Electroencephalogram of asymptomatic adult subjects

Objectives: The objective of this study is to investigate the incidence of epileptiform activity, focal or generalized slowing, patterns of uncertain significance and the effects of hyperventilation, photic stimulation and sleep on the electroencephalogram of asymptomatic adult subjects. Methods: The studied group consisted of 100 male subjects with a mean age of 34 years (range 18–45 years). Each subject was screened closely for personal or family history of seizures, HIV, head trauma and drug abuse. Half of the subjects had a magnetic resonance imaging scan (MRI). Results: In no subject resting or activated EEG showed any epileptiform activity or excessive slowing (focal or generalized). One subject demonstrated an H-response, one disclosed an alpha asymmetry of more than 50% and one showed slow alpha variant. Fourteen and 6 positive burst (12%) and small sharp spikes (11%) were the two most common patterns of uncertain significance. Conclusion: In a carefully screened population of young and middle age adults, the incidence of epileptiform activity, photoparoxysmal response or excessive slowing is less than 1%.