New Diagnostic Tests Are Developed

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New Diagnostic Tests Are Developed

Overview

Advances in medical diagnostics in the early twentieth century armed physicians with new tools and methods for diagnosing the maladies of their patients. Scientists borrowed from recent advances in physics, chemistry, and microbiology to create valuable technologies for the diagnosis of disease and injury. A half-century of war and social change prompted the development of some new tests, while meticulous planning in disease prevention resulted in the development of other diagnostic methods.

Background

Prior to 1900 the physician's main diagnostic tools were his assessment skills and his microscope. The relatively new science of bacteriology offered confirmation of some infectious diseases, although most often diagnosis was made according to the patient's symptoms and the course of the disease. The Wasserman test, designed in 1906 by German bacteriologist August von Wasserman, provided a definitive diagnosis for syphilis, a sexually transmitted disease known since ancient times. Wassermann built on newly discovered basics of immunity to create a test that showed the presence of antibodies in the blood or spinal fluid in persons infected with syphilis.

Before the Wasserman test, physicians often had difficulty making a diagnosis of syphilis until its late stages, when the patient was no longer infectious to others. The early stages of the disease caused mild symptoms for which many did not seek treatment. Early syphilis may last up to two years, and throughout this phase the disease can be transmitted, often unknowingly. This resulted in periodic epidemics of the disease throughout the world. The Wassermann test proved valuable until after World War II, when it was largely replaced with the VDRL (Venereal Disease Research Laboratory) test in 1946. Similar in technique, the VDRL test used a more specific antigen (the substance capable of inducing the formation of the antibody), and was less difficult and time consuming to perform.

German physics professor Wilhelm Konrad Roentgen (1845-1923) made one of the most important and long-lasting contributions to medical diagnostics with his discovery of X-rays. Although discovered in 1885 and instantly recognized for its potential medical benefits, the practical matters of confirming Roentgen's work, and designing, manufacturing, and installing equipment delayed X-ray's availability in most hospitals until after the turn of the century. The first X-ray facilities in the United States were located in Boston, where physicians were soon overwhelmed with patients. By the end of World War I, X-ray machinery in hospitals throughout the United States aided physicians to visualize fractures and disorders of internal structures. Roentgen was awarded the 1901 Nobel Prize for Physics for his illuminating discovery.

Electrocardiography, first introduced in 1901, provided physicians with valuable information on the conduction and performance of the heart. Dutch physician Willem Einthoven (1860-1927) developed the technique, based on the previous work of British physiologist Augustus D. Waller (1856-1922). Einthoven modified a string galvanometer (at the time galvanometers were used for underwater telegraph lines) to record the deflections that represented the contractions of the upper and lower chambers of the heart. By applying electrodes to the body, minute amounts of electrical current from the heart led the deflections to the galvanometer, where they were represented as tracings called electrocardiograms. Einthoven's first machine weighed over 600 lb (272 kg).

By 1950, electrocardiographs were small, portable, and capable of pinpointing irregularities in heart rhythm, as well as aiding in the diagnosis of heart enlargement, thyroid disease, hypertension (high blood pressure), and myocardial infarction (heart attack). For his invention of the electrocardiogram and further research on the phases of the electrical activity of the heart, Einthoven was awarded the 1924 Nobel Prize for Physiology or Medicine.

Electroencephalogram (EEG) tests provided insight into the electrical activity of the brain. First introduced in the 1920s, EEG interpretation was likened to a scientific art, requiring many years of comparative experience. Thus, other than by a few pioneering experts, EEG was not widely used until the early 1940s. EEG records the changes in electrical potential in various aspects of the brain by electrodes placed on the scalp, which are attached to an amplifier. The amplified impulses move an electromagnetic pen that records the brain waves. Physicians then screen the wave tracings and the spectral background of the EEG for particular features, such as spikes, that may indicate the presence of injury or illness. EEG was particularly helpful in the diagnosis of epilepsy, and was also used to aid in the diagnosis of brain tumors and brain dysfunction.

