Rapid eye movement sleep without atonia in patients with sleep-related fronto-temporal epilepsy

Interictal epileptiform discharges (IEDs) increase during non-rapid eye movement (NREM) sleep, and decrease or disappear in REM sleep, especially during phasic REM sleep. REM sleep without atonia (RSWA), and its possible effects on IEDs, has not yet been studied.

A retrospective review of 10-year data retrieved 205 adults with fronto-temporal epilepsy, with full clinical data, 18-channel EEG and polysomnography. Tonic and phasic REM sleep periods were analyzed, and REM atonia was scored with the latest criteria. EEG recordings and IEDs were also re-evaluated in NREM sleep from the first and second halves of the night, and during phasic/tonic REM, and RSWA periods.

RSWA was detected in 31 patients (15.1%) with epilepsy. Total number of IEDs was 18.2 ± 9.5, being significantly higher in patients with treatment-resistant epilepsy (TRE) than in those without TRE (p = 0.046). The number of IEDs was significantly higher in tonic REM than in phasic REM (p = 0.001). Patients with RSWA had more IEDs in phasic (p = 0.003) and tonic (p = 0.037) REM. The number of IEDs in phasic REM periods in patients without RSWA was significantly lower in patients without TRE in compared to those with TRE (p = 0.044). IEDs in REM sleep were significantly more common in patients with RSWA, mainly in tonic REM periods, and in patients with TRE.

Our data demonstrate for the first time that the suppressing role of REM atonia on IEDs was diminished or lost in the presence of RSWA, including being more prominent in patients with TRE.