Abstracts

Patients with intractable epilepsy are candidates for several therapeutic options. Physicians may have difficulty assessing the potential risks and benefits of one therapy as compared with another. We performed this pilot study to assess the risks and potential benefits of vagus nerve stimulation (VNS) therapy as compared with the addition of a new antiepileptic drug (AED).
This was a prospective nonrandomized open-label cohort pilot study of the addition of VNS therapy versus the addition of one of three recently approved AEDs (Topamax, Lamictal, or Gabitril). 16 patients with refractory epilepsy were enrolled. Therapy (VNS or AED) was chosen by patients in consultation with their treating physician. Changes in AEDs were allowed as clinically indicated. Patients were followed for up to 14 months. Outcome measures included seizure rates, side effects as assessed by VA toxicity rating scales with questions added specific to VNS therapy, and quality of life as assessed by QOLIE-31.
Seven of the sixteen patients enrolled in the study elected the AED arm and 9 elected the VNS therapy arm. Between-group comparisons were performed using the Wilcoxon[rsquo]s rank-sum test. At baseline, patients in both groups had a median of 2.0 AEDs. The median age of the patients in the AED arm was 32 years, and the median age for the VNS arm was 30 years. Patients in the AED arm had a median of 17 years of epilepsy compared with 15 years in the VNS arm. The AED patients had a median of 6.0 failed prior AED treatments, and the VNS patients had a median of 8.0. The patients who elected VNS appeared sicker at baseline. Median monthly seizure frequency at baseline was 5 seizures per month for the AED arm (range, 3 to 16) versus 16 (range, 6 to 190) for the VNS arm (p=0.038). Median QOLIE-31 scores at baseline were 57.8 for the AED arm versus 48.8 for the VNS arm. Median VA neurotoxicity rating at baseline was 12.5 (range, 0 to 55) for the AED arm (n=6) versus 51 for the VNS arm (range, 10 to 65) (p=0.088).
At the last recorded visit for each patient, 4 patients in the VNS arm (44%) versus 3 patients in the AED arm (43%) had a 50% reduction in seizures (p=NS). Median change in the QOLIE-31 was a 0.4% score decrease for the AED arm and a 4.0% score increase (improvement) for the VNS arm (p=NS). Median change on the VA toxicity scale was a 20.0% worsening in the AED arm (n=6) compared with a 66.7% improvement on VNS therapy (p=0.047).
This pilot study demonstrated no significant difference between VNS and AED therapy on seizure outcome or quality of life, but a significant difference in favor of VNS therapy in regards to toxicity. However, the study is confounded by the small number of patients and the differences in the populations at baseline. Results of this study highlight the need for a randomized comparison trial of VNS therapy versus AEDs with a larger number of patients.
[Supported by: Cyberonics, Inc.]