Abstract P58: Motor Recovery After Chronic Stroke Correlates With Diffusion Tensor Measures of Ipsilesional Cerebral and Cerebellar White Matter Integrity

Abstract

Introduction: We aimed to determine whether white matter (WM) tract integrity improved after a brain-computer interface (BCI) rehabilitation program for chronic stroke patients with upper extremity weakness. Mean diffusivity (MD) was calculated from diffusion tensor imaging (DTI) and is an indication of the integrity of axons and myelination in WM. MD is a biomarker in subacute stroke for post-stroke motor deficits and recovery. Methods: DTI scans were performed with 9 chronic hemiplegic stroke patients within 2 weeks of initiation and completion of a 12-week BCI rehabilitation program. All patients were a minimum of 6 months post-stroke. MD was then calculated using DSI-Studio for WM tracts in each patient at both pre- and post-therapy time points. Motor function was evaluated at these time points using the upper extremity portion of the Fugl-Meyer Assessment (UEFM). Voxelwise statistical analysis comparing pre- and post-intervention MD values was carried out using tract-based spatial statistics (TBSS). Relationships between MD measures in regions of interest and changes in motor function were estimated with Spearman correlations. Results: Voxelwise analysis using TBSS showed no significant group-level change in MD of WM tracts throughout the brain after completing BCI rehabilitation. However, the change in MD in ipsilesional cerebral WM was positively correlated with UEFM change (Spearman’s rho = 0.75, p = 0.02) as was the pre-BCI MD in the ipsilesional cerebellar WM (rho = 0.78, p = 0.01). The correlations between contralesional MD measures and UEFM change were not statistically significant. Conclusion: Correlation between changes in mean diffusivity of ipsilesional cerebral white matter and motor improvement in chronic stroke supports the literature that recovery may be mediated by axonal remyelination and regeneration. Furthermore, we find that pre-therapy, ipsilesional cerebellar white matter MD correlates with motor recovery and as such may serve as a predictive measure of the effectiveness of BCI therapy for patients.