[Genetic aspects of symptomatic epilepsy based on waking and sleep EEG recordings in siblings].

Waking and sleep EEG-recordings were carried out in siblings of patients with various idiopathic and symptomatic seizure types. Rates of epileptic activity (e.a.) were found in the symptomatic ones varying between 24.1% (Complex partial seizures) and 46.7% (Symptomatic absences). 1/4 to 1/2 of the e.a. was recorded exclusively in sleep, so that sleep recordings are also necessary for such investigations. 2.5-4/sec. spike wave-complexes were predominantly seen; benign foci and photosensitivity were recorded in a smaller number of siblings. More e.a. was observed in idiopathic (72%) than in symptomatic absences (46.7%). On the other hand the same rates (42:41%) as well as almost the same EEG-patterns were found in idiopathic and symptomatic generalized tonic-clonic seizures. When counting the single epileptic discharges more e.a. was seen in siblings of patients with the idiopathic type than the symptomatic one (one discharge every 53 sec.:229.3 sec.). Most e.a. was found in the age group 6-14 years in siblings of all seizure types; therefore, this age dependent penetrance does not depend on the seizure type, but on the recorded spike wave-complexes, benign foci and photosensitivity which occur most frequently in this age range. A multi-factorial mode of inheritance is assumed.