Vagus nerve stimulation versus “best drug therapy” in epilepsy patients who have failed best drug therapy

Vagus nerve stimulation versus ''best drug therapy'' in epilepsy patients who have failed best drug therapy I would like to thank Dr. Hoppe and colleagues for their recent study published in Seizure examining vagus nerve stimulation (VNS) versus ''best drug therapy'' in medically refractory epilepsy patients. 1 However, I have concerns regarding the authors' methodology and conclusions. In this retrospective matched pairs case–control study, 20 intractable epilepsy patients who received VNS in addition to best medical therapy experienced no additional therapeutic benefit after >2 years compared to 20 individuals who received best medical therapy alone. Both groups were retrospectively selected from a significantly larger pool of patients found to be poor candidates for resective epilepsy surgery after having failed medical therapy. Thus, the essence of the question posed is: do patients who fail best drug therapy benefit more from further best drug therapy or from VNS? As both groups experienced clinical improvement in this study, with lower seizure frequency and improved psychological outcome, the authors imply VNS is no better than best medical therapy alone for medically refractory epilepsy. This sentiment is also reflected in Dr. Hoppe's recent editorial in Seizure provocatively entitled ''Vagus nerve stimulation: Urgent need for the critical reappraisal of clinical effectiveness .'' 2 My concerns involve study design, equivalency of the two patient groups, inflated outcomes in the control group, and wider implications of over interpreting a spurious finding. The authors argue that while nearly all previous VNS patient studies have shown a degree of efficacy, those investigations did not adequately examine therapeutic effectiveness, as they did not contain a control group. What is not clear, however, is why control patients in this study – those receiving best drug therapy alone – improved so dramatically during the period of observation. Does best medical therapy truly result in a >50% decrease in seizure frequency in >60% of patients who are already medically refractory? It is well documented that after failing 2 or more antiepileptic medications, intractable epilepsy patients are unfortunately unlikely to achieve seizure freedom with additional medication trials. 3,4 And while several new anti-seizure medications have become available since 1990, 5 these novel agents have had only a modest impact on the rate of intractable epilepsy. 6–8 One potential explanation for the apparent success of best drug therapy described by Hoppe et al. is that the patients were not already receiving ''best drug therapy'' before the …