How the RNS Stimulator Can Help Epilepsy Patients

The RNS stimulator gives new hope to epilepsy patients with medication-resistant epilepsy. Recently approved by the FDA, the system may help reduce the frequency of seizures. This is a big leap forward because it gives another treatment option to patients who don’t respond well to epilepsy medication. Many of these patients can’t undergo surgical treatment either, because their epilepsy also affects areas in the brain that perform important functions.

The RNS stimulator delivers brief, pinpointed electrical stimulation to the brain–much like a pacemaker works for the heart. The system consists of a small neuro-stimulator implanted within the skull under the scalp, a battery and one or two wires that a surgeon locates where the seizures seem to originate within the brain or on the surface of the brain.

Preliminary data convincingly showed that the RNS stimulator reduces seizures. Results from a three-month, randomized control trial of 191 patients with drug-resistant epilepsy support the FDA approval.

The study showed that by three months after the implanted device was turned on, patients experienced a nearly 38 percent reduction in the average number of seizures per month, compared to about 17 percent reduction in patients who had the implanted device turned off. At the end of three months, the median reduction in seizures was 34 percent with active use and about 19 percent with the device turned off. During the trial, 29 percent of patients with an active device experienced at least a 50 percent reduction in the overall number of seizures, compared to 27 percent for those with the implanted device turned off.

While it is not as effective as epilepsy surgery at eliminating seizures, for many patients–including those with seizures starting from both sides of the brain–the RNS stimulator represents the only hope for improving seizures. Furthermore, as research continues to determine how to predict seizures and stop them with brain electrical stimulation, the technology is bound to improve.

This post was written by Ashesh Mehta, MD, director of epilepsy surgery at North Shore-LIJ's Comprehensive Epilepsy Care Center and head of the Laboratory of Multimodal Brain Mapping at the Feinstein Institute for Medical Research.  

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