Anodal Contralesional tDCS Enhances CST Excitability Bilaterally in an Adolescent with Hemiparetic Cerebral Palsy: A Brief Report

Abstract

Hemiparetic cerebral palsy (HCP), weakness on one side of the body typically caused by perinatal stroke, is characterized by lifelong motor impairments related to alterations in the corticospinal tract (CST). CST reorganization could be a useful biomarker to guide applications of neuromodulatory interventions, such as transcranial direct current stimulation (tDCS), to improve the effectiveness of rehabilitation therapies. We evaluated an adolescent with HCP and CST reorganization who demonstrated persistent heightened CST excitability in both upper limbs following anodal contralesional tDCS. The results support further investigation of targeted tDCS as an adjuvant therapy to traditional neurorehabilitation for upper limb function.

Keywords: Brain Excitability; Hemiparesis; Motor Evoked Potential; Perinatal Stroke; Transcranial Direct Current Stimulation.

Figure 1.

A) Coronal and B) Axial views of participant’s T1-weighted MRI scan. Images are presented in radiological orientation (left side of the image displays the right hemisphere).

Figure 2.

TMS assessment results displayed for intervention participant for A) Left Hand B) right Hand C) Left Wrist D) Right Wrist. Line graphs display MEP amplitudes (calculated from peak to peak, Mean +/− Standard Deviation) at each time point; Waterfall plots illustrate a subset of 10/20 trials (odd-numbered) at Pre-tDCS, Post 0, Post 30, and Post 60 assessments. The TMS pulse was delivered at time 0, with plots displaying EMG recordings from 50 msec before the TMS pulse to 100 msec after the TMS pulse. No MEPs were recorded at the baseline assessment (pre-tDCS) in the Right ED. Between Pre-tDCS and Post 0 assessments, the participant received 1.5 mA anodal tDCS to the right hemisphere while participating in the TrackTest fine motor activity. The diagram depicts an M1-SO montage wherein the left (lesioned) hemisphere displays the cathode placed on the forehead, and the right (non-lesioned) hemisphere displays the anode placed over the motor hotspot. Sample TrackTest traces are shown from the participant’s pre-test trials, completed with his left hand.