Penetrating carotid artery injuries

Historical perspective

The first documented case of the treatment of a cervical vascular injury is attributed to the French surgeon Ambrose Paré (1510–1590), who was able to ligate the lacerated carotid artery and a jugular vein of a wounded soldier. The patient’s survival was complicated by the development of a profound neurologic defect consisting of aphasia and left-sided hemiplegia. In 1803, Fleming ligated the lacerated common carotid artery of a sailor with a successful outcome. In 1811, Abernathy ligated the lacerated left common and internal carotid arteries in a patient who had been gored by a bull. This patient developed profound hemiplegia and subsequently died from this injury. During World War I, Makins reported 128 patients of which 30% underwent carotid artery ligation with subsequent neurologic deficits. These complications prompted a conservative approach to the treatment of the acutely injured carotid arteries reserving operative intervention for complications. During World War II Lawrence reported only two attempts at repair of a carotid artery injury, and only four repairs were reported from the Korean conflict by Hughes. Both Cohen and Rich reported 50 carotid artery injuries from the Vietnam conflict for an incidence of 5%. Thirty-eight were common injuries and 12 were internal carotid artery injuries. It was not until the 1970s that significant civilian series emerged in the literature incorporating knowledge derived from military experiences ( Table 1 ).

Incidence and mechanism of injury

Carotid artery injuries are estimated to be present in 6% to 13% of all penetrating injuries to the neck. Asensio has reported an incidence of 11% to 13% carotid arterial injuries for all penetrating neck injuries. According to Demetriades carotid artery injuries are present in 6% of all penetrating injuries to the neck and account for 22% of all cervical vascular injuries. Weaver estimates that cervical vessels are involved in 25% of penetrating head and neck trauma and that carotid artery injuries account for 5% to 10% of all arterial injuries. In 1970, Rich reported a 5% incidence in his hallmark series of 1000 arterial injuries reported from Vietnam. Penetrating mechanisms of injury are responsible for the vast majority of carotid artery injuries. Gunshot wounds, rarely shotgun wounds, and occasionally lacerations by jagged and cutting objects such as glass often produce these injuries.

Anatomy

The anatomy of the neck is unique. In no part of the body are there so many vital structures located within such tight confines, nor is there any other area of the body that includes representative structures of so many different systems—the cardiovascular, respiratory, digestive, endocrine, and central nervous systems. All neck structures are invested by two fascial layers: the superficial fascia that encompasses the platysma, and the deep cervical fascia that encompasses the sternocleidomastoid muscle. The pretracheal fascia attaches to the thyroid and cricoid cartilages and blends with the pericardium in the thoracic cavity. The prevertebral fascia encompasses the prevertebral muscles and blends with the axillary sheath, which houses the subclavian vessels. The carotid sheath is formed by all three components of the deep cervical fascia. Such tight fascial compartmentalization of the neck structures limits external bleeding from vascular injuries, thus minimizing the chance of exsanguination.

The neck is divided into three anatomic zones: zone I extends from the clavicle to the cricoid cartilage, zone II extends from the cricoid to the angle of the mandible, and zone III extends from the angle of the mandible to the base of the skull. These zones are used to describe the location of injury in the neck. The origin of the common carotid arteries differs on the two sides. On the left the common carotid artery originates from the aortic arch whereas the right common carotid artery arises from the brachiocephalic artery. However, in the neck the anatomy is the same.

The common carotid artery originates in the neck behind the sternoclavicular joint. Each artery courses obliquely upward from beneath this joint and terminates at the level of the upper border of the thyroid cartilage, where it divides into the external and internal carotid arteries. The common carotid artery is the largest artery in the neck. It has a widened portion known as the carotid bulb at its bifurcation, which is innervated by the nerve of Hering, a branch of the glossopharyngeal nerve. The carotid bulb contains a specialized sensory organ, known as the carotid body, which is a vascular chemoreceptor located at the bifurcation on the posteromedial side. The common carotid artery, internal jugular vein, and vagus nerve are contained within the carotid sheath. There are no branches from the common carotid artery prior to its bifurcation. The external carotid artery is the smaller of the two terminal branches of the common carotid artery and extends from the upper portion of the thyroid cartilage to the angle of the mandible. The internal carotid artery ascends into the skull, piercing the skull via the foramen lacerum as it passes into the carotid canal of the temporal bone from its origin at the upper border of the thyroid cartilage, terminating intracranially by dividing into the anterior and middle cerebral arteries.

At the upper border of zone II the surgeon will often encounter the common facial vein, which is often ligated or retracted when exposing carotid artery injuries. The hypoglossal nerve crosses anteriorly to the internal carotid artery at the upper borders of zone II of the neck. The marginal mandibular branch of the facial nerve is located directly under the inferior border of the mandible.