Implantable device designed to detect, stop seizures under study at MCG
A small electronic device implanted in the skull that detects oncoming seizures then delivers a brief electrical stimulus to the brain to stop them is under study at the Medical College of Georgia.
MCG is among some dozen U.S. centers participating in a study to determine if the neurostimulator device can help patients whose seizures are not well controlled by drugs.
"We really want another option for treating patients who are not effectively helped by existing treatments," says Dr. Anthony Murro, neurologist, epileptologist and a principal investigator on the study. "If this works out, it could represent a new way of treating epilepsy that is unlike drug treatment where people live with the side effects of drugs they take every day to prevent seizures."
"If this works as well as we hope it works, it could absolutely revolutionize epilepsy surgery," says Dr. Joseph Smith, MCG neurosurgeon specializing in stereotactic and functional surgery. Dr. Smith, who has performed epilepsy surgery at MCG Medical Center since 1985, says if the study proves the device is effective, he can see patients preferring the new approach to today's standard that often includes removing areas of the brain where abnormal electrical activity originates, called the seizure focus.
At MCG Medical Center, the device will be used in about 20 patients age 18-65 who have not gotten their seizures controlled on at least two medications and have at least four seizures per month; seizure activity is closely monitored through a diary and monthly doctor visits for three months before patients are eligible.
"We use the patient's seizure pattern which we recorded long before surgery to develop the parameters we use to detect future seizures," Dr. Smith says. During the procedure he creates a form-fitting defect for the device in the skull near the seizure focus and uses tiny screws to hold it securely in place. Once he implants the device, up to two electrodes are placed within the brain near the seizure focus. Afterward, a modified laptop computer is used to look at electrical activity picked up by the neurostimulator and to program the device to recognize the patient's seizure activity. If the neurostimulator detects abnormal activity, it sends an electrical stimulus to stop it, a stimulus that appears to go unnoticed by patients, the doctors say. Study patients will be followed for about two years to assess how well the device works.
MCG doctors already have used it as a temporary measure to try and stop seizures in 15 patients whose seizure activity already was being monitored. In one patient with frequent seizures, they were able to compare seizure activity with and without the stimulation in an effort to further analyze its contribution to stopping seizures. The experience prompted the MCG doctors to want to study the implantable device.
Doctors already have experience using electrical activity to help control seizures. A pacemaker-like device called the vagus nerve stimulator has been used for about six years that regularly electrically stimulates the vagal nerve in the neck, sending signals to the brain. The vagus nerve stimulator has helped reduce seizure frequency but is unlikely to make many patients seizure-free. "If they still have a seizure, even just one every several months, most patients still have trouble driving, getting and keeping a job and living a normal life," Dr. Murro says. "So the goal is to stop all seizures."
They also have years of experience using electrical stimulation in the brain, including deep brain stimulation which uses high-frequency stimulation to inhibit overactive areas of the brain involved in movement in patients with Parkinson's disease.
About 1 in 200 people have seizures and about 1 out of 3 cannot get their seizures under control with one or more medications. Some patients also are not candidates for traditional epilepsy surgery where the seizure focus is removed because the location of the focus increases the risk of resulting problems or deficits. "This device may be a major help for those patients, I think," Dr. Smith says.
He and Dr. Murro also agree that if the implantable neurostimulator is proven to be safe and effective it may benefit many epilepsy patients in the future. "We would expect that hospitalization and risk of complication would be much less than that of traditional epilepsy surgery," Dr. Murro says.
As with other epilepsy surgery, they also hope this new approach will provide a lifelong solution, requiring only battery replacement.
For more information about the study, call Dr. Patty Ray, study coordinator, at 706-721-6260.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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