Intervention-Induced Motor Cortex Plasticity in Hemiparetic Children With Perinatal Stroke.

Background: Clinical trials are suggesting efficacy of intensive therapy combined with brain stimulation to improve hand function in hemiparetic children with perinatal stroke. However, individual variability exists and the underlying neuroplasticity mechanisms are unknown. Exploring primary motor cortex (M1) neurophysiology, and how it changes with such interventions, may provide valuable biomarkers for advancing personalized neurorehabilitation.
Methods: Forty-five children (age 6-19 years) with hemiparesis participated in PLASTIC CHAMPS, a blinded, sham-controlled, factorial clinical trial. All received 80 hours of goal-directed intensive upper extremity therapy. They were randomized into 4 groups: repetitive transcranial magnetic stimulation (rTMS) of contralesional M1, constraint therapy, both, or neither. Stimulus recruitment curves (SRC), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) for lesioned and contralesional M1 were investigated using TMS. Clinical assessments including the Assisting Hand Assessment (AHA) and Canadian Occupational Performance Measure (COPM) were conducted pre- and postintervention.
Results: All children completed the intervention and both function (AHA) and goal performance (COPM) improved with additive effects of rTMS and constraint ( P < .01). After intervention, motor-evoked potential (MEP) amplitudes from the contralesional M1 to the less-affected hand increased (n = 16, P < .02). SRC from the contralesional M1 to the less-affected hand increased (n = 25, P < .01). SICI of the contralesional M1 to the less-affected hand decreased (n = 30, P < .04). No changes were observed for ICF in either hemisphere ( P > .12).
Conclusion: TMS applied before/after intensive neuromodulation therapies can explore M1 neurophysiology and plasticity in children with cerebral palsy. Increased MEP sizes and decreased SICI may reflect mechanisms of interventional plasticity and be potential biomarkers of individualized medicine.