Electrically stimulated auras as a potential biomarker of the epileptogenic zone

Electrocortical stimulation mapping (ESM) is often performed in patients undergoing stereoelectroencephalography (SEEG) prior to epilepsy surgery, with the goal of identifying functional cortex and preserving it postoperatively. ESM may also evoke a patient's typical seizure semiology. The purpose of this study was to determine whether the sites at which typical auras are evoked during ESM are associated with other known clinical and electrophysiologic biomarkers of the epileptogenic zone: the seizure onset zone (SOZ), the early spread zone (ES), and high-frequency oscillations (HFOs). We found that the sites at which auras were provoked were not consistently associated with known biomarkers (p = 0.09). We conclude that evoked auras during ESM may reflect electrical spread rather than true epileptogenicity, and that a larger study is needed to assess their potential value as independent epileptic biomarkers.