The U.S. Food and Drug Administration (FDA) recently approved the use of a device, known as an RNS stimulator, to treat severe cases of epilepsy and prevent the disorder from progressing to seizures, the federal agency announced today.

With the help of a small neurostimulator implanted in a patient’s skull, beneath his or her scalp, doctors now have a method to treat epilepsy and prevent seizures after medications fail. The neurostimulator, which connects via electrodes to the damaging regions of the patient’s brain, recognizes misfiring signals and normalizes them to the rest of the brain’s behavior, according to Christy Foreman, director of the Office of Device Evaluation at the FDA. The device has been deemed to be safe; the most frequent side-effects are implant site infection and premature battery depletion.

Affecting around 2.3 million adults and 467,711 children in the United States, epilepsy ranks as the third-most common neurological disorder behind Alzheimer’s disease and stroke. Approximately one in 26 people will be diagnosed with epilepsy at some point in their lives, according to the Centers for Disease Control and Prevention. Epilepsy is characterized by abnormal electrical activity in the brain that, when left unabated, can lead to convulsive seizures. Sufferers’ behavior may grow unusual and they may lose consciousness. Those who have the disorder often face severe, ongoing symptoms: about 40 percent of epileptics continue to have seizures despite treatment.

The FDA’s approval comes on the heels of a successful randomized trial of 191 drug-resistant epilepsy patients. The study lasted three months. After the device got turned on, patients experienced a dramatic 38 percent reduction in the number of seizures each month. During the trial, 29 percent of patients saw a 50 percent reduction in the total number of seizures — compared to the passive group, those whose devices were turned off, who experienced only a 27 percent reduction.

A two-year follow-up found that the reduction in seizures remained constant. Despite these successes, there are some downsides to the treatment: patients whose RNS stimulator remains active cannot receive certain tests that rely on electric or magnetic stimulation, including magnetic resonance imaging (MRI), electroconvulsive therapy (ECT) or transcranial magnetic stimulation (TMS), as their device, even when turned off, can pick up certain signals and cause brain damage.

Earlier this week, the FDA announced its approval of anti-seizure drug called Aptiom, which the agency recommends epileptics take as an add-on medication to reduce the frequency of partial seizures. “Some patients with epilepsy do not achieve satisfactory seizure control from existing treatments,” said Dr. Eric Bastings, acting director of the Division of Neurology Products in the FDA. “It is important we continue to make new treatment options available to patients.”