Continuous positive airway pressure therapy for obstructive sleep apnea reduces interictal epileptiform discharges in adults with epilepsy

- Spike rate was compared at baseline and after CPAP in patients with epilepsy and OSA.
- PAP therapy reduced total, sleep, and wake spike rates in the absence of AED change.
- The reductions were observed in all sleep stages excluding REM sleep.
- PAP therapy produced a significant improvement in sleep continuity and nadir SPO2.
- OSA may increase epileptogenicity that can be reversed with PAP in epilepsy.

Obstructive sleep apnea (OSA) is highly prevalent, affecting 25% of men and 10% of women. We recently reported a prevalence of OSA of 30% among 130 adults with epilepsy unselected for sleep disorder complaints, including 16% with moderate-to-severe disease, rates that markedly exceed general population estimates. Treatment of OSA with continuous positive airway pressure (CPAP) therapy or upper airway surgery reduces seizures in many cases. A single study reported a reduction in interictal spike rate with CPAP in 6 patients with OSA. We explored the effect of CPAP therapy on spike rate in 9 adults with epilepsy and OSA. Interictal epileptiform discharges were quantified during a diagnostic polysomnogram (PSG) and a second PSG using therapeutic CPAP. Spike rates were calculated for each recording during wake and sleep stages. Continuous positive airway pressure therapy was associated with significant reductions in median (quartiles) spike rate overall (77.9 [59.7-90.7] %), in wakefulness (38.5 [0.3-55] %), and in sleep (77.7 [54.8-94.7] %) but not in REM sleep. Continuous positive airway pressure therapy also produced a significant improvement in oxygen saturation and arousals. Our work extends a single prior observation demonstrating beneficial effects of CPAP therapy on interictal EEG in patients with epilepsy with comorbid OSA and supports the hypothesis that sleep fragmentation due to OSA contributes to epileptogenicity.