weak, too forceful, too uncoordinated, or too poorly controlled for the task at hand. Unwanted movements may occur at rest. Intentional movement may become impossible. These conditions are examples of movement disorders.

Abnormal movements themselves are symptoms of underlying disorders. In some cases, the abnormal movements are the only symptoms. The more common diseases causing motor disorders include:

• spinal cord injury (SCI)
• stroke
• multiple sclerosis (MS)
• muscular dystrophy (MD)
• huntington's chorea (HC)
• cerebral palsy (CP)
• dystonias
• tremor
• myasthenia gravis (MG)
• parkinsonism (PD)
• Tourette syndrome

Other causes of motor disorders are Wilson's disease (WD), inherited ataxias (Friedreich's ataxia), Machado-Joseph disease, and spinocerebellar ataxias), and encephalopathies.

Causes and symptoms

Causes

Movement is produced and coordinated by several interacting brain centers, including the motor cortex, the cerebellum, and a group of structures in the inner potions of the brain called the basal ganglia. Sensory information provides critical input on the current position and velocity of body parts, and spinal nerve cells (neurons ) help prevent opposing muscle groups from contracting simultaneously.

To understand how movement disorders occur, it is helpful to consider a normal volunteer movements, such as reaching to touch a nearby object with the right index finger. To accomplish the desired movement, the arm must be lifted and extended. The hand must be held out to align with the forearm, and the forefinger must be extended while the other fingers remain flexed.

THE MOTOR CORTEX. Voluntary motor commands begin in the motor cortex located on the outer, wrinkled surface of the brain. Movement of the right arm is begun by the left motor cortex, which generates a large volley of signals to the involved muscles. These electrical signals pass along upper motor neurons, through the midbrain, to the spinal cord (SC). Within the SC, these signals connect to lower motor neurons, which convey the signals from the SC to the surface of the muscles involved. Neural activation of the muscles causes contraction, and the force of contraction pulling on the skeleton causes movement of the arm, hand, and fingers.

Damage to, or death of any of the neurons along this path, can cause weakness or paralysis of the affected muscles.

THE CEREBELLUM. Once the movement of the arm is initiated, sensory information is needed to guide the finger to its precise destination. In addition to sight, the most important source of information comes from the "position sense," provided by the many sensory receptors located within the limbs (proprioception). Proprioception allows a person to touch his or her nose with a finger even with the eyes closed. The balance organs in the ears provide important information about posture. Both postural and proprioceptive information are processed by a structure at the rear of the brain, called the cerebellum. The cerebellum sends out electrical signals to modify movements as they progress, "sculpting" the barrage of voluntary commands into a tightly controlled, constantly evolving pattern. Cerebellar disorders cause inability to control the force, fine positioning, and speed of movements (ataxia). Disorders of the cerebellum may also impair the ability to judge distance, so that a person underor overreaches the target (dysmetria). Tremor during voluntary movements can also result from cerebellar damage.

THE BASAL GANGLIA. Both the cerebellum and the motor cortex send information to a set of structures deep within the brain that helps control involuntary components of movement (basal ganglia). The basal ganglia send output messages to the motor cortex, helping to initiate movements, regulate repetitive or patterned movements, and control muscle tone.

Circuits within the basal ganglia are complex. Within this structure, some groups of cells begin the action of other basal ganglia components, and some groups of cells block the action. These complicated feedback circuits are not entirely understood. Disruptions of these circuits are known to cause several distinct movement disorders. A portion of the basal ganglia, called the substantia nigra, sends electrical signals that block output from another structure, the subthalamic nucleus. The subthalamic nucleus sends signals to the globus pallidus, which in turn blocks the thalamic nuclei. Finally, the thalamic nuclei send signals to the motor cortex. The substantia nigra, then begins movement, and the globus pallidus blocks it.

This complicated circuit can be disrupted at several points. Loss of substantia nigra, cells increases blocking of the thalamic nuclei and prevents them from sending signals to the motor cortex. Degeneration of these nerve cells, as in PD, results in lower production of dopamine and fewer connections with other nerve cells and muscles, leading to a loss of movement (motor activity).

In contrast, cell loss in early HD decreases the blocking of signals from the thalamic nuclei, causing more cortex stimulation and stronger, but uncontrolled, movements.

Disruptions in other portions of the basal ganglia are thought to cause tics, tremors, dystonia, and a variety of other movement disorders, although the exact mechanisms are not well understood.

Some movement disorders, including HD, are caused by inherited genetic defects and inherited ataxias. Some diseases that cause sustained muscle contraction limited to a particular muscle group (focal dystonia) are inherited, but others are caused by trauma. The cause of most cases of PD is unknown, although genes have been identified for some familial forms.

ANTAGONISTIC MUSCLE PAIRS. This picture of movement, however, is too simple. One important refinement to it comes from considering the role of opposing, or antagonistic, muscle pairs. Contraction of the bicep muscle, located on the top of the upper arm, pulls on the forearm to flex the elbow and bend the arm. Contraction of the triceps, located on the opposite side, extends the elbow and straightens the arm. Within the spine, these muscles are normally wired so that willed (voluntary) contraction of one is automatically accompanied by blocking of the other. In other words, the command to contract the biceps provokes another command within the spine to prevent contraction of the triceps. In this way, these antagonist muscles are kept from resisting one another. Spinal cord or brain injury, can damage this control system and cause involuntary simultaneous contraction and spasticity, an increase in resistance to movement during motion.

While the peripheral mechanism, antagonistic muscle pairs, is certainly important, it is not the only one of concern with regard to movement disorders. Central pattern generators (CPGs) in the spinal cord are especially relevant because of their role in sensory processing. Filtration and processing of sensory input is accomplished locally, where the response of spinal pattern generator circuitry fits into continual movement, as necessary. Thus, although the brain receives much of the sensory input, the responses to spinal inputs are first the responsibility of the local spinal circuitry. Multi-segmental reflexes and anticipatory postural adjustments are as critical in the etiology of these syndromes.

Common conditions causing motor disorders

SPINAL CORD INJURY (SCI). Spinal cord injury (SCI) is very complex and can be very serious. An injury can affect the body in a multitude of ways depending on where the spinal cord (SC) is damaged. It is the largest nerve in the body and is composed of nerve fibers. These nerve fibers that manage the body's communication systems are responsible for its motor, sensory, and autonomic functions. They act as messenger between the brain and the rest of the body. The vertebral column—protective bone segments—surrounds the SC, perhaps because of its important in the nervous system. Approximately 18 in (39 cm) long, the SC runs from the base of the brain, down the middle of the back, to the waist. Nerve fibers in the upper SC are upper motor neurons (UMNs). Spinal nerves branching off the SC that run up and down the neck and back are lower motor neurons (LMNs), and branch off between each vertebrae and go out to all part of the body. The lower spinal nerve fibers continue down through the spinal canal to the sacram (tailbone) at the end of the SC.

