Abstracts

RATIONALE: Use of the vagal nerve stimulator (VNS) is associated with ~30% improvement in seizure activity in published reports. We sought to determine whether there was a difference in response to VNS treatment comparing patients without and with cognitive impairment. METHODS: Thirty eight patients had VNS placement at the Allegheny General Hospital Epilepsy Center between 1996 and 2000. Thirty patients with >3 mo use of the VNS were studied, 50% of them being cognitively impaired. Various seizure types and epileptic syndromes were included in the patient population. Retrospective chart review and telephone interviews were conducted to determine seizure frequency and severity, and quality of life (QOLIE) before and after placement of the VNS. The QOLIE scale was 1=very good, 2=good, 3=fair, 4=poor, and 5=very poor. Whole group statistics and those for patients without and with cognitive impairment were generated. RESULTS: For the entire group of 30 patients, 40% reported >50% reduction in seizure frequency and severity, 20% reported some improvement but <50% reduction, and QOLIE was improved in 47% of patients. The following statistics were obtained comparing patients without (w/o) and with (w) cognitive impairment: 1) >50% reduction in seizure frequency: 33%(w/o),47%(w); 2) <50% reduction in seizure frequency: 13%(w/o),26.5%(w); 3) No reduction in seizure frequency: 53%(w/o),27%(w); 4) Reduction in seizure severity was ~67% for both groups; 5) QOLIE was improved in 33%(w/o),60%(w). CONCLUSIONS: Use of the VNS resulted in improved seizure frequency and severity, and improved QOLIE in patients without and with cognitive impairment. Patients with cognitive impairment demonstrated greater improvement in seizure frequency and QOLIE compared to patients without cgnitive impairment. The improved QOLIE in cognitively impaired patients was not strictly associated with the degree of improvement in seizure control.