Locomotor Training Remodels fMRI Sensorimotor Cortical Activations in Children After Cerebral Hemispherectomy

Abstract

Purpose. This study examined whether locomotor training, which included body weight—supported treadmill therapy, improved walking and induced cortical representational adaptations using functional magnetic resonance imaging in the remaining sensorimotor network after cerebral hemispherectomy. Methods. Hemispherectomy patients (n = 12) underwent 2 weeks of gait training for at least 30 hours each. They were tested pre- and posttraining with the Fugl-Meyer Motor Assessment, unassisted single-limb stance time, and usual and fastest walking speeds. Three patients performed voluntary ankle movements as the functional magnetic resonance imaging activation task pre- and posttraining. Control subjects included 5 healthy children tested 2 weeks apart, 2 of whom trained on the treadmill, and 2 hemispherectomy patients who received upper extremity rehabilitation and no gait therapy. Results. Although patients reported improvements with gait training, behavioral outcomes did not significantly change. Training was associated with increased volume and intensity of cortical activation in the primary sensorimotor (S1M1), supplementary motor, motor cingulate, and secondary somatosensory cortex for the paretic foot, along with greater overlap in the representation for each moving foot in S1M1 and the supplementary motor area of the remaining hemisphere. Control subjects showed a decrease in activation in these cortical regions after training. Conclusions. Locomotor training of hemispherectomy patients improved mobility subjectively in association with functional magnetic resonance imaging evidence of cortical remodeling with ankle dorsiflexion. These findings support the notion that hemispherectomy patients may respond to rehabilitation interventions through mechanisms of activity-dependent cortical plasticity. The authors hypothesize that developmentally persistent descending ipsilateral and contralateral corticospinal tracts may allow the remaining hemisphere to maintain bilateral lower extremity motor control after surgery.