Tailoring epilepsy surgery to achieve seizure freedom

Epilepsy is the most common severe chronic neurological condition. In Switzerland, about 30% of patients with focal epilepsy do not respond to antiepileptic medication, which results in about  200 new patients per year that could benefit from epilepsy surgery. During surgery, EEG recordings may be crucial to identify the minimal area of cortex whose removal is necessary to achieve postsurgical seizure freedom. However, current methods achieve seizure freedom only in about 60% of patients. New biomarkers to tailor the area of surgical removal are therefore urgently needed. High-frequency oscillations (HFO) in the EEG have recently emerged as biomarkers to detect epileptogenic tissue more specifically than by standard methods. In earlier work, our team at Zürich has successfully devised an automated computer algorithm to identify a clinically relevant HFO. In the proposed project, we will validate the algorithm prospectively in a larger patient cohort together with Genève. We will try new electrode designs to optimized recording. Furthermore, we will extend HFO detection to HFO evoked by electrical brain stimulation to study seizure onset and propagation areas. Measuring HFO rapidly and accurately before and during surgery is an exciting prospect that may add substantially to current diagnostics. This pioneering technology will provide a competitive edge for our hospitals and improved treatment options for patients with epilepsy. Participants: Prof. Dr. Johannes Sarnthein, University of Zurich Prof. Dr. Serge Vulliémoz, University of Geneva Dr. Pierre Mégevand, University of Geneva Dr. Tommaso Fedele, University of Zurich