Abstracts

Vagus nerve stimulation (VNS) has been reported to improve daytime sleepiness in patients with epilepsy when measured at 3 months post-treatment, however the long term effects of VNS on excessive sleepiness are unknown. To assess whether VNS results in sustained and clinically relevant improvements in excessive daytime sleepiness (EDS), we measured patients[apos] daytime sleepiness levels before and after the use of VNS., Patients seen by a single epileptologist (AV) in the Baylor Comprehensive Epilepsy Center completed questionnaires for the Epworth Sleepiness Scale (ESS) prior to beginning VNS and at periodic intervals thereafter. The ESS is a standardized and validated scale used to assess sleepiness. A score of greater than 10 is indicative of excessive daytime sleepiness (EDS). To determine if VNS results in a clinically significant improvement in daytime functioning, we examined the effect of VNS on sleepiness in patients who suffered from EDS prior to VNS. Only improvements in the ESS to levels less than 10 were considered clinically meaningful. Medication dosage and seizure frequency were evaluated to determine if they influenced ESS scores., Eighteen consecutive patients with refractory epilepsy who underwent implantation of a vagus nerve stimulator were asked to participate in this study and 14 complied. The mean age of patients who participated in the study was 32 years (range 17-63; Male:5, Female:9). Mean follow-up period was 13 months (range 3-32 months). The mean pre-implantation ESS score for all enrolled patients was 11.8. The mean post-implantation scores at approximately 3 months, 6 months and 12 months were 9.8, 9.6 and 10.1 respectively. Eight of the 14 patients had pre-implantation EDS (ESS score greater than 10). Of these eight EDS patients, four never exhibited meaningful improvement in their ESS at any time-point after VNS was initiated, while two had transient improvements and only two had sustained improvement at last follow-up. This could not be explained by medication changes or changes in seizure frequency., VNS may reduce daytime sleepiness in patients with epilepsy. The effects in our patients were not as robust as have been previously reported and the effects may also not be sustained., (Supported by Peter Kellaway, PhD Foundation for Research. We would like to thank Elizabeth Miae Kim for her help with data collection.)