title: The association between preoperative spinal cord rotation and postoperative C5 nerve palsy.
abstract: BACKGROUND
  C5 nerve palsy is a known complication of cervical spine surgery. The development and etiology of this complication are not completely understood. The purpose of the present study was to determine whether rotation of the cervical spinal cord predicts the development of a C5 palsy.
  
  
  METHODS
  We performed a retrospective review of prospectively collected spine registry data as well as magnetic resonance images. We reviewed the records for 176 patients with degenerative disorders of the cervical spine who underwent anterior cervical decompression or corpectomy within the C4 to C6 levels. Our measurements included area for the spinal cord, space available for the cord, and rotation of the cord with respect to the vertebral body.
  
  
  RESULTS
  There was a 6.8% prevalence of postoperative C5 nerve palsy as defined by deltoid motor strength of ≤ 3 of 5. The average rotation of the spinal cord (and standard deviation) was 2.8° ± 3.0°. A significant association was detected between the degree of rotation (0° to 5° versus 6° to 10° versus ≥ 11°) and palsy (point-biserial correlation = 0.94; p < 0.001). A diagnostic criterion of 6° of rotation could identify patients who had a C5 palsy (sensitivity = 1.00 [95% confidence interval, 0.70 to 1.00], specificity = 0.97 [95% confidence interval, 0.93 to 0.99], positive predictive value = 0.71 [95% confidence interval, 0.44 to 0.89], negative predictive value = 1.00 [95% confidence interval, 0.97 to 1.00]).
  
  
  CONCLUSIONS
  Our evidence suggests that spinal cord rotation is a strong and significant predictor of C5 palsy postoperatively. Patients can be classified into three types, with Type 1 representing mild rotation (0° to 5°), Type 2 representing moderate rotation (6° to 10°), and Type 3 representing severe rotation (≥ 11°). The rate of C5 palsy was zero of 159 in the Type-1 group, eight of thirteen in the Type-2 group, and four of four in the Type-3 group. This information may be valuable for surgeons and patients considering anterior surgery in the C4 to C6 levels.
authors.affiliation: Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA. eskanderms@upmc.edu
authors.forename: Mark S
authors.initials: MS
authors.lastname: Eskander
authors.forename: Steve M
authors.initials: SM
authors.lastname: Balsis
authors.forename: Chris
authors.initials: C
authors.lastname: Balinger
authors.forename: Caitlin M
authors.initials: CM
authors.lastname: Howard
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Lewing
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Eskander
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Aubin
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lange
authors.forename: Jason
authors.initials: J
authors.lastname: Eck
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Connolly
authors.forename: Louis G
authors.initials: LG
authors.lastname: Jenis
mesh_terms: D000328:Adult; D000368:Aged; D020516:Brachial Plexus Neuropathies / Q000209:etiology* / Q000503:physiopathology; D002574:Cervical Vertebrae / Q000473:pathology / Q000601:surgery*; D015331:Cohort Studies; D019299:Decompression, Surgical / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D010243:Paralysis / Q000209:etiology / Q000503:physiopathology; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012399:Rotation; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013116:Spinal Cord / Q000503:physiopathology*; D013126:Spinal Nerve Roots / Q000503:physiopathology; D013130:Spinal Stenosis / Q000175:diagnosis / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult