Post-stroke motivational decline was associated with lesions in the left deep white matter involving the corticospinal tract and superior longitudinal fasciculus.

Declined motivation is a common issue among patients recovering from stroke and is a key determinant of rehabilitation outcomes. This study aimed to identify brain lesion locations associated with declined motivation, as measured by the vitality index, an observational measure of motivation in activities of daily living (ADLs) that can be applied even in patients with aphasia or dementia, in a clinical cohort of stroke patients. A total of 147 individuals with first-ever stroke were included. Lesion-symptom mapping using support vector regression was conducted to identify brain regions associated with vitality index scores at admission, while controlling for lesion size and age. The extent to which these lesions disrupted major white matter tracts was further examined using a publicly available tractography analysis tool. The analysis revealed that lesions within a specific region of the left corona radiata were significantly associated with lower vitality index scores. This region overlapped with the corticospinal tract and the superior longitudinal fasciculus. Tractography results indicated that damage in this region affected more than 50% of the corticospinal tract as well as superior longitudinal fasciculus II and III. Lower vitality index scores were also associated with motor paralysis, aphasia, and reduced independence in activities of daily living. Although causality cannot be inferred from this cross-sectional design, these findings highlight a critical deep white matter region potentially contributing to motivational decline following stroke and suggest targets for early assessment and individualized rehabilitation strategies.