Injuries to the Neck

Arvin Chun-Yin Gee

Kelli D. Salter

Donald B. McConnell

Donald D. Trunkey

The optimal management and care of both blunt and penetrating neck trauma has undergone significant evolution in the last few decades. However, optimal management of some injuries remains unclear and is the subject of active investigation. Many of the changes have been spurred by the development of new diagnostic and therapeutic technologies that have increased the safety and efficacy of nonsurgical management.

Historically the management of neck trauma has been influenced by military experience with high-energy missile and blast injuries. This generated protocols that mandated surgical neck exploration, which lowered the rate of missed injuries but increased the number of nontherapeutic surgeries. However, in this age of “cost-containment” and evidence-based medicine, the economic cost, resource utilization, and high morbidity of exploratory neck surgery has led to some authors and trauma centers questioning this management protocol in civilian practice.

As with all other anatomic locations, blunt and penetrating injuries often require different management approaches. Considering the plethora of vital structures that reside in this compact anatomic region, neck injuries can result in significant morbidity and mortality. Seemingly innocuous wounds may not manifest clear signs or symptoms, and potentially lethal injuries could be easily overlooked or discounted. Therefore the surgeon faced with initially managing a traumatically injured person must be cognizant of the currently recommended guidelines for the evaluation and the management of neck injuries.

In this overview, we review, in a systems fashion, the diagnosis and management of the various blunt and penetrating injuries encountered by the surgeons managing these patients. This chapter provides practical guidelines and algorithms for the safe evaluation and management of civilian patients, with soft tissue injuries of the neck. Cervical spinal cord injuries and cervical spine fractures will not be addressed in this chapter.

EPIDEMIOLOGIC FEATURES

Most neck trauma is due to a penetrating mechanism. As shown in Fig. 1, most of the penetrating neck trauma in the United States occurs as a result of interpersonal violence with firearms being the most common weapon of choice. These injuries most often affect the vascular system or results in injury of the great vessels or lung apices (see Fig. 2). Blunt neck trauma stems from a variety of etiologies. Motor vehicle crashes, falls, hangings, and chiropractic neck manipulations have all been documented to lead to blunt injuries.

Penetrating neck trauma represents approximately 5% to 10% of all trauma cases that present to the emergency department. Approximately 30% of these cases are
accompanied by injury outside of the neck zones as well. The current mortality rate in civilians with penetrating neck injuries ranges from 3% to 6%. Whereas blunt neck trauma is fairly common, actual soft tissue injuries from blunt trauma is relatively rare and has been estimated to be < 1% of all neck injuries.¹ Despite its relative rarity, blunt laryngotracheal (LT) trauma carries a mortality rate that can be as high as 40%, whereas the mortality rate of penetrating LT injuries is approximately 20%.²

Figure 1 Mechanism of penetrating neck injuries in the United States.

Figure 2 Distribution of systems injured by penetrating neck injury. (From Bell RB, Osborn T, Dierks EJ, et al. Management of penetrating neck injuries: A new paradigm for civilian trauma. J Oral Maxillofac Surg. 2007;65:691-705.)

ANATOMIC FEATURES

Successful management of neck injuries depends on a clear understanding of the anatomy of the neck. The close proximity of vital structures with the anterior third of the neck is clearly demonstrated in the cross-sectional view of the neck as shown in Fig. 3.

Figure 3 A cross-section drawing of the neck anatomy. (From McConnell DB, Trunkey DD. Management of penetrating trauma to the neck. Adv Surg. 1994;27:97-127.)

Figure 4 Zones of the neck. Zone I: thoracic inlet to the cricoid cartilage; zone II: cricoid cartilage (highlighted by the arrow) to the mandibular angle; zone III: mandibular angle to the skull base. (Adapted from Gray H. Anatomy of the human body, 20th ed. Philadelphia: Lea & Febiger; 1918. Bartleby.com, 2000. http://www.bartleby.com/br/107.html.)³

For the purposes aiding clinical decisions for diagnostic testing and management, surgeons have described the neck by dividing it into three anatomic zones in the caudal to cranial orientation as shown in Fig. 4. The six organ systems within these neck zones include vascular, respiratory, digestive, neurologic, endocrine, and skeletal. The vascular system includes the innominate, subclavian, axillary, carotid, jugular, and vertebral vessels. The respiratory system includes the larynx, trachea, and the lung. The
digestive system includes the pharynx and esophagus. The neurologic system includes the spinal cord, brachial plexus, cranial nerves, and the sympathetic chain. The endocrine system includes the thyroid and parathyroid. The skeletal system includes the cervical spine, clavicle, upper rib cage, and skull base.

