Language and motor function thresholds during pediatric extra-operative electrical cortical stimulation brain mapping

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

“…The geometry of current spread into the brain tissue during ESM, and its effects on electrical activity of different types of cells in the cerebral cortex, are not well defined. 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 .…”

“…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 . 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 .…”

ECoG high-gamma modulation versus electrical stimulation for presurgical language mapping

“…Also, it is known that the current strength required to cause interference with language tasks, is a function of age, after-discharge thresholds, and prior stimulation [31, 32]. Especially in children, a higher current strength, often above the after-discharge threshold, is required for interference with language task(s) [1, 3, 33]. In fact, the optimal current strength for ESM is not well-established, and varies across centers.…”

“…ESM is associated with risks of after-discharges, seizures, and pain, which can all interfere with comprehensive mapping [1, 2]. There is also evidence for language thresholds to exceed after-discharge thresholds particularly in younger children [3]. Moreover, because it must be done sequentially for electrode pairs, ESM is time consuming, effectively limiting the number of sites that can be tested.…”

Presurgical language mapping using event-related high-gamma activity: The Detroit procedure

“…Electrical stimulation mapping is a powerful tool to localize the cortical areas essential in performing a given behavioral task, but carries several limitations as summarized in Table 1. Furthermore, the sensitivity of stimulation mapping for localization of the primary language areas might be suboptimal in young children, particularly in those younger than 10 years (Nakai et al, 2017; Schevon et al, 2007; Zea Vera et al, 2017). Unfortunately, non-invasive language mapping using functional MRI (fMRI) may be difficult to employ on young children who cannot minimize head motions during language tasks.…”