title: Trans-synaptic degeneration of motoneurons distal to chronic cervical spinal cord compression in cervical spondylotic myelopathy.
abstract: OBJECTIVE
  To assess the effect of chronic cervical spinal cord compression upon remote motor unit function in patients with cervical spondylotic myelopathy (CSM).
  
  
  METHODS
  Fifty-three CSM patients and 47 healthy subjects were included. Bilateral motor unit number estimations (MUNEs) were recorded from both abductor digiti minimi and abductor pollicis brevis, and bilateral flexor carpi radialis (FCR) H-reflexes were examined in all subjects along with the nine-hole peg test (NHPT). The main outcome measures included the number of motor units, the average single motor unit potential (SMUP) area, the FCR Hmax/Mmax ratios and the NHPT time.
  
  
  RESULTS
  Statistically significant results compared to healthy controls included increased average SMUP area, increased FCR Hmax/Mmax ratio and increased NHPT time (p < 0.05). Abnormal SMUP was observed in 10/53 (18.9%) CSM patients along with reduced motor units in 3 of these 10 patients, while the FCR Hmax/Mmax ratios in the CSM patients with abnormal MUNE were higher than those in others (p < 0.05). There was a positive correlation between the NHPT time and the average SMUP area, and a negative correlation was noted between the NHPT time and the number of motor units (p < 0.05).
  
  
  CONCLUSIONS
  In CSM patients, the motor units below the level of compression may exhibit dysfunction, which is likely a result of trans-synaptic degeneration. Both cervical spinal cord compressive injury and this trans-synaptic degeneration contribute to the impairment of fine motor ability in CSM patients. Therefore, treatment and rehabilitation efforts should account for these two dysfunctions.
authors.affiliation: a Department of Orthopedics, Huashan Hospital , Fudan University , Shanghai , China.
authors.forename: Chaojun
authors.identifier: http://orcid.org/0000-0002-1165-2528
authors.initials: C
authors.lastname: Zheng
authors.affiliation: b Department of Physical Medicine and Rehabilitation , Upstate Medical University, State University of New York at Syracuse , Syracuse , NY , USA.
authors.forename: Yu
authors.identifier: http://orcid.org/0000-0003-2770-2371
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: a Department of Orthopedics, Huashan Hospital , Fudan University , Shanghai , China.|c Department of Orthopedics, The Fifth People's Hospital , Fudan University, Shanghai , China.
authors.forename: Feizhou
authors.identifier: http://orcid.org/0000-0002-7199-7982
authors.initials: F
authors.lastname: Lu
authors.affiliation: a Department of Orthopedics, Huashan Hospital , Fudan University , Shanghai , China.
authors.forename: Xiaosheng
authors.identifier: http://orcid.org/0000-0003-2979-0870
authors.initials: X
authors.lastname: Ma
authors.affiliation: d Department of Hand Surgery, Huashan Hospital , Fudan University, Shanghai , China.
authors.forename: Dong
authors.identifier: http://orcid.org/0000-0003-3388-0334
authors.initials: D
authors.lastname: Tian
authors.affiliation: a Department of Orthopedics, Huashan Hospital , Fudan University , Shanghai , China.
authors.forename: Jianyuan
authors.identifier: http://orcid.org/0000-0001-6876-7820
authors.initials: J
authors.lastname: Jiang
mesh_terms: D000328:Adult; D000368:Aged; D066193:Cervical Cord / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000473:pathology*; D018482:Muscle, Skeletal / Q000294:innervation*; D011999:Recruitment, Neurophysiological; D012183:Retrograde Degeneration / Q000209:etiology / Q000473:pathology* / Q000503:physiopathology; D013117:Spinal Cord Compression / Q000150:complications* / Q000209:etiology; D055009:Spondylosis / Q000150:complications*
keywords: Trans-synaptic degeneration; cervical spondylotic myelopathy; motor unit number estimation