Accessory transverse foramina in the cervical spine: incidence, embryological basis, morphology and surgical importance

Rare anatomic variation on a 10,000-year-old South American skeleton: the case of Iuzu, Toca dos Coqueiros, Piauí State, Brazil

PURPOSE

A skeleton named Iuzu has been unearthed from an exceptional middle Holocene burial in Toca dos Coqueiros site, in Serra da Capivara National Park (UNESCO World Heritage Site, Piauí State, Brazil). During a bioarchaeological analysis of its remains, we discovered that Iuzu was suffering from rare vertebral malformations. A double foramen transversaria, the agenesis of a foramen on the atlas and the hypoplasia of the transverse process of the axis have been highlighted. We aimed to deduce the clinical consequences of the malformation on the patient's health.

METHODS

We proceeded to macroscopic observation and radiography of the bones, then we search for other examples of such a pathology in archaeological litterature.

RESULT

The malformation caused vascular insufficiency that may have led to neurological lesions leading to various pains and troubles. The very rare malformations Iuzu presented have not been found on a paleoindian skeleton from South America so far.

CONCLUSION

This case allowed us to examine the conditions of selection of individuals buried in southern Piauí during the Middle Holocene, during which time this rite does not seem to predominate.

Can the transverse foramen/vertebral artery ratio of double transverse foramen subjects be a risk for vertebrobasilar transient ischemic attacks?

The C6 is the cervical vertebra into which the vertebral artery enters the passage of the transverse foramen and it is the vertebra most affected by double transverse foramina. There is currently little information about the relation between the vertebral artery and the double transverse foramen in C6. We aimed to test whether subjects with a double transverse foramen in C6 have a reduced transverse foramen/vertebral artery ratio when compared with normal anatomy subjects who possess a single transverse foramen which may be a risk for transient vertebral artery stenosis. We measured the area of the transverse foramen and the vertebral artery in 27 double transverse and 56 normal anatomy subjects using computed tomography angiography. We found significant differences in the area of the transverse foramen between double transverse and normal subjects (P < 0.001) but not between the vertebral artery area of double transverse and normal subjects (P = 0.829). The subjects with double transverse foramina have a reduced transverse foramen/vertebral artery ratio, which may be a possible risk for transient vertebral artery stenosis.

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

PURPOSE

The purpose of this study is to examine variations of the foramen transversarium and the vertebral artery in computed tomography angiographies (CTa) of the cervical spine, investigate their coexistence, and present possible considerations regarding such variations in spine surgical procedures.

METHODS

Fifty CTa of the neck were retrospectively reviewed. Transverse and anteroposterior diameter of the foramen and diameter of the vertebral artery were measured. Variations of the foramen and the vertebral artery were detected.

RESULTS

Cervical CTa of 32 males and 18 females (mean age 66.4 ± 10.78 years), all belonging to the Indo-European race, were reviewed. Variations of the foramen transversarium were found in 17 vertebrae (4.85%) of 15 patients (30%). Duplication of the foramen was the most frequent variation, followed by the open foramen, the absence of the foramen, the triple foramen, and the hypoplastic foramen. Variations of the vertebral artery were found in 7 patients (14%) and asymmetry was found in 12 (24%) patients. Moreover, six patients presented with hypoplastic vertebral arteries (12%). When examining coexistence, 60% of patients exhibiting variations in the transverse foramen were also exhibiting variations or asymmetry in the vertebral artery, compared to 25.7% of patients with no foramen variations (p = 0.02).

CONCLUSIONS

Vertebral artery injury is not common but may be a disastrous complication during cervical spine surgery. Proper preoperative planning is essential for any surgeon and exact knowledge of the anatomy in each patient is essential. This study strongly recommends the preoperative use of a CTa when suspicion of a variation is present and implied by a foramen variation. These slides can be retrieved under Electronic Supplementary Material.

Anatomical variations of the foramen transversarium in cervical vertebrae: findings, review of the literature, and clinical significance during cervical spine surgery

PURPOSE

To describe certain anatomical variations of the foramen transversarium, in spine cervical vertebrae in a contemporary specimen of an Indo-European population and approach their clinical importance during cervical spine surgery.

METHODS

102 cervical vertebrae (C₂-C₇) from 17 different skeletons, intact without any degenerative or traumatic disorders, which belonged to the collection of the Department of Anatomy, were examined. The age of specimens at the time of their death was between 25 and 65 years. All foramina were measured with a digital caliper.

RESULTS

The average size of the normal foramina was: 6.49 mm × 5.74 mm on the right side and 6.65 mm × 5.76 mm on the left side. Regarding the variations, we found two cervical vertebrae (1.96 %), one C₃ and one C₆, in which the right foramen transversarium is clearly smaller than the left. The exact dimensions of these foramina are: 2.3 mm × 2.5 mm on the right side and 6.54 mm × 8 mm on the left side in the first vertebra and 2.8 mm × 3.74 mm on the right side and 6 mm × 7.5 mm on the left side, in the second one. We also observed double foramina in 14 vertebrae (13.72 %). In seven vertebrae, the duplication was bilateral (6.86 %). We finally found one vertebra (0.98 %) with triplication of the foramen transversarium on the left side.

CONCLUSIONS

Summarizing, 10 out of our 17 skeletons were presented with variations (extremely narrow or multiple foramina). This finding of hypoplastic, duplicated and triplicated foramina transversaria in unexpectedly high rates raises questions about the integrity of the contained structures, the possibility of a different path for them. These variations may induce an extra-osseous position of the vertebra artery, and the ignorance of such an event may have catastrophic consequences during a surgery in the cervical spine.