title: Anatomy of stroke injury predicts gains from therapy.
abstract: OBJECTIVE
  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.
authors.affiliation: University of California, Irvine Medical Center, Orange, CA 92868-4280, USA.
authors.forename: Jeff D
authors.initials: JD
authors.lastname: Riley
authors.forename: Vu
authors.initials: V
authors.lastname: Le
authors.forename: Lucy
authors.initials: L
authors.lastname: Der-Yeghiaian
authors.forename: Jill
authors.initials: J
authors.lastname: See
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Newton
authors.forename: Nick S
authors.initials: NS
authors.lastname: Ward
authors.forename: Steven C
authors.initials: SC
authors.lastname: Cramer
mesh_terms: D004525:Efferent Pathways / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009044:Motor Cortex / Q000473:pathology*; D011237:Predictive Value of Tests; D020127:Recovery of Function / Q000502:physiology*; D012371:Robotics / Q000379:methods; D020521:Stroke / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy*