Pediatric constraint-induced movement therapy is associated with increased contralateral cortical activity on functional magnetic resonance imaging.

The mechanism behind constraint-induced movement therapy (constraint therapy) success is unknown. Study objectives were to evaluate cortical change after modified constraint therapy and explore a novel approach to quantify developmental disregard. Five participants underwent modified constraint therapy. Functional magnetic resonance imaging (MRI) and clinical measures were done pretreatment and posttreatment. Developmental disregard indices were calculated. Four participants showed clinical improvement posttreatment. Functional MRI laterality indices were variable pretreatment and exclusively contralateral among participants posttreatment. The disregard index range was -12.9 to 62.6 among participants. Disregard indices were correlated with change scores after treatment on the Pediatric Motor Activity Log amount of use domain (r = .93, P = .02), Assisting Hand Assessment (r = .93, P = .02), and grip strength (r = .92, P = .03). Study results suggest that a shift to or persistence of contralateral cortical activity for affected hand movement is important for constraint therapy mechanism of action; and developmental disregard may be a predictor of positive response to treatment.