Electroencephalographic abnormalities in addition to bilaterally synchronous 3 mper second spike and wave activity in petit mal

Abstract

1. 1. In 100 consecutive patients in whom clinical petit mal attacks were associated with 3 per sec. spike and wave activity the presence of focal, lateral and diffuse EEG abnormalities was studied. 2. 2. In 51 cases the background activity of the EEG was essentially normal. In 35 cases focal or lateralizing abnormalities were present. In 14 cases the background activity was diffusely abnormal. 3. 3. Sixty-two patients were female. The average age of onset of petit mal was seven years. Nineteen had close relatives with a history of convulsions. Six patients had abnormal neurologic findings. Eleven were low in intelligence. Forty patients had atypical features to their seizures. Forty-nine had other types of seizures in addition to petit mal. Possible etiologic factors were present in the histories of only six patients. 4. 4. Correlations were noted between the presence of EEG abnormalities other than synchronous 3 per sec. spike and wave activity and ( a) mental retardation and ( b) abnormal findings on neurologic examination. 5. 5. The possible meaning of the high incidence of abnormalities, other than 3 per sec. spike and wave discharges, in terms of the genesis of petit mal activity is discussed.