FV 24 Connectome-based lesion symptom mapping: Disconnection patterns underlying specific aspects of motor impairment after stroke

Abstract

Introduction: An accurate prediction of motor impairment from lesion information after stroke remains challenging, highlighting the complexity of structure-function relationships. While corticospinal tract (CST) integrity has been shown to correlate with motor impairment after stroke1, far less is known about the functional relevance of cortico-cortical connections for distinct aspects of motor function. Therefore, we investigated whether it is possible to infer distinct aspects of individual motor impairment and identify crucial task-specific connections using connection-based lesion-symptom mapping (CLSM) in acute stroke patients. Methods: Individual disconnectomes were estimated for 114 ischemic stroke patients using lesion masks designed based on routine MRI data and a normative structural connectome 2 . Relative grip strength and four subtests of the Action Research Arm Test 3 were performed to assess movements with varying demands of multi-joint movements, strength and fine-grained control. Nested and cross-validated support vector regressions (SVR) estimated impairment across motor tasks based on CLSM data and CST damage. Results: For each motor task, CLSM-SVR significantly predicted individual motor impairment (p<0.05 permutation testing) with higher or similar accuracy compared to CST-SVR. CLSM and CST-integrity represented largely independent aspects of variance in motor impairment. Permutation testing identified disconnection patterns underlying SVR predictions (Fig. 1). Discussion: Disconnections between ipsilesional subcortical motor areas and bihemispheric cortical motor areas were indicative of impairment across all motor tasks. Movements relying on fine-grained motor control were impacted by ipsilesional motor-temporal, and -prefrontal disconnections. Multi-joint movements involving proximal musculature relied on diverse interhemispheric (pre-)motor-prefrontal and -temporal connections, which may reflect several compensatory ways of motor execution. In summary, lesion-induced cortico-cortical disconnections were associated with distinct aspects of individual motor impairment, highlighting the potential of CLSM to further our understanding of crucial white matter structures in the human motor network.