Review of central nervous system pathology in human immunodeficiency virus infection

Aseptic meningitis, subacute encephalitis, and vacuolar myelopathy are the three diseases of the central nervous system that are specifically related to or associated with human immunodeficiency virus (HIV) infection. HIV encephalitis initially is associated with myelin pallor and gliosis of the centrum semiovale, which is found in more than 90% of brain from patients dying with the acquired immunodeficiency syndrome. With increased severity of disease, multiple glial nodules with the multinucleated cells characteristic of HIV encephalitis are present throughout the cerebral white matter, basal ganglia, and cerebral cortex, and also may be found in cerebellum, brainstem, and spinal cord. HIV has been demonstrated in monocytes and multinucleated cells by electron microscopy, immunohistochemical techniques, and in situ hybridization. Vacuolar myelopathy occurs in approximately 30% of patients and is characterized by vacuolation of the white matter of the spinal cord that is most prominent in the posterior and lateral columns at thoracic levels. The severity of the pathological lesions correlates not only with symptoms and signs of spinal cord disease but also with dementia. Although the incidence of vacuolar myelopathy is increased in patients with HIV encephalitis, its etiology is not yet established.