After-discharges and seizures during pediatric extra-operative electrical cortical stimulation functional brain mapping: Incidence, thresholds, and determinants

Electrocorticographic high‐gamma modulation with passive listening paradigm for pediatric extraoperative language mapping

“…Also, HGM mapping does not involve the risks of ESM‐induced ADs and seizures. Occurrence of ADs during ESM compromise the validity of the functional localization, and ESM‐induced seizures can even preclude successful completion of mapping . In children unable to cooperate with conventional language tasks, story listening–associated HGM can provide useful data to the neurosurgeon.…”

“…Recently, it has been shown that ESM current thresholds for cortical excitability and functional responses are correlated, but their patient‐related or technique‐related determinants remain unknown . Given the high prevalence of ADs during ESM, including ADs occurring at remote sites, it is possible that some of the functional responses during ESM localize not to the cortex directly beneath the stimulated electrode pair, but rather to another node of the functional network with preferential connectivity to the stimulated site . This is a probable explanation for the distributed topography of HGM compared to ESM language sites (Figures and ).…”

“…Occurrence of ADs during ESM compromise the validity of the functional localization, and ESM-induced seizures can even preclude successful completion of mapping. 1 In children unable to cooperate with conventional language tasks, story listening-associated HGM can provide useful data to the neurosurgeon. If the child can participate in a naming task even for a brief duration, HGM can further help classify electrodes before confirmatory ESM.…”

“…A recent study including 122 patients showed ESM to be associated with after-discharges (ADs) in 77% and seizures in 35% of patients. 1 More importantly, the current thresholds for language function were higher than AD thresholds at all ages, which would require stimulation at currents higher than cortical excitability thresholds and increase the risk of ESM-induced seizures. 2 These considerations have encouraged development of an alternate method for functional brain mapping based on power changes time-locked to language tasks in electrocorticographic (ECoG) spectra.…”

“…There have been long‐standing concerns about the safety, neurophysiologic validity, and application in children of this electrical stimulation mapping (ESM). A recent study including 122 patients showed ESM to be associated with after‐discharges (ADs) in 77% and seizures in 35% of patients . More importantly, the current thresholds for language function were higher than AD thresholds at all ages, which would require stimulation at currents higher than cortical excitability thresholds and increase the risk of ESM‐induced seizures .…”