Brain mapping gives hope to people with intractable epilepsy
Sophisticated brain-mapping techniques were used to pinpoint and surgically target the source of Laura Koellsted's seizures, which plagued her for nine years. Credit: Norbert von der Groeben
For nine years, Laura Koellsted tried as hard as she could to lead a normal life. It was not easy. Every day, from deep within her brain, a cluster of cells would fire all at once, out of sequence, as out of control as a fast-moving storm.
Those cellular misfires Koellsted experienced were seizures. Hers were so frequent, unpredictable and debilitating — her right leg would kick out uncontrollably and she would crash to the floor — that she wasn't safe doing anything. She couldn't care for her two young children. She couldn't work. She couldn't drive. Finally, to limit her falls, she stayed in bed, and when she had to move around her home, she crawled instead of walking.
Sometimes medications would work, but not permanently. Koellsted had become one of those people whose seizures become intractable to medication — and she turned to Stanford's Intractable Epilepsy Program for help. Epilepsy specialists from several medical and scientific disciplines were part of the team that used advanced forms of seizure mapping (to pinpoint the source of Koellsted's seizures) and functional brain mapping, safely enabling the surgery that returned the 38-year-old resident of Albany, Calif., to a normal life.
"Treating intractable epilepsy is like a hunt with many twists and turns," said Josef Parvizi, MD, PhD, associate professor of neurology and neurological sciences and director of the Intractable Epilepsy Program. "Each person's seizures are unique, with a unique origin and a unique seizure network that the abnormal brain waves traverse."
Once, neurologists did not have a technology to detect the origin of epileptic seizures deep within the brain. Now, with state-of-the-art technology, they can apply the highest power of magnetic-resonance imaging scanner, called a 7-Tesla, to look for certain sorts of seizure causes, including scars and lesions. They can also use a video-based electroencephalography to gauge electrical activity in the brain.
But when a seizure's source is deep in the brain, as Koellsted's was, physicians must place electrodes directly on the surface of the brain; the skull interferes with seizure detection. Doctors will either place a set of electrodes in a gridlike netting on the brain or place individual electrodes into strategically selected areas, "like a spying microphone," Parvizi said. The most detailed method of seizure hunting involves a combination of this intracranial recording and functional brain mapping, where doctors stimulate the seizure area through the electrodes to determine what body behavior is controlled by that area.
"Implanting electrodes over the surface of the brain allows us to go beyond the skull," Parvizi said, "so we can listen to what's happening from inside the brain instead of what we can hear from the outside. From the outside you can hear the explosions, but you can't hear who is whispering and who is saying what to whom." Using this functional brain mapping technique provided information crucial for identifying the source of Koellsted's seizures.
What Parvizi and the intractable epilepsy team found in Koellsted's brain made treatment an even more delicate task than usual. Her seizures came from the part of the brain that controls sensation and movement in her legs, an area difficult to see or listen to because it's where the two halves of the brain overlap. "With thick bone and such a deep source, we would have been blind to the seizure's abnormal brain waves by just listening through the skull," Parvizi said.
With the electrodes placed near the origin of Koelsted's seizures, Parvizi could stimulate the brain tissue to determine what body function was controlled by that part of her brain. After a fourth day of testing and mapping her brain in the hospital, Parvizi came into Koellsted's room and said, "We found it. We're going to get it."
Before the team proceeded, they warned Koellsted of the risk: If something went wrong with the surgery, she might lose feeling in her legs. "I didn't care," Koellsted said. "I was in agony. Even without feeling, I could learn to function again as a human being. I could be a mother to my children and a wife to my husband. And I could go back to work."
The surgery took eight hours. The degree of precision was so demanding that the neurosurgeon did not use a scalpel. Instead, she suctioned out cells, removing just those in the main hub of the seizure source. Koellsted recalled her first moment in the recovery room. "I remember waking up and someone saying, 'Can you move your foot?' I said, 'Yes,' and they said, 'OK, you're not paralyzed.' I remember being very happy and going back to sleep."
"When patients with intractable epilepsy come to Stanford for treatment," Parvizi said, "what they will find is a unique team that fuses clinical care and science. We collaborate with our colleagues in multiple departments throughout Stanford Hospital & Clinics and Stanford University, including computer science, engineering, psychology and radiology. We get together to improve our current methods or to invent entirely new ways of mapping the brain, which will at the end lead to better treatment options for our patients. On the clinical side, we also get together to discuss each and every single epilepsy surgery case. We meet on a weekly basis, and a group of 10 to 20 clinicians who aren't afraid of opposing each other brainstorm about the best treatment options for individual patients."
Koellsted still takes a couple of medications to control her seizures, which have now stopped completely. Their absence helped her convince the California Department of Motor Vehicles to let her take a driver's test to regain her license. She passed.
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