ABSTRACT NUMBER: ESOC2026A1214 DISENTANGLING MOTOR SEVERITY AND RECOVERY AFTER STROKE THROUGH ACUTE STRUCTURAL CONNECTOMICS

Abstract Background and aims Upper-limb motor recovery depends on the initial motor severity and on brain reorganization. Brain structural reorganization that supports motor recovery may be challenging to characterize because of its strong association with initial motor severity. We aimed to characterize the impact of acute stroke on the white matter and structural connectome, and its relationship with both initial motor severity and recovery. Methods One hundred and fifty patients with a first-ever unilateral stroke and an upper limb motor deficit were included. Median motor severity assessed by the Fugl-Meyer assessment for the upper extremity was 26 on day seven and 52 at 3 months. Lesion masks were manually drawn on DWI sequence (<7 days) and then used to compute tract-specific disconnection severity and voxel-wise probabilities of structural disconnection. The latter was used to filter a normative tractography, estimate each patient's connectome, and characterise each node’s topology using graph theory (Figure 1). Results Acute disconnection of the ipsilesional corticospinal tract and frontal thalamic projections was significantly correlated with both motor severity and recovery. In contrast, acute disconnection of the anterior division of the cingulate gyrus was specifically associated with motor recovery. Connectome topology analysis showed that motor recovery was specifically linked to the connection strength of ipsi- and contralesional caudal anterior cingulate and the clustering coefficient of contralesional somatomotor network, including both primary and secondary motor areas. Conclusions By distinguishing motor severity from recovery, these findings emphasize the anterior cingulate and contralesional sensorimotor network as key contributors to motor recovery, regardless of initial impairment. Conflict of interest Thomas Jacquemont-Fulneau. nothing to disclose Annibale Antonioni. nothing to disclos Lina Daghsen. nothing to disclose Justine Bouvier. nothing to disclose Caroline Legendre. nothing to disclose Charlotte Rosso. nothing to disclose Figure 1 - belongs to Conclusions