title: Distal-type cervical spondylotic amyotrophy: assessment of pathophysiology from radiological findings on magnetic resonance imaging and epidurally recorded spinal cord responses.
abstract: METHODS
  Six cases with distal-type cervical spondylotic amyotrophy are reported.
  
  
  OBJECTIVE
  To investigate the pathophysiology of distal-type cervical spondylotic amyotrophy from magnetic resonance imaging and intraoperative evoked spinal cord responses.
  
  
  BACKGROUND
  Cervical spondylotic amyotrophy had a characteristic clinical symptom of severe muscular atrophy with no or insignificant sensory deficit. Selective ventral root lesions or intrinsic spinal cord lesions have been proposed as the pathophysiology of cervical spondylotic amyotrophy, but they have not been well understood.
  
  
  METHODS
  Six patients with distal-type cervical spondylotic amyotrophy were described, and their magnetic resonance imaging and evoked spinal cord potentials after median nerve, motor cortex, and spinal cord stimulation were investigated.
  
  
  RESULTS
  Sagittal T2-weighted magnetic resonance imaging showed high signal intensity change within the spinal cord at C4-C5, C5-C6, and C6-C7. All patients underwent laminoplasty. The attenuation of postsynaptic potentials with preserved presynaptic potentials at C4-C5, C5-C6, and C6-C7 was characteristic in the evoked spinal cord potentials after median nerve stimulation. The amplitude of the evoked spinal cord potentials after median nerve stimulation was preserved at C2-C3. This means that lateral posterior column in the spinal cord had less or no involvement in distal-type cervical spondylotic amyotrophy. Concomitant hyperactivity of the patellar tendon reflex was correlated with the abnormality in the evoked spinal cord potentials after transcranial electric stimulation.
  
  
  CONCLUSIONS
  The results suggest a longitudinal gray matter lesion as one pathophysiologic feature, and that less damage to the lateral posterior column is the reason for the preservation of sensory function in the patients with distal-type cervical spondylotic amyotrophy described in this study.
authors.affiliation: Department of Orthopaedic Surgery, Yamaguchi University School of Medicine, Minami-Kogushi, Ube, Yamaguchi, Japan. yuh1248@tw.hosp.yamaguchi-u.ac.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kaneko
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Taguchi
authors.forename: Kouichiro
authors.initials: K
authors.lastname: Toyoda
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Kato
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Azuma
authors.forename: Shinya
authors.initials: S
authors.lastname: Kawai
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004568:Electrodiagnosis; D005071:Evoked Potentials; D005260:Female; D006225:Hand / Q000503:physiopathology; D018737:Hand Strength; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology; D013117:Spinal Cord Compression / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D013128:Spinal Osteophytosis / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery