Seizure-zapping Implant Gives Epilepsy Patients Hope
02/21/11 Portland, Ore.
New device in clinical trial at OHSU short-circuits attacks before they happen.
For Angie Nice, an end to her epileptic seizures would mean being able to participate in two activities many people take for granted: Work and travel.
They're activities that don't come easily for Nice, 38, since she can suffer as many as four seizures a day. But she hopes a national clinical trial she's participating in through Oregon Health & Science University will someday allow her to take a trip out of town and hold down a job without worry.
"I would like to do some more traveling and see if I can get another job," said Nice, who lives in Portland. "Right now, mom and I were looking into a job, but they don't want me because I have too many seizures."
Nice underwent surgery Sept. 25 to have a battery-powered, microprocessor-controlled device implanted on her brain. The Responsive Neurostimulator system, or RNS, is programmed to detect abnormal electrical patterns created by epileptic activity, and responds with pulses of electrical current to the activity site with the goal of aborting the seizure before clinical symptoms occur.
The device measures 1.5 inches by 2.5 inches and is placed on top of the brain in a space created by removing a piece of skull. It's attached to two leads, which may either be depth leads implanted deep in the brain at the site of epileptic activity, or cortical strip leads placed on the surface of the brain above the activity site.
The surgery takes about four hours, after which study participants are randomly split into two groups: one with the stimulator initially turned off and the other with the device turned on. They're then followed over a four-month blinded evaluation period, after which all participants will have stimulation turned on.
OHSU is one of 28 sites around the country conducting a two-year, double-blinded trial of the device's safety and effectiveness called the RNS System Pivotal Clinical Investigation. The sites aim to recruit a total of 240 adult subjects ages 18 to 70 - 10 of them at OHSU - with disabling motor simple partial seizures, complex partial seizures or secondarily generalized seizures. Disabling seizures are those severe enough to cause injuries or significantly impair functional ability. NeuroPace, a Mountain View, Calif.- based medical device manufacturer and developer of the RNS system, is sponsoring the nationwide, multicenter study.
David Spencer, M.D., associate professor of neurology in the OHSU School of Medicine and co-director of the OHSU Comprehensive Epilepsy Center, said a new, safe and effective approach to treating seizures that are not responding to medications is badly needed.
"Most seizure treatments, such as medication, affect the whole body and may cause side effects from their actions on other parts of the body or brain. They may not specifically target the part of the brain where the seizures are starting," he said. "The RNS device is a 'smart device' because it treats only the seizure focus and only when it detects that a also works automatically - the patient does not have to remember to take a pill or activate the device."
Ann Nice, Angie Nice's mother, said her daughter has undergone multiple surgeries to treat or eliminate her seizures, including one to implant a vagus nerve stimulator, or VNS, which sends 30-second electrical impulses to the left vagus nerve in the neck every five minutes.
"The VNS didn't actually help Angie," Ann Nice said. "She's been on many experimental drugs. She didn't really have a lot of options. She was willing to do this (RNS trial) with the hopes that if not this, somewhere down the road it might lead to something that would help her."
Tim Donahue of Portland, whose 24-year-old son, Casey, also suffers from epileptic seizures, has "high hopes" for the RNS trial in helping his son. Like Angie Nice, Casey had a VNS implant, which he carried for seven years before receiving the RNS implant in June. "The VNS was turned off anyway and hadn't been functioning for at least three years. It seemed like it brought on more seizures than anything," he said.
But the RNS is "cutting-edge" stuff, he said. The implant is constantly calibrating by picking up Casey's brain activity and downloading it to a computer that sends data back to OHSU researchers. "If he has a seizure during the day, we're able to send that data right away," Tim Donahue said. "There's a wand that attaches to the laptop. You just hold it over the implant and it sends data to the laptop and then phones it in."
Donahue said he isn't sure whether Casey's implant is turned on, but he has seen subtle changes in the pattern of his son's seizures. "There've been times I could have sworn that it was turned on," he said. "I think it has to do more with the surgery. After surgery, Casey's seizure patterns changed quite a bit. One time he went seven, eight days without a seizure."
Donahue added that he hopes the "little power surges" the RNS device provides "will stop that storm from occurring and keep the brain waves in a regular pattern."
An estimated 2.7 million Americans suffer from active epilepsy. About 200,000 new cases of the neurological disorder are diagnosed each year, and its prevalence increases with age, with 326,000 children 14 and younger, and 570,000 people in the 65-and-older age group affected.
Spencer emphasized that in this early stage, only a small number of patients with epilepsy may benefit from the RNS. They're typically individuals who have not achieved good seizure control with medications,and who are not good candidates for epilepsy surgery. "However, this group of patients has often had long struggles with seizure control and is really in need of new approaches to therapy."