title: Degeneration of the injured cervical cord is associated with remote changes in corticospinal tract integrity and upper limb impairment.
abstract: BACKGROUND
  Traumatic spinal cord injury (SCI) leads to disruption of axons and macroscopic tissue loss. Using diffusion tensor imaging (DTI), we assessed degeneration of the corticospinal tract (CST) in the cervical cord above a traumatic lesion and explored its relationship with cervical atrophy, remote axonal changes within the cranial CST and upper limb function.
  
  
  METHODS
  Nine cervical injured volunteers with bilateral motor and sensory impairment and ten controls were studied. DTI of the cervical cord and brain provided measurements of fractional anisotropy (FA), while anatomical MRI assessed cross-sectional spinal cord area (i.e. cord atrophy). Spinal and central regions of interest (ROI) included the bilateral CST in the cervical cord and brain. Regression analysis identified correlations between spinal FA and cranial FA in the CST and disability.
  
  
  RESULTS
  In individuals with SCI, FA was significantly lower in both CSTs throughout the cervical cord and brain when compared with controls (p≤0.05). Reduced FA of the cervical cord in patients with SCI was associated with smaller cord area (p = 0.002) and a lower FA of the cranial CST at the internal capsule level (p = 0.001). Lower FA in the cervical CST also correlated with impaired upper limb function, independent of cord area (p = 0.03).
  
  
  CONCLUSIONS
  Axonal degeneration of the CST in the atrophic cervical cord, proximal to the site of injury, parallels cranial CST degeneration and is associated with disability. This DTI protocol can be used in longitudinal assessment of microstructural changes immediately following injury and may be utilised to predict progression and monitor interventions aimed at promoting spinal cord repair.
authors.affiliation: Department of Brain Repair and Rehabilitation, University College London Institute of Neurology, University College London, London, United Kingdom. p.freund@ucl.ac.uk
authors.forename: Patrick
authors.initials: P
authors.lastname: Freund
authors.forename: Torben
authors.initials: T
authors.lastname: Schneider
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Nagy
authors.forename: Chloe
authors.initials: C
authors.lastname: Hutton
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Weiskopf
authors.forename: Karl
authors.initials: K
authors.lastname: Friston
authors.forename: Claudia A
authors.initials: CA
authors.lastname: Wheeler-Kingshott
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Thompson
mesh_terms: D016880:Anisotropy; D016022:Case-Control Studies; D002574:Cervical Vertebrae / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009410:Nerve Degeneration / Q000150:complications* / Q000473:pathology*; D011712:Pyramidal Tracts / Q000473:pathology*; D013119:Spinal Cord Injuries / Q000150:complications* / Q000473:pathology*; D034941:Upper Extremity / Q000473:pathology*