Abstracts

Rationale: Obstructive sleep apnea (OSA) commonly coexists with epilepsy, and treatment of OSA may decrease seizure frequency. It is not clear whether patients with refractory epilepsy have a higher prevalence of OSA. The purpose of this study was to compare the prevalence of OSA in patients with medically refractory vs. well-controlled epilepsy, and to determine whether there are any differences between these two populations concerning age, gender, body mass index (BMI), hypertension, diabetes, and smoking status. Methods: This is a retrospective chart review study of 286 epilepsy patients, 18-92 years of age, who were seen in consultation at the Comprehensive Epilepsy Center of the Jacobs Neurological Institute, University at Buffalo from 2005 to 2010. All patients had completed the same questionnaire which included Epworth Sleepiness Scale (ESS), seizure frequency (Engel Criteria), smoking status, and other co-morbidities. Patients who had recurrence of any complex partial or generalized seizure in a year despite compliance with seizure medications were classified as medically refractory (Engel seizure frequency of 5 or more). Seizure freedom was defined as lack of recurrence of any complex partial or generalized seizure in the past year. Student t-test was used to compare continuous variables. Chi square test was used for categorical variables to compare OSA, age, gender, BMI, hypertension, diabetes, and smoking status between the two groups. Significance was set at p < 0.05. Results: Out of 286 patients with a diagnosis of epilepsy, 151 (52.8%) were medically refractory by the study criteria, and135 (47.2%) had well-controlled epilepsy. Twenty-two (14.6%) patients with refractory epilepsy and 19 (14.1%) with well-controlled epilepsy had a confirmed OSA diagnosis based on polysomnography data. As previously reported in the literature for general population, we found that in our epilepsy population hypertension, diabetes, BMI > 30 and Age > 50 were significant factors in determining OSA. However, comparing the sub-population of medically refractory and well-controlled epilepsy patients, we did not find any significant difference with regards to the rate of OSA, age, gender, ESS, hypertension, diabetes, or smoking status. The only factor which was significantly different between the two sub-population was higher BMI in medically refractory (mean 28.6) compared to patients with well-controlled epilepsy (mean 26.93, p = 0.0435). The use of Continuous Positive Airway Pressure (CPAP) in the medically refractory epilepsy patients with OSA resulted in improved seizure frequency in 5 out of 13 (38%); however, in two of these patients other contributing factors to seizure freedom were identified. Conclusions: There is a much higher prevalence of OSA in our epilepsy population compared with the general population (14.3% vs. 4.41%). Although we did not find any significant difference of OSA prevalence in our patients with refractory epilepsy and well-controlled epilepsy, treatment of OSA in patients with refractory epilepsy improved their seizure control.