The effect of posterior bridging of C-1 on craniovertebral junction surgery

J Neurosurg Spine. 2006 Jul;5(1):50-2. doi: 10.3171/spi.2006.5.1.50.


Object: The groove for the vertebral artery (VA) may be bridged on C-1, forming a canal through which the artery passes. Because this variant may significantly affect the commonly performed C-1 posterior laminectomy, the authors studied the incidence and radiological appearance of this anatomical feature in surgical specimens.

Methods: Anatomical measurements were performed using a Vernier caliper (accurate to 0.1 mm) on 166 dry C-1 vertebrae. In addition, a convenience sample of 172 cervical x-ray films was evaluated. Partial osseous bridging was detected in eight (4.8%), and a complete osseous bridge, forming the canalis arteriae vertebralis (canal for the VA), was seen unilaterally (eight on the left and two on the right) in 10 (6%) and bilaterally in eight (4.8%) of the dry vertebrae. On lateral radiography, a complete bone bridge was observed on nine (5.2%) and a partial bridge on 10 (5.8%) of the 172 studies.

Conclusions: The discovery of a common variant may necessitate an immediate change in surgical management, and this anomaly could even increase the rate of surgery-related complications. The VA canal, present in the C-1 vertebra in approximately 5% of the specimens evaluated, was a variant that may be protective against VA injury. Knowledge of this variant may help the surgeon undertaking procedures in the C-1 region.

MeSH terms

  • Adult
  • Atlanto-Occipital Joint / surgery
  • Body Weights and Measures
  • Cervical Vertebrae / diagnostic imaging*
  • Cervical Vertebrae / pathology*
  • Female
  • Humans
  • Incidence
  • Laminectomy
  • Male
  • Ossification, Heterotopic / diagnostic imaging*
  • Ossification, Heterotopic / epidemiology
  • Ossification, Heterotopic / pathology*
  • Radiography
  • Retrospective Studies
  • Spinal Nerves / diagnostic imaging
  • Spinal Nerves / pathology
  • Vertebral Artery / diagnostic imaging
  • Vertebral Artery / pathology