Abstract
Objectives Idiopathic Generalised Epilepsy is not a benign condition with increasing evidence of enduring cognitive deficits beyond seizures. We aimed to describe the temporal distribution, duration, and relationship to sleep of interictal discharges (IEDs) using outpatient ambulatory 24-hour EEG recordings (aEEG) in juvenile absence epilepsy (JAE).
Methods We retrospectively identified 15 patients with JAE undergoing treatment adjustment with at least three aEEGs between 2012–2020. JAE was classified with onset of first or predominant absence seizures after age 9 years. We used a published automated detection algorithm to assist aEEG review and recorded the timing and length of IEDs. Following training, PH/AD independently marked IEDs with any uncertain or discordant IEDs resolved by WD. For each individual recording, the timing and length of the discharges was plotted against 24-hour clock.
Results 15 patients (onset age 9 to 16 years), had a total of 14701 IEDs (median 104; IQR 11 – 403). 9917 (67.5%) IEDs occurred between 22:00 and 07:00 (individual aEEG median 63%; IQR 49.8% – 92.3%). IEDs show an overall pattern of clustered discharges during sleep compared to a more sporadic frequency in wakefulness. In addition, during sleep IEDs oscillate between high frequency peaks and quiescent periods throughout the night.
Conclusion JAE demonstrates a cyclical pattern in the distribution of IEDs with two-thirds occurring during sleep. The oscillating pattern of IEDs during sleep has not been previously reported in humans and suggests coupling to a sleep phase generator, a critical time for memory encoding.
