Longitudinal studies of motor cortical excitability and transcallosal inhibition after subcortical stroke

Objective: To study serial changes in motor cortical excitability and transcallosal inhibition during post-acute and chronic phases up to one year after subcortical stroke. Methods: Single-pulse and paired-pulse trans cranial magnetic stimulation (TMS) were performed 3 times in 20 patients to obtain multiple measures, such as motor threshold, contralateral and ipsilateral silent periods, and short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF). Twenty-one healthy subjects were also studied. Results: The results suggest that overall excitability on the unaffected motor cortex was increased and transcallosal inhibition from the unaffected to affected hemisphere was enhanced in the post-acute phase. These changes on the unaffected side returned to be normal following recovery rehabilitation. Conclusion: Excitability changes from the unaffected hemisphere are strongly associated with motor recovery. The results may help improve individualized rehabilitation strategies after stroke.