The spine is divided into four sections. At the top of the spinal column is the cervical spine. It is composed of eight cervical nerves and seven cervical vertebrae. Further down is the thoracic spine, which includes the chest and twelve thoracic vertebrae. The lumbar spine is below that, and comprises five lumbar vertebrae. The bottom section is the sacral area, and there the bones fuse together into one bone.

When the SC is damaged by either a traumatic injury or from a disease, all nerves above the injury level still function normally. Those from the point of injury and below, however, are damaged, and messages between the brain and parts of the body that could once be sent are no longer are no longer possible. The patient must undergo physical examination by the doctor to earn the exact location of injury to the spinal cord. Frequently, the physician will use a "pinprick" test," which evaluates the patient's level of feeling (sensory level). X rays are also frequently used to image the affected vertebrae. The patient's input is critical; he or she will be asked what parts of the body can be moved, and all major muscle groups will be tested (motor level) for strength. All of these tests are important, as they reveal what nerves and muscles are functioning. Each SCI is unique, and is defined by its type and level. Its level will be judged by the lowest level on the SC after which there is absence of feeling and/or movement (motor level).

Loss of feeling and/or movement in the head, neck, shoulder, arms, and/or upper chest is termed "tetraplegia," and is injury at level C1 to T1. The cervical spine is the highest part of the spinal cord and is designated by the letter "C." The thoracic spine is next to the highest, and is designated by the letter "T." T2 to S5 is paraplegia. The higher on the vertebral column, the closer the SCI is to the brain. Therefore, someone with a T-8 (thoracic spine; eight of 12 thoracic vertebrae) level injury would have more feeling and movement than someone with a C-5 (cervical spine; five of seven cervical vertebrae) level of injury.

STROKE. During a stroke, brain tissue is destroyed. This is cause by some malfunction of the brain's blood vessels. There are two major classifications of stroke: hemorrhagic and ischemic. The most common type of stroke is ischemic, caused by the same kind of vascular disease as heart attack. By "ischemic" it is meant that the blood flow to an area is insufficient; there is not enough oxygen to support the cells. The brain cells will cease to function if blood circulation is not restored quickly enough after a stroke. Cell death by lack of oxygen is termed "infarction." To be more specific, physicians often refer to this type of infarction as "cerebral." As of 2001, stroke is the third leading cause of disability and the fifth leading cause of death in the United States. Annually, 500,000 people suffer strokes; 150,000 die of them.

A hemorrhagic stroke happens with the rupture of a blood vessel. Bleeding occurs inside the skull. Usually, the cause is hypertension, or high blood pressure—but it can also be caused by trauma. An aneurysm (a sac formed by localized dilatation of the wall of an artery, a vein or the heart) may also cause a hemorrhagic stroke. Whatever the origin of the stroke, bleeding can rip through the tender connections within the brain, and ultimately compress brain cells until they die.

The extent of the damage due to stroke depends on the severity of the stroke and where in the brain the blood supply was suspended. Each area of the brain is served by specific blood vessels; if a blood vessel in the area that controls muscle movements became blocked, those muscles will be weak, or paralyzed. The loss of function is greatest immediately after a stroke, but some usually some function is regained. Some brain cells do die, while some injured cells may recover. Bleeding on the brain, such as from a head injury or brain aneurysm, can also cause brain cell death from lack of oxygen. Symptoms may resemble those of a stroke. The best prevention for a stroke is for the patient to discuss risk factors with a physician.

MULTIPLE SCLEROSIS (MS). Multiple sclerosis (MS) is a demyelinating disease that is related to the inflammatory process. One feature of MS is multiple, separate, and harmful neurologic episodes caused by central nervous system (CNS) lesions. The result is multiple, clearly defined areas (plaque) of myelin (the protective sheath around nerves) in the brain's white matter SC known as perivenous distribution (i.e., not in the peripheral nervous system).

MS occurs early in the inflammatory phase, and disrupts the messages that are being transmitted within the body. The disease is called MS because the scar tissue (sclerosis) forms at various locations. Some of the diseased areas of the myelin may cause no obvious symptoms, while other areas may interfere with functions or sensations controlled by the brain or SC. For this reason, the symptoms and the severity of the disability varies greatly among persons with MS.

The cause of MS remains unknown, but many think that it may be an autoimmune disease. Normally, the immune system works by recognizing foreign invaders and producing its own cells to counteract or defend against attacks. In MS, the immune system is disrupted as the body incorrectly identifies itself as an invader and begins to attack its own cells. The body no longer recognizes myelin as its own and declares war on this nerve tissue. Further, linkage studies have noted significant genetic factors. A common first symptom is visual impairment, due to optic neuritis (inflammation of the optic nerve).

MUSCULAR DYSTOPHY (MD). Muscular dystrophy (MD) encompasses a number of progressive hereditary diseases that makes muscles weaken and degenerate. Not a contagious disease, there are a multitude of variations. Each type has its own pattern of heredity, onset age, and speed with which muscle is lost. Alterations in specific genes causes different types of disease. There was no prevention or cure for MD as of 2006. However, because of research being done at this time, there is reason for hope for a cure.

HUNTINGTON'S CHOREA (HC). A genetically inherited disease, Huntington's chorea (HC) has neurological and psychotic characteristics. The forties or fifties are the usual ages of onset, but early and late onset are also possible. Either neurological or psychotic changes can mark the beginning of the disease. Symptoms of neurological changes may vary, but can begin with chorea—a series of movements that resemble dancing, with jerkiness and one part of the body moving to another. One might display clumsiness, jumpiness, and become fidgety. There may be movement in the face, particularly around the jaw, and walking may become difficult. It may be difficult to maintain posture. Paranoia, personality changes, and confusion may present, as well. It is also possible for dementia to occur.

Diagnosis of HC is dependent upon clinical symtomatology and MRI (magnetic brain imaging), as well as discovering family history of the disease. An MRI that reveals atrophy (shrinkage) of part of the basal ganglia, which is involved in movement and known as the caudate nucleus, is characteristic of HC.

CEREBRAL PALSY. In cerebral palsy (CP), abnormal development of or damage to motor areas in the brain disrupts the brain's ability to control movement and posture. The term CP is a term used to describe a group of chronic disorders impairing control of movement that appear in the first few years of life and generally do not worsen over time. Symptoms differ from person to person, and may change over time. Individuals with the disease may have difficulty with fine motor tasks (e.g., writing), and balance or walking. They may have involuntary movements. Cerebral palsy, which may be congenital (present at birth) or acquired after birth, results from brain injury that does not worsen over time. Possible causes of CP include developmental abnormalities of the brain, brain injury caused by low oxygen levels (asphyxia) or poor circulation, infection, and trauma to the fetus or newborn. Doctors encourage pregnant women to follow a program of regular prenatal care beginning early in pregnancy to help prevent CP.

