The idea that we can implant a Star Trek-type device that will detect seizures and interrupt them without causing injury is entirely new. And exciting. And scary.
Especially for those people with epilepsy that have seizures that begin at one focal point in the brain, but aren’t appropriate for epilepsy surgery.
Brain stimulation has now been shown to offer significant relief to patients with intractable seizures for whom drugs and other treatments have not worked.
This is the major finding of a first-of-its-kind study of responsive electric brain stimulation in adults with “medically refractory,” or hard to treat, epilepsy.
“For the third of people who have tried two or three medications for their epilepsy, but are still having seizures, the standard of care is removing the abnormal part of the brain that is causing seizures.
Over 50 percent of patients undergoing surgical removal of brain tissue causing seizures will be cured of their epilepsy,” says Jason M. Schwalb, M.D., Director, Movement Disorder and Behavioral Neurosurgery at Henry Ford Health System.
“However, there are people who are not candidates for this type of surgery because of potential side-effects. Until now, we have not had great treatment options. The RNS system is an attractive option for these patients, especially since it is reversible.”
The NeuroPace Responsive Neurostimulation System (RNS) consists of a miniaturized, implanted computer (that’s flat and about the size of a half-dollar). It can detect seizures from electrodes implanted into or on the surface of the brain and then delivers an electrical pulse to stop them.
In clinical trials, 191 adults, ages 18 to 70, whose disabling epileptic seizures had not been controlled by medications, were chosen.
Most of the patients had suffered from epilepsy for 20 years or more and were taking an average of three drugs to control their seizures.
A third had already tried Vagus Nerve Stimulation, (VNS), and the other third had already tried epilepsy surgery.
They were studied at 32 medical sites throughout the U.S. for three years, beginning in late 2005.
The study objective was to demonstrate the safety and effectiveness of the RNS System as an adjunctive therapy.
The purpose was to reduce the frequency of seizures in people with partial onset seizures from no more than two focal points that are refractory.
Or for people on two or more antiepileptic medications.
All patients were implanted just under the scalp to a neurostimulator which was connected to insulated lead wires with small electrodes at the end.
Surgeons locate this spot, known as the “seizure focal points,” prior to surgery using a combination of brain imaging and electroencephalogram (EEG) recording.
The leads are then implanted in the patient’s brain or on the brain surface near where seizures are believed to start.
Activity in the brain is directly recorded from surface electrodes on the skull, or electrocorticography (ECoG).
And then, when a seizure is detected by the RNS, a brief, mild electrical shock is delivered to suppress it.
Abnormal brain activity was recorded for a month, and then patients were chosen at random to receive either electric stimulation or to be given “sham,” or no treatment.
The researchers found:
The 97 patients who were treated with the RNS system had 37.9 percent fewer seizures than before surgery.
Those 94 patients in the sham, or untreated group, had only 17.3 fewer seizures than before surgery.
When those in the sham group had the RNS system turned on, seizures were significantly reduced.
There was no difference between the two groups in the number of adverse events associated with the treatment.
And the effects of the treatment led to significant improvements in patients’ quality of life at the 1 and 2 year check-up.
(Medically refractory epilepsy patients with frequent seizures are at risk of depression, suicidal thoughts and actions, memory loss, and SUDEP, or sudden unexplained death in epilepsy.)
There was also an improvement in some aspects of cognition.
More good news: The trial also demonstrated less serious adverse events than comparative surgical procedures.
“For people who cannot control their seizures effectively with medication, the data show the RNS System may be a safe and effective treatment option,” said Martha Morrell, M.D., Chief Medical Officer of NeuroPace, Inc. and Clinical Professor of Neurology at Stanford University.
“The results also indicate the device became even more effective over time.
These findings, drawn from a data set that includes people living with the most difficult type of epilepsy to manage, truly speak to the potential of responsive neurostimulation in controlling seizures.”
Unlike the Vagus Nerve Stimulator (VNS), Responsive Neurostimulation (RNS) is designed to detect abnormal electrical activity in the brain and respond by delivering electrical stimulation to normalize brain activity before the patient experiences seizure symptoms.
While other devices stimulate the nervous system continuously or in a predetermined pattern, the Neurostimulator implant is unique in that it monitors the brain, delivering jolts of electricity only when it detects the abnormal electrical activity that signals the onset of a seizure.
“It’s like dousing a spark before it becomes a flame,” said Martha Morrell, Neuropace’s chief medical officer.
After surgery, patients go through an optimization period, during which doctors program the RNS to recognize a typical pattern that precedes the seizure and deliver a particular pattern of electrical activity.
With a programmer, a laptop computer with specially designed software — plus a wand and special interface — direct communication is made with the implanted RNS neurostimulator.
Patients wave that wand over the device to download data recorded before and after stimulation, so that physicians can monitor how well these parameters are working and adjust them accordingly.
But Responsive Neurostimulation is not for everybody.
And there are some key disadvantages to the RNS device that should be considered before implantation.
While you cannot feel the implanted device, it does require maintenance and care.
As a battery-powered device, replacement of the batteries will be required every couple of years and replacement of the entire RNS device will also be necessary.
Surgery to implant the RNS device will require a hospital stay generally lasting up to three days.
Battery replacement procedures for the RNS often can be performed on an outpatient basis but, again, will require medical intervention and impose some additional financial cost.
But the future looks bright.
“Until now, drugs have been the mainstay of therapy for people with epilepsy,” said Dr. Nathan Fountain, a UVA neurologist and director of the F. E. Dreifuss Comprehensive Epilepsy Program.
“The idea that we can implant a Star Trek-type device that will detect seizures and interrupt them without causing injury is entirely new.
Many people with epilepsy have seizures that begin at one focal point in the brain, but they aren’t appropriate for epilepsy surgery.
If we show that responsive neurostimulation is safe and effective, then it has the potential to help many patients with epilepsy lead more normal lives.”
The future is here…NOW!
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