Abstracts

Rationale: Recent evidence suggests that obstructive sleep apnea (OSA) affects up to one-third of patients with epilepsy, strikingly higher than the general population and potentially increasing the risk of medical intractability (Malow et al., 2003; Manni et al., 2003). Several studies have shown that treatment of OSA can improve seizure control. In one study, treatment of OSA with CPAP normalized the apnea-hypopnea index (AHI) and markedly reduced spike rate in a small number of patients (Oliveria et al., 2000). We report two cases of refractory focal epilepsy and co-morbid OSA in whom video polysomnography with EEG (VPSG) was performed prior to and after initiation of therapeutic CPAP aiming to assess the impact of CPAP on the frequency of interictal discharges. Methods: Case 1 underwent routine VPSG at baseline and after one month of stable CPAP therapy. Case 2 had been diagnosed with OSA and treated at an outside facility and underwent two consecutive nights of VPSG (with and without therapeutic CPAP) during a presurgical VEEG evaluation. Spikes were quantified for the night recording and spike rate (spikes per min) was calculated by sleep stage. Night 1 was without CPAP; Night 2 was with CPAP. Results: Results Variable Case 1 Case 2 Night 1 Night 2 Night 1 Night 2 Overall count 738 243 687 52 Spike Rate WASO 11.78 0.30 0.11 0.02 Stage 1 9.76 4.8 13.88 1.11 Stage 2 7.95 2.69 27.55 1.92 SWS 0 0 0 0 REM - - 0.69 0.13 Total Sleep Time (min) 290 314 410 301 Sleep Efficiency 63.3 87.3 70.0 95.2 Sleep Latency (min) 3.0 15.0 4.5 1.0 WASO (min) 133 17.5 112 19 Stage 1 (%) 4.3 2.5 1.8 0.9 Stage 2 (%) 86.9 85.2 52.1 63.3 SWS (%) 0 0 23.7 22.8 REM (%) 8.8 12.3 22.4 13.0 Arousals 46 57 63 40 Awakenings 31 3 24 4 Arousal Index 9.5 4.5 8.0 9.2 Stage Shifts 92 68 81 49 AHI overall 17.9 0.0 14.9 0.0 AHI REM 35.3 0.0 40.4 0.0 AHI Supine 17.1 0.0 25.2 0.0 Conclusions: These preliminary data support the concept that OSA increases excitability in the epileptic brain. Reversal of sleep fragmentation and sleep deprivation with CPAP may explain these findings. Further studies are needed to determine the potential role and effect of CPAP in the treatment of epilepsy. (Funded by Cleveland Clinic.)