Adjunctive vagus nerve stimulation therapy significantly reduced seizure activity for more than a third of children with drug-resistant epilepsy in the largest retrospective, multicenter study of the therapy to date.
Dr. Iren Orosz of Medical University of Lübeck, Germany, and her colleagues at 11 medical centers across Europe found that 130 (37.6%) of 346 patients with drug-resistant epilepsy had at least a 50% reduction in seizures 12 months after being implanted with a vagus nerve stimulation (VNS) device. This included 19 (5.5%) who were rendered seizure free and 111 (32.1%) who achieved a 50%-99% reduction in seizure frequency. A total of 59 patients (17.1%) had a 25%-49% reduction in seizures and 136 patients (39.3%) had a seizure reduction of 25% or less.
The authors reviewed medical records of children who were implanted with a VNS Therapy device during April 1995-April 2010. The children were aged 6 months to 17.9 years at implantation. All patients had a mean of 6.9 antiepileptic drugs (AEDs) prior to implantation; 45% had predominantly generalized seizures. The investigators assessed the change in frequency of the children’s predominant seizure type from baseline, defined as the 3 months prior to device implantation to 12 months after. They defined response as a reduction in baseline seizure frequency of at least 50%. Authors also assessed the incidence of adverse events, and noted clinicians’ assessments of the patients’ health outcomes, quality of life, and seizures (Epilepsia 2014 Sept. 17 [doi:10.1111/epi.12762]).
The rate of reduction in baseline seizure frequency of at least 50% increased over time from 32.5% at 6 months to 37.6% at 12 months to 43.8% at 24 months and “was higher in a subgroup of patients who had no change in antiepileptic drugs during the study,” wrote Dr. Orosz and her coauthors. Dr. Orosz currently works as a visiting assistant professor in the department of radiological sciences at the University of California, Los Angeles.
Responder rates were “comparable to rates from randomized controlled trials of new AEDs in adult and pediatric patients with drug-resistant epilepsy,” the authors wrote.
The study was supported by Cyberonics, the manufacturer of VNS Therapy. Some of the authors are employees of, or have received grant support, consultant fees, or speaker honoraria from, the company.