Unlike pathological tests of general organs such as the liver, pancreas, and lungs, neuropathological tests involve various characteristics, as described below. These may make neuropathology somewhat difficult to understand; however, this knowledge can be gained through experience, which should help familiarize medical care staff with the subject.
Unlike other organs, the nerve tissue differs by site-specific cell structures such as form and density, and unless these can be ascertained, it is difficult to determine whether the observed findings are within the normal range or are abnormal. Therefore, outlines of the cellular structure of several typical neural sites should be known.
Neuronal streaming and its formation are largely completed during the fetal stage; however, myelination sequentially occurs for several years after birth. Thus, it is important to understand this pattern when determining the presence or absence of a developmental disorder. In addition, dark brown pigmented granules of neuromelanin begin to form in the neurons of the substantia nigra and locus ceruleus from adolescence; therefore, it may be difficult to evaluate the reduced formation of neuromelanin in certain age groups. On the other hand, waste products such as lipofuscin accumulate from early stage in neurons of the inferior olivary and dentate nuclei. Accordingly, the time when substances accumulate differs by region, and it is important to be familiar with the nervous tissue of various age groups. Furthermore, various neuronal substructures form with age (explained in detail in the discussion); however, it is sometimes difficult to determine whether the accumulation of substances exceeds physiological levels.
Disruptive lesions at certain sites can further lead to secondary degeneration of other sites with connecting fibers. Therefore, it is important to ascertain whether a lesion is primary or secondary in order to determine the mechanism underlying its formation in the nerve tissue.
With certain neurological diseases, the relationship between the lesion site and clinical symptoms must be examined. For this, the knowledge of neuroanatomy and symptomology is required when each site is damaged.
The main pathological staining used at present is hematoxylin and eosin (H&E); however, there are several other staining methods specific to various parts consisting of the nerve tissue. By using such methods, the quality of the neuropathological test is improved and lesion formation is explained. Therefore, it is important to know which of these staining methods are used relatively routinely. In addition, when staining for neurodegenerative diseases, it is important to use several general antibodies for determining the appropriate diagnostic approach and clarifying the grounds for diagnosis.