Fibers from the dorsal premotor cortex elicit motor-evoked potential in a cortical dysplasia

Objective:To identify the fibers originating from the dorsal premotor cortex (dorsal PMC) that contribute to motor-evoked potentials (MEP), we have applied integrated functional neuronavigation and awake surgery during removal of an epileptic cortical dysplasia located in the right premotor cortex.Methods:Chronic subdural electrodes were employed for functional mapping during a routine invasive evaluation for intractable epilepsy. After the fibers originating from the dorsal PMC were plotted into the tractography-integrated functional neuronavigation, subcortical MEPs and clinical symptoms were examined during resection of the epileptogenic dorsal PMC.Results:During removal of the epileptogenic area, MEPs were elicited by electrical stimulation of the fibers originating from the dorsal PMC, which were separated from the pyramidal tracts from the precentral gyrus. Resection of the dorsal PMC and its fibers caused a transient dysmetric movement of the left toe without motor weakness.Conclusion:Functional corticospinal tract fibers originating from the dorsal PMC can be defined and removed safely under local anesthesia with the aid of integration of functional neuronavigation and subcortical electrical stimulation.