Abstracts

Rationale: REM (Rapid Eye Movement) sleep is well known to suppress abnormal epileptiform activity - both interictal discharges and subsequent seizure activity. This is presumed to be secondary to the EEG desynchronization in REM sleep, likely acting to interrupt and suppress the spatial and temporal summation of epileptiform activity into seizures. There are case reports of occasional breakthrough of aforementioned phenomena within REM sleep; however, the goal of this study is to systematically evaluate all admissions to the Epilepsy Monitoring Unit (EMU) for activation of epilepsy in REM sleep. Methods: We conducted a retrospective review of patients admitted to the Health Sciences Centre Winnipeg EMU from 2014-2015 for cases with exacerbation of epilepsy in REM sleep. We then reviewed the continuous video-EEG (electroencephalogram) telemetry recordings of these identified patients, and conducted a detailed chart review of the two year periods both preceding and succeeding the admission itself, after which several parameters were compared and contrasted to assess for potential patterns associated with this unique patient population. More specifically, we looked at the patient age, gender, patterns of onset, family history, seizure semiology, seizure types, characteristic EEG findings, neurological examination findings, aura, localization, pathology, degree of treatment resistance, and seizure burden antecedent to the time of EMU admission. Emphasis was placed upon REM sleep time, epileptiform activity within REM sleep, and seizures recorded from REM sleep. Results: Out of 63 patients, we found only four patients (6%) ranging in age from 30-60 years admitted for 6-9 days in duration. Not one had a known history of status epilepticus prior to EMU admission, yet all demonstrated epileptiform activity and seizures in REM. Notably, one patient had continuous epileptiform activity throughout REM, which was consistent with electrographic status epilepticus. Total recorded REM sleep in the EMU varied from 19-286 minutes, with epileptiform activity occupying 10.1-100% of REM sleep in each patient. Total REM sleep-associated seizures (ranging 1-3/patient) comprised a fraction of total recorded seizures (16-38/patient) within the course of the EMU admission. Conclusions: Our case series highlights potential significant variability of the effect of REM sleep on epilepsy between individuals. In fact, all four of our subjects clearly demonstrated a paradoxical effect of REM sleep in which there was a proepileptic, rather than an antiepileptic effect, with paradoxical activation of interictal epileptiform discharges and seizures in REM sleep - even to the point of electrographic status epilepticus. Our findings suggest several hitherto unknown mechanisms in REM sleep's usual ability to protect against seizures and discharges, and their rare paradoxical activation, which merits further study. Funding: No funding