Sensorimotor cortex reorganization in subacute and chronic stroke: A neuronavigated TMS study

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Corticospinal system integrity is a key biomarker for stroke recovery.
• Mapping corticospinal topography in subacute stroke and its changes during recovery is challenging and poorly understood.

Purpose of the Study:

• To quantify the corticospinal system's topographic landscape in sensorimotor cortices during subacute and chronic stroke phases using transcranial magnetic stimulation (TMS).
• To differentiate neuroplasticity mechanisms by analyzing changes in the extent (area) and robustness (amplitude) of corticospinal activation.

Main Methods:

• Utilized a transcranial magnetic stimulation (TMS) based mapping approach.
• Mapped corticospinal activation in ipsilesional and contralesional sensorimotor cortices before (PRE) and after (POST) intervention in 10 chronic and 8 subacute stroke subjects.
• Quantified reorganization by dissociating changes in the area and amplitude of the sensorimotor activation territory.

Main Results:

• Observed distinct patterns of corticospinal reorganization between subacute and chronic stroke stages.
• Demonstrated that changes in the expanse (area) and robustness (amplitude) of sensorimotor activation contribute uniquely to observed reorganization.
• Identified differences in neurophysiological mechanisms underlying stroke recovery at different time points post-stroke.

Conclusions:

• Stroke recovery involves distinct neuroplasticity mechanisms in subacute versus chronic phases.
• TMS-based topographic mapping provides valuable insights into corticospinal system changes and recovery trajectories.
• Understanding stage-specific mechanisms can inform targeted rehabilitation strategies for stroke survivors.