Asymmetry in fractional anisotropy of the corticospinal tract correlates with measures of body structure/function and activity in the chronic phase after stroke.

BACKGROUND

Imaging biomarkers of corticospinal tract (CST) involvement show significant correlations with the upper extremity Fugl-Meyer Assessment (FMA) - a measure of body structure and function within the International Classification of Functioning, Disability, and Health framework (ICF) - particularly in the acute and subacute phases after stroke. However, the relationships between CST biomarkers and the FMA, as well as with ICF activity-level outcomes, remain insufficiently characterized.

OBJECTIVE

This cross-sectional study investigated, in 36 individuals in the chronic phase after stroke, the correlation between three markers of CST integrity, (1) asymmetry in fractional anisotropy measured in the posterior limb of the internal capsule (FA-PLIC), (2) asymmetry in cerebral peduncle (CP) area, and (3) the CST lesion load, and outcomes of body function/structure and activity.

METHODS

The participants were assessed with the FMA and the Wolf Motor Function Test (WMFT) consisting of a timed component (WMFT-Time) and the Functional Ability Scale (WMFT-FAS). Associations between imaging and clinical measures were analyzed with Pearson correlation coefficients.

RESULTS

FA-PLIC asymmetry was significantly correlated with FMA (r = 0.33; p = 0.047) and WMFT-FAS (r = 0.35; p = 0.035), but not with WMFT-Time (r = 0.26; p = 0.120). No significant correlations were observed between CP area asymmetry or CST lesion load and any of the outcome measures.

CONCLUSIONS

Our findings support FA-PLIC asymmetry as a biomarker of CST involvement, associated with the FMA and with the quality of movement during execution of functional tasks, in the chronic phase after stroke.