The Association between Superior Longitudinal Fasciculus, Motor Recovery and Outcome after Stroke

Introduction: Parietofrontal interactions are mediated by the superior longitudinal fasciculus (SLF) and are crucial to integrate visuomotor information and mediate fine motor control. Here, we aimed to characterize in stroke patients with upper limb motor deficits the evolution of white matter integrity of both part of the SLF (SLF I and SLF II) and its relation to both motor outcome and recovery.<br><br>Materials and methods : Fractional anisotropy (FA) values over the SLF I, SLF II and corticospinal tract (CST) and upper limb motor performance evaluated by both the Fugl-Meyer (FM-UL) score and maximum grip strength (GS) were measured for 16 patients at 3 weeks, 6 weeks and 12 weeks post-stroke. FA changes over time were assessed using repeated-measures Friedman ANOVA and correlations between motor recovery, motor outcome at 12 weeks and FA values in the CST, SLF I and SLF II at 3 weeks were performed using Spearman's rank-order correlation.<br><br>Results: FA values in the SLF I and SLF II in the affected hemisphere changed significantly over time (p: 0.027 and 0.016). FA values in the ipsilesional SLF I and SLF II at 3 weeks correlated with motor recovery at 12 weeks when assessed by the FM-UL (rho: 0.502, p: 0.04 and rho: 0.510, p: 0.04 respectively) but not when assessed by GS. FA values in the SLF I and SLF II were not correlated with motor outcome.<br><br>Conclusion: Both SLF I and SLF II appeared to participate in poststroke motor recovery of complex movements but not in motor outcome. These results argued that visually/spatially oriented motor tasks as well as more complex motor tasks using parietal associative areas should be used for poststroke rehabilitation strategies.<br><br>Funding Information: The project was partly funded by the “Fondation Pour la Recherche sur les Accidents Vasculaires cérébraux” and by the Mindmaze company. The research leading to these results has received funding from “Investissements d’avenir” ANR-10-IAIHU-06.<br><br>Declaration of Interests: The authors do not report any financial or personal relationships that could inappropriately influence or bias this work.<br><br>Ethics Approval Statement: This study was conducted according to established good clinical practice guidelines and was approved by the local ethical committee (CPP Sud Mediterranée III). Written informed consent from each participant or from a legal proxy/family member was obtained.