title: Dynamic changes in corticospinal tracts after stroke detected by fibretracking.
abstract: OBJECTIVE
  The integrity of motor pathways and functional connectivity patterns are important in assessing plastic changes related to successful recovery, to obtain prognostic information and to monitor future therapeutic strategies of stroke patients. We tested the following hypotheses: (1) that changes in axonal integrity along the corticospinal tract after stroke can be detected as a reduction in fractional anisotropy; and (2) that sustained low fractional anisotropy is indicative of axonal loss and therefore is correlated with poor motor outcome, as measured by specific neurological motor scores.
  
  
  METHODS
  We developed a segmentation tool based on magnetic resonance diffusion tensor imaging in conjunction with three dimensional fibretracking for longitudinal studies of the corticospinal tract, and used specific neurological motor scores to test the hypotheses in five stroke patients within the first week and 30 and 90 days after the stroke.
  
  
  RESULTS
  Reduction in fractional anisotropy within the first weeks after stroke reflected a decline in axonal integrity, leading to Wallerian degeneration, and demonstrated a correlation between the temporal evolution of fractional anisotropy and motor function in patients with poor motor outcome.
  
  
  CONCLUSIONS
  The study demonstrated the feasibility of fibretracking as a segmentation tool for mapping distal parts of the corticospinal motor pathways and showed that fractional anisotropy in the segmented corticospinal tract is a sensitive measure of structural changes after stroke.
authors.affiliation: Centre of Functionally Integrative Neuroscience, Aarhus University, Denmark. moller@pet.auh.dk
authors.forename: M
authors.initials: M
authors.lastname: Møller
authors.forename: J
authors.initials: J
authors.lastname: Frandsen
authors.forename: G
authors.initials: G
authors.lastname: Andersen
authors.forename: A
authors.initials: A
authors.lastname: Gjedde
authors.forename: P
authors.initials: P
authors.lastname: Vestergaard-Poulsen
authors.forename: L
authors.initials: L
authors.lastname: Østergaard
mesh_terms: D000368:Aged; D016880:Anisotropy; D001369:Axons / Q000473:pathology; D002544:Cerebral Infarction / Q000150:complications* / Q000175:diagnosis; D003943:Diagnostic Techniques, Neurological; D038524:Diffusion Magnetic Resonance Imaging; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009410:Nerve Degeneration / Q000175:diagnosis / Q000209:etiology; D011712:Pyramidal Tracts / Q000503:physiopathology*; D013997:Time Factors; D014855:Wallerian Degeneration / Q000175:diagnosis* / Q000209:etiology