DYSTONIAS. Dystonias are sustained muscle contractions that often cause twisting or repetitive movements and abnormal postures. Dystonias may be limited to one area (focal) or may affect the entire body (general). Focal dystonias may affect the neck (cervical dystonia or torticollis), the face (one-sided, or hemifacial spasm), contraction of the eyelid (blepharospasm), contraction of the mouth and jaw (oromandibular dystonia), simultaneous spasm of the chin and eyelid (Meige syndrome), the vocal cords (laryngeal dystonia), or the arms and legs (writer's and occupational cramps). Dystonia may be painful and incapacitating.

TREMORS. Uncontrollable (involuntary) shaking of body parts are known as tremors. Tremors may occur only when muscles are relaxed, during actions, or when holding active postures.

MYASTHENIA GRAVIS (MG). Myasthenia gravis (MG), a chronic autoimmune disease, is characterized by fluctuating degrees of weakness of the skeletal, or voluntary muscles. Muscle weakness of increasing severity is the key symptom of this disorder; it worsens with activity, and improves after periods of rest. It does not always include muscles that control facial expression, such as muscles of the eyes, talking, chewing, and swallowing, but can affect the muscles involved with breathing, the neck, and limb movements. A defect in the transmission of nerve impulses to muscles is responsible for MG. The symptoms of MG range in type and degree. It is not directly genetic, and it is not infectious. It can be controlled through medications that improve neuromuscular transmission, thereby improving muscle strength, or through medications that suppress the manufacture by the body of abnormal antibodies. Because of unpleasant, major side effects, these drugs must be used with caution and monitored carefully. Myasthenia gravis is caused by an autoimmune response attack on acetyl-choline (neurotransmitter) receptors at muscular junctions.

PARKINSON'S DISEASE (PD). The possibility of developing Parkinson's disease, or parkinsonism, increases with age, with age of onset usually not less than 40 years of age. Approximately 500,000 people in the United States suffer from the disease, which affects both sexes equally. The cause of its most common form, PD (as well as related disorders) is not known—though genetic risk has been identified as a probable factor by the National Institutes of Health. Interestingly, the disorder is observed at the same rate in almost part of the globe, and is as common today as it was in late 1800s.

The two terms, Parkinson's disease (PD) and parkinsonism, are used interchangeably, as they both describe patients with the same symptoms. The four primary symptoms of PD are tremor or trembling, rigidity or stiffness of the limbs and trunk, bradykinesia (slowness of movement), and impaired balance and coordination.

There are a number of causes of parkinsonism, including degenerative neurologic disease, metabolic conditions, toxins, drugs, viral encephalitis (von Economo's disease), and related disorders result from the loss of dopamine, a chemical messenger responsible for transmitting signals within the brain. When certain nerve cells (neurons) that produce dopamine die or become impaired, dopamine is depleted. The result is nerve cells that fire out of control. Individuals with PD are then unable to direct or control their movements in a normal manner. The disease, which is usually not inherited, is both chronic and progressive, with subtle early symptoms and gradual progression.

Management of a movement disorder begins with determining its cause. Physical and occupational therapy may help to compensate for lost control and strength. Pharmacologic therapy can help to compensate for some imbalances of the basal ganglionic circuit. For instance, levodopa (L-dopa), or related compounds, can substitute for the loss of dopamineproducing cells in PD. Conversely, blocking normal dopamine action may be used to treat some hyperkinetic disorders, including tics. Oral medications can also help to reduce overall muscle tone. Local injections of botulinum toxin (Botox) can selectively weaken overactive muscles in dystonia and spasticity. Destruction of peripheral nerves through injection of phenol can reduce spasticity. It should be noted, however, that all of these treatments have some side effects.

Other movement disorders

Tic disorders are very quick, involuntary, rapid, non-rhythmic, and short-lived movements or sounds; tics can sometimes be controlled briefly. Tics are usually repeated movements. They commonly involve the motor systems and often involve the facial muscles, such as the eyelids or eyebrows. The most well-known tic disorder is Tourette syndrome. Tourette syndrome (TS) is an abnormal condition that causes uncontrollable facial grimaces and tics, and arm and shoulder movements. Tourette syndrome is best known, perhaps, for uncontrollable vocal tics that include grunts, shouts, and use of obscene language (coprolalia). It is also known as Gilles de la Tourette syndrome. Tics are more common among males than females. As with Tourette syndrome, tics may be associated with head injury, stroke, carbon monoxide poisoning, and mental retardation.

Myoclonus is a sudden, shock-like muscle contraction. Myoclonic jerks may occur singly or repetitively. Unlike tics, myoclonus cannot be controlled even briefly.

Postural instability is the loss of ability to maintain upright posture, caused by slow or absent righting reflexes (those that help to maintain balance).

Spasticity is a condition in which certain muscles are continuously contracted, causing stiffness or tightness of the muscles.

Flaccid paralysis is the loss of muscle tone of the paralyzed part and an accompanying absence of reflexes.

Diagnosis

A complete and thorough clinical examination should be performed. Diagnosis of movement disorders requires a careful medical history and a thorough physical and neurological examination. A thorough orthopedic exam may be important because patients with increased muscle tone may develop curvature of the spine (scoliosis ), hip dislocation, and tendon shortening. During the neurologic exam, the doctor will observe the individual's posture, tone, symmetry, and reflexes.

Certain symptoms may indicate a movement disorder disease. Doctors will pay special attention to the rate of development of children with CP, particularly with regard to head size and head growth, since abnormalities in these areas may point to a brain problem. Eye problems, such as blurred or double vision, red-green color distortion, or blindness in one eye, may occur. When combined with muscle weakness in extremities and paresthesias (transitory abnormal sensory feeling such as numbness or prickling), MS may be suspected.

Diagnostic tests should be conducted. These include brain imaging studies, such as computed tomography (CT) scan, positron emission tomography (PET), or magnetic resonance imaging (MRI) scans. Routine blood and urine analyses are performed. A lumbar puncture (spinal tap) may be necessary. Video recording of the abnormal movement is often used to analyze movement patterns and to track progress of the disorder and its management. Genetic testing is available for some forms of movement disorders. If MS is suspected, physicians may study the patient's cerebrospinal fluid and the antibody, immunoglobulin G.

Treatment

Ongoing clinical studies indicate that estrogen may have beneficial effects on controlling movement disorders, such as PD, chorea, dystonia, tics, and myoclonus.

