CORTICOSPINAL INPUT ONTO MOTOR-NEURONS PROJECTING TO ANKLE MUSCLES ININDIVIDUALS WITH CEREBRAL-PALSY

Cross-correlograms between voluntarily active soleus (SOL) and tibiali s anterior (TA) motor units were generated From seven control subject: , and six subjects with spastic cerebral palsy (CP). Short-duration ce ntral peaks were observed in three subjects with spastic diplegia only . All subjects demonstrated reciprocal inhibition in TA following elec trical stimulation of group I afferents to SOL, and all subjects with CP demonstrated strong activation of both TA and SOL in response to tr anscranial magnetic stimulation. Responses in SOL were stronger than t hose observed from controls. These data support the existence of abnor mal corticospinal projections to soleus motor neurons in individuals w ith spastic CP. In spastic diplegia. short-term discharge synchrony be tween SOL and TA motor units may reflect abnormal interneuronal modula tion at the spinal level. Abnormal corticospinal projections and/or mo dulation of spinal interneurons may contribute to the disordered movem ent patterns and co-activation observed in this population.