Obstructive sleep apnea in drug-resistant epilepsy: A significant comorbidity warranting diagnosis and treatment

Abstract

Introduction: Drug-resistant epilepsy is a debilitating condition that warrants new therapeutic options. The last two decades have seen a growing interest in the relationship between epilepsy and obstructive sleep apnea syndrome (OSAS), which could ultimately yield non-pharmaceutical treatment strategies. Based on a Medline search of the literature, this review develops lines of evidence for a clinically significant role of OSAS in refractory epilepsy.

State of the art: OSAS is a primary sleep disorder that could presumably lower the seizure threshold via mechanisms such as sleep fragmentation, oxygen desaturation and chronic sleep deprivation. In comparison to the general population, patients with epilepsy probably have a higher prevalence of OSAS (9-33 % overall; 13-16 % with moderate to severe OSAS). Several common risk factors for OSAS have proven to be significant in patients with epilepsy, notably advanced age, male gender and obesity. Moreover, certain specific conditions, such as refractory seizures, antiepileptic polytherapy and vagus nerve stimulation, appear to render these patients particularly vulnerable to OSAS. Prospective data regarding the efficacy of continuous positive airway pressure (CPAP) therapy for seizure control is scarce. However, there is compelling retrospective evidence that severe OSAS can exacerbate the seizure burden and that CPAP may yield a pronounced reduction in seizure frequency, excessive daytime somnolence and, potentially, cognitive complaints.

Perspectives: In the light of the severity of drug-resistant epilepsy and its impact on quality of life, our current knowledge justifies systematic questionnaire screening for OSAS and a low threshold for referral to sleep laboratory exploration. In the long run, a large prospective trial is needed to confirm the therapeutic interest of CPAP treatment for mild to moderate OSAS in patients with epilepsy.

Conclusion: OSAS is a significant comorbidity of drug-resistant epilepsy that has the potential to yield new treatment options for better seizure control.

Keywords: Continuous positive airway pressure; Epilepsy; Nocturnal frontal lobe epilepsy; Obstructive sleep apnea; Vagus nerve stimulation.