Low amplitude EEGs in demented AIDS patients.

We have observed an unusual low amplitude, slow and featureless electroencephalogram (EEG) pattern in some human immunodeficiency virus (HIV) infected patients without focal lesions on computerized tomography (CT scan) of the head. Out of 17 cases, 13 with AIDS and 4 with HIV positive status, 6 had low amplitude EEGs with slowing, all in the AIDS group. Nine of the 13 AIDS patients were demented, and 4 of these demented patients had slow verbal responses and mutism, indicating advanced HIV-related dementia. All 4 had low amplitude, slow EEGs. The patients with low amplitude, slow EEGs also had atrophy on CT scan by visual assessment and by measurement of ventricular indices. Of 17 age-matched controls referred for non-specific complaints such as headache and dizziness or for psychiatric disorders, 3 had EEGs read as low amplitude with slowing; two had normal mental status and one was psychotic. Although this EEG pattern is not etiologically specific, it may correlate with advanced dementia and atrophy on CT scan in AIDS patients.