ICNC Abstracts, ICNC 2018

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Utility of neuronavigated transcranial magnetic stimulation (nTMS) for functional motor mapping in infants and toddlers
Harper Lee Kaye, Gabrielle Block, Saeed Kayhanian, Hannah Purtell, Ugur Damar, Alexander Rotenberg

Last modified: 2018-09-12

Abstract


Introduction

Transcranial magnetic stimulation (TMS) is a method for non-invasive cortical stimulation, where intra-cranial currents are generated by an extra-cranial magnetic field. nTMS is FDA-approved for presurgical mapping of the motor cortex. However, little is known about the feasibility in very young children (≤2y), as the stimulation intensity required to elicit a motor evoked potential (MEP) often approximates maximal machine output (MO) of a conventional TMS device. Additionally, the safety and tolerability profile of nTMS for this age group is not well established. We present a case series of children <2y who underwent nTMS motor mapping.

Methods

6 children (5 intractable epilepsy, 1 healthy; range 6mo-1.7y) were enrolled. nTMS, paired with surface electromyography (EMG), was delivered at 100%MO via a figure-of-eight coil, guided by individual MRI and frameless stereotaxy. Single-pulses were delivered to the left and right motor cortices, and bilateral MEPs were obtained for the abductor pollicis brevis, deltoid, and tibialis anterior muscles.

Results

MEPs for all 6 target muscles were elicited with stimulation in 6/6 participants. Motor maps were generated during post-hoc analysis. All children tolerated nTMS motor mapping and related set-up (head-tracking device, and EMG electrodes). There were no instances of seizure, and no other adverse events occurred.

Conclusions

Despite a developmentally-regulated high motor threshold, nTMS in children age <2y is feasible, without adverse consequences. Notably, patients in our series-defined age group tolerate this technique and successful functional motor mapping was achieved in all cases.

Keywords


Transcranial magnetic stimulation; Noninvasive brain stimulation; Pediatric neurosurgery

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