Deep brain stimulation, which inactivates the thalamus or globus pallidus through electrical shocks, may be useful to ease tremor of the arm in individuals with ET and tremor due to MS. In PD, the procedure may improve arm speed and dexterity, reduce tremor, and block the involuntary movements (dyskinesia) associated with the medications used to treat the disease.

Surgical destruction, or inactivation of basal ganglionic circuits, has proven effective for PD, and as of 2001 is being tested for other movement disorders. Transplantation of fetal cells into the basal ganglia has produced mixed results in PD.

Health care team roles

Nursing and allied health professionals play a key role in educating individuals with movement disorders about their conditions and appropriate treatment options. Physical, speech, and occupational therapy are often essential to the rehabilitation of individuals with movement disorders. Psychological counseling may be helpful to the individual and to family members and close friends.

The patient who has had a stroke may be treated by doctors, therapists, and nurses who work to keep the patient's muscles strong, prevent muscular contractions, avoid the bedsores that can result from being in one position for too long, and teach the patient to walk and talk again. With SCI, expert nursing care is important to prevent complications from weakness and paralysis, including bedsores. Physical and occupational therapy help to preserve muscle function and teach techniques to help the patient function despite lost functionality.

Prognosis

The prognosis for a patient with a movement disorder depends on the nature of the disorder. The age of onset has major implications in prognosis.

Prevention

Prevention depends on the specific disorder. With some diseases, certain preventive strategies can be particularly helpful. In the case of MS and stroke, for example, smoking cessation would drastically reduce the number of cases. Longtime smokers may face a much higher risk of both MS and stroke, according to researchers at Harvard University. In the case of MS, women who smoked at least one pack per day for at least 25 years had a greater chance of developing the disorder than nonsmokers.

A number of permanent cases of parkinsonism that presented in the early 1980s were caused by a contaminant found in some illicit street drugs. For the most part, cases of the disease induced by legal, prescribed drugs were only temporary: when the drug was stopped, the symptoms stopped, too. Permanent parkinsonism had only been the result of the contaminant found in the street drug.

In 1996, clinicians at the University of Hawaii found that patients with high blood levels of uric acid, a natural antioxidant, have a lower chance of developing parkinsonism and gout (acute inflammatory arthritis) than people with lower levels. The study concluded that people with high levels of the antioxidant, uric acid, may be more resistant to developing parkinsonism. This was also shown in a pilot student in 1991, when investigator Stanley Fahn of Columbia University found that parkinsonism patients who were administered large doses of oral vitamin C and synthetic vitamin E supplements (3000 mg and 3200 iu daily, respectively) delayed the progression of the disease. He concluded that it was likely that it was the vitamin C alone, or in combination with vitamin E that actively worked.

• Parkinsonism (PD). Deprenyl (selegiline), administered early in the onset of the disorder, can slow progression of the disease. Antioxidants such as vitamin E and selenium may be of some benefit, as well.
• Spinal cord injury (SCI). Attention to following safety precautions may help to reduce the risk of SCI. The most frequent causes of SCI are motor vehicle crashes, falls, violence, and sports and recreation, especially diving. Proper protective equipment should be used if an injury is possible, and appropriate safety measures should be practiced. Depth of water should be checked and obstructions should be noted before diving. When in an automobile, seat belts should always be used.
• Stroke. Major risk factors include high blood pressure, high cholesterol level, smoking, and diabetes. Drugs, such as aspirin (half of an adult tablet or one children's tablet daily), can be taken to reduce the tendency of blood platelets (responsible for the clotting of blood) to form dangerous blood clots, a major cause of stroke. When stronger drugs are needed, a doctor may prescribe anticoagulants, such as heparin or warfarin (Coumadin). Research in the year 2001 suggests that paralysis and other symptoms may be prevented or reversed if certain drugs that break up clots are given within three hours of the onset of a stroke.

KEY TERMS

Botulinum toxin (Botox)— Any of a group of potent bacterial toxins or poisons produced by different strains of the bacterium Clostridium botulinum. The toxins cause muscle paralysis, and thus force the relaxation of a muscle in spasm.

Cerebral palsy (CP)— A movement disorder caused by a permanent brain defect or an injury present at birth, or shortly after. It is frequently associated with premature birth. Cerebral palsy is not progressive.

Computed tomography (CT)— An imaging technique in which cross-sectional x rays of the body are compiled to create a three-dimensional image of the body's internal structures.

Encephalopathy— An abnormality in the structure or function of tissues of the brain.

Fetal tissue transplantation (FTT)— A method of treating PD and other neurological diseases by grafting brain cells from human fetuses onto the basal ganglia. Human adults cannot grow new brain cells, but developing fetuses can. Grafting fetal tissue stimulates the growth of new brain cells in affected adult brains.

Huntington's chorea (HC)/disease (HD)— A rare, genetically inherited condition with both neurological and psychiatric manifestations that begins with either type of change. The chorea is progressive, and presents as jerky muscle movements and mental deterioration that ends in dementia. The symptoms of HC usually appear in patients in their 40s or 50s; however, early- or late-onset is possible. Huntington's chorea may also cause clumsiness, jumpiness, and fidgetiness, and facial movements—particularly around the jaw—may occur. It may become difficult to walk and can affect posture. Paranoia, confusion, or personality changes may be noted. A significant dementia develops as the disease progresses. There is no cure or effective treatment for the condition.

Levodopa (L-dopa)— A substance used in the treatment of PD. Levodopa can cross the blood-brain barrier that protects the brain. Once in the brain, it is converted to dopamine, and thus can replace the dopamine lost in PD.

Magnetic resonance imaging (MRI)— An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.

Paraplegia— Paralysis of the lower half of the body involving both legs and usually due to disease or injury to the spinal cord.

Parkinson's disease (PD)— A slowly progressive disease that destroys nerve cells in the basal ganglia and thus causes loss of dopamine, a chemical that aids in transmission of nerve signals (neurotransmitter). Parkinsonism is characterized by shaking in resting muscles, a stooping posture, slurred speech, muscular stiffness, and weakness.

Positron emission tomography (PET)— A diagnostic technique in which computer-assisted x rays are used to track a radioactive substance inside a patient's body. Biochemical activity of the brain can be studied using PET.

Progressive supranuclear palsy— A rare disease that shows some of the same features of PD, but differs in several ways. They usually do not develop tremors, but they have rigidity, bradykinesia (slow movements), and falls. The disorder gradually destroys nerve cells in the parts of the brain that control eye movements, breathing, and muscle coordination. The loss of nerve cells causes palsy (paralysis) that slowly gets worse as the disease progresses. The palsy affects the ability to move the eyes vertically (up and down) at first. Their eye movements then become even more restrictive (ophthalmoplegia). The ability to relax the muscles is lost, as is control over balance.

