Neurophysiological Predictors of Proximal Motor Rehabilitation in Stroke Patients with Corticospinal Tract Damage

Background/Objectives: Upper-limb motor dysfunction is common after stroke, and patients often have limited recovery during rehabilitation. In this study, we aimed to investigate the relationship between contralesional neurophysiological parameters and the effects of rehabilitation on upper-limb motor function in stroke patients with corticospinal tract damage. Methods: Forty patients with subacute stroke with an absent MEP response on the ipsilesional side before admission were included. Contralesional neurophysiological parameters, including resting motor threshold, contralesional MEP, contralesional short-interval intracortical inhibition (short-ICI), and contralesional long-interval intracortical inhibition (long-ICI), were assessed via transcranial magnetic stimulation (TMS) pre-admission. The coefficients of variation for MEP, short-ICI, and long-ICI were calculated to assess cortical stability. Rehabilitation effect was measured using changes in the Fugl-Meyer assessment score after 21 days of rehabilitation. Results: No single contralesional parameter significantly predicted rehabilitation effect. Further exploratory analysis revealed that a model combining contralesional neurophysiological parameters was associated with proximal limb motor function recovery. Short-ICI played a prominent role in this exploratory model. Conclusions: Contralesional neurophysiological markers demonstrated limited predictive value in patients with stroke with moderate-to-severe motor dysfunction and damaged corticospinal tract function on the ipsilesional side. However, a model combining multimodal contralesional TMS measures, particularly short-ICI, may offer incremental value in predicting proximal limb motor improvement following 21-day rehabilitation. Although this mechanism was not directly measured, the findings suggest a compensatory role of the cortico-reticulo-spinal pathway. These exploratory results should be interpreted with caution regarding their clinical applicability and are premature as a predictive tool, pending rigorous external validation.