Prediction of Motor Outcome in Patients With Severe Upper Limb Impairment After Stroke Using Motor Evoked Potentials

IntroductionIdentifying the individuals who may achieve a favorable upper limb function after severe stroke-related upper limb impairment remains challenging. Incorporating a biomarker, motor-evoked potential (MEP), may improve prediction accuracy.ObjectivesTo evaluate the prediction accuracy of baseline MEP status for upper limb motor outcome at 3 months post-stroke and to determine the predictive association between MEP status and upper limb motor outcome.MethodsThis prospective longitudinal cohort study included patients ≥18 years of age with severe upper limb impairment within 4 weeks post-stroke. MEP status was examined with transcranial magnetic stimulation at baseline. The primary outcome was the Fugl-Meyer Assessment upper extremity score (FMA) at follow-up 3 months post-stroke. The accuracy was determined by comparing MEP status (MEP present or absent) with 2 FMA outcome categories (FMA ≤ or >17) including calculation of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The predictive association between MEP status and 3 FMA outcome categories (FMA: 0-4; 5-17; and 18-66) was examined using ordinal logistic regression.ResultsOf 80 included patients, 74 completed follow-up. Overall accuracy was 75.7% (95% confidence interval [CI]: 64.3%-84.9%). Specificity was 80.3% (95% CI: 68.2%-89.4%), sensitivity 53.8% (95% CI: 25.1%-80.8%), PPV 36.8% (95% CI: 16.3%-61.6%), and NPV 89.1% (CI 95% 77.8%-95.9%). MEP presence was strongly associated with a higher motor outcome category at follow-up (odds ratio: 6.6; 95% CI: 2.1-21.9; P = .001).ConclusionsAssessing MEP status is a clinically relevant approach for predicting upper limb motor outcomes in patients with severe upper limb impairment after stroke.Trial Registry NameiTMS-Implementing Transcranial Magnetic Stimulation to Assess Cortico-spinal Tract Integrity. https://clinicaltrials.gov/study/NCT06153017. Registration number: NCT06153017.