Determining Electrode Placement for Transcranial Direct Current Stimulation: A Comparison of EEG- Versus TMS-Guided Methods

Abstract

Transcranial direct current stimulation (tDCS) is increasingly researched as an adjuvant to motor rehabilitation for children with hemiparesis. The optimal method for the primary motor cortex (M1) somatotopic localization for tDCS electrode placement has not been established. The objective, therefore, was to determine the location of the M1 derived using the 10/20 electroencephalography (EEG) system and transcranial magnetic stimulation (TMS) in children with hemiparesis (CWH) and a comparison group of typically developing children (TDC). We hypothesized a difference in location for CWH but not for TDC. The 2 locations were evaluated in 47 children (21 CWH, 26 TDC). Distances between the locations were measured pending presence of a motor evoked potential. Distances between the EEG and TMS locations that exceeded the 2.5 cm × 2.5 cm rubber electrode area are reported in percentages [95% confidence interval] in CWH—nonlesioned hemisphere was 68.8% [41.3-89.0], lesioned: 85.7% [57.2-98.2]; TDC—dominant hemisphere 73.9% [51.6-89.8], nondominant: 82.6% [61.2-95.0]. Distances that exceeded the 3 × 5 cm electrode sponge area in CWH—nonlesioned was 25.0% [7.3-52.4], lesioned was 28.6% [8.4-58.1]; TDC—dominant was 52.2% [30.6-73.2], nondominant was 43.5 [23.2-65.5]). Distances that exceeded the 5 × 7 cm electrode sponge area in CWH—nonlesioned was 18.8% [4.0-45.6] and lesioned was 21.4% [4.7-50.8]; TDC—dominant was 21.7% [7.5-43.7] and nondominant was 26.1% [10.2-48.4]. Individual variability in brain somatotopic organization may influence surface scalp localization of underlying M1 in children regardless of neurologic impairment. Findings suggest further investigation of optimal tDCS electrode placement. EEG and TMS methods reveal variability in localizing M1 in children regardless of stroke diagnosis. This study was registered on clinicaltrials.gov NCT020I5338.

Transcranial Direct Current Stimulation (tDCS) Paired with Occupation-Centered Bimanual Training in Children with Unilateral Cerebral Palsy: A Preliminary Study

“…Neurophysiologic responses were assessed with TMS using a 70 mm coil using a Magstim 200 stimulator (Magstim Company Ltd., Dyfed, United Kingdom). TMS methods are previously described in other publications [34, 35]. Briefly, bilateral electromyography data was monitored in real time and stored in a laptop computer using a customized LabVIEW program (v2012, National Instruments, Austin, Texas, USA) for offline analysis using a custom Matlab program (MathWorks, Natick, Massachusetts, USA).…”

Less-Affected Hand Function in Children With Hemiparetic Unilateral Cerebral Palsy: A Comparison Study With Typically Developing Peers

“…The secondary objectives included six within-group comparisons of differences in hand function and motor thresholds for CTD, and children with UCP as grouped by contralateral, and ipsilateral motor patterns and two between-group comparisons of differences in motor thresholds for CTD and children with UCP with contralateral patterns of motor representation. Hand function was measured using speed during functional tasks with the Jebsen Taylor Test of Hand Function (JTTHF) 29 and gross hand strength as measured by hydraulic grip dynamometry (Jamar Dynamometer, Patterson Medical, Warrenville, IL, USA). The post-hoc objective was to examine the relationship between the performance on the JTTHF and grip strength with the presence of a MEP as elicited by transcranial magnetic stimulation.…”

Non-Invasive Brain Stimulation in Children With Unilateral Cerebral Palsy: A Protocol and Risk Mitigation Guide

“…Policies established at individual institutions and regulatory oversight mechanisms may reflect different protocols. Indeed, between our own laboratories at different sites, we have discovered variations in the existing study criteria ( 49 , 63 , 83 ). One approach is to include children of any age who have been seizure-free for 2 years.…”