Multimodal evoked potentials (PRVEP, BAEP, mSEP) were recorded in 56 HIV-1 seropositive outpatients free from opportunistic CNS pathologies and/or overt HIV-1 encephalopathy. EPs were altered in 17 of 39 (43.6%) seropositive subjects without AIDS (group A) and in 13 of 17 (76.5%) patients with AIDS (group B). A high incidence of subclinical alterations (30.8%) were found in group A patients. Significant BAEP (I-III, III-V, I-V) interpeak latency and mSEP (N9-N13, N9-N20) conduction time prolongations were found in group a and B patients. PRVEP P100 was significantly prolonged only in group B. An inverse relationship between BAEP interpeak latencies and CD4 count was found. Our findings support the hypothesis of an important role of immunodepression in the development of neurophysiologic abnormalities, together with a preferential involvement of acoustic pathways, in the course of HIV-1 infection
