Motor evoked potentials of the lower extremity in predicting motor recovery and ambulation after stroke: A cohort study

Objective: To assess the prognostic value of motor evoked potentials (MEPs) in the lower extremity with respect to motor recovery and functional recovery in stroke patients. Design: Cohort study. Setting: The department of neurology at a university hospital. Participants: Thirty-eight acute-stroke patients with complete paralysis (paralysis subgroup) or severe paresis (paresis subgroup) of the lower extremity. MEPs of the vastus medialis and the tibialis anterior muscles were recorded between days 3 and 10 after stroke onset. Interventions: Not applicable. Main Outcome Measures: A separate proximal leg motor score (maximum. 16 points) and crural motor score (maximum, 2 points) were defined within the lower-limb subset of the original Fugl-Meyer Motor Assessment to evaluate the motor performance at regular intervals until 6 months after stroke. The transfer item of the Barthel Index and the Functional Ambulation Categories scores were used to assess transfer and walking ability. Results: For the paralysis subgroup (n=30), the follow-up was complete in 27 patients (2 patients died, 1 patient underwent above-knee amputation). At 26 weeks, 20 patients experienced proximal motor recovery (mean score +/- standard deviation. 11.70+/-4.48), and 12 of them also showed crural motor recovery (mean score, 1.40+/-.51). Nine patients (33%) could perform an independent transfer safely, and 7 (26%) had learned to walk independently. Analysis revealed significant relationships for tibialis anterior muscle MEPs and motor recovery of crural le g muscles (odds ratio [OR] = 18.00; 95% confidence interval [CI], 1.31-894.40), but not for vastus medialis muscle MEPs and proximal motor recovery (OR=6.00; 95% CI, .53-303.00). We found no association between vastus medialis muscle MEPs and recovery of ambulation. However, tibialis anterior muscle MEPs seemed to provide a test with prognostic value for the ability to per-form independent transfers (OR = 17.50; 95% CI, 1.36-267.00), but not for walking (OR = 5.25: 95% CI, .40-77.57). Patients in the paresis sub-group experienced more favorable motor and functional recovery than did those in the paralysis subgroup. Conclusions: Tibialis anterior muscle MEPs registered in subacute phase after stroke may provide important prognostic information, both for motor recovery of the crural muscles and for the ability to perform independent transfers in patients with initial complete paralysis of the lower extremity. Vastus medialis muscle MEPs were not predictive for motor and functional recovery.