Anatomy of Stroke Injury Predicts Gains From Therapy

Abstract

Background and Purpose-Many therapies are emerging that aim to improve motor function in people with stroke.Identifying key biological substrates needed for treatment gains would help to predict treatment effects and to maximize treatment impact. The current study addressed the hypothesis that behavioral gains from therapy targeting distal upper extremity are predicted by the structural integrity of key motor system white matter tracts. Methods-Twenty-three subjects with chronic left-sided stroke underwent robotic therapy targeting the distal right upper extremity. MRI was obtained at baseline and used to outline the infarct. For each subject, the degree to which stroke injured each of 4 descending white matter tracts (from the primary motor cortex, supplementary motor area, dorsal premotor cortex, and ventral premotor cortex, respectively) was determined. Correlations between tract-specific injury and behavioral gains from therapy were then examined. Results-Numerous examples were found whereby tract-specific injury predicted treatment gains. The strongest correlations pertained to stroke injury to tracts descending from the primary motor cortex and dorsal premotor cortex. Infarct volume and baseline behavior were weak predictors of treatment gains. Conclusions-Extent of injury to specific motor tracts predicts behavioral gains from treatment in subjects with chronic stroke. This supports a role for these tracts in mediating treatment effects and reinforces the importance of lesion location in stroke. Tract-specific injury was stronger than infarct volume or baseline clinical status at predicting gains, identifies subjects with sufficient biological substrate to improve from therapy, and so might be useful as an entry criterion in repair-based trials. (Stroke. 2011;42:421-426.)

PREP2: A biomarker‐based algorithm for predicting upper limb function after stroke

“…The template corticospinal and sensorimotor tracts were then nonlinearly registered to each patient's T1‐weighted image. A stroke lesion mask was hand‐drawn on each patient's T1‐weighted image and the percentage of tract voxels that overlapped the stroke lesion was calculated 16, 19…”

“…We sought to determine if TMS could be used in fewer patients than originally proposed or even eliminated, and whether the diffusion‐weighted MRI biomarker could be replaced with a simpler measure of stroke lesion load obtained from T1‐weighted images alone 11, 16…”

Anatomy and physiology predict response to motor cortex stimulation after stroke

“…Next, the degree to which stroke injured the white matter tract descending from primary motor cortex was determined, as described previously 10 ; this method for determining tract-specific injury has been found to be a significant predictor of behavioral gains in subjects with chronic stroke undergoing motor-based therapy.…”

Rehabilitation and Plasticity

“…In predicting therapy gains, the degree of injury to descending tracts from primary motor and premotor cortices is an important surrogate marker. It correlated with gains achieved after hand robotic therapy (Riley et al 2011). Bilateral arm training improved the arm impairment in chronic stroke survivors.…”