LONG-TERM OUTCOME OF PATIENTS RECEIVING VAGUS NERVE STIMULATION: EXPERIENCE AT AN EPILEPSY CENTER
Abstract number :
3.287
Submission category :
Year :
2002
Submission ID :
1371
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Marianna V. Spanaki, Linda S. Allen, Wade M. Mueller, George L. Morris III. Neurology, Medical College of Wisconsin, Milwaukee, WI; Neurology, St Luke[ssquote]s Regional Epilepsy Center, Milwaukee, WI
RATIONALE: To describe the long-term outcome of patients receiving vagus nerve stimulation (VNS) Therapy.
The efficacy of VNS Therapy is widely thought to continue to improve through the first 12 months, but reports of long-term outcome are scarce. This study traces the 5-year and greater outcome of VNS patients followed at an epilepsy center.
METHODS: We reviewed records to identify and characterize patients receiving VNS Therapy for 5 years or more and followed at our university-based epilepsy center. We compared changes in seizure frequency between baseline and 1 year, between baseline and long-term follow-up (ranging from 5 to 7 years), and between 1 year and long-term follow-up with the Wilcoxon signed rank test.
RESULTS: Twenty-six patients receiving VNS Therapy and followed for at least 5 years were included in the study. Epilepsy syndrome was classified as partial epilepsy in 23 patients, as primary generalized epilepsy in 2, and as atypical absence in 1. Median patient age was 40 years (range, 23 to 60). Median age at onset of epilepsy was 8 years (0 to 44). Median number of antiepileptic drugs (AEDs) was 2 (0 to 4) at baseline, 1 year, and long-term follow-up. At baseline, the median number of seizures per month was 16.5 (2 to 2800). After 1 year of VNS therapy, the median reduction in seizure frequency was 27.6% (-100 to 100) (p=0.0053), at long-term follow-up, 72.5% (-100 to 100) (p[lt]0.0001), and from 1 year to long-term follow-up, 33.3% (100 to 0) (p[lt]0.0001). After 1 year of VNS Therapy, only 6 patients had no changes in seizure frequency or type. However, by long-term follow-up, seizure frequency had decreased for 4 of the 6. In addition, between 1 year and long-term follow-up, seizure frequency decreased for 19 of the 26 patients. By long-term follow-up, 22 of the 26 patients had experienced at least a 50% reduction in seizure frequency.
CONCLUSIONS: Although the median number of AEDs remained constant, median seizure frequency declined after patients in this study completed 1 year of VNS Therapy. Most patients with unchanged seizure frequencies after 1 year did experience reductions by long-term follow-up. Therefore, the seizure-reducing effect of VNS Therapy seems to continue beyond 1 year. On the basis of these findings, we suggest that physicians continue VNS Therapy in patients who have not shown a response after 1 year.