Longitudinal Study of Motor Evoked Potential in Patients with Acute Ischemic Stroke

Hong, Chan; Kim, Jong Yeol; Suh, Chung Kyu

Abstract

BACKGROUND: The prognostic value of motor evoked potentials(MEP) by transcranial magnetic timulations(TMS) in acute stroke has not been well established. To determine the value of MEP as predictors of motor and functional recovery we examined correlations of neurophysiological measurements of central motor conduction time(CMCT) and functional assessments. METHOD: A longitudinal study was performed on 32 first-ever acute ischemic stroke patients. The cortical and cervical motor evoked potentials(MEPs) along with the degree of extremity weakness, the NIH stroke scale, and the Barthel index were performed in the period immediately following stroke and after 3-4 months of the onset.
RESULTS
Five groups of patients were divided on the basis of MEP responses following the cortical stimulation; initial normal response following the normal one (group I; 11), initial delayed response following a normal or still delayed one (group II; 3/group III; 0), and an initial absent response with the reappearance of CMCT or still absent one (group IV; 8/group V; 10). Patients in group I,II and IV had consistently lower scores in motor weakness degree and NIH scale and higher scores in the Barthel index both at initial and follow-up studies, and achieved significantly better functional recovery(p<0.01).
CONCLUSIONS
Discordant results of MEP in predicting the prognosis of stroke may result from the disregard of group IV, which had previously been considered as a poor outcome group solely because no cortical MEP responses were recorded at the initial study. As the MEP alone during the acute stage could not differentiate group IV from group V which had a persistent absence of cortical MEP responses, the evaluation of the neurological deficit at the same time is needed for better prediction of prognosis.