MEP Variability May Help Predict Motor Recovery After Stroke

The study included 77 patients with subacute stroke (mean age, 68.5 years; 41.6% women) and 10 age- and sex-matched healthy controls. Researchers measured MEP amplitude and trial-to-trial amplitude variability in both hemispheres at rest early after stroke and again following a two-month, high-intensity daily rehabilitation program. Motor outcomes were assessed with the Fugl-Meyer Upper Extremity scale and a Motor Recovery Index.

At baseline, mean MEP amplitude and variance were lower in the affected than unaffected hemisphere (0.16 vs 0.38 mV and 0.013 vs 0.038 mV², respectively). In the affected hemisphere, amplitude increased by follow-up to 0.21 mV (P=0.01), while variance did not change significantly. Baseline amplitude was associated with follow-up Fugl-Meyer scores, but not with degree of recovery. Baseline variability was associated with both follow-up Fugl-Meyer scores and the Motor Recovery Index.

The findings suggest that MEP amplitude and variability may capture different aspects of motor pathway function. Variability is a potential recovery biomarker, but this observational study does not establish its predictive performance in clinical use or show that using it to guide rehabilitation improves outcomes.