SEEG: New Hope for Severe Epilepsy

Pinpoints seizures’ origins for more effective surgery

images of brain

One of the major challenges of using surgery to treat epilepsy has always been finding the place in the brain where the person’s seizures begin.

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The more precisely doctors can pinpoint this area, the better they can focus efforts for surgical treatment. This is especially important in the delicate landscape of the brain where surgeons work to remove as little tissue as possible.

Now, a relatively new procedure called stereoelectroencephalography (SEEG) is significantly boosting success rates of epilepsy surgery. It allows doctors to be much more precise in targeting the origin of seizures, and gives hope to people with severe epilepsy.

Before SEEG, the chances of eliminating seizures after epilepsy surgery were low — only about 20 to 30 percent. But now, SEEG has brought the rates of long-term success up to 55 to 60 percent.

“This is truly a breakthrough,” says epileptologist Jorge Gonzalez-Martinez, MD. “In the last 20 years, we’ve found new imaging technologies, new treatment tools and new medications, but there was really no change in the outcomes. That’s because we were always missing the localization.”  

Before and after SEEG

About 70 percent of people with epilepsy respond to treatment with medication. The other 30 percent who don’t respond to medication consider surgery.

In the past, doctors used a type of invasive electroencephalography that involved removing large portions of a person’s skull and placing electrodes on the surface of the brain. This allowed for tracking seizure activity in a monitoring lab.

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But the information is incomplete. “These superficial electrodes cannot pick up on seizures coming from the deep areas of the brain,” says Dr. Gonzalez-Martinez.

With the less invasive SEEG procedure, doctors create small incisions in the skull, just 2 millimeters in diameter. They then pass about 10 to 15 tiny probes into the areas deep in the brain where they believe seizures are originating.

A road map for surgery

Patients stay in the hospital for about a week after the procedure when the electrodes are implanted. Doctors monitor seizure activity as each probe detects it. This creates a road map for a more precise — and effective – surgery several weeks later.

During this period of monitoring, doctors also use small electrical pulses to identify the portions of the brain that control speech, motor skills, facial movements and other functions.

“Once we know where the seizures are originating and where these functional areas are located, we know what we can remove and what we must preserve for a person to be seizure-free without any neurological deficit,” Dr. Gonzalez-Martinez says.

New hope for those with epilepsy

A variation of SEEG has been used in Europe for more than 50 years. However, the procedure was highly complex with multiple stages over several days.

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In 2009, Dr. Gonzalez-Martinez was the first to bring the technique to North America, simplifying it to only a two-hour surgical procedure. Since then, doctors from several epilepsy centers across the U.S. have traveled to Cleveland Clinic to learn more about SEEG from Dr. Gonzalez-Martinez.

“We can now offer hope for patients that once had no hope,” he says. “My dream is that one day we can do noninvasive tests, localize the seizures and then stop them without resection.”

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