Abstracts

Rationale: The efficacy, tolerability and complications of VNS were analyzed retrospectively among patients with refractory epilepsy. Methods: All patients in whom VNS implantation had been carried out in our centre between June 1999 and February 2008, and who had at least one year of follow up were included. The primary outcome variable was the percentage reduction in total seizure frequency at a minimum of 18 months post implantation, compared with the preimplantation baseline. Seizure frequency was recorded at each follow-up visit from seizure calendars or from family recall, if the former was not available. Self reported quality of life and any adverse effects of the treatment were assessed. Patients were considered as responders when they had at least 50% decrease in seizure frequency at 1 year post implantation. Results: Sixty seven patients underwent implantation of VNS of which fifty five patients met the study inclusion criteria. The mean follow-up period was 3.8 years (range 1.6 -8 years). 45 % of patients (N=25) were considered as responders. 9 patients (16%) experienced a change in seizure pattern (1developed non epileptic attacks, 1 had change in seizure diurnal pattern and 7 had severe generalized seizure changed to milder form). 58% (N=32) of patients self reported improvement in quality of life while 7% (N=4) felt an increase in self awareness. 12% (N=7) patients underwent generator replacement. Conclusions: Long term efficacy and tolerability of VNS is maintained over several years. VNS may be an efficacious and safe mode of adjunctive treatment that could be offered to patients with medically and surgically refractory seizures. There are no predictive clinical characteristics of who will respond to treatment