Stereo-EEG for Epilepsy Surgery

SEEG for Epilepsy

Adding to the cutting-edge diagnostic tools available at the UCSF Epilepsy Center, neurosurgeons have begun to use stereo-electroencephalography (SEEG) as part of the presurgical evaluation for select patients.

SEEG involves implanting depth electrodes – thin wires no wider than the tip of a pencil lead – through small openings in the skull. These electrodes can precisely characterize the electrical activity of deep structures in the brain, detecting patterns of electrical abnormality that can define the seizure foci, or the area of the brain where seizures are originating.

The standard procedure for localizing the seizure foci requires placing a large array of electrodes called a subdural grid on the surface of the brain. To expose the brain’s surface, patients need to undergo a larger surgery called a craniotomy.

While subdural grids remain the gold standard for presurgical evaluation, SEEG may be used when suspected seizure foci is located in areas inaccessible to grids – like the singulate, insula, and orbitofrontal cortex – or for patients who are unable to tolerate a more invasive craniotomy.

The minimally invasive nature of SEEG makes it safer and patients are likely to have less pain and better wound healing. Candidates for this methodology are determined by MRI scans, type of seizures, and other patient-specific factors.

Sophisticated software and imaging technology is needed to monitor the placement of the depth electrodes, and only a handful of institutions in the United States have begun using this approach.