title: Corticospinal tract diffusion abnormalities early after stroke predict motor outcome.
abstract: BACKGROUND
  Prognosis of long-term motor outcome of acute stroke patients with severe motor impairment is difficult to determine.
  
  
  OBJECTIVE
  Our primary goal was to evaluate the prognostic value of corticospinal tract (CST) injury on motor outcome of the upper limb compared with motor impairment level and lesion volume.
  
  
  METHODS
  In all, 10 acute stroke patients with moderately severe to severe motor impairment of the upper limb underwent diffusion tensor imaging (DTI) and testing of upper limb strength and dexterity at acute, subacute, and chronic poststroke time points. A density-weighted CST atlas was constructed using DTI tractography data from normal participants. This CST atlas was applied, using a largely automated process, to DTI data from patients to quantify CST injury at each time point. Differences in axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) of the ipsilesional CST relative to the contralesional CST were measured.
  
  
  RESULTS
  Acute loss in CST AD correlated most strongly and significantly with subacute and chronic strength and dexterity and remained significant after adjusting for acute motor impairment or lesion volume. Subacute loss in CST FA correlated most strongly with chronic dexterity, whereas subacute behavioral measures of limb strength correlated most strongly with chronic strength measures.
  
  
  CONCLUSIONS
  Loss in acute CST AD and subacute CST FA are strong prognostic indicators of future motor functions of the upper limb for stroke patients with substantial initial motor impairment. DTI-derived measure of CST injury early after stroke may have utility in health care planning and in design of acute stroke clinical trials.
authors: MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, USA Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors: Benjamin N
authors: BN
authors: Groisser
authors: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors: William A
authors: WA
authors: Copen
authors: Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors: Aneesh B
authors: AB
authors: Singhal
authors: MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, USA Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
authors: Kelsi K
authors: KK
authors: Hirai
authors: MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, USA Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA judith@nmr.mgh.harvard.edu.
authors: Judith D
authors: JD
authors: Schaechter
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D056324:Diffusion Tensor Imaging; D005260:Female; D018737:Hand Strength; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement; D011379:Prognosis; D011712:Pyramidal Tracts / Q000473:pathology*; D020521:Stroke / Q000473:pathology*; D034941:Upper Extremity / Q000503:physiopathology*; D055815:Young Adult
keywords: corticospinal tract (CST); dexterity; diffusion tensor imaging (DTI); motor impairment; motor recovery; prediction; prognosis; strength; stroke; upper limb