CTV10 - Triple variation of right inferior thyroid artery and vertebral arteries bilaterally and its clinical implications

Introduction/Purpose: This case report demonstrates unique anatomical variations of the arterial network in the neck and thorax and discusses their clinical significance. Understanding the anatomical variations in the origin and course of inferior thyroid and vertebral arteries and their relationship to surrounding structures is of vital importance in neck, heart, and spine surgeries from an anterior approach.

Methods or Case Description: Routine cadaveric dissection of the neck and thorax of a 94-year-old female donor body was performed bilaterally to demonstrate the arterial supply within the neck and thorax.

Outcomes: We report a combination of rare anatomical variations in the donor body: (i) on the right side, the inferior thyroid and vertebral arteries (RITA & RVA) originated as the first and second branches of the right subclavian artery (RSCA), respectively, (ii) the left vertebral artery (LVA) originated directly from the aortic arch, proximal to the origin of the left subclavian artery (LSCA). RITA had a common branch of 43 mm in length that bifurcated into a 20 mm superior branch and an 11.5 mm inferior branch supplying the lower lobe of the thyroid gland. The common, superior, and inferior branches of RITA had a measured diameter of 3 mm, 1.5 mm, and 2 mm, respectively. The RVA had a length of 32.5 mm and a diameter of 5.5 mm that narrowed to 3.75 mm right before entering the transverse foramen at C6 vertebral level. Interestingly, the presence of a 90° angle of the RVA was observed during its prevertebral course. The LVA measured 90.5 mm in length. Its diameter at the aortic arch measured 3 mm and 3.25 mm right before entering the transverse foramen at the vertebral level of C6.

Conclusion: Knowledge of anatomical variations of the aortic arch and branches of the subclavian artery is crucial for clinicians and surgeons. Prior identification of the vascular anomalies as a preventive measure to avoid complications and iatrogenic injuries during vascular surgeries is critical.