Ambulatory 24-hour EEG recording in epileptic infantile spasms

Twenty-four h cassette recording (MEDILOG 9000) where obtained in 22 untreated infants (23 records) with a West syndrome (idiopathic: n = 12, symptomatic: n = 10). All these infants had had a 3 h polygraphic recording. Tracings were visually analyzed for sleep stages. Electro-clinical seizures and infraclinical discharges were listed according to their type and the stage of vigilance. Two hundred twenty-eight critical events were recorded in 22 cassette recordings: isolated spasms, clusters of spasms, partial or generalized discharges followed or not by clusters of spasms. Sixty per cent of these fits occurred during wakefulness, 27% during non REM sleep, 13% during awakening and none during REM sleep. Partial discharges, followed or not by clusters of spasms, were only present in cases with unfavourable outcome. In benign spasms the hypsarrhythmic pattern was present between spasms in each cluster, but not in cases with unfavourable outcome. Compared with 3 h polygraphic recordings, 24 h cassette recordings gave supplementary data on the presence, type and timing of seizures in 16 of out 22 cases.