Patients vary widely in their response to cortical electric stimulation (CES). A retrospective analysis of 92 patients with medically intractable epilepsy who underwent CES was unable to detect any clinical or demographic factors that would explain the varied response to the procedure. Corley et al also found striking variability and a wide range of motor, sensory, and speech response thresholds between patients and within the different regions of the brain in the same patient.
Corley JA, Nazari P, Rossi VJ, et al. Cortical stimulation parameters for functional mapping. Seizure. 2017;45:36-71.