Incidence

Cervical vessels are involved in 25% of head and neck trauma, and carotid artery injury constitutes 5%³ of all arterial injuries. Penetrating injury is the leading mechanism of injury, with gunshot wounds accounting for half of them, while blunt trauma comprises less than 10%,⁴ most of them due to motor vehicle crashes. Mortality still has been very high, ranging between 10% and 30%, with an incidence of permanent neurologic deficit of 40%.⁵

Mechanism of Injury

Carotid artery injuries usually result from high-velocity missiles or direct impacts to the head. While high-velocity missiles may injure directly or by concussive forces, or cause secondary injury by bone fragments, low-velocity missile injuries are confined to the missile tract. Blunt injuries may result from direct impacts to the vessel causing disruption of the wall or as a result of bony fragments from associated injuries.⁶ Motor vehicle crashes account for the majority of blunt neck injuries. Drivers and passengers on motorcycles, bicycles, jet skis, and snowboards can also sustain blunt neck injuries from direct impact.⁷

In order to provide a guideline in the management of penetrating neck injuries, the wounds to the neck have been grouped into three separate zones: zone I, injuries from the clavicle to the cricoid cartilage; zone II, injuries between the cricoid and angle of mandible; and zone III, injuries above the angle of mandible and the base of the skull.⁸

Of the three zones of the neck, zone II is the easier to expose via an incision parallel to the anterior border of the sternocleidomastoid muscle. Zone I often requires a median sternotomy for the more proximal portions of the common carotid artery. In zone III, the internal carotid artery is approached by extending the sternocleidomastoid incision to the ear into the postauricular space.

Diagnosis

Physical examination of patients with traumatic neck injuries is of paramount importance. The importance is confirmed by the fact that vascular injuries of the neck are associated with mortality rates up to 30% and are present in approximately 25% of all neck injuries. Signs such as expanding hematoma of the anterior or posterior triangle of the neck, audible cervical bruit, palpable thrill, abrasions on the neck secondary to seatbelts, and neurological deficits, are highly suggestive of a vascular injury of the neck. Additional findings include ipsilateral Horner’s syndrome, active bleeding from oropharyngeal wounds, cranial nerves IX to XII deficits, and a diminished pulse in the ipsilateral superficial temporal artery.

Color-flow duplex (CFD) has emerged a valuable and accurate tool in the assessment of traumatic vascular injuries. Numerous studies have documented the accuracy CFD in the diagnosis of cervical vascular trauma, especially in zone II injuries to the neck.^9–15 When performed by a trained technologist and interpreted by a practitioner familiar with the nuances of flow disturbances, CFD correlates with contrast angiography in over 90% of zone II carotid injuries. Color-flow duplex has the advantage of being noninvasive and does not require contrast agents, thus making in-hospital follow-up examinations safe. Unfortunately, due to the adjacent bony structures, CFD is not useful in diagnosis of zone I and III injuries. Also, because the accuracy of CFD is so highly dependent on the personnel performing and interpreting the study and the availability of the personnel is variable after hours, use of CFD is limited even in trauma centers with Level 1 distinction. As usage of emergency-room ultrasound imaging increases in the secondary assessment of intracavitary trauma patients, extension of the scanning to include the neck may become commonplace. Color-flow capability of the ultrasound machine and appropriate training for acute care practitioners would be required.

With advances in the speed of acquisition and the enhanced software allowing elaborate reconstructive views, computerized tomography angiography (CTA) has become more commonly used as a diagnostic modality in traumatic neck injuries. With many patients already being evaluated with CT scans of the cervical spine, chest, and abdomen, CTA has the advantage of not requiring additional transport of the critically injured patient. This is especially the case in head-injured patients where a CT scan of the head is crucial to evaluate the existence of concurrent intracranial hematomas, parenchymal brain injury, or cerebral edema; here CTA of the neck to screen for extracranial and intracranial major vascular trauma is efficacious. In comparing CTA to CFD, Mutze and associates¹⁶ demonstrated that CTA was more sensitive in detecting blunt carotid injuries and recommended contrast material-enhanced studies to avoid the morbidity of a missed cervical vascular injury. Unfortunately, CTA requires the use of nephrotoxic contrast agents to adequately delineate the vascular anatomy, which, when combined with the contrast load required for scanning of the chest and abdomen, increases the possibility of renal toxicity in the hemodynamically compromised trauma patient.

