Dreams interrupted: characteristics of REM sleep-associated seizures and status epilepticus.

Study objectives: Seizures are rare in rapid eye movement sleep (REM). However; seizures sometimes occur in REM, and a small number of focal epilepsy patients display their maximum rate of interictal epileptiform discharges in REM. We sought to systematically identify and characterize seizures in REM.

Methods: We reviewed all admissions to the Epilepsy Monitoring Unit (EMU) at the Winnipeg Health Sciences Centre over 12-months in 2014-2015. American Academy of Sleep Medicine sleep-stage scoring was initially applied in the standard 30-second epochs. Then, to capture sudden changes in sleep-wake state on shorter timescales that are associated with seizure formation and propagation, we re-scored ictal and peri-ictal EEG epochs every 1 second. Patients found to have seizures in REM were subject to chart review spanning three years pre- and post-admission.

Results: REM seizures occurred in 3/63 EMU patients. Notably, one patient exhibited continuous epileptiform activity, consistent with focal nonconvulsive electrographic status epilepticus, throughout REM cycles for each night of her admission. Otherwise, discrete REM seizures constituted a small fraction of the other patients' total seizures (range 5.0-8.3%), occurred shortly after REM onset from non-REM 2, and were manifest as minor epileptic arousals.

Conclusions: Our results confirm that REM seizures are rare, while highlighting outliers who widen the known spectrum of heterogeneous sleep effects on seizures/epilepsy. We also report the first case of paradoxical status epilepticus in REM.