[Study on the constancy of EEG characteristics in epileptic patients (author's transl)].

These investigations were based on the question regarding the reliability of a single EEG recording in patients with epilepsy. 114 patients patients (age 11-74 years, median 33 years) underwent five EEGs at an interval of three months during a period of one year. A "constant" characteristic was a continuously developed dysrhythmia. "Moderately constant" was an intermittent dysrhythmia, an alpha background activity and a general slowing of the background activity. "Inconstant" was a "parenrhythmia" and focal disturbances as well as epileptiform patterns. Similarly inconstant was the lateralization of epileptiform patterns. The lateralization of focal disturbances and a dysrhythmia was moderately constant. The great constancy of a continuously developed dysrhythmia makes it hardly suitable for a functional follow-up. The applications of epileptiform patterns and focal disturbances for therapy planning is, however, limited due to their inconstancy. Because of its moderate constancy the background activity (in different recordings) is a suitable indicator for an overdosage of antiepileptic drugs.