Today on Neurology Update I’d like to discuss the treatment of drug-resistant epilepsy with responsive neurostimulation or RNS.
RNS is a battery-powered device implanted in the skull connected to one or two electrodes. When an electrode detects abnormal electrical activity, the device responds with an electric shock to prevent the development of an epileptic seizure. It’s the same principle as an automatic implanted, cardiac defibrillator.
Approximately 30% of people with epilepsy are drug-resistant.1 Removal of the seizure focus by epilepsy surgery is the most definitive treatment for these patients. However, many drug-resistant patients may not be surgical candidates because of multiple epileptic foci, location of the epileptic focus in eloquent cortex, or other considerations.
In addition to RNS, FDA approved neuromodulation treatment for drug-resistant epilepsy includes vagus nerve stimulation, or VNS. In clinical practice, both devices are typically used in addition to antiepileptic drugs.
Vagus nerve stimulation received FDA approval in 1997, while the Neuropace RNS System was more recently approved in 2013. Deep brain stimulation, or DBS, for epilepsy has not received US FDA approval, but is available in Europe and Canada.
RNS should be considered for patients with drug-resistant epilepsy who are not surgical candidates, or who have already failed surgery. RNS may also be used in patients who have failed VNS.
In the RNS pivotal trial of 191 patients, the responder rate, or percentage of patients achieving at least a 50% seizure reduction, was 44% at one year and 55% at two years.1
A recent RNS longitudinal study of 126 patients with neocortical seizures followed for an average of 6 years revealed a median seizure reduction of 61-76% in years 5 to 6 with a responder rate of 55%.
Adverse events include surgical site pain, headache, dysesthesias, infections and perioperative hemorrhage.1,3
To summarize, here are 5 facts about RNS:
1. RNS, or responsive neurostimulation, is a neuromodulation device for the treatment of drug-resistant epilepsy.
2. RNS should be considered in patients with drug-resistant epilepsy who are not surgical candidates, have failed epilepsy surgery, or have failed VNS.
3. RNS requires one or two electrodes to be implanted in the brain as well as a pulse generator fixed to the skull.
4. The overall responder rate is 55%, even higher in patients with mesial temporal sclerosis.
5. Surgical complications are infrequent, but infection and hemorrhage may occur.
Thank you for listening to today’s Neurology Update on responsive neurostimulation for the treatment of epilepsy. I’m Dr. Andrew Wilner, reporting for Neurology Times.
1. Dalkilic EB. Neurostimulation devices used in treatment of epilepsy. Curr Treat Options Neurol. 2017;19:1-7.
2. Geller EB, Skarpaas TL, Gross RE et al. Brain-responsive neurostimulation in patients with medically intractable mesial temporal sclerosis. Epilepsia. 2017;58:994-1004.
3. Jobst BC, Kapur R, Barkley GL et al. Brain-responsive neurostimulation in patients with medically intractable seizures arising from eloquent and other neocortical areas. Epilepsia. 2017;58:1005-1014.