[2026-08-21] Serial Assessment of Corticomotor Pathway Continuity and Upper Extremity Recovery in Subacute Stroke: A Preliminary Study

Abstract

Background: Upper extremity weakness is common after stroke and significantly affects functional independence. Transcranial magnetic stimulation (TMS) has been used to assess corticomotor pathway integrity and predict motor recovery, but evidence in the subacute phase remains limited.

Objectives: To use serial TMS to examine corticomotor pathway continuity and its association with upper extremity recovery in patients with early subacute stroke and impaired hand function.

Methods: In this preliminary prospective cohort, patients 1 to 6 months after first-ever stroke with upper extremity impairment (Fugl-Meyer Assessment for Upper Extremity [FMA-UE] ≤ 53) underwent serial single-pulse TMS using the visual observation of movement method with a parabolic coil. Motor response (MR) presence and motor threshold were recorded bilaterally, with contralesional stimulation of the affected hand when the ipsilesional MR was absent. The primary outcome was the FMA-UE. Secondary outcomes included the Shoulder Abduction and Finger Extension score, Box and Block Test, Barthel Index, spasticity, and muscle strength. Assessments were performed between 1 and 6 months poststroke.

Results: Seven participants were enrolled (5 completed at least 2 follow-ups). Ipsilesional MR presence was not associated with FMA-UE. Three of 4 initially MR-absent participants showed late MR appearance at approximately 4 to 5 months poststroke, 2 of whom achieved clinically meaningful motor improvement. One participant who remained ipsilesionally MR-absent showed a contralesional response at 6 months. Across the cohort, Barthel Index scores improved in all participants, while muscle strength and spasticity remained relatively stable despite variable motor recovery.

Conclusions: Early subacute corticomotor pathway continuity was not clearly associated with upper extremity recovery, and the early absence of a MR should not be used to limit rehabilitation. Serial assessment revealed late reemergence of corticomotor responses, suggesting that subacute corticomotor continuity is dynamic rather than fixed. Rather than a large cross-sectional correlation study, future work should use serial, electromyography-based TMS within individual patients to track whether the MR or functional performance plateaus first, supporting progress monitoring and realistic expectation-setting.