A transcranial magnetic stimulation study for the investigation of corticospinal motor pathways in children with cerebral palsy

•TMS is a non-invasive tool for investigating neuronal plasticity in children with CP.•TMS parameters (MEPs and CMCT) might be used for reorganization of corticospinal pathways.•MEP abnormalities are consistent with the MRI patterns in children with CP. The aim of this study is to perform transcranial magnetic stimulation (TMS)-based investigation of corticospinal motor pathways in children with cerebral palsy (CP) secondary to hypoxic-ischemic encephalopathy (HIE). TMS parameters including motor evoked potentials (MEPs) and central motor conduction time (CMCT) were recorded in 38 children with CP and 46 age-matched healthy controls. The z-score of MEPs were analyzed with respect to the types of MRI patterns of cortical involvement in children with CP. MEP latency values were correlated with the weight and height of children and to reflect the maturation of the corticospinal pathway. TMS evoked MEPs with prolonged onset latencies in 64% of children with CP while 10% of the CP group failed to elicit MEPs. Related with the MRI pattern, multicystic encephalomalacia (89%) was associated with the highest rates of abnormal cortical MEPs, as followed by periventricular leukomalacia (80%), basal ganglia involvement (66%) and focal cortical involvement (60%) patterns. Children with CP as compared with healthy controls had similar CMCT values on the upper and lower extremities in children with all cortical MR patterns. MEP abnormalities with TMS were consistent with the extent of motor cortex lesions on MRI patterns in CP children with HIE.