BALTIMORE -- Surgery is still the best option for drug-refractory epileptic patients, but vagus nerve stimulation continues to look promising for those patients who aren't easy candidates for resective surgery, Dr. Christian Elger said at a conference on clinical electrophysiology sponsored by the EEG and Clinical Neuroscience Society.
The idea is for patients to wear a self-controlled vagus nerve stimulation (VNS) device that can be activated the moment they experience the onset of aura to indirectly stimulate the brain and prevent an epileptic seizure. The device, which looks much like a pacemaker, can be implanted, leaving a small scar.
Efficacy rates vary depending on the population. However, many studies indicate response rates in the 45%-50% range for drug-refractory patients. Patients are considered "responders" if they cut their seizure frequency by half or more, explained Dr. Elger, professor and chair of the department of epileptology at the University of Bonn (Germany).
Children sometimes do even better. In an Australian study involving 16 children and adolescents with refractory epilepsy, 63% reduced their seizure frequency by at least half and 25% achieved at least 90% reductions (Acta Neurol. Scand. 105:13-17, 2002).
But in another study conducted by Dr. Elger and his colleagues among 100 adults and 32 children who underwent VNS, at 3 months 48% of the adults responded, compared with only 20% of the children.
Yet regardless of the patient population, all studies seem to indicate that the duration of VNS therapy appears to be the most important determinant in the treatment's success. Importantly, it can take more than a year to achieve maximum improvements possible from vagus nerve stimulation, a fact that's made it a difficult sell to third-party payers, he added.
Yet it's clear that in some patients, the wait does pay off. In a registry-based study involving about 5,900 patients who underwent the nerve treatment, at 3 months follow-up, 23% of patients had cut their seizures by at least half. …