ABSTRACT

Objectives:

Vertebral artery (VA) injury as a complication of C1–C2 transarticular or C2 pedicular screw placement is commonly related to the anatomic positional variations of the VA in C2 intraosseous canal. These variations cause the C2 isthmus or pedicle, which constitute the screw path, to be narrower than normal. Narrowing of the C2 isthmus is well known as a high-riding pattern of VA (HRVA), and narrowing of the C2 pedicle is, recently, named as a medial-shifting pattern of VA (MSVA). Herein, we investigated the prevalence of HRVA and MSVA in general population.

Methods:

The study population was represented by 216 CT-angiograms consecutively pulled from our radiology database (125 male, 91 female, mean age 62,7 years). VAs were assessed for the anomalous course in the C2 vertebra by measurements of isthmus thickness, internal height, and pedicle width. Particular note was made on VA dominance.

Results:

In 53 (24 %) of the 216 patients, there was at least one VA variation. HRVA was identified in 40 (18 %) and MSVA in 45 (20,8 %) patients. Ipsilateral co-occurrence of HRVA and MSVA was highly significant (P<0,01). The relationship between VA dominance and variations was statistically significant (P<0,05).

Conclusions:

Because of the high prevalence of various intraosseous courses of VA and also high possibility of ipsilateral co-occurrence of HRVA, MSVA and as well as dominant VA, preoperative imaging should be performed if C2 instrumentation required.