Relationship Between Cortical Excitability Changes and Cortical Thickness in Subcortical Chronic Stroke

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Ischemic stroke alters motor network excitability, but the link to structural brain changes remains unclear.
• Previous research suggests microstructural integrity of motor tracts influences cortical excitability post-stroke.
• The relationship between cortical thickness changes and motor network excitability after stroke is under-explored.

Purpose of the Study:

• To investigate the association between cortical thickness (CT) and motor cortical excitability in well-recovered chronic stroke patients.
• To compare CT in stroke patients with healthy controls and analyze its relationship with clinical data.

Main Methods:

• Re-analysis of transcranial magnetic stimulation (TMS) data, motor evoked potentials, and CT data in 14 chronic stroke patients and 17 healthy controls.
• Whole-brain and region-of-interest analyses to correlate CT with motor excitability and clinical scores.
• Focus on patients with isolated supratentorial subcortical lesions.

Main Results:

• Stroke patients displayed significantly reduced CT in the ipsilesional primary motor cortex and other secondary motor/non-motor regions.
• Affected areas included regions along the central, inferior frontal, and intraparietal sulci, and cingulate cortices.
• No significant relationship was found between the degree of CT reduction and stroke-related motor network excitability or clinical outcomes.

Conclusions:

• Chronic stroke is associated with widespread cortical thickness reduction, particularly in the ipsilesional hemisphere.
• Despite structural changes, cortical thickness reduction does not appear to directly correlate with motor network excitability or functional recovery in this cohort.
• Further research is needed to elucidate the complex interplay between structural and functional recovery post-stroke.