title: Safe atlantoaxial fixation using a laminar screw (intralaminar screw) in a patient with unilateral occlusion of vertebral artery: case report.
abstract: METHODS
  A case of atlantoaxial fusion using an intralaminar (unilateral-crossing laminar screw) screw is presented in a patient with unilateral vertebral artery communication with the basilar artery.
  
  
  OBJECTIVE
  To document the significance of the intralaminar screw technique in the aforementioned case.
  
  
  BACKGROUND
  Vertebral artery injury is directly linked with intraoperative or perioperative death if the vertebral artery communicates only unilaterally to the basilar artery or has an obvious dominant side. In this situation, irrespective of whether the pedicle is confirmed to be sufficient for pedicle screw placement, if the vertebral artery is violated, fatal complications will occur. The literature reports that even proficient surgeons cannot guarantee 100% accuracy in pedicle screw placement. The intralaminar screw technique is currently the safest with regard to avoiding violation of the vertebral artery. Biomechanical studies have also shown this technique to ensure sufficient strength.
  
  
  METHODS
  The patient had rheumatoid atlantoaxial subluxation, and the right vertebral artery alone communicated with basilar artery, while the left ended blind. She underwent atlantoaxial fixation with an intralaminar screw (unilateral-crossing laminar screw) of the axis and lateral mass atlas screws inserted via the posterior arch.
  
  
  RESULTS
  The intralaminar screw (unilateral-crossing laminar screw) was completed, and comprised lateral mass atlas screws and rods. There were no complications during and after surgery. Good bone union was achieved.
  
  
  CONCLUSIONS
  Patients with unilateral dominant vertebral artery are good candidates for the intralaminar screw technique, even if the pedicle anatomy is sufficient to insert pedicle screws.
authors.affiliation: Department of Musculoskeletal Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsubara
authors.forename: Jun
authors.initials: J
authors.lastname: Mizutani
authors.forename: Muneyoshi
authors.initials: M
authors.lastname: Fukuoka
authors.forename: Tsunetoshi
authors.initials: T
authors.lastname: Hatoh
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kojima
authors.forename: Takanobu
authors.initials: T
authors.lastname: Otsuka
mesh_terms: D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D001863:Bone Screws; D005260:Female; D006801:Humans; D008875:Middle Aged; D011859:Radiography; D013123:Spinal Fusion / Q000295:instrumentation*; D014711:Vertebral Artery / Q000000981:diagnostic imaging / Q000601:surgery; D014715:Vertebrobasilar Insufficiency / Q000000981:diagnostic imaging* / Q000601:surgery