We are hereby describing a case of refractory pediatric epilepsy where resection of  perirolandic seizure foci was performed successfully under neurophysiologic guidance.

Pediatric neurophysiologic sensory-motor mapping is frequently unsuccessful, due to inability to localize central sulcus (CS) and primary motor cortex (M1). These shortcomings result from poor somatosensory evoked potentials (SSEP)  and high M1 depolarization thresholds respectively, both reflections of the immaturity of the central nervous system.

An 8-year-old boy with developmental delay,  debilitating focal epilepsy  and epileptic encephalopathy underwent phase 2 video EEG monitoring. The recordings showed seizures with early involvement of several depth electrodes located within the right parieto-frontal regions,  and an early motor semiology involving the left arm. The patient underwent neurophysiologically guided resection of the seizure foci under general anesthesia.  Pre-resection electrocorticography (ECoG) via a 64 contact grid showed abundant perirolandic epileptiform discharges (ED), maximal postcentrally. Cortical recordings of high amplitude median SSEP and a low depolarization threshold led to successful CS localization and identification of M1, respectively. A subdural strip electrode placed over the precentral gyrus and secured in position, allowed simultaneous ECoG  and motor monitoring during the resection of the postcentral foci. Initially, ECoG showed near continuous runs of ED, unchanged by cortical electrical stimulation. Under steady state anesthesia, at a constant propofol infusion rate,  this activity decreased in frequency and stopped altogether towards the end stages of the resection, as the M1 threshold increased by 7 mA. Post-resection fronto-parietal ECoG recordings were quiet. Post-operatively, the patient became seizure free, showed cognitive improvement and no motor deficits.

Increased cortical excitability may lead to successful functional mapping in children. Under steady anesthetic conditions, increases in the M1 threshold during resection of  nearby epileptic foci may be an early sign of decrease in the abnormal regional cortical excitability.