Figure 23-1. Zones of the neck.
The inferior and lateral extensions of zone I are often contested and debated. While this is not well described, our practice is to classify lateral and inferior (superior mediastinal) injuries by zone I principles. Because proximal control involves a thoracic incision, we believe zone I extends to the junction of the subclavian and axillary arteries laterally and inferiorly to the mediastinal great vessels.
Injury to the posterior neck should be treated differently than injury to the anterior neck. It makes sense that tracheal and esophageal injuries would be less common with posterior injury, as they are protected by the spine. Injuries to the spine should be more common in this anatomic region.
Often, more than one zone can be injured by a single trajectory; such as an injury through both zone II and zone I. Management of these “multizone” injuries is guided by the standard principles used for the more challenging zone, usually zone I or zone III.
The platysma muscle envelops the neck and originates from the pectoralis major and deltoid muscles. Though clinical practice has evolved, most classic algorithms of treating penetrating neck trauma stated that injuries penetrating the platysma muscle in zone II of the neck mandated direct operative intervention, whereas those penetrating the platysma in zones I and III mandated additional studies via either angiography or other imaging modalities.5
Obvious injury to the neck, with the presence of an expanding hematoma or other hard signs of vascular injury, should lead the provider to obtain definitive endotracheal access as the first step in the resuscitation. Similarly, air bubbling through the wound, hoarseness, or an obviously transected trachea, should guide the treatment team toward immediate and definitive airway control.
In the event that orotracheal intubation cannot proceed (rapidly expanding hematoma, destructive laryngeal trauma, patient habitus, excessive debris within the oropharynx, etc.); an emergent surgical airway should be expeditiously obtained. Cricothyroidotomy and emergency tracheostomy remain the safest and most reliable methods of emergent surgical control of the airway. Some investigators have shown promising results with percutaneous tracheostomy performed in the emergency setting, though this should only be contemplated by experienced clinicians.9 If tracheal transection is visualized in the wound, intubation of the distal tracheal segment with an endotracheal tube or any available airway device can be lifesaving (Fig. 23-2).
Though obtaining a safe and definitive airway is the priority in all injured patients with airway compromise, awareness of potential concomitant cervical spine injury must be considered in patients with blunt trauma. Maintaining cervical stabilization during movement and intubation is paramount and is best accomplished by maintaining the head and neck in neutral position with the help of a competent assistant trained in such maneuvers. The same caution is not needed in patients with penetrating trauma, as patients presenting alive and neurologically intact are highly unlikely to have unstable cervical spine fractures.10,11
Figure 23-2. Intubation of a distal tracheal transection in the neck.
A rapid assessment of the neurologic state of the patient can give insight into the nature of a neck injury, as a dense hemiplegia may be the result of carotid arterial injury and subsequent ischemic stroke. It is imperative to recognize the patient with a lateralizing neurologic defect early, as revascularization may result in hemorrhagic conversion of a cerebral infarction.
After the primary survey and adjunctive radiographic procedures (chest radiograph, abdominal sonography), a thorough secondary survey should be performed, with focus on the structures of the neck. A hematoma across the base of the neck, which was caused by an automobile seatbelt, may portend a blunt cerebrovascular injury (BCVI). Extensive subcutaneous emphysema in the tissues of the neck usually represents air tracking up from a pneumothorax, but can represent an injury to the airway. Injury to the esophagus is possible, but subcutaneous air is rarely the only symptom of esophageal injury. Similarly, an audible bruit or palpable thrill may indicate major vascular injury that requires prompt attention.
SELECTIVE VERSUS MANDATORY EXPLORATION
Few would argue that penetrating injuries to the neck, with hard signs of injury (pulsatile hemorrhage, expanding hematoma, shock, air emanating from the wound, massive hemoptysis), mandate immediate surgical exploration. In the absence of these hard signs of injury, most favor a selective approach with clinical examination and diagnostic radiographs.
While diagnostic exploration may make sense for zone II injuries, diagnostic preoperative evaluation certainly makes sense for injuries in zone I and zone III. Penetrating injury in zone I puts vascular structures, trachea, and esophagus at risk. Physical examination can be misleading and different incisions may be needed depending on which structures are injured and the level at which they are injured. Thus, in stable patients, diagnostic work up is wise. This generally involves endoscopy, contrast studies, or both to investigate the possibility of an esophageal injury. While asymptomatic tracheal injuries are quite rare, many have favored a diagnostic bronchoscopy in these injuries. In the past, vascular structures were investigated by means of catheter angiography, with noninvasive axial imaging as the most common modality in the current era.
Unfortunately, in unstable patients with a zone I trajectory, localization of the injury may not be possible preoperatively. In such a case, the clinician should make an estimate as to which structures are most likely to be injured. The initial incision should be tailored to quickly expose that area. If exposure is inadequate or a different structure has been injured, the incision should be lengthened, or a second incision should be made. This process continues until the injury is controlled or the patient has died.
Aerodigestive injuries are not an issue in zone III; however the difficulty in surgical management of vascular injuries in zone III makes preoperative imaging very attractive. In the past, angiography was used as the sole diagnostic test in stable patients. If patients are unstable, clinicians must weigh the difficulty of diagnostic exploration against the time it would take to use alternative hemostatic methods. In some cases, if catheter hemostasis is immediately available, temporary control with finger pressure or a balloon, as a bridge to rapid diagnostic angiography and catheter hemostasis may actually be quicker than direct operative exploration. In most areas of the world, this approach is only appropriate in a few highly advanced centers. In most centers, while difficult, direct surgical exploration is the wisest course in the unstable patient.