Figure 5 Surface anatomy of the head and neck with the incision for an anterior sternocleidomastoid approach. The solid black line indicates the anterior border of the patient’s left sternocleidomastoid muscle. (Modified from Gray H. Anatomy of the human body, 20th ed. Philadelphia: Lea & Febiger; 1918. Bartleby.com, 2000. http://www.bartleby.com/br/107.html.)³

Serving as the line of demarcation, the sternocleidomastoid muscle separates the neck into anterior and posterior triangles. Most of the important vascular and visceral organs lie within the anterior triangle bounded by the sternocleidomastoid posteriorly, the midline anteriorly, and the mandible superiorly. Except for individual nerves to specific muscles, few vital structures cross the posterior triangle, which is delineated by the sternocleidomastoid, the trapezius, and the clavicle (with the exception of the region just superior to the clavicle). The area of injury depends on the mechanism of injury. Overall, zone II is the most commonly injured area (see Fig. 5).⁴

Zone I, the base of the neck, is demarcated by the thoracic inlet inferiorly and the cricoid cartilage superiorly. Vascular structures at greatest risk in this zone include the innominate vessels, jugular veins, common carotid artery origin, subclavian vessels, and vertebral artery. Other important nonvascular structures located within this zone include the brachial plexus, trachea, esophagus, apices of the lungs, thoracic duct, cervical spine, and cervical nerve roots. Surgical exposure of these structures, particularly the vascular structures, is difficult because of the presence of the clavicle. Furthermore, signs of a significant injury in the zone I region may be hidden from inspection by residing within the chest or the mediastinum.

Zone II encompasses the midportion of the neck and is defined as the region between the cricoid cartilage and the angle of the mandible. Important structures in this region include the carotid and vertebral arteries, jugular veins, pharynx, larynx, trachea, esophagus, and cervical spine and spinal cord. Zone II, in comparison with zones I and III, is the most easily accessible region for clinical examination and surgical exploration. Therefore, zone II injuries are likely to be the most apparent on physical examination and are also the easiest to evaluate intraoperatively without the aid of preoperative diagnostic testing.

Zone III defines the superior aspect of the neck and is bounded by the angle of the mandible and the base of the skull. Diverse structures, such as the salivary and parotid glands, cervical spine, the distal extracranial carotid arteries, jugular veins, and major nerves (including cranial nerves IX-XII), traverse this zone. Zone III is not amendable to easy physical examination or surgical exploration; therefore, injuries in zone III can require special diagnostic studies to aid in management.

PREHOSPITAL MANAGEMENT

The evaluation of a patient with penetrating neck trauma should always begin with Advanced Trauma Life Support, a paradigm that starts with a directed primary survey emphasizing airway, breathing, and circulation. However, attempts to manage the airway and resuscitate the patient in the field are ill advised and potentially dangerous. Therefore, the scene time should be kept to a minimum,
especially if there is a short transport time to the nearest designated trauma center.

Bleeding control can be achieved by direct pressure and the risk of an air embolism can be reduced by the placement of patient in the Trendelenburg position. Placement of intravenous (IV) lines can be attempted en route to the hospital. Oxygen can be administered by mask or nasal cannula. However, assisted ventilation with bag-valve-mask may be contraindicated because it may result in massive subcutaneous emphysema or air embolus in patients with an open LT injury. Furthermore, prehospital endotracheal intubation should be attempted only in patients in extremis, have a compromised airway, or have anticipated prolonged transport times. Most low-velocity gunshots and stab wounds do not result in airway compromise, but high-velocity gunshot and shotgun wounds and severe blunt trauma will often necessitate emergent airway management.

Traumatized airways are usually challenging to intubate because of the primary injury, blood, tissue, local edema, and debris. Blind intubation can result in the endotracheal tube creating a false passage or complete the transection of an injured trachea resulting in severe morbidity. Blind intubation should not be attempted because of its inherent low success rate and the high mortality of a failed blind intubation. It is important to remember that a surgical airway is sometimes needed and prehospital personnel must be prepared for this scenario before any attempts at endotracheal tube placement.

Cervical spine protection by means of a neck collar remains a common practice during the prehospital transportation. Given the high incidence of cervical spine fracture associated with high-energy penetrating neck injuries, cervical immobilization should be attempted when feasible.⁵ However, it should be abandoned if it would cause an undue delay or hindrance to emergent management of the patient and may, in fact, be harmful in patients with an expanding hematoma that may cause respiratory obstruction.

Zone I injuries can have a concomitant pneumothorax, which can be simply treated during transport by placing a large-bore needle and IV catheter into the pleural space. Additionally, if a large venous injury is suspected, peripheral IV line placement should be on the contralateral side to the injury to minimize fluid extravasation and to maximize the ability to replete the patient’s intravascular volume.

