Stroke recovery beyond initial severity: the complementary roles of brain structure and brain function in acute stroke.

Stroke frequently results in long-term impairments, limiting independence and quality of life. Accurate prediction of recovery trajectories is essential for personalizing rehabilitation strategies. While structural brain metrics such as corticospinal tract (CST) integrity have been widely studied, they incompletely explain motor outcome variability. Functional brain activity, quantified by sensorimotor activity in the beta (β) frequency range, has emerged as a promising biomarker of motor system integrity and plasticity potential. This study examined 30 acute stroke survivors and 26 healthy controls, assessing how brain function and brain structure relate to initial severity and 6-month outcome accounting for initial severity, using clinical MRI/CT and electroencephalography during passive finger movement and rest. With respect to brain structure, grey and white matter damage were associated with initial severity, whereas no associations with 6-month outcome while accounting for initial severity were observed. In contrast, regarding brain function, β-activity in response to passive movement and resting state activity were related to 6-month outcome while accounting for initial severity, independent of initial severity. Multivariate regression analyses revealed that combining initial severity, structural information (CST damage) and brain function (sensorimotor β-activity) provided the most accurate model of both global and upper limb-specific 6-month outcome (R 2 = 80.0% and 73.6%, respectively). These findings underscore the importance of integrating functional and structural neural markers for improved stroke outcome prediction.