Recurrent attacks of unconsciousness with diffuse EEG alpha activity

A 45-year-old patient presented with recurrent attacks of unconsciousness, which resembled sleep. However, EEG recordings during these attacks showed diffuse, frontal-dominant 10-Hz alpha activity. Both the attacks and EEG changes reversed promptly with intravenous flumazenil, but not with methylphenidate, atropine or placebo. The attacks could not be prevented with methysergide, flumazenil, clonidine, piracetam or phenytoin. Laboratory investigations revealed a temporal lobe arachnoid cyst, a distal motor and sensory polyneuropathy, abnormal auditory evoked responses during the attack, an abnormal silent period latency and abnormal melatonin regulation. Similar attacks were reported by history in two siblings and in the proband's late father. It is postulated that the attacks of unconsciousness could involve gamma-aminobutyric acid- (GABA)-mediated mechanisms.