More Indications for VNS Treatment

January 21, 2005

Encouraging research emerged last month regarding vagus nerve stimulation (VNS) for the treatment of epilepsy patients. About 25 different presentations at the American Epilepsy Society’s annual meeting in New Orleans focused on VNS. The FDA approved VNS Therapy in July 1997 as an adjunctive treatment for adults and children older than 12 years with partial-onset seizures and resistance to antiepileptic drugs. Marketed by Cyberonics Inc, of Houston, Tex, VNS Therapy is the only FDA-approved electrical stimulation device for epilepsy. The device, which resembles a pacemaker, provides intermittent electrical stimulation to a patient’s left vagus nerve, which, in turn, activates areas of the brain. It is implanted in the left chest area, and wires run under the skin to the nerve in the neck.

Encouraging research emerged last month regarding vagus nerve stimulation (VNS) for the treatment of epilepsy patients. About 25 different presentations at the American Epilepsy Society's annual meeting in New Orleans focused on VNS. The FDA approved VNS Therapy in July 1997 as an adjunctive treatment for adults and children older than 12 years with partial-onset seizures and resistance to antiepileptic drugs. Marketed by Cyberonics Inc, of Houston, Tex, VNS Therapy is the only FDA-approved electrical stimulation device for epilepsy. The device, which resembles a pacemaker, provides intermittent electrical stimulation to a patient's left vagus nerve, which, in turn, activates areas of the brain. It is implanted in the left chest area, and wires run under the skin to the nerve in the neck. In one of the presentations, a Cleveland Clinic Foundation group of researchers looked into how VNS Therapy can be used for children younger than 12. The investigators examined the records of 22 patients who had VNS device implantation at the Cleveland Clinic between 1997 and 2003. "What we're finding is that it works in both children and adolescents and our feeling is that it works better than it does in the adult group," Prakash Kotagal, MD, who led the study, told Applied Neurology. "The under-12 group does even better than the adolescent group." All of the patients had been receiving antiepileptic medication, but their particular cases were resistant to drug therapy. With VNS treatment, the median seizure frequency reduction amounted to 60% at 3 months after implantation and 71% after 6 months, with 2 patients becoming seizure-free 6 to 12 months after implantation. Adversely, however, postoperative wound infection developed in 3 patients, and the device was explanted from 2 of them within 3 to 5 weeks. (Alexopoulos AV, Loddenkemper T, Pestana E, et al. Vagus nerve stimulation in preadolescent children with pharmacoresistant epilepsy. Epilepsia. 2004;45[suppl 7]:152). "VNS is a useful treatment modality, especially for patients who are not candidates for epilepsy surgery and the other treatments have failed. The good thing is that people who respond to that maintain the response, which tends to get better over time," Kotagal said. "It doesn't work for everybody. You have to select candidates carefully," he added. A higher infection rate was noted in mentally retarded individuals, suggesting that it might be prevented by taking additional precautions to protect the incision. He also explained that in some cases with negative results referred to the Cleveland Clinic, he has noticed a lack of appropriate physician monitoring after implantation. "It is necessary to work with the device intensively over the first year or two to optimize the response," he said. Another presentation at the epilepsy meeting involved a Salt Lake City team of investigators who, after reviewing demonstrative evidence regarding the efficacy of VNS in patients with refractory partial epilepsy, studied whether the treatment had efficacy in patients with refractory primary generalized epilepsy. They followed the records of 102 patients seen in the VNS clinic at the University of Utah Hospital in September 2003. Of those patients, 13 had been diagnosed with primary generalized epilepsy and had the VNS device implanted between 2000 and 2003. Of the 13 patients, 6 (46%) experienced a reduction in frequency of generalized tonic-clonic (GTC) seizures, 3 had no change, and 4 had an increase in GTC seizure frequency 6 months after implantation. But for those who did experience a reduction, the average decrease in seizure frequency amounted to more than 72%. The researchers recorded a 78% frequency reduction after 24 months in 7 of the 9 patients for whom data were available. (Shen Y, Constantino T, Matsuo F, Lorie B. Efficacy of vagal nerve stimulation in treating patients with medically refractory primary generalized epilepsy. Epilepsia. 2004;45[suppl 7]:149).