Tuberous sclerosis: long-term follow-up and longitudinal electroencephalographic study.

We analyzed 320 electroencephalograms done on 60 patients having tuberous sclerosis. The main features in EEGs were diffuse slowing in the background activity, slow spike-wave discharges, focal and multifocal spike discharges, and amplitude asymmetries. No significant changes occurred in EEGs during the follow-up. No characteristic pattern was identified for diagnosing TS. Severe abnormalities were seen in patients who had infantile spasms and frequent seizures, and who were mentally retarded. Slow spike-wave abnormality was less frequent in patients who had mild mental retardation and few seizures. The pathological findings did not offer any clue to the frequently recorded EEG abnormalities.