Central motor reorganization in cerebral palsy patients with bilateral cerebral lesions

Transcranial magnetic stimulation (TMS) has been used to describe cortical plasticity after unilateral cerebral lesions. The objective of this study w as to find out whether cortical plasticity occurs after bilateral cerebral lesions. We investigated central motor reorganization for the arm and leg m uscles in cerebral palsy (CP) patients with bilateral cerebral lesions usin g TMS. Seventeen patients (12 with spastic diplegia, 1 with spastic hemiple gia, and 4 with athetoid CP) and 10 normal subjects, were studied. On CT/MR I, bilateral periventricular leukomalacia was observed in all spastic patie nts with preterm birth. In two normal subjects, motor responses were induce d in the ipsilateral tibialis anterior, but no responses were induced in an y normal subject in the ipsilateral abductor pollicis brevis (APB) or bicep s brachii (BB). Ipsilateral responses were more common among CP patients, e specially in TMS of the less damaged hemisphere in patients with marked asy mmetries in brain damage: in 3 abductor pollicis brevis, in 6 BBs, and in 1 5 tibialis anteriors. The cortical mapping of the sites of highest excitabi lity demonstrated that the abductor pollicis brevis and BE sites in CP pati ents were nearly identical to those of the normal subjects. In patients wit h spastic CP born prematurely, a significant lateral shift was found for th e excitability sites for the tibialis anterior. No similar lateral shift wa s observed in the other CP patients. These findings suggest that ipsilatera l motor pathways are reinforced in both spastic and athetoid CP patients, a nd that a lateral shift of the motor cortical area for the leg muscle may o ccur in spastic CP patients with preterm birth.