Multimodal evoked potentials in HIV infected patients

Abstract

We studied 126 HIV seropositive patients (106 men, 20 women; mean age: 32 years): 45 had neurological signs, 81 had none. Multimodal evoked potential (MEP) assessment included: visual EPs by flash and reversal checkerboard; brain-stem auditory EPs; somatosensory EPs by stimulation of the median nerve. Evaluation also included: electroencephalography, electromyography with measurement of conduction velocities, neuroimaging (CT scan and MRI). We found abnormal MEPs for all modalities. The prevalence of abnormal results was high in neurologically symptomatic patients; in non-neurological subjects, the changes were more dramatic as HIV infection progressed. Whatever the stage of the disease, the modalities were equally affected. MEPs were abnormal in 54.7% of patients: in 41.8% of those without neurological signs vs. 85.7% of those with these signs. Comparison of MEPs and other electrophysiological procedures and neuroimaging techniques showed the high sensitivity of MEPs at all stages of the disease. EMG was sensitive and complementary to MEPs. EEG and neuroimaging showed abnormalities principally at the neurological symptomatic stage. Our results agree with those found in the literature. Abnormal MEPs may: (1) indicate latent neurological involvement of the visual, auditory and somatosensory pathways, (2) help diagnose an encephalitis suspected on neuropsychological, non-quantifiable testing.