Magnetic resonance arteriography (MRA) is a viable imaging tool to evaluate the extracranial and intracranial vasculature; however, application to trauma patients is not widely accepted. MRA shares the advantage of CTA in that other areas can be imaged simultaneously and in being noninvasive, but unlike CTA, MRA uses a non-nephrotoxic contrast agent. Miller and colleagues¹⁷ prospectively screened selected patients for blunt cerebrovascular injuries and compared the diagnostic modalities, CTA, and MRA, and contrast angiography (CA) in 143 trauma patients. Compared to CA, MRA and CTA had sensitivities of 50% and 47%, respectively, for carotid artery injuries. Similar results were demonstrated for blunt vertebral artery screening with MRA and CTA having respective sensitivities of 47% and 53%. Based on their findings, these authors cautioned against routine use of these modalities for screening of cervical vascular injuries. Compounding this report is the fact that MRA is not easily accessible in the majority of hospitals, and the presence of metallic orthopedic instrumentation limits widespread usage for trauma patients.

Contrast angiography still remains the gold standard with which all other diagnostic modalities are compared. This is especially true in zones I and III vascular injuries where accurate definition of the vascular pathology is essential to planning operative approaches. With the advent of endovascular surgery, CA has the distinct advantage of being the only diagnostic modality where treatment of the vascular abnormality can be rendered immediately after the diagnosis is established.

Treatment

Surgical reconstruction remains the mainstay therapy for carotid arterial injuries. Ligation, a treatment option of the past, is only reserved for cases of extensive injury or life-threatening exsanguination. In patients with signs of extensive pulsatile hemorrhage, expanding hematomas with or without airway compromise, immediate surgical exploration is recommended. Neurological evaluation should always be document prior to surgical intervention. Despite having a dense neurological deficit preoperatively, surgical repair is still recommended. Weaver and associates¹⁸ demonstrated that regardless of the initial neurological deficit, mortality and final neurological status improved after surgical arterial repair. Since this report, subsequent studies documented similar success with surgical repair.^19,20

Despite the success of operative intervention, nonoperative management of carotid injuries is justified in certain clinical scenarios. For example, in patients diagnosed with a carotid artery occlusion, a significant neurological deficit, and a large cerebral infarct on the ipsilateral side, observation is the preferred treatment of choice due to the poor prognosis in this subgroup of patients. Similarly, in patients with carotid artery occlusion and a normal neurological examination, observation and anticoagulation therapy for a period of at least 3 months is recommended to avoid any propagation of existent thrombus.

Likewise, patients diagnosed with “minimal” vascular injuries based on CFD or CA do not require as aggressive surgical approach. Minimal injuries can be described as nonobstructive or adherent intimal flaps and pseudoaneurysms less than 5 mm in size. Initial work by Stain and coworkers²¹ documented the safety of observation in 24 nonocclusive arterial injuries. Patients in this study were managed nonoperatively and subsequently studied arteriographically at 1–12 weeks after injury. Resolution, improvement, or stabilization of the injury occurred in 21 injuries (87%). Progression was noted in three, and only one required repair. There were no cases of acute thrombosis or distal embolization. Later, Frykberg et al.²² documented a similar report with data extending to 10 years with comparable excellent results, thus confirming the wisdom of this approach.

In patients undergoing open surgical repair, basic surgical principles and techniques for the management of arterial injuries must be followed. In preparation for the procedure, availability of vascular clamps and instrumentation, as well as intraluminal shunts should be confirmed. The operative field should include not only the area of injury, but also the ipsilateral chest wall, an area up throughout zone III of the neck, and a thigh for a vein graft harvest site. In general, zone I injuries require exposure through a median sternotomy and zone II via an incision along the anterior border of the sternocleidomastoid muscle. Zone III injuries of the neck are more difficult to expose and to gain adequate exposure of the distal internal carotid artery, anterior subluxation or osteotomy of the mandible is required.

Once proximal and distal vascular control is established, injured vessels are debrided to macroscopically normal arterial wall. Fogarty catheters should be passed selectively and gently, both proximal and distal to the arterial injury, to remove any intraluminal thrombus. It is extremely important not to overinflate the balloon, lest the endothelial lining be damaged and arterial spasm or thrombosis result. Both proximal and distal arterial lumens are flushed with heparinized saline solution. Systemic heparinization, if not contraindicated, is of benefit to decrease the risk of thrombus formation or clot propagation. Placement of an intraluminal shunt is a helpful adjunct to maintain antegrade flow to the ipsilateral cerebral cortex and is strongly recommended particularly for proximal internal carotid artery or carotid bulb injuries. In this scenario, standard indications for the selective use of shunting in elective carotid artery surgery should not apply. Proximal common carotid injuries may be repaired without distal shunting because the external carotid artery provides adequate collateral flow. The type of repair is dictated by the extent of arterial damage. Repair of injured vessels can be accomplished by lateral suture patch angioplasty, end-to-end anastomosis, interposition graft, or, when adjacent soft injury is extensive, a bypass graft. If possible, an all-autogenous arterial repair with a vein graft is recommended. However, prosthetic grafts, such as expanded polytetrafluoroethylene (ePTFE), can be used with excellent outcomes, especially in the common carotid artery reconstructions.

