In 2013, the Food and Drug Administration approved an implantable medical device to treat epilepsy. Now, doctors from the Rush Epilepsy Center in Illinois are the first to couple it with a novel electrode placement planning system, which is enabling the device to better reduce seizures.
Epilepsy is a condition characterized by frequent seizures, affecting around 1 in 26 people in the US at some point in their lives.
The device, called the NeuroPace RNS System, works by using "on-demand" direct stimulation in order to find abnormal electrical activity in the brain and send small bits of electrical stimulation. By doing this, the device suppresses seizures before they begin, the doctors from Rush explain.
According to the Centers for Disease Control and Prevention (CDC), epilepsy affects 2.3 million adults in the US and over 450,000 children under the age of 17.
In their approval release, the Food and Drug Administration (FDA) explain that the RNS System is used alongside drugs in patients over the age of 18 with three or more "disabling seizures" each month and who have not responded to two or more medications for epilepsy.
The device is surgically implanted under the scalp in the skull, and it is then connected to electrodes placed in specific parts of the brain where the seizures begin. To record data and regulate responsive stimulation, a computer chip in the skull also communicates with the system.
Modeling system predicts where electrical activity begins in brain
The RNS System is implanted in the skull, just under the scalp.
Image credit: FDA
"Many people with epilepsy have scores of unpredictable seizures every day that make it impossible for them to drive, work or even get a good night's sleep," says Dr. Marvin Rossi, co-principal investigator of the NeuroPace Pivotal Clinical Trial and assistant professor of neurology at the Rush Epilepsy Center.
He and his team explain that the novel electrode placement modeling system developed at Rush utilizes a computer mapping system that allows the surgeons to place electrodes at the exact location in the brain's temporal lobe.
Stimulating these electrodes results in a calming of the epileptic circuits. Additionally, the modeling system can predict where the activity begins and disperses in the brain, so the device can better calm these circuits, reducing seizures.
The team also notes that the device works as an electroencephalogram directly in the brain, where it records brain activity.
Half of patients in Rush trial experienced complete seizure cessation
Prior to its FDA approval, the RNS System underwent a 3-month randomized control trial of 191 patients with drug-resistant epilepsy.
From that trial, results showed that 29% of patients with an active device experienced a 50% reduction in total number of disabling seizures in the 3-month blinded period, compared with 27% for patients with the device turned off.
Additionally, nearly half of the patients enrolled in decade-long clinical trials of the device coupled with the electrode placement planning system at Rush experienced complete elimination of seizures, the team says.
Dr. Rossi says the device is now being used at Rush "as a foundation and inspiration for building cutting-edge hybrid stimulation therapy-drug molecule delivery systems."
He explains that devices for treating epilepsy provide hope for the thousands of patients in the US who are not able to control the condition with medication:
"Not long ago, it was highly unlikely that these patients would ever be free of their seizures. Now, several of our Rush patients with this device are actually able to drive, lower or even eliminate their medications and aren't as limited as they once were.
There is no doubt that quality of life of the majority of our implanted patients is significantly improved."
In the US each year, about 150,000 new cases of epilepsy are diagnosed, and the condition results in an estimated annual cost of $15.5 billion in medical costs and lost earnings.
Medical News Today recently reported on a task force of epilepsy experts, who created a new clinical definition for epilepsy. The main result of this new definition is that it allows for epilepsy to become "resolved" in certain cases, for example, if someone has not had a seizure for 10 years.
Written by Marie Ellis