Abstracts

Objective: To assess the efficacy of treating medically intractable epilepsy with vagal nerve stimulation (VNS) and its effects on behavioral adjustment. Methods: Eighteen patients between the ages of 9 and 24 (mean 16.2 years) were implanted and followed closely between two and twenty-two months. Medication and VNS parameters were adjusted by pediatric neurology for optimal seizure control. The Nisonger Child Behavior Rating Form was used to assess post-implantation behavioral adjustment at regular follow-up intervals. Results: Three out of 18 patients had >75% reduction in seizures, four had a 50% reduction, five had less than 50%, and five had no change. One patient had worsening of his seizure disorder. Seven patients had Lennox-Gastaut syndrome: Two had >75% improvement, two had <50%, and three were unchanged. Three patients had prior corpus callosotomies: One patient initially had a 90% improvement at 13 months post-implant, but at 22 months returned to the pre-implant seizure frequency; another patient has an >75% improvement at 15 months post-implant, and the third patient is unchanged at 9 months post-implant. Improvements in behaviour did not always correlate with better seizure control. There were no surgical complications. Conclusion: VNS is an emerging option for treatment of medically intractable seizures, not necessarily restricted to partial seizures but also to seizure disorders that persist after epilepsy surgery. Effects on behaviour may not be dependent on seizure control. Our preliminary results are not as encouraging as those documented by others. A tremendous degree of variability of the seizure disorder with time was found, especially when anticonvulsant medication were adjusted, added, or changed. It seems that VNS is an additional modality toward seizure control, but its efficacy is highly variable.