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Research and Clinical Trials

Return to Deep in the Brain, Doctors Tame Epilepsy Overview

More on Deep in the Brain, Doctors Tame Epilepsy

Deep in the Brain, Doctors Tame Epilepsy

Information from the SANTE Clinical Trial on Deep Brain Stimulation

New York (Aug 23, 2010)

A female doctor examines brain scans at a viewing station

In patients with epilepsy uncontrolled electrical signals create a sort of electrical storm in the brain, which results in a seizure. Russian author Fyodor Dostoyevsky, who had epilepsy, describes the moments preceding his seizures as "of great calm, full of understanding." But these moments were simply "a premonition of that final second (never more than a second) with which the seizure itself began. That second was, of course, unbearable." While the frequency and severity of seizures varies from person to person, epileptics can experience several disruptive seizures each day. Most people with epilepsy are helped by current anti-seizure medications or by surgery to remove the brain tissue that is the source of the seizures. But about a quarter of patients are not helped by medications and cannot undergo surgery.

graphic of quote from article

In a recent study of the effectiveness of deep brain stimulation (DBS), doctors permanently implanted probes attached to a small, pacemaker like device in the brain in the hope that the signals emitted from the probes would interfere with the errant electrical signals at work in epilepsy. More than half of patients in the study – all of whom had not gotten relief from other treatments – experienced a reduction in the frequency of their seizures, and 13 percent were seizure-free two years after implantation of the device. "The study showed significant improvements in seizure frequency in this group of patients who were not responding very well to medical therapy," said Michael Kaplitt, a neurosurgeon at NewYork-Presbyterian/Weill Cornell Medical Center.

How DBS Works

Dr. Kaplitt and his colleagues, NewYork-Presbyterian/Weill Cornell neurologist Douglas Labar and Lawrence Hirsch, a neurologist at NewYork-Presbyterian/Columbia University Medical Center, all participated in the study, called SANTE (Stimulation of the Anterior Nucleus of the Thalamus for Epilepsy). Patients in the trial had surgery to implant the small, battery-operated neurostimulator, which has a history of use in Parkinson's disease. "We've been using this device for Parkinson's disease and tremors for almost 10 years, it was simply going into a different spot in the brain," Dr. Kaplitt said.

Michael G. Kaplitt, M.D., Ph.D.
Michael G. Kaplitt, M.D.,
Ph.D.

In patients with Parkinson's surgeons place the probes exactly into the spot in the brain where electrical nerve signals generate the Parkinson's symptoms. In the SANTE study the probes are implanted only in the thalamus, "a collection of cells located deep in the center of the brain that act like a communication relay network," said Dr. Labar. Nerve fibers radiate from the thalamus to other parts of the brain and signals travel back and forth along these fibers, including to areas that can generate seizures, he added.

"Seizures are believed to become full-blown by spreading from a hyperactive part of the brain through this circuit to the rest of the brain," Dr. Kaplitt added. In the SANTE trial researchers tested this idea: if little electrical pulses are continuously sent through the probe into the thalamus, the spread of these irregular signals will be interrupted and seizures will be prevented from spreading to the rest of the brain. "The constant stimulation in that area basically creates electrical noise that prevents signals from the hyperactive area from spreading to the rest of the brain," Dr. Kaplitt said.

Douglas R. Labar, M.D., Ph.D.
Douglas R. Labar, M.D.,
Ph.D.

SANTE Trial Design

The SANTE trial was divided into different phases, said Dr. Kaplitt. During the first phase 157 patients had the device implanted and it was either turned on or off – patients did not know which and neither did their doctors. At the end of three months, patients who had the stimulation turned on had improved by about 40 percent, while those in the control group had improved by around 20 percent. In the next phase all the patients had the device turned on and the control group quickly improved as much as the patients whose devices had been on already for three months.

graphic of quote from article

In the follow-up phase in which everybody's device was turned on, many patients showed continued improvement, Dr. Kaplitt said. "At one year the patients improved, at two years they were even further improved. By the end of two years about 60 percent of patients had more than a 50 percent improvement in their seizure frequency," Dr. Kaplitt said.

Lawrence J. Hirsch, M.D.
Lawrence J. Hirsch, M.D.

Although the device appeared very safe, said Dr. Hirsch, some patients reported that they were more depressed but most of them had prior depression that was simply exacerbated, and some patients reported more memory problems. When their memory was tested by a neuropsychologist it was not worse than before, but they felt that it was worse. "So we're going to have to watch those things fairly closely," he said.

Food and Drug Administration Approval

Drs. Labar and Kaplitt participated in a Food and Drug Administration (FDA) expert review panel, which voted in favor of approving DBS for epilepsy and it is likely to be approved and become available for routine use some time next year. "There are many needy patients whose seizures are persisting despite trials of a lot of medications, and it will be helpful to be able to offer them something with even a modest benefit," Dr. Labar said. "For these patients any degree of benefit is better than the alternatives, which are no alternatives."

Dr. Douglas Labar discusses the surgical treatments available to patients with epilepsy.

Future Research in Epilepsy

Researchers will continue to study the use of DBS in epilepsy and focus on fine-tuning how best to use the device, said Dr. Hirsch. "There are many different ways to set the stimulator. You can stimulate at all different frequencies. In SANTE the device was set to cycle with 30 seconds on and 5 minutes off. So we can test all different settings, and we may find settings that are better, or we may figure out how to pick patients that are more likely to respond. We've already proven that it works to some degree, and there's still a lot of hope for further improvement."

Contributing faculty for this article:

Lawrence J. Hirsch, M.D., is an Attending Neurologist at NewYork-Presbyterian/Columbia University Medical Center and a Clinical Professor of Neurology at Columbia University College of Physicians and Surgeons.

Michael G. Kaplitt, M.D., Ph.D., is the Director of Stereotactic and Functional Neurosurgery at NewYork-Presbyterian/Weill Cornell Medical Center and an Associate Professor of Neurological Surgery in Neurology and Otorhinolaryngology at Weill Cornell Medical College.

Douglas R. Labar, M.D., Ph.D., is the Director of the Division of Clinical Neurophysiology at NewYork-Presbyterian/Weill Cornell Medical Center and a Professor of Neurology and Neuroscience at Weill Cornell Medical College.

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