title: C2 nerve root sectioning in posterior atlantoaxial instrumented fusions: a structured review of literature.
abstract: OBJECTIVE
  To review published series describing C1-2 posterolateral instrumentation, comparing outcomes in patients who had and did not have C2 nerve sacrifice.
  
  
  METHODS
  Online databases were searched for English-language articles between 1994 and April 2011 pertaining to posterior atlantoaxial instrumentation with C1 lateral mass and C2 screws. Twenty studies describing 732 patients with C2 nerve preservation and 6 studies describing 361 patients with C2 sacrifice met inclusion criteria.
  
  
  RESULTS
  All but one small study without a control group were retrospective case series, making all evidence class III. Excluding C2 nerve dysfunction, no neurological deterioration was observed. Three instances of vertebral artery injury were secondary to soft tissue dissection and one was secondary to C1 screw insertion. There were seven instances of C1 screw malposition in the preservation group and none in the section group. Reported in roughly 20% of patients, mean estimated blood loss tended to be lower with C2 nerve sectioning (213 vs. 471 mL) and operative times were somewhat shorter (118 vs. 132 minutes). C2 nerve section resulted in greater symptomatic numbness (11.6% vs. 1.3%; P < 0.0001) but less neuropathic pain (0.3% vs. 4.7%; P = 0.0002) compared with C2 preservation.
  
  
  CONCLUSIONS
  Sacrifice of the C2 nerve root to aid in the insertion of C1 lateral mass screws when performing posterior atlantoaxial instrumented fusions is a treatment option (class III). It may decrease blood loss and operative duration, potentially advantageous in elderly or frail patients. Numbness occurred in roughly 12% of patients, an outcome that may be unacceptable to certain patient populations, but neuropathic pain was nearly absent in reported studies with nerve section. C2 nerve preservation and retraction for C1 screw placement may have higher incidence of neuropathic pain (~5%). Rates of fusion are universally high independent of C2 nerve technique.
authors: Neurosurgical Care, LLC, Royersford, Pennsylvania, USA. robertelliottmd@gmail.com
authors: Robert E
authors: RE
authors: Elliott
authors: Matthew M
authors: MM
authors: Kang
authors: Michael L
authors: ML
authors: Smith
authors: Anthony
authors: A
authors: Frempong-Boadu
mesh_terms: D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D011183:Postoperative Complications / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D011859:Radiography; D013123:Spinal Fusion / Q000379:methods*; D013126:Spinal Nerve Roots / Q000033:anatomy & histology / Q000502:physiology / Q000601:surgery*