Vagus nerve stimulation for epilepsy, clinical efficacy of programmed and magnet stimulation.
ABSTRACT Vagus nerve stimulation (VNS) by intermittent and programmed electrical stimulation of the left vagus nerve in the neck, has become widely available. It is an effective treatment for patients with refractory epilepsy. Patients can be provided with a magnet that allows to deliver additional stimulation trains. Since earlier studies have demonstrated the persistence of a stimulation effect after discontinuation of the stimulation train, we evaluated the clinical efficacy of VNS both in the programmed intermittent stimulation mode and magnet stimulation mode.
A group of 30 patients (16 F, 14 M) with medically refractory partial epilepsy, who were unsuitable candidates for resective surgery, were included in the study. The patients, their companions and caregivers were instructed on how to administer additional stimulation trains using a hand-held magnet when an aura or a seizure onset occurred. Patients or caregivers could recognize habitual seizures and were able to evaluate sudden interruption of these seizures. Using seizure diaries, detailed accounts of magnet use and regular clinic follow-up visits, data on seizure frequency and severity and number of magnet applications were collected. Patients who provided unreliable information were excluded from the analysis.
Forty-seven percent of all patients had an improvement in seizure control with a reduction in seizure frequency of more than 50% during a mean follow-up of 33 months (range: 4-67 months). More than half of the patients used the magnet and provided reliable information. In 63% of patients who were able to self-administer or receive additional magnet stimulation, seizures could be interrupted, be it consistently or occasionally. More than half of the patients who reported a positive effect of magnet stimulation became responders. In most cases the magnet was applied by a caregiver.
To our knowledge, this study is the first to explore the efficacy of magnet-induced vagus nerve stimulation. Results suggest that the magnet is a useful tool that provides patients and mainly caregivers with an additional means of controlling refractory seizures. Additional controlled studies comparing programmed stimulation and magnet-induced stimulation in monitoring conditions are warranted.
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ABSTRACT: Neurostimulation as a treatment for epilepsy has been around for almost 20 years in the form of vagus nerve stimulation. Newer types of neurostimulation are being developed and stand on the brink of approval for use. The two newest therapies, not yet approved in the United States, are deep brain stimulation and the Responsive Neurostimulator System . In fact, in Europe, approval has already been given for deep brain stimulation and newer forms of vagus nerve stimulation. Efficacy is similar between these therapies, and side effects are moderate, so what will be the future? The challenge will be to learn how to use these therapies correctly and offer the right treatment for the right patient.Epilepsy currents / American Epilepsy Society. 09/2012; 12(5):188-91.
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ABSTRACT: The purpose of this study was to evaluate long-term seizure reduction and on-demand magnet use in children and adolescents with drug-resistant epilepsy who were treated with vagus nerve stimulation therapy. Fifty-seven children and adolescents under 18 years of age with drug-resistant epilepsy were implanted with a vagus nerve stimulation therapy device. Seizure reduction was evaluated at 6, 12, 24, 36, and 48 months after implantation. Magnet effect on seizure frequency was evaluated during the first week after implantation and after 6, 12, 24, 36, and 48 months of treatment. The mean reduction in seizure frequency compared with baseline was significant at all time points up to 48 months post-implantation. At 12 months, the average reduction in seizure frequency was 52.4%, and at 48 months, it was 53.1% (observed case analysis). The use of a magnet to deliver extra "on-demand" stimulation between cycles resulted in cessation of seizures in 16.1% of patients, partial effect in 73.2%, and no effect in 10.7%, when evaluated within 1 week of implantation. The magnet effect decreased slightly with increasing time after implantation. A sub-analysis of children ≤12 years of age (N = 34) showed similar results after 36 months of follow-up. The therapy was well tolerated regardless of age. Vagus nerve stimulation therapy is a safe and effective adjunctive treatment for children and adolescents of all ages with drug-resistant epilepsy.Child s Nervous System 01/2012; 28(4):621-8. · 1.24 Impact Factor
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ABSTRACT: In spite of the high success rate of many surgical procedures for pharmacoresistant epilepsy, a substantial number of patients do not become seizure-free. Different strategies for electrical modulation of the brain such as Deep Brain Stimulation, Vagal Nerve Stimulation and Transcraneal Magnetic Stimulation have gained considerable interest in the last decade as alternative therapies for patients with medically refractory epilepsy. Research into the mechanism of action of the strategies for electrical modulation of the brain suggests a crucial role of different molecules and channels such as glutamate, γ-aminobutyric acid, adenosine, brain-derived neurotrophic factor, calcium channels, sodium channels as well as extracellular potassium. Electrical modulation of the brain may reduce the overexpression of P-glycoprotein, a drug efflux transporter that reduces the absorption of antiepileptic drugs. Electrical modulation of the brain induces long-term effects associated with beneficial consequences on clinical symptoms observed during the postictal state. In addition, electrical modulation of the brain might also promote the neurogenesis in subjects with pharmacoresistant epilepsy in whom this process is decreased. Targeting the regulatory pathways in charge of the effects of electrical modulation of the brain is discussed as a means to improve its efficacy. Electrical modulation of the brain combined with pharmacotherapy may represent an innovative approach to avoid epileptogenesis, reduce seizure activity, induce beneficial effects during the postictal state, diminish the amount of antiepileptic drugs, and improve alertness, memory and mood in pharmacoresistant epilepsy.Pharmacology [?] Therapeutics 01/2013; · 7.79 Impact Factor