title: Plasticity of the injured human spinal cord: insights revealed by spinal cord functional MRI.
abstract: BACKGROUND
  While numerous studies have documented evidence for plasticity of the human brain there is little evidence that the human spinal cord can change after injury. Here, we employ a novel spinal fMRI design where we stimulate normal and abnormal sensory dermatomes in persons with traumatic spinal cord injury and perform a connectivity analysis to understand how spinal networks process information.
  
  
  METHODS
  Spinal fMRI data was collected at 3 Tesla at two institutions from 38 individuals using the standard SEEP functional MR imaging techniques. Thermal stimulation was applied to four dermatomes in an interleaved timing pattern during each fMRI acquisition. SCI patients were stimulated in dermatomes both above (normal sensation) and below the level of their injury. Sub-group analysis was performed on healthy controls (n = 20), complete SCI (n = 3), incomplete SCI (n = 9) and SCI patients who recovered full function (n = 6).
  
  
  RESULTS
  Patients with chronic incomplete SCI, when stimulated in a dermatome of normal sensation, showed an increased number of active voxels relative to controls (p = 0.025). There was an inverse relationship between the degree of sensory impairment and the number of active voxels in the region of the spinal cord corresponding to that dermatome of abnormal sensation (R(2) = 0.93, p<0.001). Lastly, a connectivity analysis demonstrated a significantly increased number of intraspinal connections in incomplete SCI patients relative to controls suggesting altered processing of afferent sensory signals.
  
  
  CONCLUSIONS
  In this work we demonstrate the use of spinal fMRI to investigate changes in spinal processing of somatosensory information in the human spinal cord. We provide evidence for plasticity of the human spinal cord after traumatic injury based on an increase in the average number of active voxels in dermatomes of normal sensation in chronic SCI patients and an increased number of intraspinal connections in incomplete SCI patients relative to healthy controls.
authors.affiliation: Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
authors.forename: David W
authors.initials: DW
authors.lastname: Cadotte
authors.forename: Rachael
authors.initials: R
authors.lastname: Bosma
authors.forename: David
authors.initials: D
authors.lastname: Mikulis
authors.forename: Natalia
authors.initials: N
authors.lastname: Nugaeva
authors.forename: Karen
authors.initials: K
authors.lastname: Smith
authors.forename: Ronald
authors.initials: R
authors.lastname: Pokrupa
authors.forename: Omar
authors.initials: O
authors.lastname: Islam
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Stroman
authors.forename: Michael G
authors.initials: MG
authors.lastname: Fehlings
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity; D013116:Spinal Cord / Q000473:pathology; D013119:Spinal Cord Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D055815:Young Adult