The search for the epicenter of epilepsy
Scandinavia’s first robot-assisted stereo-EEG implantation has been carried out at Karolinska. The technology opens the door to treating twice as many patients with severe epilepsy.
Every year, about 10 patients with epilepsy are surgically treated at Karolinska. With this new monitoring method, that number could increase by 5 or 10.
"I hope to improve the daily lives of these patients," says neurosurgeon Ulrika Sandvik. "They can be exhausted by their seizures and have difficulty managing their jobs. Some frequently fall and hurt themselves. Growing children with severe seizures risk having their development impaired."
For a very small number of patients, the most common method of treatment—seizure medication—doesn't work. In those cases, a meticulous investigation is done to see if surgical treatment is an option.
"The seizures could be caused by something like a scar, a deformity or a tumor," Sandvik explains. "In some less serious cases, this can be corrected surgically or using laser ablation."
The normal procedure to detect these kinds of changes in the brain is an EEG, which picks up the activity in the neural cells, combined with an MRI scan.
Better data in some cases
But there also seizures and epilepsy that are more difficult to interpret, which occur even though the brain looks perfectly normal in the MRI scans. In those cases, stereotactic EEG (SEEG) can be used to measure activity inside the brain.
"The signals between nerve cells spread extremely quickly, which makes it difficult to detect where an epileptic seizure starts. Stereotactic EEG gives us much better data," Sandvik says. In the beginning of January, her team completed Scandinavia's first robot-assisted implantation of SEEG electrodes in a patient.
The precise placement of the electrodes is programmed into the robot, which serves as a sort of GPS during the operation and shows the neurosurgeon exactly where and at what angle to place them. "This improves our precision and shortens the operation time by about three hours," Sandvik says.
A total of 14 electrode leads with 107 contacts were positioned in the patient's brain. After the operation, they are connected to a monitor to register brain activity.
The SEEG monitoring goes on for about a week before the electrodes are removed. The patient's medication is then gradually reduced to monitor seizure activity. A small electric current is applied to trigger a seizure and to test speech and other functions. The patient is awake and participating.
"Such an extensive investigation is only done if we have good reason to believe the epilepsy can be surgically treated. If we find a seizure focus, the patient has a 75% chance of a reduction in seizures, or even becoming seizure-free," Sandvik says.
Text: Catarina Thepper, Photo: Catarina Thepper, Carin Tellström
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