An implanted stimulator being studied at Thomas Jefferson University Hospital may be able to predict and prevent seizures before they start in people with uncontrolled epilepsy.
Researchers at the Jefferson Comprehensive Epilepsy Center are enrolling patients in a study of the Responsive Neurostimulator System (RNS) made by Neuropace to determine if it is effective in stemming seizures. The system contains a computer chip that detects seizures and then delivers electric current to the brain to stop them.
“If it works as well as we hope, this device will be an exciting leap forward in the field,” said Michael Sperling, M.D., director of the Jefferson Comprehensive Epilepsy Center and the Baldwin Keyes Professor of Neurology, Jefferson Medical College of Thomas Jefferson University. “This is the first closed-loop system being used in humans designed to stop seizures.”
Earlier devices, such as a vagal nerve stimulator, gave out intermittent electrical stimulation to stop seizures, but never directly to the brain, explained Christopher Skidmore, M.D., principal investigator of the study at Jefferson. The RNS only delivers an electrical current when a seizure is detected and stimulation is needed.
More than two million people in the U.S. have epilepsy, the third most common neurological disorder in the country. Approximately 30 to 40 percent of people with epilepsy have seizures that cannot be controlled with medications, leaving many unable to work or drive.
Uncontrolled seizures related to epilepsy are generally treated with antiepileptic medications. However, many individuals treated with medication alone continue to experience seizures or medication side effects. Uncontrolled epilepsy can severely diminish quality of life and is often associated with increased rates of injury, depression, and death. Some people with severe epilepsy may be candidates for epilepsy surgery to remove the part of the brain that triggers the seizures, but this is not always feasible.
The RNS system is an implantable device designed to detect abnormal electrical activity in the brain and deliver small amounts of electrical stimulation in response. It is placed by a surgeon within the skull and beneath the scalp. The device is then connected to two wires containing electrodes that are placed within the brain or resting on the brain surface in the area of the seizure focus. By continuously monitoring brain electrical activity, after identifying the “signature” of a seizure's onset, the device delivers brief electrical stimulations with the intention of suppressing the seizure before any symptoms occur.
An early study of the RNS system in 65 adults with medically uncontrolled epilepsy indicated that the device was safe.
As this is a controlled study, all study participants will receive the implant but only half of them will have the device activated in the initial phase. The others will have the device activated 16 weeks after surgery once the controlled phase is complete, said Dr. Sperling.
“Patients who have the device activated one month after surgery will be monitored weekly at the epilepsy center to tweak the chip's programming for optimal performance,” Dr. Skidmore said.
Patients will also receive a device that is able to scan the chip for information about seizures just by holding a wand over the scalp, he said. The information can then be downloaded by the patient onto a computer and sent via telephone to epilepsy researchers to review.
Participants in the RNS study must be from 18 to 70 years of age and meet the following requirements:
- have disabling (significant enough to impair functional abilities or day-to-day life activities) motor simple partial seizures, complex partial seizures and/or secondarily generalized seizures;
- failed treatment with a minimum of two antiepileptic medications; and
- experienced an average of three or more disabling seizures every 28 days for three consecutive periods prior to enrollment and have no more than two regions that induce seizures in the brain.