Tourette syndrome (TS)— An abnormal condition that causes uncontrollable facial grimaces and tics, and arm and shoulder movements. Tourette syndrome is best known, perhaps, for uncontrollable vocal tics that include grunts, shouts, and use of obscene language (coprolalia). Also known as Gilles de la Tourette syndrome.

Wilson's disease (WD)— An inborn defect of copper metabolism in which free copper may be deposited in a variety of areas of the body. Deposits in the brain can cause tremor and other symptoms of PD.

Resources

BOOKS

Adler, Charles H. and J. Eric Ahlskog, eds. Parkinson's Disease and Movement Disorders: Diagnosis and Treatment Guidelines for the Practicing Physician. Totowa, N.J.: Humana Press, 2000.

Cicala, Roger S, MD. Brain Disorders Sourcebook. Lincolnwood, IL: Lowell House; NTC/Contemporary Publishing Group, Inc., 1999.

Floyd, R.T., and Clem W. Thompton. Manual of Structural Kinesiology. Dubuque, IA: McGraw-Hill, 2001.

Jankovic, Joseph, and Eduardo Tolosa, ed. Parkinson's Disease and Movement Disorders. Baltimore: Williams & Wilkins, 1998.

Sawle, Guy, ed. Movement Disorders in Clinical Practice. Oxford: Isis Medical Media, 1999.

Vander, Arthur, James Sherman, and Dorothy Luciano. Human Physiology: the Mechanisms of Body Function. Boston: McGraw-Hill, 2001.

PERIODICALS

Journal of Neuroscience Nursing. American Association of Neuroscience Nurses, 4700 W. Lake Avenue, Glenview, IL 60025. (888) 557-2266. 〈http://www.aann.org〉.

ORGANIZATIONS

American Spinal Injury Association. 345 E. Superior Street, Chicago, IL 60611. (312) 238-1242. 〈http:/www.asia-spinalinjury.org〉.

Muscular Dystrophy Association, 3300 East Sunrise Drive, Tucson, AZ 85718-3208, (520) 529-2000 or (800) 572-1717. 〈http://www.mdausa.org/〉.

Myasthenia Gravis Foundation of America, Inc., 5841 Cedar Lake Road, Suite 204, Minneapolis, MN 55416, (952) 545-9438 or (800)541-5454. 〈http://www.myasthenia.org〉.

National Institute of Neurological Disorders and Stroke. P.O. Box 5801, Bethesda, MD 20824, (800) 352-9424. 〈http://www.ninds.nih.gov〉.

National Spinal Cord Injury Association, The Zalco Building, 8701 Georgia Avenue, Suite 500, 8701 Georgia Avenue, Silver Springs, MD 20910, (800) 962-9629 or (301) 588-6959. 〈http://www.spinalcord.org〉.

National Spinal Cord Injury Statistical Center, UAB-Spain Rehabilitation Center, Rm 544, 619 19th Street South, SRC 544, Birmingham, AL 35249-7330, (205) 934-5359.

Paralyzed Veterans of America. 801 18th Street NW, Washington, DC 20006, (800) 424-8288 or infor@pva.org, 〈http://www.pva.org〉.

The Movement Disorder Society. 611 East Wells Street, Milwaukee, WI 53202, (414) 276-2145. 〈http://www.movementdisorders.org〉.

WE MOVE. 204 West 84th Street, New York, NY 10024. (800) 437-MOV2 or (212) 875-8389. 〈http://www.wemove.org〉.

OTHER

"Smoking Risk Factor for Multiple Sclerosis: Study." National Library of Medicine. National Institutes of Health. Medline Plus. 〈http://www.nlm.nih.gov/medlineplus/news/fullstory_2440.html〉.

"Spinal Cord Injury Information Network: Understanding Spinal Cord Injury and Functional Goals." University of Alabama at Birmingham. 〈http://www.spinalcord.uab.edu〉.

Movement Disorders

Definition

Movement disorders are a group of diseases and syndromes affecting the ability to produce and control movement.

Description

Though it seems simple and effortless, normal movement in fact requires an astonishingly complex system of control. Disruption of any portion of this system can cause a person to produce movements that are too weak, too forceful, too uncoordinated, or too poorly controlled for the task at hand. Unwanted movements may occur at rest. Intentional movement may become impossible. Such conditions are called movement disorders.

Abnormal movements themselves are symptoms of underlying disorders. In some cases, the abnormal movements are the only symptoms. Disorders causing abnormal movements include:

• Parkinson's disease
• Parkinsonism caused by drugs or poisons
• Parkinson-plus syndromes (progressive supranuclear palsy, multiple system atrophy, and cortical-basal ganglionic degeneration)
• Huntington's disease
• Wilson's disease
• Inherited ataxias (Friedreich's ataxia, Machado-Joseph disease, and spinocerebellar ataxias)
• Tourette syndrome and other tic disorders
• Essential tremor
• Restless leg syndrome
• Dystonia
• Stroke
• Cerebral palsy
• Encephalopathies
• Intoxication
• Poisoning by carbon monoxide, cyanide, methanol, or manganese.

Causes and symptoms

Causes

Movement is produced and coordinated by several interacting brain centers, including the motor cortex, the cerebellum, and a group of structures in the inner portions of the brain called the basal ganglia. Sensory information provides critical input on the current position and velocity of body parts, and spinal nerve cells (neurons) help prevent opposing muscle groups from contracting at the same time.

To understand how movement disorders occur, it is helpful to consider a normal voluntary movement, such as reaching to touch a nearby object with the right index finger. To accomplish the desired movement, the arm must be lifted and extended. The hand must be held out to align with the forearm, and the forefinger must be extended while the other fingers remain flexed.

THE MOTOR CORTEX. Voluntary motor commands begin in the motor cortex located on the outer, wrinkled surface of the brain. Movement of the right arm is begun by the left motor cortex, which generates a large volley of signals to the involved muscles. These electrical signals pass along upper motor neurons through the midbrain to the spinal cord. Within the spinal cord, they connect to lower motor neurons, which convey the signals out of the spinal cord to the surface of the muscles involved. Electrical stimulation of the muscles causes contraction, and the force of contraction pulling on the skeleton causes movement of the arm, hand, and fingers.

Damage to or death of any of the neurons along this path causes weakness or paralysis of the affected muscles.

