P269 Utility of TMS in presurgical mapping of eloquent cortices in children

Abstract

Introduction The unique ability of TMS to non-invasively induce evoked responses and virtual lesions combined with improved accuracy afforded by image guidance has spurred its clinical applications. While the utility of presurgical motor and language mapping using TMS has been demonstrated in adults ( Picht, 2013 , Tarapore, 2012 ), its use in pediatric patients is in its infancy ( Narayana, 2015 ). We report here, successful functional mapping of both motor and language cortices using TMS in children. Methods Thirty-nine children (23 M, age range 0.6–18 years) undergoing surgery for brain tumors or refractory epilepsy underwent motor and language mapping using a navigated TMS system (Nexstim 4.3) (see Table 1 for the location of the lesions and type of mapping). The motor mapping (n = 22) included determination of localization and extent of primary motor cortex for hand and mouth. Language areas were localized as patients (n = 26) performed an object-naming paradigm implemented in the Nexspeech module (Nexstim Inc.) using 5 Hz TMS. TMS was applied to lateral temporal and frontal regions in both hemispheres and the observed errors were categorized using previously established criteria ( Picht, 2013 ). Results All patients tolerated TMS and did not experience any serious adverse effects. Motor cortex was successfully mapped in all but one patient. The TMS motor maps aided in determining the surgical approach and extent of resection in all patients (see Fig. 1-top). Language area localization and hemispheric dominance were successfully determined in 22 of the 26 patients. TMS derived language maps were used in conjunction with MEG, fMRI, WADA and cortical stimulation mapping in determining the surgical approach and extent of resection in these patients (see Fig. 1-bottom) ( Babajani-Feremi, 2016 ). Conclusions TMS is a safe and noninvasive means of localizing motor and language functions and recent improvements in accuracy and ease of application of TMS are especially beneficial in pediatric neurosurgery and neurology. We believe that the critical information that TMS provides, coupled with its ease of use, will result in increasing pediatric applications in the near future. Download : Download high-res image (264KB) Download : Download full-size image Download : Download high-res image (637KB) Download : Download full-size image