Neuropathologist

Definition

A pathologist is a medical doctor who is specialized in the study and diagnosis of the changes that are produced in the body by various diseases. A neuropathologist is a specialized pathologist who is concerned with diseases of the central nervous system (the brain and spinal cord). Often a neuropathologist is concerned with the diagnosis of brain tumors.

A neuropathologist is also an expert in the various aspects of diseases of the nervous system and skeletal muscles. This range of disease includes degenerative diseases, infections, metabolic disorders, immunologic disorders, disorders of blood vessels, and physical injury. A neuropathologist functions as the primary consultant to neurologists and neurosurgeons.

Description

A neuropathologist is a medical doctor who has pursued specialized training. Aspects of this training include neurology, anatomy, cell biology, and biochemistry. Typically, a patient will not see a neuropathologist. Rather, the specialist works in the background, in the setting of the laboratory, to assist in the patient's diagnosis. In the path that leads to the diagnosis of a tumor, disease, or other malady, a neuropathologist typically becomes involved at the request of a neurologist . It is the neurologist who suspects a problem or seeks to confirm the presence of a tumor, based on tests such as magnetic resonance imaging (MRI) or a computed assisted tomography (CAT) scan. The neurologist can obtain some of the tissue of concern in a procedure known as a biopsy , as well as obtaining fluid or cell samples.

It is this material that is sent to the pathology lab where the neuropathologist seeks to identify the nature of the problem. The diagnosis of brain and spinal cord related damage often involves a visual look at the samples using the extremely high magnification of the electron microscope. The neuropathologist can assess from the appearance of the sample whether the sample is unaffected or damaged. For example, in brain tissue obtained from a patient with suspected Alzheimer disease , the neuropathologist will look for evidence of the presence of amyloid plaques, which are caused by abnormal folding of protein. As well, the neuropathologist will look for other diagnostic signs that support or do not support the suspected malady.

In the case of a tumor, part of a neuropathologist's responsibility is to identify the tumor and grade it as malignant or benign. This is no small task, as there are literally hundreds of different types of tumors. The correct identification greatly aids the subsequent treatment process and the patient's prognosis.

The neuropathological analysis of a tumor is concerned mainly with two areas. The first is the origin of the tumor in the brain. Determining the tumor's origin aids in naming the tumor. Secondly, the neuropathologist determines if the tumor displays signs of rapid growth. The speed of growth of the tumor can be quantified as a grade. A result such as "grade three astrocytoma" is very informative to the neurologist. Even if the neuropathologist determines that a brain or spinal cord tumor is benign, the location of the tumor may still pose serious health risks, and this important determination is also usually made by the neuropathologist.

Another important tool that a neuropathologist uses to examine tissue samples is histology. The treatment of a thin section of a sample with specific compounds that will bind to and highlight (stain) regions of interest in the specimen allows the neuropathologist to determine if the stained regions are normal or abnormal in character. The histological stains can be applied to a section that has been sliced from the sample at room temperature or at a very low temperature. The use of frozen sections can help preserve structural detail in the specimen that might otherwise be changed at a higher temperature.

The assessment of a stained specimen by the neuropathologist is typically done by examining the material using a light microscope. This type of microscope does not magnify the specimen nearly as much as does the electron microscope. But such high-power magnification is not necessary to detect the cellular changes in the stained specimen. By carefully selecting the stain regimen, a skilled neuropathologist can reveal much detail about a specimen. Histological examinations can also be done much more quickly and easily than electron microscopic examinations. Saving time can be important in diagnosis and treatment, especially when dealing with brain tumors.

Finally, one of the consultative duties of a neuropathologist can also include legal testimony. Their expert knowledge can be useful in court cases in which the mental state or functional ability of a person is an important consideration.

Resources

BOOKS

Nelson, James S. Principles and Practice of Neuropathology. New York: Oxford University Press, 2003.

OTHER

Department of Neurology, University of Debrecen, Hungary. Neuroanatomy and Neuropathology on the Internet. <http://www.neuropat.dote.hu/> (February 10, 2004).

ORGANIZATIONS

American Association of Neuropathologists (AANP). 2085 Adelbert Rd., Cleveland, OH 44106. (216) 368–2488; Fax: (216) 368–8964. aanp@cwru.edu. <http://www.aanp-jnen.com>.

Brian Douglas Hoyle, PhD