Abstract
Age-dependent epilepsy in infancy is composed of infantile spasms and earlyinfantile epileptic encephalopathy with suppression-brust (E. I. E. E.). In this study, occurrence time and analysis of clinical seizures of this epilepsy during sleep and wakefulness were examined electrophysiologically by means of overnight sleep polygraphy. Two cases of infantile spasms (Case 1, Case 2) and one case of E. I. E. E. were studied. The polygraphic recordings were performed on each subject on the first night. The second overnight sleep polygraphy was conducted when the clinical seizures in Case 2 and the case of E. I. E. E. increased.
The clinical seizures in the cases of infantile spasms occurred shortly after awakening. In Case 1, the same EEG findings and eye movements as in the clinical seizures were observed during REM sleep without any apparent clinical seizures. The clinical seizures in the case of E. I. E. E. occurred more frequently during NREM sleep than during wakefulness and REM sleep. After the ceasing of clinical seizures, the state transfered mostly to REM sleep or wakefulness. The ictal EEG in the cases of infantile spasms showed hypersynchronous activities. The ictal EEG in the case of E. I. E. E. exhibited synchronous bursts of high voltage slow waves mixed with spikes, and the EEG before and after clinical seizures showed flattening of the trace.
In the next place, the series of spasms in each subject were examind and the results were as follows: the duration of the spasm in the cases of infantile spasms was about 1 second and the interval between the spasms was 3 to 10 seconds. Usually the duration of spasm in the series became longer gradually and then reached a constant level, and became shorter gradually towards the end. But in a few series of spasms in case 2, the duration of spasm was the longest at first and became shorter gradually towards the end. In most series of spasms, the interval between spasms became shorter when the duration of spasm became longer and it became longer when the duration of spasm became shorter. The mean duration of spasm in the case of E. I. E. E. was 5 to 7 seconds and mean interval between spasms was about 20 seconds. In the case of E. I. E. E., the duration of spasms in the series had no constant trend but the interval between spasms became shorter towards the end. In addition, the duration of spasm and the interval between spasms in the case of E. I. E. E. were more irregular than those in the cases of infantile spasms.
