Epilepsy is one of the most common disorders of the nervous system, affecting almost 2 million people in the United States, including 300,000 kids under the age of 14. In many cases there may be no detectable cause at all, or it can stem from tumors, strokes, congenital conditions or brain injuries.
Just as epilepsy can have many causes, there are also many possible treatments, from medication and diet to a procedure called vagal nerve stimulation, where a small battery implanted under the skin sends electrical pulses to the brain to ward off impending seizures.
About 50 percent of people have focal epilepsy, in which doctors are able to tell that a lesion, or malformation in the brain, is causing seizures. Surgeons can then remove the lesion, but brain surgery is a difficult option, especially for children, because of the risk for infection and potential damage to functional brain areas.
Peter Warnke, MD, is a neurosurgeon who specializes in stereotactic surgery, in which doctors use images of the brain to plan procedures and guide their movements to a specific target in the brain. This kind of technique is ideal for procedures in children because it can be done through a much smaller incision than traditional surgery. Surgeons rely on images from a CT scanner or 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 is working with a new stereotactic technique to treat focal epilepsy that uses a laser fiber to ablate, or basically burn away, the troublesome nerve cells in the lesion 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 place it next to the lesion. 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, Warnke and his team can measure the temperature of the beam via the MR images. The longer the heat is applied, the further it spreads through the surrounding tissue, and once the necessary heat has fully covered the lesion, they stop and pull out the fiber through the skin.
“You can plan these procedures exactly, and you avoid the side effects of going through eloquent brain and causing potential damage,” Warnke said. “The infection risk is much, much lower than open surgery, the cognitive and psychological side effects of operating in these deep areas of the brain are much less.”
Warnke said that after traditional surgery to remove focal lesions, about 68 percent of patients are seizure-free. But in early trials of the laser fiber procedure at other institutions almost 99 percent of patients are seizure-free after 6 months. He’s not ready to use the word “cure” until patients have gone more than 3 years without seizures, but he’s encouraged by the effectiveness and precision of these early results.
“The real advantage of the laser ablation is that you can watch the procedure online while you do it without opening the brain and seeing what you do. That’s the beauty of the concept,” he said.