Current Imaging Technology
In recent years, computed tomography (CT) has become much more widely used to evaluate the possibility of neck injury. CT is extremely attractive as it is a single study that is rapidly available in virtually every center and provides a three-dimensional evaluation of the neck. In patients with injury patterns that put the upper mediastinal structures at risk as well, CT can evaluate both areas for potential injury, simultaneously. CT may be very effective at excluding injuries in some cases. For example, a patient with a gunshot wound to the neck that has a clearly demonstrated CT trajectory that avoids all vital structures, most likely only needs observation and no additional diagnostic testing. Other patients, such as those with significant amounts of subcutaneous air or a trajectory that is close to vital structures, such as the carotid artery and/or the esophagus, may need additional diagnostic testing.
Penetrating Neck Trauma
In 2002, Gonzalez et al. prospectively evaluated patients with penetrating injury to zone II of the neck that did not have an indication for emergent surgical exploration.13 Patients then underwent dynamic CT imaging and had a barium esophagram, followed by mandatory surgical exploration of the neck. Investigators noted a total of four esophageal injuries, two of which were seen on surgical exploration only and were not identified on either CT scan or esophagram. However, both injuries missed on diagnostic evaluation were less than 0.5 cm and were the result of stab wounds. The authors speculated that the injuries may have healed spontaneously. The most commonly missed injury by CT scan was jugular venous injury; which likely needed no therapy.13
In a large prospective study involving Los Angeles County, University of Southern California Medical Center, and the R Adams Cowley Shock Trauma Center at the University of Maryland, all asymptomatic patients presenting with a penetrating neck injury and no signs of injury were safely observed and investigators reported zero missed injuries. In the same series, patients with soft signs of injury (venous oozing, nonexpanding or nonpulsatile hematomas, minor hemoptysis, dysphonia, dysphagia, and subcutaneous emphysema) underwent multidetector CT angiography (CTA). Investigators achieved 100% sensitivity and 97.5% specificity in detecting all clinically significant injuries.14
Blunt Neck Trauma
Plain film radiography is not adequate to identify injuries to structures in the neck. However pneumothorax, hemothorax, air in the subcutaneous tissues, nasogastric tube displacement, or mediastinal widening are all indicative of significant force that would be sufficient to injure structures within the neck.
BCVI diagnosis deserves special mention, as disagreement still persists as to the optimal screening test for diagnosis. In the past, BCVI was usually diagnosed late, after the patient had suffered a stroke. Diagnostic angiography then virtually always demonstrated an internal carotid artery injury. Therapy included anticoagulation, but was mainly supportive as the damage had already been done. Additionally, catheter angiography is invasive and carries some risk of iatrogenic vascular injury and/or periprocedural stroke.
Additional debate has focused on the ideal test for diagnosis of BCVI, with some suggesting angiography and some CTA. In a study of 146 patients at risk for BCVI, investigators imaged all patients with 16-slice CTA and four-vessel cerebral angiography. They noted a sensitivity of 97.7% and a specificity of 100% with the utilization of CTA for the diagnosis of BCVI.18 However, authors in Memphis examined 684 patients and found the sensitivity of CTA to be 51% with a specificity of 97%.19 Despite the disparate findings, survey results illustrate that 90% of trauma surgeons utilize CTA as their preferred diagnostic modality for BCVI.20
MANAGEMENT OF SPECIFIC INJURIES
Blunt Cerebrovascular Injury (BCVI)
Blunt injuries to the carotid and vertebral arteries are the result of a direct blow to the vessel itself or an extreme flexion, extension, or lateral rotational injury. If located in the carotid artery, these injuries typically occur at the base of the skull. Vertebral artery injury usually is located in the portion of the vessel protected by the cervical spine. These areas are difficult to explore surgically.
The work of Biffl and colleagues in 199921,24 highlighted the importance of screening for BCVI when certain anatomic injuries or injury patterns were observed (Table 23-1). Subsequently, organizational guidelines have been disseminated by the Eastern Association for the Surgery of Trauma (EAST) based on review of the literature with the aim of guiding screening practices for BCVI (Table 23-2).27 Investigators have shown that up to 30% of patients diagnosed with BCVI may have no radiographic or clinical risk factor that would guide the clinician to screen for these injuries.15 Recent data has also identified an association between BCVI and nontraditional risk factors such as serious chest injury.17 Thus, a high index of suspicion must be maintained in order to effectively diagnose and treat BCVI.
Given the seeming inability of screening guidelines to accurately identify patients at risk for BCVI, some centers have gone to blanket screening.15 All polytrauma patients with a blunt mechanism of injury undergo CT scan of the cervical spine with contrast timed to image the carotid and vertebral arteries in conjunction with a chest and abdominal CT scan, obviating the need for a second contrast study. While data on this blanket screening is limited, it does enable the identification of injuries early in the course of workup and identifies injuries in patients that would otherwise not be screened secondary to lack of criteria.15 Patients with identified injuries generally receive a formal CT angiogram as their follow-up study.
If stroke can be avoided with prompt initiation of therapy, functional outcomes after BCVI are good.28 However, many patients with BCVI have multisystem trauma and are thus not deemed suitable for antiplatelet therapy or systemic anticoagulation. In a 2009 study, almost one-third of patients with BCVI were identified as not candidates for therapy, with an overall stroke rate of 12%. Stroke-related mortality was 50%.16
Table 23-1 Signs and Symptoms of Blunt Cerebrovascular Injury