EMERGENCY DEPARTMENT/TRAUMA BAY MANAGEMENT

Airway Management

Upon arrival at the emergency department, the patient should be surveyed and treated for immediate life-threatening conditions as delineated in the Advanced Trauma Life Support protocols.⁶ Airway management is the first and most challenging priority in the management of severe penetrating neck injury. In a review by Vassiliu et al., 29% of patients with LT trauma and 41% of patients with pharyngoesophageal (PE) trauma required emergency intubation.⁷

Airway compromise may arise due to direct trauma or severe edema to the larynx or trachea or from external compression by a stable or expanding hematoma. Management of airway in patients with penetrating neck injury should be individualized according to the condition of the patient, the nature of the injury, and the experience of the trauma team.

Ideally, there is an experienced anesthesiologist on the trauma team to assist with advanced airway management. A surgeon should always be present in case an emergent surgical airway is warranted because up to one fourth of patients with aerodigestive tract trauma have failed rapid sequence induction intubation.⁷ If a surgical airway is required and there is an obvious LT wound, the endotracheal tube can be carefully inserted under direct vision into the distal airway. Creation of surgical airway in these challenging conditions requires a closely coordinated team effort between the surgeons and the anesthesiologists.

In most emergent situations a cricothyrotomy is the surgical airway of choice rather than a tracheostomy. The more inferior placement of a tracheostomy has a lower rate of tracheal stenosis than with cricothyrotomies. However, the exposure required for a tracheostomy is often more technically challenging due to the location of the anterior jugular veins and the thyroid gland and its associated vasculature. A cricothyrotomy safely avoids the thyroid gland and most of the anterior vessels of the neck. The higher rate of late complications associated with cricothyrotomy can be avoided by electively converting it to a tracheostomy 1 to 2 days after the patient’s condition allows for the procedure.

Circulation Management

As in the prehospital setting, the patient should be placed in the Trendelenburg position when there is active bleeding to reduce the risk of air embolism from venous injuries. Hemorrhage control can often be achieved simply by direct pressure in most patients. However, in the event that external pressure is not effective, as in the case of bleeding from the vertebral or subclavian vessels, digital compression with a gloved index finger inserted into the wound may be more effective in temporizing the bleeding en route to the operating room.

Regardless of the zonal location of injury, exsanguinating hemorrhage, expanding hematoma, refractory shock, airway compromise, and severe subcutaneous emphysema (see Table 1) are all indications for immediate surgical exploration and intervention.⁸ Finally, for those patients in cardiac arrest or imminent cardiac arrest, an anterior
resuscitative thoracotomy may be indicated if an injury to zone I vasculature is suspected.⁹ The thoracotomy exposure should allow for intrathoracic direct control of zone I vascular injuries. However, the survival rate following resuscitative thoracotomy for penetrating neck injury is very poor.

TABLE 1 INDICATIONS FOR EMERGENT NECK EXPLORATION

Indication for Emergent Exploration
Exsanguinating hemorrhage
Expanding hematoma
Shock refractory to resuscitation
Airway compromise
Severe subcutaneous emphysema

SECONDARY SURVEY

History and Physical Examination

Following airway management and circulation stabilization, the secondary survey should be conducted to evaluate for concomitant injuries. Especially in instances where a neck injury is present or suspected, a thorough head and neck examination is mandatory. Clinical examination has been shown to have good sensitivity for detecting clinically significant vascular injury in cases of zone II penetrating injuries.¹⁰,¹¹

Particular attention should be given to the LT, vascular, and PE systems to evaluate for “hard” signs, which are pathognomonic of injury, and “soft” signs, which are suspicious but not diagnostic of significant injury (Table 1). These steps, together with the laboratory and diagnostic studies, are used to identify the likely injury complex and direct further treatment or diagnostic testing. In general, “hard” signs usually warrant a surgery without specific diagnostic studies, whereas “soft” signs require further diagnostic evaluation to identify those patients with significant injuries requiring surgical repair. The clinical examination should also include assessment of the nervous system through the use of the Glasgow Coma Scale, localizing signs, pupils, cranial nerves, spinal cord, brachial plexus, phrenic nerve, and the sympathetic chain.

