Motor recovery following stroke: a transcranial magnetic stimulation study

Objectives: To verify the usefulness of early recording of motor evoked pot entials (MEPs) in predicting motor outcome after stroke and to investigate the neural mechanisms underlying functional recovery following stroke. Methods: We performed a comparative analysis of the behaviour of motor resp onses evoked by transcranial magnetic stimulation (TMS) of the ipsilateral and contralateral motor cortex in the affected and unaffected thenar muscle s of 21 consecutive patients with acute stroke. Results: According to the behaviour of MEPs in the affected muscles, patien ts could be divided into 3 groups: (a) 10 subjects with absent responses to TMS of both the damaged and undamaged hemisphere, whose motor recovery was poor and related to the size of MEPs on the normal side; (b) 5 subjects wi th larger MEPs upon TMS of the ipsilateral (undamaged) than of the contrala teral (damaged) cortex, whose good recovery possibly resulted from the emer gence of ipsilateral pathways; (c) 6 subjects with larger MEPs in the affec ted than in the unaffected muscles, whose good recovery was possibly subser ved by alternative circuits taking over cortical deafferentation. Conclusions: Early MEP recording in acute stroke provides useful informatio n on the clinical prognosis and the different mechanisms of motor recovery. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.