EEG features in transient global amnesia.

Forty-seven patients with one or more episodes of transient global amnesia (TGA) were studied by means of standard and 24-hour ambulatory cassette recording electroencephalography (EEG). Only one individual, with a left frontal hemorrhage, had intracranial lesions. TGA was multiple in 16 of the patients (34%), the attacks recurring with an average time span of one every 3 years. No patient required anticonvulsant therapy and all episodes of TGA were self-limited and rather benign. Only 13 patients were known to be hypertensive and 2 had a history of classic migraine. The average time span of EEG recordings after TGA was 2.7 days. Three individuals had recordings during the actual clinical attack, 2 of whom had paroxysmal abnormalities (one with periodic lateralized epileptiform discharges and the other with left temporal sharp wave and central spike and wave discharges). The remaining patient had no change in the EEG. The percentage of EEG abnormalities encountered was 36% (17 patients) but only 10.6% (5 patients) disclosed specific paroxysmal activity. Activation procedures, sleep and 24-hour ambulatory studies were overall of no additional value to the standard recordings. TGA seemingly represents a benign circulatory disturbance affecting the memory zones of the brain, rather than a primary epileptic disorder.