Marna McKenzie
University of Manitoba
Objective There is a complex relationship between sleep and epilepsy that is not fully understood. While REM sleep generally tends to suppress interictal epileptiform discharges (IEDs) and seizures, some patients continue to have breakthrough IEDs during REM sleep. Our understanding of the effects, if any, of these breakthrough IEDs on clinical outcomes in patients with epilepsy is unclear. The purpose of this study is to determine if frequent epileptiform activity during REM sleep and/or less REM sleep overall in the Epilepsy Monitoring Unit (EMU) is associated with poor clinical outcomes. Methods EEG recordings from 63 patients in the adult epilepsy monitoring unit (EMU) over a 12-month period were retrospectively analyzed to calculate for each patient: (1) total duration of REM sleep and (2) proportion of epileptiform REM, defined as the proportion of REM sleep recorded that was comprised of IEDs or seizures. A detailed chart review from a four-year period (EMU admission +/- 2 years) was also performed. Multivariate linear regressions and Mann-Whitney U Tests were performed as appropriate. Results 59/63 (93.7%) patients achieved REM sleep during their EMU admission. The median duration of total REM sleep recorded was 43.3 (IQR 20.9 – 73.2) minutes per patient. 39/59 (66.1%) patients revealed breakthrough IEDs and/or seizures during REM sleep in the EMU. The median proportion of epileptiform REM was 0.7% (IQR 0 – 8.4%). Increased epileptiform REM was associated with an increase in peak seizure frequency – a 1% increase of epileptiform REM was associated with an increase of approximately two seizures per month (beta=2.0, p=0.006). Increased epileptiform REM was also associated with treatment-resistant epilepsy (median 2.7% epileptiform REM in treatment-resistant group, n=33 vs 0.01% in treatment-responsive group, n=26; unadjusted p=0.004) Significance Increased epileptiform activity during REM sleep is associated with an increased peak seizure frequency and treatment-resistant epilepsies. Clarifying the role and predictive power of epileptiform REM would be exceptionally meaningful for patients with epilepsy as it could improve patient education and allow for a better understanding of expectations throughout the disease course.
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