title: Analysis of C5 palsy after cervical open-door laminoplasty: relationship between C5 palsy and foraminal stenosis.
abstract: METHODS
  A retrospective study.
  
  
  OBJECTIVE
  To determine the clinical and imaging characteristics of postoperative C5 palsy after cervical open-door laminoplasty.
  
  
  BACKGROUND
  Postoperative C5 palsy is a common complication of cervical laminoplasty, and although there are several hypotheses regarding its etiology, the pathogenesis and preventive measures remain unidentified and many controversies remain.
  
  
  METHODS
  A total of 141 consecutive patients (100 men and 41 women) who had undergone open-door laminoplasty for cervical myelopathy between 2006 and 2009 were included in this study. Postoperative C5 palsy was defined as deltoid muscle weakness of a grade <3 in manual muscle test. The patients were divided into 2 groups: 1 that had experienced C5 palsy (PG; the palsy group) and the other that had not (NPG; the nonpalsy group). The parameters evaluated were the incidence of C5 palsy, the level at which spinal cord compression appeared preoperatively, the spinal cord level showing a T2 high-signal intensity lesion on magnetic resonance imaging, T2 high-signal intensity lesions newly appearing postoperatively, and the diameters of the C4/5 and C5/6 foramens.
  
  
  RESULTS
  The incidence of C5 palsy was 6.4% (9/141 cases). There were no significant differences between the 2 groups in sex, age, diagnosis, operation time, blood loss, level of spinal cord compression, level of T2 high-signal lesion, or new T2 high-signal lesions. The average diameter of the C4/5 foramen was 1.99 mm in the PG and 2.76 mm in the NPG (P<0.005). In contrast, the average diameter of the C5/6 foramen was 2.35 mm in PG and 2.50 mm in the NPG.
  
  
  CONCLUSIONS
  There was a significant difference in the diameter of the C4/5 foramen between the PG and the NPG. The results suggest that the main etiology of C5 palsy is impairment of the C5 nerve root induced by preexisting C4/5 foraminal stenosis.
authors: Department of Orthopaedic Surgery, Spine Center, Niigata Central Hospital, Niigata, Japan. kkatsu_os@yahoo.co.jp
authors: Keiichi
authors: K
authors: Katsumi
authors: Akiyoshi
authors: A
authors: Yamazaki
authors: Kei
authors: K
authors: Watanabe
authors: Masayuki
authors: M
authors: Ohashi
authors: Hirokazu
authors: H
authors: Shoji
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015984:Causality; D002574:Cervical Vertebrae / Q000601:surgery; D015897:Comorbidity; D019299:Decompression, Surgical / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007796:Laminectomy / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D010243:Paralysis / Q000453:epidemiology* / Q000601:surgery*; D015995:Prevalence; D012189:Retrospective Studies; D018570:Risk Assessment; D013117:Spinal Cord Compression / Q000453:epidemiology* / Q000601:surgery*; D013130:Spinal Stenosis / Q000453:epidemiology* / Q000601:surgery*; D016896:Treatment Outcome