Study of foramen transversaria of first cervical vertebrae and its variations

Introduction Knowledge of variations in foramen tranversarium of first cervical vertebrae is surgically relevant, as its anatomical relation with third part of vertebral artery is one of the proposed causative factor for cervicogenic headache. This study was aimed to determine the incidence, morphological and morphometrical variations of foramen transversarium (FT) of atlas vertebrae in North Indian population. Methods Fifty atlas vertebrae were collected from osteology museum of Maulana Azad Medical College, New Delhi. Each vertebra was examined for the presence of foramen tranversarium and their dimensions were measured. Any other variation observed was also noted. Results were statistically analysed for side and size variation. Results 96% of vertebrae displayed bilateral presence of complete foramen in transverse process. Transverse foramen varied in shape with majority of vertebrae showing larger anteroposterior diameter than mediolateral diameter. The area ranged from 23.85mm2 to 38.06mm2 on right and 22.23mm2 to 39.41 mm2 on left side. No significant side variation in measurements of transverse foramen was noticed. 2% of vertebrae showed absence of FT and 2% had absent costal element. Conclusion Vertebral artery is predisposed to conditions like vertebrobasilar insufficiency, Barre Liou and cervicogenic syndromes. The spinal surgeons, neurosurgeons and radiologists should be aware of variations of FT of atlas and suggestively an absence of transverse foramen as it might affect the trajectory of the vertebral artery.