Facilitation of motor evoked potentials in ischemic stroke patients: prognostic value and neurophysiologic correlations

Objective: To investigate the predictive value of paired transcranial magnetic stimulation (TMS) at rest in stroke patients in comparison with the predictive value derived from data obtained by single TMS during facilitation. Methods: Fifty-six patients with a single ischemic lesion and no electromyographic responses from single TMS in the resting affected hand muscles participated in the study. TMS assessment was performed 32 days post-stroke. It consisted of a single stimulation at maximal output during facilitation (controlateral hand grip and elbow flexion) and a paired-pulse stimulation at rest with two stimuli at maximal output at interstimulus intervals ranging from 15 to 100 ms. Two blind clinical assessments using the ‘motricity index’ were carried out 26 and 76 days post-stroke. Results: Thirty-seven percent of patients were responsive to single TMS during facilitation, had better clinical scores at both evaluations and better clinical recovery. Fifty-four percent of patients responded to paired TMS, had better clinical scores at the second evaluation and better clinical recovery. All patients who responded to the single stimulation paradigm also responded to the paired one. Conclusions: A positive correlation was found between the responsiveness to both the TMS paradigms (facilitation procedure and paired stimulation) and clinical recovery. This underlines the importance of facilitation during single TMS in stroke patients and suggests that paired TMS at rest might supplement this procedure in stroke studies.