Brain Circuitry, Neuromodulation, and Rehabilitation in Unilateral Cerebral Palsy

Abstract

Background We investigated the safety and preliminary efficacy of transcranial direct current stimulation (tDCS) combined with occupation-centered, bimanual training in children and young adults with unilateral cerebral palsy (UCP). This study utilized cathodal tDCS to the non-lesioned hemisphere, an intervention hypothesized to inhibit excitation of the non-lesioned hemisphere. Methods Eight participants with contralateral or bilateral corticospinal tract (CST) circuitry participated in an open-label study with multiple-baseline design and combined intervention. The combined intervention consisted of 10 sessions of tDCS applied to the non-lesioned hemisphere (20 minutes) concurrently with bimanual motor training tailored to the child’s goals (120 minutes). We measured safety by monitoring the frequency of adverse events and measured intervention efficacy with the Assisting Hand Assessment. Other measurements included subjective (Canadian Occupational Performance Measure - COPM) and neurophysiologic (single pulse amplitude, cortical silent period - CSP, and motor mapping) data. Results All 8 participants were evaluated with all safety, behavioral, and neurophysiologic measures. No serious adverse events occurred. All children demonstrated improvement on at least one measure of hand function. We noted achievements of clinically significant improvements on hand function measures however no significant differences with group-level pre/post comparisons were found. Significant group-level increases were observed with subjective measures such as performance (p=.01, mean change: 2.76, 95% CI 1.77 to 3.74) and satisfaction (p=.02, mean change: 2.54, 95% CI: 1.34 to 3.74) on the COPM and the ABILHAND (p=0.04, mean change 0.19, 95% CI: 0.02 to 0.37). Neurophysiologic data suggest a decrease in amplitude of single-pulse transcranial magnetic stimulation (TMS) responses in the non-lesioned hemisphere as hypothesized, although group-level pre/post-test comparisons were non-significant. However, a decrease in the CSP duration (p<.03) and increases in the motor mapping sites suggest an excitatory influence of cathodal tDCS on the non-lesioned hemisphere. Conclusions The neurophysiologic effect of cathodal tDCS to the non-lesioned hemisphere confirmed the hypothesized inhibitory effect on amplitude of responses but also documented an excitatory effect on CSP duration and mapping sites. Future studies combining additional assessment measures and computational modeling will contribute to our understanding of the neurophysiologic influence of tDCS in children with UCP. Clinical Trials Registration: Clinicaltrials.gov NCT 02250092.