Morphometric Study of Foramina Transversaria and the Incidence of Accessory Foramina in Cervical Spine of Indian Population

Abstract

Introduction: The Foramina Transversaria (FT) are known to exhibit variations in their size, shape and they may be absent or duplicated/triplicated. The deformation of foramina may result in derangement of neurovascular structures passing through these foramina. This necessitates the need of extensive analysis of variation of the foramina. Aim: To present morphometric details of FT of cervical vertebrae as well as incidence of accessory FT in intact cervical spine of Indian population and to make a comparison with previous studies done. Materials and Methods: The study was conducted on 319 FT of 161 dry cervical vertebrae of 23 complete vertebral spines of Indian population (3 FT were absent in 2 C7 vertebrae). For morphometric measurements, transverse and anteroposterior diameters were measured on both sides of all cervical vertebrae using digital vernier calliper. Accessory transverse foramina were also noted and photographed. Mean, range and standard deviation of morphometric measurements of these foramina were analyzed. The comparison was made between their various parameters on right and left side using student’s t-test and p-value. Results: Transverse and anteroposterior diameters were higher on left side than right. Mean value of foramen transversarium of C1 was highest on both sides where as of C7, it was lowest. Forty two cervical vertebrae (26.09%) among 161, showed accessory FT. Here, 25 vertebrae (15.53%) showed unilateral and 17 vertebrae (10.56%) bilateral showed accessory foramen. Accessory foramina were most commonly seen in C6 vertebrae. Two C7 vertebrae showed absence of FT, one bilaterally and one unilaterally. Accessory foramina were always smaller than main foramina transversarium. All accessory foramina were located posterior to main foramina transversarium except in one C4 vertebrae where accessory foramen was present anterior to main foramina transversarium. Conclusion: The present morphometric study done on intact cervical vertebral column demonstrates that different cervical vertebrae (C1-C7) shows considerable variation in terms of their size, shape and number of FT. This detailed report on morphology of cervical vertebrae would be useful for neurosurgeons and will help in better surgical outcome. It would also help radiologist for better understanding.

Keywords

• accessory foramen transversarium
• anteroposterior diameter
• cervical vertebra
• transverse diameter