The neurologic complications of HIV-1 infection are both common and varied. Indeed, only rarely do the central and peripheral nervous systems of HIV-infected patients remain unaffected through the course of untreated disease. Because each of the individual neurologic disorders is discussed in more detail elsewhere in this volume, the major purpose of this chapter is to provide an overview and a general guide to diagnosis and management.

Although the major susceptibility to neurologic complications occurs in the late phase of HIV-1 infection, at the time when immunosuppression leads to a marked increase in vulnerability to a host of conditions, patients may also manifest certain neurologic afflictions early in infection.

Because the neurologic complications of early and late HIV-1 infection differ, they are considered separately. Indeed, because of these stage-related differences in susceptibility, when approaching diagnosis in HIV-infected patients it is important to characterize their “background” systemic HIV-1 infection, either clinically with respect to the presence or absence of previous opportunistic infections indicating compromised immunity or by assessment of surrogate markers, particularly the blood CD4+ lymphocyte count. Emerging data suggest that susceptibility to late neurologic complications can be delayed or reversed by highly active antiretroviral therapy (HAART), sustaining the value of the CD4+ count in predicting disease vulnerability.