Nervous system involvement in asymptomatic HIV seropositive individuals: A cognitive and electrophysiological study

Background: A significant proportion of human immunodeficiency virus (HIV) seropositive subjects may have subclinical asymptomatic involvement of the central and peripheral nervous system. Aims: To detect subclinical neurological involvement in asymptomatic HIV seropositive individuals by clinical, mini mental state examination (MMSE) and various electrophysiological tests. Material and Methods: MMSE, EEG, nerve conduction (NC), and multimodality-evoked potential studies were evaluated in 20 asymptomatic HIV seropositive subjects. Results: The majority of the subjects were young (mean age: 29.5 ± 8.9 yrs) and female (85%). The mean MMSE score was 25.8 ± 2.3, which was marginally less than that of matched controls (26.3 ± 2.4). Four subjects had a score of less than 23 suggesting subclinical cognitive impairment. EEG (n=19) was mildly abnormal in 8 cases: low alpha index (n=4), excess of fast background activity (n=3) and intermittent bursts of slow waves along with sometimes sharp waves (n=4). Motor NC studies (n=20) revealed a decreased mean nerve conduction velocity (NCV) compared to controls in the right median (P<0.05) and CP (P<0.001) nerves. Sensory NC studies revealed a decreased mean NCV in both the median (P<0.001) and sural (P<0.001) nerves compared with controls. Brainstem auditory evoked potential (BAEP) studies showed the involvement of the peripheral auditory pathway (23.5%). The somatosensory evoked potential (SSEP) study detected a delay of N20 latency in two. Only 3 subjects came for follow-up after 6 months. Conclusion: Asymptomatic HIV seropositive subjects may have subclinical central and peripheral nervous system involvement. Long-term follow-up studies are essential for better understanding of the significance of these changes.