ANTAGONISTIC MUSCLE PAIRS. This picture of movement is too simple, however. One important refinement to it comes from considering the role of opposing, or antagonistic, muscle pairs. Contraction of the biceps muscle, located on the top of the upper arm, pulls on the forearm to flex the elbow and bend the arm. Contraction of the triceps, located on the opposite side, extends the elbow and straightens the arm. Within the spine, these muscles are normally wired so that willed (voluntary) contraction of one is automatically accompanied by blocking of the other. In other words, the command to contract the biceps provokes another command within the spine to prevent contraction of the triceps. In this way, these antagonist muscles are kept from resisting one another. Spinal cord or brain injury can damage this control system and cause involuntary simultaneous contraction and spasticity, an increase in resistance to movement during motion.

THE CEREBELLUM. Once the movement of the arm is initiated, sensory information is needed to guide the finger to its precise destination. In addition to sight, the most important source of information comes from the "position sense" provided by the many sensory neurons located within the limbs (proprioception). Proprioception is what allows you to touch your nose with your finger even with your eyes closed. The balance organs in the ears provide important information about posture. Both postural and proprioceptive information are processed by a structure at the rear of the brain called the cerebellum. The cerebellum sends out electrical signals to modify movements as they progress, "sculpting" the barrage of voluntary commands into a tightly controlled, constantly evolving pattern. Cerebellar disorders cause inability to control the force, fine positioning, and speed of movements (ataxia). Disorders of the cerebellum may also impair the ability to judge distance so that a person under- or over-reaches the target (dysmetria). Tremor during voluntary movements can also result from cerebellar damage.

THE BASAL GANGLIA. Both the cerebellum and the motor cortex send information to a set of structures deep within the brain that help control involuntary components of movement (basal ganglia). The basal ganglia send output messages to the motor cortex, helping to initiate movements, regulate repetitive or patterned movements, and control muscle tone.

Circuits within the basal ganglia are complex. Within this structure, some groups of cells begin the action of other basal ganglia components and some groups of cells block the action. These complicated feedback circuits are not entirely understood. Disruptions of these circuits are known to cause several distinct movement disorders. A portion of the basal ganglia called the substantia nigra sends electrical signals that block output from another structure called the subthalamic nucleus. The subthalamic nucleus sends signals to the globus pallidus, which in turn blocks the thalamic nuclei. Finally, the thalamic nuclei send signals to the motor cortex. The substantia nigra, then, begins movement and the globus pallidus blocks it.

This complicated circuit can be disrupted at several points. For instance, loss of substantia nigra cells, as in Parkinson's disease, increases blocking of the thalamic nuclei, preventing them from sending signals to the motor cortex. The result is a loss of movement (motor activity), a characteristic of Parkinson's.

In contrast, cell loss in early Huntington's disease decreases blocking of signals from the thalamic nuclei, causing more cortex stimulation and stronger but uncontrolled movements.

Disruptions in other portions of the basal ganglia are thought to cause tics, tremors, dystonia, and a variety of other movement disorders, although the exact mechanisms are not well understood.

Some movement disorders, including Huntington's disease and inherited ataxias, are caused by inherited genetic defects. Some disease that cause sustained muscle contraction limited to a particular muscle group (focal dystonia) are inherited, but others are caused by trauma. The cause of most cases of Parkinson's disease is unknown, although genes have been found for some familial forms.

Symptoms

Abnormal movements are broadly classified as either hyperkinetic—too much movement—and hypokinetic—too little movement. Hyperkinetic movements include:

• Dystonia. Sustained muscle contractions, often causing twisting or repetitive movements and abnormal postures. Dystonia may be limited to one area (focal) or may affect the whole body (general). Focal dystonias may affect the neck (cervical dystonia or torticollis ), the face (one-sided or hemifacial spasm, contraction of the eyelid or blepharospasm, contraction of the mouth and jaw or oromandibular dystonia, simultaneous spasm of the chin and eyelid or Meige syndrome), the vocal cords (laryngeal dystonia), or the arms and legs (writer's cramp, occupational cramps). Dystonia may be painful as well as incapacitating.
• Tremor. Uncontrollable (involuntary) shaking of a body part. Tremor may occur only when muscles are relaxed or it may occur only during an action or holding an active posture.
• Tics. Involuntary, rapid, nonrhythmic movement or sound. Tics can be controlled briefly.
• Myoclonus. A sudden, shock-like muscle contraction. Myoclonic jerks may occur singly or repetitively. Unlike tics, myoclonus cannot be controlled even briefly.
• Chorea. Rapid, nonrhythmic, usually jerky movements, most often in the arms and legs.
• Ballism. Like chorea, but the movements are much larger, more explosive and involve more of the arm or leg. This condition, also called ballismus, can occur on both sides of the body or on one side only (hemiballismus).
• Akathisia. Restlessness and a desire to move to relieve uncomfortable sensations. Sensations may include a feeling of crawling, itching, stretching, or creeping, usually in the legs.
• Athetosis. Slow, writhing, continuous, uncontrollable movement of the arms and legs.

Hypokinetic movements include:

• Bradykinesia. Slowness of movement.
• Freezing. Inability to begin a movement or involuntary stopping of a movement before it is completed.
• Rigidity. An increase in muscle tension when an arm or leg is moved by an outside force.
• Postural instability. Loss of ability to maintain upright posture caused by slow or absent righting reflexes.

Diagnosis

Diagnosis of movement disorders requires a careful medical history and a thorough physical and neurological examination. Brain imaging studies are usually performed. Imaging techniques include computed tomography scan (CT scan), positron emission tomography (PET), or magnetic resonance imaging (MRI) scans. Routine blood and urine analyses are performed. A lumbar puncture (spinal tap) may be necessary. Video recording of the abnormal movement is often used to analyze movement patterns and to track progress of the disorder and its treatment. Genetic testing is available for some forms of movement disorders.

Treatment

Treatment of a movement disorder begins with determining its cause. Physical and occupational therapy may help make up for lost control and strength. Drug therapy can help compensate for some imbalances of the basal ganglionic circuit. For instance, levodopa (L-dopa) or related compounds can substitute for lost dopamine-producing cells in Parkinson's disease. Conversely, blocking normal dopamine action is a possible treatment in some hyperkinetic disorders, including tics. Oral medications can also help reduce overall muscle tone. Local injections of botulinum toxin can selectively weaken overactive muscles in dystonia and spasticity. Destruction of peripheral nerves through injection of phenol can reduce spasticity. All of these treatments may have some side effects.

Surgical destruction or inactivation of basal ganglionic circuits has proven effective for Parkinson's disease and is being tested for other movement disorders. Transplantation of fetal cells into the basal ganglia has produced mixed results in Parkinson's disease.

KEY TERMS

Botulinum toxin— Any of a group of potent bacterial toxins or poisons produced by different strains of the bacterium Clostridium botulinum. The toxins cause muscle paralysis, and thus force the relaxation of a muscle in spasm.

