title: C1-C2 instability with severe occipital headache in the setting of vertebral artery facet complex erosion.
abstract: OBJECTIVE
  An exact understanding of patient vertebral artery anatomy is essential to safely place screws at the atlanto-axial level in posterior arthrodesis. We aim to report a case of erosion of the left vertebral artery into the C1-C2 facet complex with resultant rotatory and lateral listhesis presenting with severe occipital headache. This represents a novel etiology for this diagnosis and our report illustrates technical considerations when instrumenting the C1-C2 segment.
  
  
  METHODS
  We report a case of severe occipital headache due to C1-C2 instability with resultant left C2 nerve compression in the setting of erosion of the vertebral artery into the C1-C2 facet complex.
  
  
  RESULTS
  A 68-year-old woman presented with a 12-month history of progressively debilitating headache and neck pain with atlanto-axial instability. Computed tomography (CT) angiography demonstrated erosion of the left vertebral artery into the left C1-C2 facet complex. In addition, the tortuous vertebral arteries had eroded into the C2 pedicles, eliminating the possibility for posterior pedicle screw placement. The patient underwent posterior arthrodesis of C1-C2 utilizing bilateral lateral mass fixation into C1 and bilateral trans-laminar fixation into C2 with resolution of all preoperative complaints.
  
  
  CONCLUSIONS
  This study constitutes the first report of a tortuous vertebral artery causing the partial destruction of a C1-C2 facet complex, as well as instability, with the clinical presentation of severe occipital headache. It hereby presents a novel etiology for both the development of C1-C2 segment instability as well as the development of occipital headache. Careful evaluation of such lesions utilizing CT angiography is important when formulating a surgical plan.
authors.affiliation: Hospital for Special Surgery, 535 East 70th Street, New York, NY, 10021, USA, fadi.taher@gmail.com.
authors.forename: Fadi
authors.initials: F
authors.lastname: Taher
authors.forename: Kristaps
authors.initials: K
authors.lastname: Bokums
authors.forename: Alexander
authors.initials: A
authors.lastname: Aichmair
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Hughes
mesh_terms: D000368:Aged; D001268:Atlanto-Axial Joint / Q000503:physiopathology* / Q000601:surgery; D001863:Bone Screws; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology* / Q000601:surgery; D019547:Neck Pain / Q000209:etiology; D009408:Nerve Compression Syndromes / Q000503:physiopathology / Q000601:surgery; D010014:Osteolysis / Q000503:physiopathology* / Q000601:surgery; D051298:Post-Traumatic Headache / Q000503:physiopathology*; D011859:Radiography; D013123:Spinal Fusion; D014711:Vertebral Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging; D021801:Zygapophyseal Joint / Q000503:physiopathology* / Q000601:surgery