The Correlation Between Vagus Nerve Stimulation Efficacy and Partial Onset Epilepsies

Abstract

PURPOSE: To evaluate the correlation between vagus nerve stimulation (VNS) efficacy and partial seizures originating from different brain regions. MATERIALS AND METHODS: The authors retrospectively analyzed the data of 46 subjects with medically intractable epilepsy who had insertion of VNS between April 1999 and July 2005. The clinical outcome was assessed with Engel classification. Subjects were divided into group A (Engel I, II, and III) and group B (Engel IV) for statistical analysis. Group A was referred as a satisfactory outcome. The statistical analysis of the data was assessed whether these parameters such as age, type of seizure, age at insertion of VNS, and lengths of follow-up affect the outcome. RESULTS: Nineteen patients (41.3%) had a satisfactory outcome (Engel II, III). The analysis of VNS efficacy demonstrated that 65% of the patients with frontal lobe epilepsy and only 15% of the patients with temporal lobe epilepsy (TLE) had a satisfactory outcome. There was a statistically significant difference between these types of epilepsyand VNS outcomes (Fisher exact test, P = 0.004). CONCLUSION: VNS is more effective in frontal lobe epilepsy than in temporal lobe epilepsy. Further studies are warranted to verify our findings and the correlation between types of epilepsy and VNS outcome.