Greek physician Nicholas Papanicolaou (1883-1962) developed the Pap test in 1939, which assists in the diagnosis of cervical cancer. During his research, Papanicolaou observed that smears prepared from secretions and cells scraped from the area near the cervix in women with cervical cancer showed cellular abnormalities. Papanicolaou reasoned that cancerous cervical lesions could be detected by observable and measurable cellular changes while the cells were still in a pre-invasive phase. The Pap test made it possible to diagnose cervical cancer in patients with no symptoms of the disease. Moreover, such early diagnosis enabled physicians to treat patients while they were in the earliest and most treatable stages of cancer. The Pap test also meant that cervical cancer could be detected and treated before it made the deadly leap (metastasis) to other sites, most commonly the uterus.

The Minnesota Multiphasic Personality Inventory, or MMPI, was developed in the late 1930s to provide an objective measure of personality and to aid in the diagnosis of mental illness. The test consisted of a set of 550 questions, interrelated to show basic personality traits. The emphasis of the test is psychiatric, and the scores were classified in terms of psychiatric categories. The examiner determines the degree to which the subject's pattern of responses to the questions resemble that of schizophrenic patients, depressed patients, and patients with other psychiatric and major personality disorders. The test was originally designed for adults. It required at least a sixth grade reading level, and was not applicable to most children below the age of 13 or retarded persons. Occasionally the test was administered to teenagers, but the results were interpreted with caution. The MMPI became one of the most widely used diagnostic tests, and was revised several times.

Impact

The advent of the MMPI and its widespread popularity among clinicians reflected the climate of social upheaval and change that was characteristic of the first half of the twentieth century. The outbreak of World War I produced large numbers of psychiatric casualties. In 1904, during the Russo-Japanese War, the Russians became the first to post psychiatrists at the front lines of battle. Although Russian clinicians were the first to determine that the mental collapse associated with the stress of war was a true medical condition, Americans and western Europeans saw "shell shock" as a new phenomenon in World War I. Military psychiatry became a legitimate field of study during this period.

By World War II psychiatric testing, including tests modeled after the MMPI, was used to screen potential victims of mental collapse. During the war, however, American forces still lost over half a million men from the fighting effort due to psychiatric collapse. The rate at which soldiers became debilitated led psychiatrists to conclude that psychiatric breakdown during the extreme stresses of war was the consequence of a normal human reaction, not of cowardice. After World War II, the National Mental Health Act of 1946 led to the creation of the National Institute of Mental Health (NIMH). In 1949 NIMH was established in response to mental health problems suffered by American veterans of both World Wars.

At the beginning of the century, the Industrial Revolution brought about technological change at a rate many Americans found difficult to accept. Although Americans left rural areas by the thousands and poured into the cities to find work in the new industries, many remained distrustful of the new technologies. X-rays were of particular concern in the post-Victorian era. Companies advertised protective garments for women (at that time it was considered daring to expose an ankle) designed to protect them from the peering indecency of misused x-rays. Other new medical technologies, such as the electrocardiogram, helped to reassure Americans that industrialization contributed to helpful technology. By 1950 new technologies were eagerly anticipated and discussed by a less wary American public that viewed technological invention as further evidence of American superiority in the postwar world.

Diagnostic tests such as the Pap test ushered in a new era of preventive medicine. Since its inception, cervical cancers dropped dramatically in countries where Pap smears are routine medical practice, and the test is considered one of the greatest life-saving techniques in medical practice. The Pap test was one of the first screening tests (tests that are performed in the absence of known disease and negative results are the norm) widely used in medicine. In contrast to other medical innovations of the early twentieth century, the Pap test was inexpensive and required simple technology.

By 1950 disease prevention became a major focus in medicine. Public health departments were established in the United States, and diagnostic screening tests were incorporated into routine medical practice throughout much of the industrialized world.

BRENDA WILMOTH LERNER