Cerebral palsy— A movement disorder caused by a permanent brain defect or injury present at birth or shortly after. It is frequently associated with premature birth. Cerebral palsy is not progressive.

Computed tomography (CT)— An imaging technique in which cross-sectional x rays of the body are compiled to create a three-dimensional image of the body's internal structures.

Encephalopathy— An abnormality in the structure or function of tissues of the brain.

Essential tremor— An uncontrollable (involuntary) shaking of the hands, head, and face. Also called familial tremor because it is sometimes inherited, it can begin in the teens or in middle age. The exact cause is not known.

Fetal tissue transplantation— A method of treating Parkinson's and other neurological diseases by grafting brain cells from human fetuses onto the basal ganglia. Human adults cannot grow new brain cells but developing fetuses can. Grafting fetal tissue stimulates the growth of new brain cells in affected adult brains.

Hereditary ataxia— One of a group of hereditary degenerative diseases of the spinal cord or cerebellum. These diseases cause tremor, spasm, and wasting of muscle.

Huntington's disease— A rare hereditary condition that causes progressive chorea (jerky muscle movements) and mental deterioration that ends in dementia. Huntington's symptoms usually appear in patients in their 40s. There is no effective treatment.

Levodopa (L-dopa)— A substance used in the treatment of Parkinson's disease. Levodopa can cross the blood-brain barrier that protects the brain. Once in the brain, it is converted to dopamine and thus can replace the dopamine lost in Parkinson's disease.

Magnetic resonance imaging (MRI)— An imaging technique that uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.

Parkinson's disease— A slowly progressive disease that destroys nerve cells in the basal ganglia and thus causes loss of dopamine, a chemical that aids in transmission of nerve signals (neurotransmitter). Parkinson's is characterized by shaking in resting muscles, a stooping posture, slurred speech, muscular stiffness, and weakness.

Positron emission tomography (PET)— A diagnostic technique in which computer-assisted x rays are used to track a radioactive substance inside a patient's body. PET can be used to study the biochemical activity of the brain.

Progressive supranuclear palsy— A rare disease that gradually destroys nerve cells in the parts of the brain that control eye movements, breathing, and muscle coordination. The loss of nerve cells causes palsy, or paralysis, that slowly gets worse as the disease progresses. The palsy affects ability to move the eyes, relax the muscles, and control balance.

Restless legs syndrome— A condition that causes an annoying feeling of tiredness, uneasiness, and itching deep within the muscle of the leg. It is accompanied by twitching and sometimes pain. The only relief is in walking or moving the legs.

Tourette syndrome— An abnormal condition that causes uncontrollable facial grimaces and tics and arm and shoulder movements. Tourette syndrome is perhaps best known for uncontrollable vocal tics that include grunts, shouts, and use of obscene language (coprolalia).

Wilson's disease— An inborn defect of copper metabolism in which free copper may be deposited in a variety of areas of the body. Deposits in the brain can cause tremor and other symptoms of Parkinson's disease.

Alternative treatment

There are several alternative therapies that can be useful when treating movement disorders. The progress made will depend on the individual and his/her condition. Among the therapies that may be helpful are acupuncture, homeopathy, touch therapies, postural alignment therapies, and biofeedback.

Prognosis

The prognosis for a patient with a movement disorder depends on the specific disorder.

Prevention

Prevention depends on the specific disorder.

Resources

ORGANIZATIONS

Worldwide Education and Awareness for Movement Disorders. One Gustave L. Levy Place, Box 1052, New York, NY 10029. (800) 437-6683. 〈http://www.wemove.org〉.

Movement disorders

Definition

Movement disorders are a group of diseases and syndromes affecting the ability to produce and control movement.

Description

Though it seems simple and effortless, normal movement in fact requires an astonishingly complex system of control. Disruption of any portion of this system can cause a person to produce movements that are too weak, too forceful, too uncoordinated, or too poorly controlled for the task at hand. Unwanted movements may occur at rest. Intentional movement may become impossible. Such conditions are called movement disorders.

Abnormal movements themselves are symptoms of underlying disorders. In some cases, the abnormal movements are the only symptoms. Disorders causing abnormal movements include:

• Parkinson's disease
• Parkinsonism caused by drugs or poisons
• Parkinson-plus syndromes (progressive supranuclear palsy , multiple system atrophy , and cortical-basal ganglionic degeneration)
• Huntington's disease
• Wilson's disease
• inherited ataxias (Friedreich's ataxia ), Machado-Joseph disease , and spinocerebellar ataxias)
• Tourette syndrome and other tic disorders
• essential tremor
• restless legs syndrome
• dystonia
• stroke
• cerebral palsy
• encephalopathies
• intoxication
• poisoning by carbon monoxide, cyanide, methanol, or manganese.

Causes and symptoms

Causes

Movement is produced and coordinated by several interacting brain centers, including the motor cortex, the cerebellum , and a group of structures in the inner portions of the brain called the basal ganglia. Sensory information provides critical input on the current position and velocity of body parts, and spinal nerve cells (neurons) help prevent opposing muscle groups from contracting at the same time.

To understand how movement disorders occur, it is helpful to consider a normal voluntary movement, such as reaching to touch a nearby object with the right index finger. To accomplish the desired movement, the arm must be lifted and extended. The hand must be held out to align with the forearm, and the forefinger must be extended while the other fingers remain flexed.

THE MOTOR CORTEX Voluntary motor commands begin in the motor cortex located on the outer, wrinkled surface of the brain. Movement of the right arm is begun by the left motor cortex, which generates a large volley of signals to the involved muscles. These electrical signals pass along upper motor neurons through the midbrain to the spinal cord. Within the spinal cord, they connect to lower motor neurons, which convey the signals out of the spinal cord to the surface of the muscles involved. Electrical stimulation of the muscles causes contraction, and the force of contraction pulling on the skeleton causes movement of the arm, hand, and fingers.

Damage to or death of any of the neurons along this path causes weakness or paralysis of the affected muscles.

ANTAGONISTIC MUSCLE PAIRS This picture of movement is too simple, however. One important refinement to it comes from considering the role of opposing, or antagonistic, muscle pairs. Contraction of the biceps muscle, located on the top of the upper arm, pulls on the forearm to flex the elbow and bend the arm. Contraction of the triceps, located on the opposite side, extends the elbow and straightens the arm. Within the spine, these muscles are normally wired so that willed (voluntary) contraction of one is automatically accompanied by blocking of the other. In other words, the command to contract the biceps provokes another command within the spine to prevent contraction of the triceps. In this way, these antagonist muscles are kept from resisting one another. Spinal cord or brain injury can damage this control system and cause involuntary simultaneous contraction and spasticity , an increase in resistance to movement during motion.

