Image: The implanted RNS system (Photo courtesy of the University of Rochester Medical Center).

A new study demonstrates how brain stimulation can offer significant relief to patients with intractable seizures, for whom drugs and other treatments have not worked.

Researchers at Henry Ford Hospital (Detroit, MI, USA), the University of Rochester Medical Center (URMC, NY, USA), and other institutions conducted a double blind, randomized trial of the NeuroPace Responsive Neurostimulation (RNS) system involving 191 adults with medically refractory epilepsy. All patients were implanted with an RNS device connected to depth or subdural leads placed at one or two predetermined seizure foci, programmed to detect abnormal electrocorticographic activity. One month after implantation, the subjects were randomized to receive stimulation in response to detections (treatment group) or to receive no stimulation (sham group). Efficacy and safety were assessed over a 12-week blinded period, and a subsequent 84-week open-label period during which all subjects received responsive stimulation.

The results showed that the 97 patients who were treated with the RNS system had 37.9% fewer seizures than before surgery; the 94 patients in the sham group, on the other hand, had only 17.3% fewer seizures than before surgery. There was no difference between the treatment and sham groups in adverse events. During the open-label period, the seizure reduction was sustained in the treatment group, and seizures were significantly reduced in the sham group when stimulation began. Significant improvements in overall quality of life were noted, and there was no deterioration in either mood or neuropsychological function. The study was published in the September 27, 2011, issue of Neurology.

“For the third of people who have tried two or three medications for their epilepsy, but are still having seizures, the standard of care is removing the abnormal part of the brain that is causing seizures. Over 50% of patients undergoing surgical removal of brain tissue causing seizures will be cured of their epilepsy,” said study coauthor Jason Schwalb, MD, director of the movement disorder and behavioral neurosurgery at Henry Ford. “However, there are people who are not candidates for this type of surgery because of potential side effects. Until now, we have not had great treatment options. The RNS system is an attractive option for these patients, especially since it is reversible.”

The NeuroPace (Mountain View, CA, USA) RNS system detects and stores a record of the brain’s electrical activity. When the device identifies seizure activity, it attempts to suppress it by sending electrical stimulation through the leads to the brain. A physician-operated programmer communicates with the RNS via a hand-held wand, allowing stored information to be reviewed. Patients can also connect a data transmitter (DTR) to provide the physician with the information, so that the response to the stimulation can be evaluated to decide on the best seizure detection and stimulation settings for the patient.

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