Sleep-disordered breathing and excessive daytime sleepiness in patients with epilepsy - a polysomnographic study

Epilepsy and sleep-disordered breathing (SDB) are relatively common disorders. SDB induces repetitive arousals and sleep fragmentation and may cause symptomatic epileptic seizures or hypoxic encephalopathy. Epileptic seizures change sleep architecture with increase of light sleep and reduction of REM sleep, which may lead to central apneas. The aim of this study was to evaluate the relationship between SDB and daytime sleepiness in patients with epilepsy, who underwent polysomnography (PSG) due to problems with breathing during sleep or due to excessive daytime sleepiness.

We enrolled 40 patients with epilepsy. Type, etiology of epilepsy and actual antiepileptic therapy was recorded. All of them underwent overnight PSG. Excessive daytime sleepiness (EDS) was assessed by Epworth Sleepiness Scale (ESS).

SDB (apnea-hypopnea index [AHI]<5) was present in 25 patients, 15 patients had no SDB (AHI≥5). EDS was present in 16 patients (40%). ESS significantly correlated with presence of symptomatic epilepsy (r=0.385, p=0.014), presence of SDB (r=0.524, p=0.001), AHI (r=0.416, p=0.003) and duration of REM sleep (r=-0.476, p=0.002). The presence of SDB (beta=0.447, p=0.002) and duration of REM sleep (beta=-0.308, p=0.029) were the only independent variables significantly associated with ESS in regression analysis.

SDB has negative influence on quality of sleep and daytime vigility in patients with epilepsy. Sleep fragmentation with the reduction of the REM sleep seems to be the most important mechanism leading to EDS. We suppose that PSG could be beneficial in all patients with epilepsy and EDS.