I | Clavicles and thoracic outlet to cricoid cartilage | Surgical management via anterior sternocleidomastoid incision is considered optimal, but endovascular treatment is often used owing to the difficulty of surgical access |
II | Cricoid cartilage to angle of the mandible | Usually accessible surgically, and endovascular treatment is only used in rare cases where patients remain asymptomatic and the lesion is surgically inaccessible |
III | Angle of the mandible to skull base | Endovascular treatment is now considered first line for zone III injuries owing to challenges associated with surgical exposure |