Structural correlates of aphasia severity, cognitive impairment, and outcome after stroke

In this study, we aimed to identify structural biomarkers linked to the severity and outcome of aphasia after a left-hemispheric stroke. We recruited 72 individuals with post-stroke aphasia and assessed their initial aphasia severity using the Aphasia Severity Rating Scale, alongside measures of naming ability and executive function. Aphasia outcome was determined for 56 out of 72 participants with available Aphasia Severity Rating Scale scores at discharge. We performed support-vector regression symptom mapping analyses at both cortical and white matter levels to examine the relationship between structural brain damage and our variables of interest (initial aphasia severity, naming, executive functions, and aphasia outcome). Our results revealed that (a) disconnections in white matter tracts within ventral and dorsal language pathways were associated with aphasia severity and naming deficits initially; and (b) disconnections in white matter tracts within executive networks (i.e., fronto-parietal, executive control, and salience networks) were related to executive dysfunction. This retrospective cohort study highlighted the crucial roles of white matter tracts within both dorsal (i.e., arcuate fasciculus, superior longitudinal fasciculus) and ventral (uncinate, inferior longitudinal, and middle longitudinal fasciculi) language streams in shaping the cognitive phenotypes of post-stroke aphasia patients, particularly concerning aphasia severity and naming impairment, by delineating distinct patterns of affected brain structures.