The Vertebral Artery Cave at C2: Anatomical Study with Application to C2 Pedicle Screw Placement

Tubbs RS, Granger A, Fisahn C, Loukas M, Moisi M, Iwanaga J, Paulson D, Jeyamohan S, Chapman JR, Oskouian RJ.The Vertebral Artery Cave at C2: Anatomical Study with Application to C2 Pedicle Screw Placement.World Neurosurg. 2016 Jul 18. pii: S1878-8750(16)30561-7. doi: 10.1016/j.wneu.2016.07.037. 

ABSTRACT

OBJECTIVE:

Knowledge of the course of the vertebral artery during instrumentation is of paramount importance. It has been shown that erosion of the C2 pedicle and body can occur due to pulsations of the adjacent vertebral artery. This often results in a 'cave' for this segment of the artery. The descriptions of this anatomy are limited. The current study was performed with the hope that these data will be of use to spine surgeons during C2 instrumentation.

MATERIALS AND METHODS:

In 40 human adult C2 bone specimens, the position of the vertebral artery in relation to the undersurface of the superior articular facet, pedicle and C2 body was observed. A classification system was utilized to better describe these relationships. Pedicle screws were then placed into selected examples of each type.

RESULTS:

We found type 0 specimens, with no cave, on 8 sides (10%). Types I, II, and III caves with minimal, moderate and significant encroachment of the pedicle were observed on 40%, 35%, and 27.5% sides, respectively. Type IV caves with erosion into the lateral C2 body and undersurface of the superior articular facet were observed on 12.5% of sides. Although larger caves were found on left sides, this did not reach statistical significance. Pedicle screw placement for types III and IV were most likely to enter the vertebral artery cave (p<0.05).

CONCLUSIONS:

Additional osteological data regarding the course of the vertebral artery while within C2 may decrease morbidity during surgery in this region.