Role of corpus callosum integrity in arm function differs based on motor severity after stroke

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• The corpus callosum (CC) is crucial for sensorimotor control.
• Its specific role in motor function post-stroke, particularly concerning different impairment levels, remains unclear.

Purpose of the Study:

• To investigate the relationship between the structural integrity of the CC's motor and sensory regions and motor function in chronic stroke survivors.
• To determine if this relationship differs based on the severity of motor impairment.

Main Methods:

• Diffusion tensor imaging (DTI) was used to assess fractional anisotropy (FA) in the CC and corticospinal tract (CST).
• Fifty-five chronic stroke patients and 18 healthy controls underwent DTI and motor behavior tests (Fugl-Meyer score).

Main Results:

• Stroke survivors exhibited significantly decreased FA in CC regions compared to controls (p < 0.001).
• Overall, CC FA positively correlated with motor function.
• In less impaired individuals (Fugl-Meyer > 39), motor function correlated with CC FA, not CST FA.
• In more impaired individuals (Fugl-Meyer ≤ 39), motor function correlated with CST FA, not CC FA.

Conclusions:

• The contribution of interhemispheric connections (CC) to motor function after stroke may depend on the degree of motor impairment.
• Findings highlight stroke's heterogeneity and suggest subgroup-specific biomarkers and treatments are needed.