TABLE 2 CLINICAL SIGNS OF NECK INJURIES

	Hard Signs	Soft Signs
Laryngotracheal	Respiratory distress	Subcutaneous emphysema
	Air bubbling	Hoarseness
	Major hemoptysis	Minor hemoptysis
Vascular	Severe hemorrhage	Stable small-moderate hematoma
	Large or expanding hematoma	Minor hemorrhage
	Absent/diminished peripheral pulses	Mild hypotension
		Proximity wound
	Bruits on auscultation
	Unexplained hypotension
Pharyngoesophageal		Painful swallowing
		Subcutaneous emphysema
		Hematemesis
(From Bell RB, Osborn T, Dierks EJ, et al. Management of penetrating neck injuries: A new paradigm for civilian trauma. J Oral Maxillofac Surg. 2007;65:691-705; Demetriades D, Salim A, Brown C, et al. Neck Injuries. Curr Probl Surg. 2007;44:13-85.)

Diagnostic Imaging

The mechanism of injury and clinical examination should determine the need and type of diagnostic imaging. As was stated earlier, patients with “hard” signs of major vascular or LT injuries, summarized in Table 2, need to undergo a surgery without delay for definitive investigations.

Chest Radiograph

A chest radiograph should be obtained in all trauma patients but is of particular importance in patients with penetrating injuries to zone I or those with any other wounds that may violate the chest cavity. Furthermore, chest and neck radiographs may be helpful in locating foreign bodies in other zones of the neck or parts of the chest cavity.

Angiography, Color Flow Doppler, and Helical Computed Tomography

Angiography has been advocated since the 1970s for the diagnosis of cervical vascular injury, particularly for injuries
in zones I and III. The gold standard has been catheter-based four-vessel digital subtraction angiography (DSA). DSA potentially allows for the immediate endovascular repair of an injury. However, angiography is often not readily available at most institutions during off-hours and it carries an estimated 2% risk of significant complications, including arterial dissection, thrombosis, embolism, and vasospasm.¹² Additionally, recent evidence suggest that routine angiography in asymptomatic patients with penetrating neck injuries is unnecessary, has a low yield, and does not offer any benefit over physical examination and other noninvasive investigations.¹³,¹⁴

Color flow Doppler (CFD) with a careful physical examination was then proposed as a safe, cost-effective, and reliable alternative to angiography. However, CFD has the disadvantage of being operator dependent and being technically difficult due to open wounds, pain, hematomas, and subcutaneous emphysema. CFDs are also limited in their ability to adequately visualize the proximal left subclavian artery, the internal carotid artery near the base of the skull, and the segments of the vertebral artery under the bony part of the vertebral canal.⁴ As with catheter-based angiography, CFD studies are unavailable in many institutions at night and on weekends. Therefore, some surgeons continued to promote a policy of routine angiography for injuries in zones I and III, regardless of the clinical findings, as well as penetrating injuries with specific diagnosis or therapeutic indications.

More recently, helical computed tomographic angiography (CTA) has emerged as a fast, minimally invasive, and accurate alternative study to conventional angiography for the screening and evaluation of cervical vascular injury. Important advantages of CTA are that it is readily available at most trauma centers regardless of the time of day and that it provides evaluation of the soft tissues, skeletal structure, and vasculature structures in <5 minutes. Several authors have advocated the liberal use of CTA in the evaluation of blunt cervical trauma because it simultaneously evaluates the vasculature and skeletal structures of the neck.¹⁵ It has been reported to have positive and negative predictive values as high as 100% and 93%, respectively, for blunt cervical vascular injury (BCVI).¹³ Use of CTA in the evaluation of penetrating neck trauma can lead to a reduction in the rate of negative neck explorations.¹⁴,¹⁶ A distinct disadvantage of CTA is that the quality of the study can be severely degraded by metallic debris that is embedded in the soft tissue following penetrating trauma, as is often seen after high-velocity missile injuries.¹⁷,¹⁸

Esophageal and Laryngotracheal Evaluation

Aerodigestive injuries are rare in blunt cervical trauma (˜1% incidence) and slightly more common following penetrating neck injuries (˜5% to 15% incidence).²,⁷ Despite their relative rarity, missed injuries to the aerodigestive tract carry a high mortality rate.

Physical findings that are suspicious for aerodigestive tract injury include hemoptysis, hematemesis, malocclusion, hoarseness, subcutaneous emphysema, and evidence of a missile trajectory tract toward the larynx or trachea. Subcutaneous or mediastinal emphysema seen on radiographic studies are concerning for aerodigestive injuries. Distal tracheal injuries may in fact manifest as a pneumothorax.² Any of these described findings mandates further LT and PE evaluation.

LT evaluation through flexible fiberoptic endoscopy is indicated in all patients with suspected LT injuries. Injuries can be directly visualized or be heralded by bleeding, cord motion abnormality, or edema. It has been estimated that only approximately 20% of patients with endoscopic findings suggestive of LT injury required surgical intervention.⁴

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