Abstracts

Rationale: To document long-term outcome of patients receiving vagus nerve stimulation (VNS) therapy for pharmacoresistant epilepsy at a University-based Epilepsy Center. Methods: We retrospectively reviewed records of patients who underwent VNS implantation and therapy at the University of Kentucky from November 1997 to December 2006. There were 119 patients implanted with a VNS, of whom 101 provided usable data. We collected data regarding demographics, seizure types, epilepsy classification, and number of antiepileptic drugs (AEDs). We also reviewed VNS parameters, seizure frequency and side effects from VNS at one month, three months, six months, one year and two years. Results: Of the 101 patients, 39 were men and 62 were women. Median age at the onset of seizures was 5 years (range birth to 57 years old). Median age at implantation was 33 years (range 8 years old to 63 years old). Eighty two patients had partial epilepsy and 19 had generalized epilepsy. The VNS was explanted in3 patients and 3 additional patients had their VNS turned off. There was no change in the mean number of AEDs at 1 year and 2 years compared to baseline. We noted maximal improvement in seizure frequency at 3 months in most patients and this was mostly sustained at 1 year. VNS was well tolerated and the device was not explanted or turned off in any patient due to side effects. Statistical analysis and further details regarding seizure characteristics and modification of VNS parameters will be provided. Conclusions: In this retrospective study, the effectiveness of VNS therapy was noted in several seizure types. VNS was effective in pediatric and adult patients and was well tolerated. Maximal improvement in seizure frequency was reached at 3 months of therapy in most patients and the improvement was mostly sustained at 1 year.