Peter Warnke

Epilepsy is one of the most common disorders of the nervous system, affecting almost two million people in the United States. Many patients can control their seizures with medication or changes to their diet, but 20 to 30 percent of patients do not respond to medication. For those needing an alternative, surgery is an option.

The standard surgery for epilepsy is an invasive, open-brain surgery. It involves removing parts of the hippocampus, amygdala or temporal lobe: parts of the brain that may have malformations or misfiring nerve cells that cause seizures. While effective, these surgeries may damage other functional areas of the brain and lead to cognitive issues and problems with vision.

The University of Chicago Medicine is one of several medical centers in the country—and the only in Chicago—offering a less invasive, more targeted surgical treatment for epilepsy. Peter Warnke, MD, and his team specialize in stereotactic surgery, in which doctors use three-dimensional images of the brain to plan procedures and guide their movements to a specific target area. Surgeons rely on images from a computed tomography (CT) scanner or magnetic resonance imaging (MRI) machine to follow the movements of their instruments as they operate, instead of creating a large opening in the skull to physically see it with their own eyes.

Warnke and his team use these techniques and a CT scanner in the operating room to guide a laser through a small, three-millimenter opening in the skull. The laser ablates, or basically burns away, the troublesome nerve cells causing the seizures. Using 3D images of the brain as a guide, they insert a laser fiber (less than 2 mm thick) through a small incision and position it next to the target area of the brain. Then, they take the patient to an MRI machine and send a laser beam through the fiber to heat up the tissue.

As this happens, doctors continuously measure the brain's temperature via the MR images. The longer the heat is applied, the farther it spreads through the surrounding tissue. Once the necessary heat has fully covered the lesion, they stop and pull out the fiber through the skin.

This will replace open surgery as a better first option. — Peter Warnke, MD

Surgeons at UChicago Medicine already perform this type of surgery for more than 30 patients per year to treat various forms of epilepsy and brain tumors in both adults and children. In August 2018, they completed their 100th ablation procedure overall, including 60 for epilepsy.

In a recent study published in the Journal of Neurology, Neurosurgery & Psychiatry, Warnke, James Tao, MD, PhD, Shasha Wu, MD, PhD, and several other UChicago Medicine colleagues reported on the results of the procedure in 21 patients with mesial temporal lobe epilepsy, the most common kind of focal epilepsy in adults. More than 50 percent of these patients were seizure-free at least 12 months after the procedure, although patients with mesial temporal sclerosis, where the nerve cell damage is concentrated in a specific area, did best, with more than 70 percent of patients becoming seizure-free.

“We’ve shown that with this technique you get the same outcome as traditional open surgery but with less neuropsycholgical side effects,” Warnke said. “The study validates the long-term results, in which many people can become free of seizures.”

UChicago Medicine is participating in a new clinical trial to follow the long-term outcomes of patients who have the laser surgery, the SLATE (Stereotactic Laser Ablation in Temporal Epilepsy) Trial. Patients with temporal epilepsy can be eligible for the trial, and Warnke believes it will become the “go-to” procedure for many types of epilepsy.

“This will replace open surgery as a better first option,” he said. “Even if it doesn’t work in some patients, you can always fall back on the traditional method. But this allows you to take the much less risky option first.”

Story originally published February 21, 2018.

Peter Warnke, MD

Peter Warnke, MD

Internationally renowned neurosurgeon Peter Warnke, MD, has performed more than 5,000 stereotactic surgeries and more than 2,000 brain tumor surgeries. Dr. Warnke provides neurosurgical care for the treatment of adults and children with movement disorders, epilepsy and brain tumors.

Read Dr. Warnke's physician bio