Programmed and magnet-induced vagus nerve stimulation for refractory epilepsy

Vagus nerve stimulation (VNS) is an effective alternative treatment for pat ients with refractory epilepsy. The generator produces intermittent stimula tion trains and does not require patient intervention. Using currently avai lable technology, continuous stimulation is incompatible with a reasonable battery life. Because earlier studies have demonstrated the persistence of a stimulation effect after discontinuation of the stimulation train, we int ended to evaluate the clinical efficacy of VNS in both the programmed inter mittent stimulation mode and the magnet stimulation mode. Patients, compani ons, and caregivers were instructed on how to administer additional stimula tion trains when an aura or a seizure onset occurred. We assumed that patie nts or caregivers could recognize habitual seizures and were able to evalua te sudden interruption of these seizures. During a mean follow-up of 35 mon ths, 46% of patients became responders, with a reduction in seizure frequen cy of more than 50%. Twenty-nine percent of patients stopped having convuls ive seizures. In two thirds of patients who were able to self-administer or receive additional magnet stimulation, seizures could be interrupted consi stently or occasionally. More than half of the patients who reported a posi tive effect of magnet stimulation became responders. Only three patients we re able to use the magnet themselves. In most cases, support from caregiver s was necessary. This study is the first to document the efficacy of magnet -induced VNS in a larger patient population during long-term follow-up. The magnet is a useful tool that provides patients who are treated with VNS an d mainly caregivers of such patients with an additional means of controllin g seizures. To further confirm the self-reported results from our patients, additional studies comparing programmed stimulation and magnet-induced sti mulation during monitoring conditions are needed.