title: Diffusion tensor imaging of somatosensory tract in cervical spondylotic myelopathy and its link with electrophysiological evaluation.
abstract: BACKGROUND
  Abnormal somatosensory evoked potential (SEP) (ie, prolonged latency) has been associated with poor surgical prognosis of cervical spondylotic myelopathy (CSM).
  
  
  OBJECTIVE
  To further characterize the extent of microstructural damage to the somatosensory tract in CSM patients using diffusion tensor imaging (DTI).
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  A total of 40 volunteers (25 healthy subjects and 15 CSM patients).
  
  
  METHODS
  Clinical, electrophysiological, and radiological evaluations were performed using the modified Japanese Orthopedic Association (mJOA) scoring system, SEP, and cord compression ratio in anatomic magnetic resonance (MR) images, respectively. Axial diffusion MR images were taken using a pulsed gradient, spin-echo-echo-planar imaging sequence with a 3-T MR system. The diffusion indices in different regions of the spinal cord were measured.
  
  
  METHODS
  Comparison of diffusion indices among healthy and myelopathic spinal cord with intact and impaired SEP responses were performed using one-way analysis of variance.
  
  
  RESULTS
  In healthy subjects, fractional anisotropy (FA) values were higher in the dorsal (0.73±0.11) and lateral columns (0.72±0.13) than in the ventral column of white matter (0.58±0.10) (eg, at C4/5) (p<.05). FA was dramatically dropped in the dorsal (0.54±0.16) and lateral columns (0.51±0.13) with little change in the ventral column (0.48±0.15) at the compressive lesions in CSM patients. There were no significant differences in the mJOA scores or cord compression ratios between CSM patients with or without abnormal SEP. However, patients with abnormal SEP showed an FA decrease in the dorsal column cephalic to the lesion (0.56±0.06) (ie, at C1/2, compared with healthy subjects [0.66±0.02]), but the same decrease was not observed for those without a SEP abnormality (0.67±0.02).
  
  
  CONCLUSIONS
  Spinal tracts were not uniformly affected in the myelopathic cervical cord. Changes in diffusion indices could delineate focal or extensive myelopathic lesions in CSM, which could account for abnormal SEP. DTI analysis of spinal tracts might provide additional information not available from conventional diagnostic tools for prognosis of CSM.
authors: Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 12 Sandy Bay Rd, Pokfulam, Hong Kong, China.
authors: Chun-Yi
authors: CY
authors: Wen
authors: Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 12 Sandy Bay Rd, Pokfulam, Hong Kong, China.
authors: Jiao-Long
authors: JL
authors: Cui
authors: Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 12 Sandy Bay Rd, Pokfulam, Hong Kong, China.
authors: Kin-Cheung
authors: KC
authors: Mak
authors: Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 12 Sandy Bay Rd, Pokfulam, Hong Kong, China.
authors: Keith D K
authors: KD
authors: Luk
authors: Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 12 Sandy Bay Rd, Pokfulam, Hong Kong, China. Electronic address: yhud@hku.hk.
authors: Yong
authors: Y
authors: Hu
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D016022:Case-Control Studies; D066193:Cervical Cord / Q000473:pathology* / Q000503:physiopathology; D002574:Cervical Vertebrae / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D013117:Spinal Cord Compression / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D055009:Spondylosis / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D066127:White Matter
keywords: Cervical spondylotic myelopathy; Diffusion tensor imaging; Fractional anisotropy; Microstructure; Spinal cord