Surgeons implant a new investigational neurostimulator in a patient with medically refractory epilepsy

Aug 5 2004

Neurosurgeons at Rush University Medical Center are the first in Chicago to implant a new investigational neurostimulator in a patient with medically refractory epilepsy. The neurostimulator may be able to suppress seizures in patients with epilepsy before any symptoms appear, much like the commonly implanted heart pacemakers which stop heart arrhythmias before any symptoms occur.

Dr. Richard W. Byrne, neurosurgeon at Rush and member of the Chicago Institute of Neurosurgery and Neuroresearch Medical Group (CINN), performed the first implant on Tuesday, June 29, on an Indiana man unlikely to benefit from surgical resection.

Byrne says this is the "Holy Grail" in epilepsy surgery and the most exciting thing he’s seen. "This device might help epilepsy patients who do not respond to current medical treatment, testing an entirely new concept in treating medically refractory epilepsy."

"Our first implanted patient has two distinct epileptic foci, one on each side of the brain, producing two different seizures so traditional surgical resection was not an option," said neurologist Dr. Michael C. Smith, the patient’s physician and co-principal investigator of the study. "Placing implants on each side of his brain at his sites of seizure onset will allow detection and treatment of his seizures much like an implantable defibrillator of the heart. If you view an epileptic seizure as a brain arrhythmia, electrical stimulation may return it to a more normal rhythm."

Until now, surgical treatments have generally involved removal of parts of the brain responsible for triggering seizures. Neurologist Dr. Donna Bergen, co-principal investigator of the study, says this new approach not only avoids removal of brain tissue, but also allows therapy to be delivered to the brain only 'on demand,' when a seizure is actually starting to appear.

"The research device is made up of two elements, one which will record the patient's brainwaves (EEG) and one which will deliver small electrical pulses to the brain. The device, about the size of a small pocket watch, was surgically placed in the patient's skull by Dr. Byrne," says Bergen.

Byrne made a small opening in the skull, placing the neurostimulator in a tray-like holder fastened to bone. The neurostimulator has two electrode wires that were precisely placed in areas of the brain where the seizures had been found to originate during preliminary testing. The electrodes can lie on the brain or be placed into locations deep within the brain. After surgery, the patient is not able to see or feel the device in the head.

"This responsive neurostimulator system is an incredibly sophisticated, quite remarkable system. Everything is closed up in the skull, so it is a self-contained system and designed to be responsive to abnormal activity in the brain," says Bergen. "When a seizure onset is detected, tiny electrical pulses will be delivered, in hopes of disrupting the abnormal brain activity and stopping the seizure."

Byrne describes this neurostimulator as a "closed loop system" and says it’s unlike the vagus nerve stimulator used in some patients with epilepsy.

The vagus nerve stimulator is programmed to stimulate at timed-intervals. If a seizure begins between intervals, the patient activates the stimulator by swiping a magnet over their chest at the location where the device is implanted.

The new investigational neurostimulator system monitors and will attempt to treat seizures. The neurostimulator reads the EEG, sees an onset of a seizure, and then sends an electrical impulse to the brain in an attempt to disrupt the seizure. The patient does not need to activate the stimulator.

Following surgery, patients in the study will come to Rush for scheduled office visits. Neurologist Dr. Marvin Rossi will use a computer to program the neurostimulator to "read the patient's seizure." When the neurostimulator senses a seizure beginning, the electrodes stimulate that part of the brain in an attempt to stop the seizure. In addition to Rush University Medical Center, nine other medical centers across the country are involved in the study.

Rush University Medical Center includes the 824-bed Presbyterian-St. Luke's Hospital; 110-bed Johnston R. Bowman Health Center; Rush University Medical College, College of Nursing, College of Health Sciences and the Graduate College.

The Chicago Institute of Neurosurgery and Neuroresearch is one of the nation's leading organizations for the diagnosis, treatment and rehabilitation of people with brain and spine disorders. Originally founded in 1987, CINN is the Midwests largest team of neurosurgeons known for their pioneering treatments in minimally invasive techniques. Through a network of eight hospitals spanning two states, CINN treats more patients with brain tumors and spine disorders than any other physician group in Illinois.

http://www.rush.edu