Adjunctive vagus nerve stimulation (VNS) therapy may significantly reduce seizure activity for more than one-third of children with drug-resistant epilepsy, according to a large, retrospective, multicenter study, which was published in the October issue of Epilepsia.
Iren Orosz, MD, a pediatrician at the 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 VNS device. This group of patients included 19 (5.5%) who became seizure free and 111 (32.1%) who achieved a 50% to 99% reduction in seizure frequency. A total of 59 patients (17.1%) had a 25% to 49% reduction in seizures, and 136 patients (39.3%) had a seizure reduction of 25% or less.
The authors reviewed medical records for children who were implanted with a VNS therapy device between April 1995 and April 2010. The children were ages 6 months to 17.9 years at implantation. All patients had taken a mean of 6.9 antiepileptic drugs (AEDs) before implantation, and 45% of patients had predominantly generalized seizures. The investigators assessed the change in frequency of the children’s predominant seizure type from baseline, defined as the three months before device implantation, to 12 months after implantation. They defined treatment response as a reduction in baseline seizure frequency of at least 50%. The study authors also examined the incidence of adverse events and noted clinicians’ assessments of the patients’ health outcomes, quality of life, and seizures.
The rate of reduction in baseline seizure frequency of at least 50% increased over time from 32.5% at six months to 37.6% at 12 months and to 43.8% at 24 months. The rate of this outcome “was higher in a subgroup of patients who had no change in AEDs during the study,” said Dr. Orosz, who is a Visiting Assistant Professor in the Department of Radiologic 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,” she concluded.
—Amy Karon