Normal and Abnormal Development of Left Vertebral Artery and Its Implications in Cervical Region Surgery

Abstract

Aortic arch (AA) anomalies occur in approximately 3-5% of cadavers, but these atypical branches remain a point of discussion in cervical region surgery. This case report describes a 73-year-old Caucasian female who died of renal failure following a complicated urinary tract infection whose left vertebral artery (LVA) originated from the AA between the left common carotid and subclavian arteries. The preforaminal part of the LVA was 5 mm in diameter and entered the C6 transverse foramen while the right vertebral artery (RVA) arose from the right subclavian was 6.5 mm in diameter and entered the C5. Embryologically, VAs are formed during weeks four through eight by development of longitudinal anastomoses linking the cervical intersegmental arteries (ISA). The ISA regress except the seventh, which becomes the proximal subclavian artery, the point of origin of the adult VA. Persons with LVA that arises from the AA may be asymptomatic; however, secondary dilatation of the RVA may be implicated in the development of cerebrovascular disorders and atherosclerotic changes due to increased blood flow. Additionally, the anatomical positioning of a left vertebral artery is important when considering an anterior approach for cervical spine surgery and other head-neck procedures when soft structures arteries, veins and muscles are retracted to reach the cervical spine. KEY WORDS: Vertebral artery anomaly, Developmental error, Cervical region surgery, Cerebral circulation, Clinical correlation.