Neural bases characterizing chronic and severe upper-limb motor deficits after brain lesion

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Chronic and severe upper-limb motor deficits frequently result from corticospinal tract damage.
• The precise clinical characteristics and underlying neural determinants of these deficits remain incompletely understood.

Purpose of the Study:

• To investigate the clinical characteristics of chronic and severe upper-limb motor deficits.
• To identify the neural bases associated with these motor deficit characteristics.

Main Methods:

• Assessed motor deficits, including spasticity, in 45 patients with brain lesions using clinical scales.
• Employed principal component analysis to extract key clinical characteristics.
• Conducted lesion analyses correlating principal components with lesion volume, sites, corticospinal tract, and regional white matter integrity.

Main Results:

• Principal component analysis identified two main characteristics: comprehensive severity and a trade-off between proximal function and wrist/finger spasticity.
• Comprehensive severity correlated with corticospinal tract integrity.
• The trade-off relationship was associated with the integrity of anterior white matter regions, including the anterior internal capsule.

Conclusions:

• Motor deficit severity is determined by corticospinal tract integrity.
• Specific motor deficit patterns, characterized by a trade-off between proximal function and spasticity, are influenced by other white matter pathways (e.g., corticoreticular).
• These findings offer insights into the neural underpinnings of complex upper-limb motor impairments.