title: Contralesional motor cortex activation depends on ipsilesional corticospinal tract integrity in well-recovered subcortical stroke patients.
abstract: BACKGROUND
  The relationship between structural and functional integrity of descending motor pathways can predict the potential for motor recovery after stroke. The authors examine the relationship between brain imaging biomarkers within contralesional and ipsilesional hemispheres and hand function in well-recovered patients after subcortical stroke at the level of the internal capsule.
  
  
  OBJECTIVE
  
  
  
  METHODS
  of functional activation and integrity of the ipsilesional corticospinal tract might predict paretic hand function.
  
  
  METHODS
  A total of 14 patients in the chronic stable phase of motor recovery after subcortical stroke and 24 healthy age-matched individuals participated in the study. Functional MRI was used to examine BOLD contrast during passive wrist flexion-extension and paced or maximum-velocity active fist clenching. Functional integrity of the corticospinal pathway was assessed by transcranial magnetic stimulation to obtain motor-evoked potentials (MEPs) in the first dorsal interosseus muscle of the paretic and nonparetic hands. Fractional anisotropy and the proportion of traces between hemispheres in the posterior limb of both internal capsules were quantified using diffusion-weighted MRI.
  
  
  RESULTS
  Patients with smaller MEPs had a weaker paretic hand and more primary motor cortex activation in their affected hemisphere. Asymmetry between white matter tracts of either hemisphere was associated with reduced precision grip strength and increased BOLD activation within the contralesional dorsal premotor cortex for demanding hand tasks.
  
  
  CONCLUSIONS
  There may be beneficial reorganization in contralesional secondary motor areas with increasing damage to the corticospinal tract after subcortical stroke. Associations between clinical, functional, and structural integrity measures in chronic stroke may lead to a better understanding of motor recovery processes.
authors.affiliation: University of Greifswald, Greifswald, Germany. martin.lotze@uni-greifswald.de
authors.forename: Martin
authors.initials: M
authors.lastname: Lotze
authors.forename: Willy
authors.initials: W
authors.lastname: Beutling
authors.forename: Moritz
authors.initials: M
authors.lastname: Loibl
authors.forename: Martin
authors.initials: M
authors.lastname: Domin
authors.forename: Thomas
authors.initials: T
authors.lastname: Platz
authors.forename: Ulf
authors.initials: U
authors.lastname: Schminke
authors.forename: Winston D
authors.initials: WD
authors.lastname: Byblow
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007100:Imitative Behavior / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009044:Motor Cortex / Q000098:blood supply / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D011712:Pyramidal Tracts / Q000503:physiopathology*; D012044:Regression Analysis; D012720:Severity of Illness Index; D020521:Stroke / Q000473:pathology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods
chemical_list: D010100:Oxygen