Monofilament 5-0 or 6-0 sutures are suitable for most peripheral vascular repairs, and all completed repairs should be tension free and covered by viable soft tissue. We consider intraoperative completion arteriography or duplex scanning to be mandatory to document technical perfection of the vascular reconstruction, visualize arterial runoff, and detect persistent missed distal thrombi. Intra-arterial vasodilators such as papaverine or tolazoline may be helpful, particularly in the pediatric age group, in reversing severe spasm in the distal arterial tree or the repaired arterial segment.

The use of endovascular therapy to treat traumatic arterial injuries has gained popularity in the management of traumatic arterial injuries. Endovascular management has the advantage of being able to treat the vascular abnormality at the time of diagnosis, if contrast angiography is the diagnostic modality being used. In addition, catheter-based treatment can access lesions that would be either difficult to surgically expose (i.e., zone III injuries) or lesions that would require extensive operative incisions (i.e., lower zone I injuries). The disadvantages to endovascular treatment are the requirement for contrast material, and the lingering possibility for surgical exploration for concomitant injuries or to evacuate extensive hematomas.

Traditionally used for treatment of small arteriovenous fistulae and short-segment dissections, covered and uncovered stents are being used for more significant arterial lesions. Joo and associates²³ reported successful management of 10 traumatic carotid arterial injuries. The lesions involved both the intracranial and extracranial carotid artery with the all arterial pathology consisting of arteriovenous fistulae or pseudoaneurysms. The authors did comment that long-term follow-up was not available in their study group; a concern with the application of this newest vascular technology. Regardless, as technology continues to advance, endovascular treatment of cervical arterial lesions should be considered, especially in high-risk patients with multiple concomitant injuries. As more operating room suites transform into high resolution fluoroscopic units and surgeons become more adept in endovascular treatment modalities, expeditious diagnosis and management of traumatic cervical vascular injuries should be expected in the future.

Incidence

The incidence reported in the literature of vertebral injuries in penetrating neck trauma varies from 1.0%–7.4%, depending on the mechanism (gunshot or stab wounds). In 1967, Stein²⁷ reported 200 consecutive penetrating neck injuries with only two patients (1.0%) with vertebral artery injuries. In a prospective study²⁸ of 223 penetrating neck injury patients evaluated with routine four-vessel angiography, there were 13 cases (7.4%) with vertebral injuries reported.

The incidence in blunt trauma is very low, and is usually associated with cervical spine fractures.

Mechanism of Injury

The most common mechanism is a gunshot wound, followed by stab wound and other penetrating neck trauma. Blunt trauma includes mechanisms such as closed head injury, ligamentous cervical spine injury, bony disruptions, and direct impacts to the neck.^29–32 Other situations in which arterial vertebral injuries can be seen are during internal jugular catheterization, angiographic procedures, cervical spine internal fixation, and diskectomy.³³

Associated Injuries

Gunshot wounds to the vertebral artery are often associated with major injuries to other vessels, the aero-digestive tract, the cervical spine, and nerves. Stab wounds are often associated with brachial plexus and internal jugular vein injuries, along with injuries to the esophagus, and occasionally a hemothorax.³⁴ Injuries to the vertebral injuries due to blunt mechanisms should be suspected in patients with facet joint dislocation or transverse foramen fracture, and closed head injuries.²⁹ According to Asensio, associated vascular injuries occur in a range from 13 to 19%, and arteriovenous fistulas between the vertebral artery and the two paired vertebral veins occur with a frequency of 11%. Similarly, associated pharyngo-esophageal injuries occur with a frequency of 11%–22%.³⁵

Diagnosis

Presentation of patients with vertebral artery trauma is highly variable. In patients presenting after penetrating vertebral artery trauma, the “hard signs” of a vascular injury (expanding hematoma, cervical bruit, pulsatile hemorrhage) were only present in 50% of patients and only 30% presented with “soft signs” (history of bleeding, proximity wound, neurological abnormality).³⁶ In fact, close to 20% of patients with vertebral artery trauma present with no overt clinical signs. As opposed to carotid arterial trauma where occlusion of a single vessel can lead to permanent neurological alterations, single occlusion of one vertebral artery often remains clinically silent. However, if bilateral vertebral artery occlusions occur, neurological symptoms would manifest.