THE CEREBELLUM Once the movement of the arm is initiated, sensory information is needed to guide the finger to its precise destination. In addition to sight, the most important source of information comes from the "position sense" provided by the many sensory neurons located within the limbs (proprioception). Proprioception is what allows you to touch your nose with your finger even with your eyes closed. The balance organs in the ears provide important information about posture. Both postural and proprioceptive information are processed by a structure at the rear of the brain called the cerebellum. The cerebellum sends out electrical signals to modify movements as they progress, "sculpting" the barrage of voluntary commands into a tightly controlled, constantly evolving pattern. Cerebellar disorders cause inability to control the force, fine positioning, and speed of movements (ataxia ). Disorders of the cerebellum may also impair the ability to judge distance so that a person under- or overreaches the target (dysmetria). Tremor during voluntary movements can also result from cerebellar damage.

THE BASAL GANGLIA Both the cerebellum and the motor cortex send information to a set of structures deep within the brain that help control involuntary components of movement (basal ganglia). The basal ganglia send output messages to the motor cortex, helping to initiate movements, regulate repetitive or patterned movements, and control muscle tone.

Circuits within the basal ganglia are complex. Within this structure, some groups of cells begin the action of other basal ganglia components and some groups of cells block the action. These complicated feedback circuits are not entirely understood. Disruptions of these circuits are known to cause several distinct movement disorders. A portion of the basal ganglia called the substantia nigra sends electrical signals that block output from another structure called the subthalamic nucleus. The subthalamic nucleus sends signals to the globus pallidus, which in turn blocks the thalamic nuclei. Finally, the thalamic nuclei send signals to the motor cortex. The substantia nigra, then, begins movement and the globus pallidus blocks it.

This complicated circuit can be disrupted at several points. For instance, loss of substantia nigra cells, as in Parkinson's disease, increases blocking of the thalamic nuclei, preventing them from sending signals to the motor cortex. The result is a loss of movement (motor activity), a characteristic of Parkinson's.

In contrast, cell loss in early Huntington's disease decreases blocking of signals from the thalamic nuclei, causing more cortex stimulation and stronger but uncontrolled movements.

Disruptions in other portions of the basal ganglia are thought to cause tics, tremors , dystonia, and a variety of other movement disorders, although the exact mechanisms are not well understood.

Some movement disorders, including Huntington's disease and inherited ataxias, are caused by inherited genetic defects. Some diseases that cause sustained muscle contraction limited to a particular muscle group (focal dystonia) are inherited, but others are caused by trauma. The cause of most cases of Parkinson's disease is unknown, although genes have been found for some familial forms.

Symptoms

Abnormal movements are broadly classified as either hyperkinetic—too much movement—and hypokinetic—too little movement. Hyperkinetic movements include:

• Dystonia: sustained muscle contractions, often causing twisting or repetitive movements and abnormal postures. Dystonia may be limited to one area (focal) or may affect the whole body (general). Focal dystonias may affect the neck (cervical dystonia or torticollis), the face (one-sided or hemifacial spasm , contraction of the eyelid or blepharospasm , contraction of the mouth and jaw or oromandibular dystonia, simultaneous spasm of the chin and eyelid or Meige syndrome), the vocal cords (laryngeal dystonia), or the arms and legs (writer's cramp, occupational cramps). Dystonia may be painful as well as incapacitating.
• Tremor: uncontrollable (involuntary) shaking of a body part. Tremor may occur only when muscles are relaxed or it may occur only during an action or holding an active posture.
• Tics: involuntary, rapid, nonrhythmic movement or sound. Tics can be controlled briefly.
• Myoclonus :a sudden, shock-like muscle contraction. Myoclonic jerks may occur singly or repetitively. Unlike tics, myoclonus cannot be controlled even briefly.
• Chorea : rapid, nonrhythmic, usually jerky movements, most often in the arms and legs.
• Ballism: like chorea, but the movements are much larger, more explosive and involve more of the arm or leg. This condition, also called ballismus, can occur on both sides of the body or on one side only (hemiballismus).
• Akathisia: restlessness and a desire to move to relieve uncomfortable sensations. Sensations may include a feeling of crawling, itching, stretching, or creeping, usually in the legs.
• Athetosis. slow, writhing, continuous, uncontrollable movement of the arms and legs.

Hypokinetic movements include:

• Bradykinesia: slowness of movement.
• Freezing: inability to begin a movement or involuntary stopping of a movement before it is completed.
• Rigidity: an increase in muscle tension when an arm or leg is moved by an outside force.
• Postural instability: loss of ability to maintain upright posture caused by slow or absent righting reflexes.

Diagnosis

Diagnosis of movement disorders requires a careful medical history and a thorough physical and neurological examination. Brain imaging studies are usually performed. Imaging techniques include computed tomography scan (CT scan ), positron emission tomography (PET) , or magnetic resonance imaging (MRI) scans. Routine blood and urine analyses are performed. A lumbar puncture (spinal tap) may be necessary. Video recording of the abnormal movement is often used to analyze movement patterns and to track progress of the disorder and its treatment. Genetic testing is available for some forms of movement disorders.

Treatment

Treatment of a movement disorder begins with determining its cause. Physical and occupational therapy may help make up for lost control and strength. Drug therapy can help compensate for some imbalances of the basal ganglionic circuit. For instance, levodopa (L-dopa) or related compounds can substitute for lost dopamine-producing cells in Parkinson's disease. Conversely, blocking normal dopamine action is a possible treatment in some hyperkinetic disorders, including tics. Oral medications can also help reduce overall muscle tone. Local injections of botulinum toxin can selectively weaken overactive muscles in dystonia and spasticity. Destruction of peripheral nerves through injection of phenol can reduce spasticity. All of these treatments may have some side effects.

Surgical destruction or inactivation of basal ganglionic circuits has proven effective for Parkinson's disease and is being tested for other movement disorders. Transplantation of fetal cells into the basal ganglia has produced mixed results in Parkinson's disease.

There are several alternative therapies that can be useful when treating movement disorders. The progress made will depend on the individual and his/her condition. Among the therapies that may be helpful are acupuncture , homeopathy, touch therapies, postural alignment therapies, and biofeedback.

Prognosis

The prognosis for a patient with a movement disorder depends on the specific disorder.

Resources

BOOKS

Martini, Frederic. Fundamentals of Anatomy and Physiology. Englewood Cliffs, NJ: Prentice Hall, 1989.

Watts, Ray L., and William C. Koller, eds. Movement Disorders: Neurologic Principles and Practice. New York: McGraw-Hill, 1997.

ORGANIZATIONS

Worldwide Education and Awareness for Movement Disorders. One Gustave L. Levy Place, Box 1052, New York, NY 10029. (800) 437-6683. <http://www.wemove.org>.

Richard Robinson