DTI measures track and predict motor function outcomes in stroke rehabilitation utilizing BCI technology.

Jie Song,Brittany M Young,Justin C Williams,Veena A Nair,Dorothy Farrar-Edwards,Mitchell E Tyler,Leo M Walton,Vivek Prabhakaran,Zack Nigogosyan,Alexander Remsik,Justin A Sattin,Kristin E Caldera

doi:10.3389/fnhum.2015.00195

Abstract

Tracking and predicting motor outcomes is important in determining effective stroke rehabilitation strategies. Diffusion tensor imaging (DTI) allows for evaluation of the underlying structural integrity of brain white matter tracts and may serve as a potential biomarker for tracking and predicting motor recovery. In this study, we examined the longitudinal relationship between DTI measures of the posterior limb of the internal capsule (PLIC) and upper-limb motor outcomes in 13 stroke patients (median 20-month post-stroke) who completed up to 15 sessions of intervention using brain–computer interface (BCI) technology. Patients’ upper-limb motor outcomes and PLIC DTI measures including fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD) were assessed longitudinally at four time points: pre-, mid-, immediately post- and 1-month-post intervention. DTI measures and ratios of each DTI measure comparing the ipsilesional and contralesional PLIC were correlated with patients’ motor outcomes to examine the relationship between structural integrity of the PLIC and patients’ motor recovery. We found that lower diffusivity and higher FA values of the ipsilesional PLIC were significantly correlated with better upper-limb motor function. Baseline DTI ratios were significantly correlated with motor outcomes measured immediately post and 1-month-post BCI interventions. A few patients achieved improvements in motor recovery meeting the minimum clinically important difference (MCID). These findings suggest that upper-limb motor recovery in stroke patients receiving BCI interventions relates to the microstructural status of the PLIC. Lower diffusivity and higher FA measures of the ipsilesional PLIC contribute toward better motor recovery in the stroke-affected upper-limb. DTI-derived measures may be a clinically useful biomarker in tracking and predicting motor recovery in stroke patients receiving BCI interventions.

Highlights

One of the most common deficits following stroke is upper-limb motor impairment, which can have a significant impact on disability and health (Coupar et al, 2012)
Given the significance of the posterior limb of the internal capsule (PLIC) to motor recovery, in this study, we systematically examined the structural integrity of the PLIC using Diffusion tensor imaging (DTI) and investigated whether the structural integrity of the PLIC correlated with upper-limb motor outcomes and thereby affected motor recovery in stroke patients receiving brain– computer interface (BCI) interventions
We found that the structural integrity of the PLIC was significantly affected by stroke and was significantly correlated with upper-limb motor outcomes

Summary

Introduction

One of the most common deficits following stroke is upper-limb motor impairment, which can have a significant impact on disability and health (Coupar et al, 2012). DTI is a non-invasive brain imaging technique that allows for quantitative evaluation of the structural integrity of white matter tracts after a stroke (Werring et al, 2000; Stinear et al, 2007; Yu et al, 2009). BCI devices provide real-time feedback to assist users to learn modulation of brain activity. This type of modulation and further enhancement with motor training may promote brain plasticity changes and eventually boost the recovery when patients have reached a functional plateau with more traditional therapies (Fallani et al, 2013; Varkuti et al, 2013). Few studies have examined the white matter structural integrity in stroke patients receiving BCI intervention

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Conclusion