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Human immunodeficiency virus type 1 (HIV-1) infection, particularly its late phase, the acquired immunodeficiency syndrome (AIDS), is complicated by a variety of central nervous, system (CNS) and peripheral nervous, system (PNS) disorders.
The most important pathogenetic determinant of susceptibility is the stage of systemic HIV-1 infection and particularly the resultant degree of immunosuppression. The underlying immune status exerts- a predominating-effect on disease vulnerability.
Discussion of the complications of late HIV-1 infection uses the empirically derived approach of the neurologist and a classification based upon neuroanatomic localization. This is founded upon the predilection of different disease processes to afflict selected parts of the CNS and PNS.
Nervous System Involvement Early in HIV-1 Infection
Based upon their frequency, major clinical attention has focused on the common neurologic sequelae of late HIV-1 infection, but the earlier phases of systemic HIV-1 infection can, although less commonly, also be accompanied by clinically important neurologic disorders.
Early Neurologic Complications of Acute HIV-1 Infection
A variety of CNS disorders have been described in the period after initial HIV-1 infection (Chapter 6) with their frequency ranging from 855 for encephalopathies and neuropathies to as high as 45% for less specific manifestations such as headache. They may occur from several days to weeks after the seroconversion-related illness that resembles mononucleosis or, less often.
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Table 14-1. Classification of The Neurologic Complications of HIV-1 Infection
According to Underlying Pathophysiologic and Pathogenetic Categories |
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| Underlying Process | Examples |
| Opportunistic infections |
Cerebral toxoplasmosis
Cryptococcal meningitis Progressive multifocal leukoencephalopathy (PML) Cytomegalovirus (CMV) encephalitis, polyradiculopathy and mononeuritis multiplex |
| Opportunistic neoplasms |
Primary central nervous system lymphoma
Metastatic lymphoma |
| Metabolic, toxic, and other complications of systemic disease |
Hypoxic encephalopathy
Sepsis Stroke |
| Functional (psychiatric) disorders |
Anxiety disorder
Psychotic depression |
|
Unique conditions (?) related to a primary effect of
HIV-1 itself |
AIDS dementia complex
Distal sensory polyneuropathy (DSPN) |
| Autoimmune disorders |
Guillain-Barri syndrome
Chronic inflammatory demyelinating polyneuropathy (CIDP) |
Neurologic Complications During the "Asymptomatic" Phase of Systemic HIV-1 Infection
Most common, among the neurologic complications manifesting during the "asymptomatic" or clinically latent phase of HIV-1 infection are demyelinating neuropathies. These resemble the subacute Guillain-Barri syndrome or chronic inflammatory demyelinating poly-neuropathy (CIDP) seen in other contexts, with the exception that the CSF often exhibits uncharacteristic, albeit mild, pleocytosis The .pathophysiology of HIV-1-related demyelinating neuropathies probably parallels that of demyelinating neuropathies in other settings and has an autoimmune basis.
Asymptomatic HIV-1 Infection of the CNS
Although clinically overt nervous system involvement may occur early in the course of HIV-1 infection, neurologically asymptomatic infection is more common. Studies of CSF in clinically well patients have shown: (1) abnormalities of routine studies, including cell count, total protein, and immunoglobulin; (2) local, intra-blood-brain barrier synthesis of anti-HIV-1 antibody; and (3) culture isolation of virus or detection of viral nucleic acid.