SHARP TRANSIENTS IN THE SLEEP EEG OF HEALTHY-ADULTS - A POSSIBLE PITFALL IN THE DIAGNOSTIC-ASSESSMENT OF SEIZURE DISORDERS

The use of sleep EEG recordings is a routine procedure in the diagnost ic work up of patients with suspected epilepsy. With respect to the di agnostic significance of paroxysmal EEG phenomena it is of importance to he informed about the incidence oi such paroxysms in EEG's of healt hy subjects. Several benign paroxysmal EEG phenomena during drowsiness or sleep have been identified (benign epileptiform transients of slee p (BETS), 14 and 6 positive spikes). Recent studies have shown that ot her, apparently aspecific, paroxysmal sharp transients may be recorded during drowsiness or sleep iii healthy subjects. In order to obtain m ore data on such paroxysmal EEG phenomena during sleep, a qualitative and semi quantitative analysis was performed on full night sleep recor dings from 60 carefully selected healthy volunteers. Only 4 recordings were completely without the studied phenomena, all others showed some suspicious paroxysmal transients and some rare yet true specific epil eptiform discharges were recorded in 8 subjects (13%), predominantly d uring transient periods of light non-REM sleep in the first two sleep cycles. The presence ol some sharp transients dining drowsiness or lig ht sleep thus should be considered as a non-specific and non-pathologi cal finding. Moreover these findings indicate the limited diagnostic s pecificity of the presence of a feu: epileptiform discharges during sl eep, especially in patients with an ambiguous clinical history of epil epsy. (C) 1998 Elsevier Science Ireland Ltd.