Color-flow duplex has a limited role as a reliable diagnostic tool. Unlike the carotid artery where a long segment of artery can be evaluated in both longitudinal and transverse planes, because of the course within the cervical spine, only the most proximal segment of the vertebral artery can be visualized in a very short longitudinal plane. Therefore, outside of documenting an occlusion, CFD can only provide information about abnormal flow patterns suggestive of pathology more distal in the vessel.

Because of the difficulty in physical examination and CFD in diagnosing vertebral arterial injuries, CTA and MRA will be the diagnostic modalities that identify the majority of abnormalities. Both imaging techniques allow visualization of all segments of the vertebral artery without obstructed shadowing from the cervical spine, thus becoming one of the main screening tools for vertebral artery trauma. Contrast angiography remains the gold for imaging the vertebral artery. Because of the ability to endovascularly treat the revealed lesion at the time of diagnosis, contrast angiography may be the preferred imaging selection.

Treatment

Contrary to the treatment of carotid artery injuries, which are managed operatively, the majority of vertebral artery injuries either do not require treatment or are treated with angiographic embolization. The only indication for operative management is for patients with active hemorrhage or those that have failed angiographic treatment methods. Also, because of the anatomical relationship with both vertebral arteries, vertebral artery occlusion is infrequently accompanied by a major neurological event. Regardless, angiographic evaluation should still be undertaken to treat underlying arteriovenous fistulae and to confirm occlusion.

Anatomy of the vertebral artery can be divided into four segments. The first portion of the vertebral artery (V-1) begins where the vertebral artery originates from the subclavian artery and extends to the sixth cervical vertebrae transverse process foramen. This area of the artery is the most accessible for surgical exposure. After positioning the patient with the head angled away from the affected side, exposure to the vertebral artery can be through an incision along the sternocleidomastoid muscle (SCMM) or a transverse supraclavicular approach (the authors’ preference). Note, however, that the incision along the SCMM does allow continuation of the incision superiorly or inferiorly to provide additional exposure. After mobilizing and retracting the SCMM laterally, and retracting the carotid sheath medially, the anterior scalene muscle with the overlying phrenic nerve is encountered. With careful medial retraction of the anterior scalene muscle and the phrenic nerve, the vertebral vein is visualized. The vertebral artery is directly posterior. To gain additional exposure, the omohyoid and the clavicular head of the SCMM may be divided.

The second portion (V-2), or the interosseous portion, extends from the transverse foramina of C-6 to C-2. Exposure of this segment of the vertebral artery requires dissection through the transverse foramina to expose the vertebral canal. Through the same exposure discussed previously, the longus coli muscle is encountered in the deep posterior aspect of the neck. Once this muscle is swept off of the underlying bony structure with a periosteal elevator, the anterior tubercle of the transverse process and the vertebral bodies are visualized. Bone rongeurs are used to remove the anterior rim of the vertebral foramen to expose the vertebral artery.^36,37 Moderate bleeding may be anticipated during this part of the dissection. Additional anterior rims may be excised for increased exposure. The vertebral artery may be safely ligated at this point. Care should be taken not to blindly place surgical clips for arterial occlusion because cervical nerve roots lie directly posterior to the artery and may be injured.

The third part of the vertebral artery (V-3) courses from where the vertebral artery exits the foramina of C-2 and extends to the foramen magnum at the base of the skull. A posterior auricular approach is required to expose this segment of the artery. The fourth part of the vertebral artery (V-4) starts at the foramen magnum and ends where both vertebral arteries join to form the basilar artery. The fourth segment of the vertebral artery can only be exposed with a craniotomy. Exposure of this segment of vertebral artery is most challenging to both the trauma and vascular surgeon, and assistance from a neurosurgeon is often required.

The preferred method for management of vertebral artery injuries is angiographically. Lesions ranging from aneurysms, arteriovenous fistulae, and pseudoaneurysms can all be treated with an array of detachable balloons, stents, coils, liquid tissue adhesives, and other hemostatic agents. Numerous authors have documented successful endovascular management of traumatic vertebral artery injuries. With the continued improvement of endovascular technology, the scope of traumatic lesions will certainly increase.