Neurological complications in HIV infection are common and are significant sources of mortality and morbidity. The associated risk factors have not been clearly defined. Several studies have patients who are suited for analysis of peripheral neuropathy and can address the important clinical question of when a subject with asymptomatic neuropathy is most at risk for progressing to painful neuropathy. Some patients in this population with advanced HIV disease will likely have asymptomatic peripheral neuropathy at baseline, and will present an excellent opportunity for prospective study. Detailed quantitative assessments will be carried out to determine the incidence and course of peripheral neuropathy in this population. Risk factors for the development of new peripheral neuropathy, worsening of existing neuropathy, and progression to symptomatic peripheral neuropathy, such as CD4+ cell counts, HIV-1 viral load, and prior nucleoside analogue use, will be evaluated. The potential additive neurotoxic effects of hydroxyurea exposure in this population can also be analyzed.

HIV-infected patients are characterized for the presence or absence of neuropathy at [AS PER AMENDMENT 03/05/02: screening], baseline, Week 24, and Week 48. Entry variables are analyzed to determine predictors of progression from asymptomatic to symptomatic neuropathy or for worsening of symptomatic neuropathy. HIV-uninfected control volunteers have 1 visit [AS PER AMENDMENT 03/05/02: or 2 visits] for nerve conduction and Quantitative Sensory Testing (QST) evaluations to demonstrate proficiency with the testing methods prior to the enrollment of HIV-infected patients. HIV-infected patients are evaluated with the components of the Total Neuropathy Score (TNS) which includes signs (motor function, sensory function, and reflexes), symptoms (motor symptoms and sensory symptoms), QST (CASE IV - vibratory, cooling, and heat pain thresholds), and nerve conduction studies (sural nerve and peroneal nerve). Other evaluations include the Gracely Pain Scale and Visual Analog Scale pain diaries, paired skin biopsies from the right thigh and distal leg (total of 2), and peripheral blood lymphocyte analysis for quantitation of mitochondrial DNA content at entry and final study visit.