The neuronal correlates of mirror illusion in children with spastic hemiparesis: A study with functional magnetic resonance imaging

Abstract

AIM: To investigate the neuronal activation pattern underly-ing the effects of mirror illusion in children/adolescents with normal motor development and in chil-dren/adolescents with hemiparesis and preserved contrala-teral corticospinal organisation. METHOD: The type of cortical reorganisation was classified according to results of transcranial magnetic stimulation. Only subjects with congenital lesions and physiological contralateral cortical reorganisation were included. Func-tional magnetic resonance imaging was performed to in-vestigate neuronal activation patterns with and without a mirror box. Each test consisted of a unimanual and a bi-manual motor task. RESULTS: Seven children/adolescents with congenital hemiparesis (10-20 years old, three boys and four girls) and seven healthy subjects (8-17 years old, four boys and three girls) participated in this study. In the bimanual experiment, children with hemiparesis showed a significant effect of the mirror illusion (p<0.001 at voxel level, family-wise error corrected at cluster level) in the dorsolateral prefrontal cortex and anterior cingulate cortex of the affected and unaffected hemispheres, respectively. No significant effects of the mirror illusion were observed in unimanual experi-ments and in healthy participants. INTERPRETATION: Mirror illusion in children/adolescents with hemiparesis leads to activation of brain areas involved in visual conflict detection and cognitive control to resolve this conflict. This effect is observed only in bimanual train-ing. We consider that for mirror therapy in children and adolescents with hemiparesis a bimanual approach is more suitable than a unimanual approach.