Quantitative analysis of unusual entrance of the vertebral artery into the cervical foramen (V2 segment) and its clinical implications

Abstract

To avoid an unexpected VA injury and to improve the efficiency of even routine cervical operations, spinal surgeons should determine whether the patient has a UE-V2S and have a full understanding of the clinical characteristics of this anomaly.

Variations of transverse foramina in cervical vertebrae: what happens to the vertebral artery?

“…Eskander et al [18] observed a C 4 , C 5 , and C 7 level of entrance in 1.8, 5.6, and 0.6% of their patients and Tellioglu et al [23] in 0.45, 1.84, and 1.84% of their patients, respectively. Entry point in the C 5 vertebra was also the most frequent variation in the study of Kim et al [6], observed in 74.8% of all unusual vertebral artery courses. In this study, entrance of the artery in the C 5 vertebra was the most common variation as well (8% of all patients), followed by entrance in the C 7 vertebra (4%) and the C 4 vertebra (2%).…”

“…Vertebral artery variations are also not an unusual finding. The most usual entry point of the artery in the spine is the C 6 vertebra [22,23], but entrance of the artery in the C 4 , C 5 , and C 7 vertebra has been also reported [5,6,18,23]. Wakao et al [5] observed a C 4 level of entrance in 1.1%, a C 5 Table 4 Coexisting variations of the foramen transversarium in patients exhibiting asymmetry in the vertebral artery level of entrance in 6.2%, and a C 7 level of entrance in 1.5% of their patients.…”

“…Although there are few studies about vertebral artery and foramina variations, their coexistence has not been investigated to the best of our knowledge. It is suspected that the size of the foramen may be correlated with blood flow, dominance, and, in some cases, entrance point of the artery [4][5][6]30]. However, anatomical studies of the transverse foramina contain no information regarding the course of the artery and studies regarding vertebral artery variations usually do not include the corresponding foramina anatomy.…”

“…3b) or during lateral decompressive maneuvers in discectomy [32]. The common course of extra-osseous vertebral arteries is usually lateral to the medial wall of the transverse foramen, although they can be also found medially, in a distance as high as 3.8 mm from the medial wall [6]. During anterior corpectomy, excessive lateral body resection is a risk factor for the integrity of the vertebral artery [32], and a duplication or triplication of the foramen, with or without a multiple artery lumen, could disorientate the surgeon.…”

“…These variations are important findings as they may be associated with variations of the vertebral artery. Limited studies, however, have examined the latter [4][5][6].…”