Anatomy

The neck contains a number of vital structures condensed into a relatively small area. Areas of greatest concern include vascular injuries, neurologic injuries, and injuries to the aerodigestive tract.

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  The anterior triangle of the neck is bordered superiorly by the inferior border of the mandible and posteriorly by the medial aspect of the sternocleidomastoid muscle. The common carotid artery bifurcates into the external and internal carotid arteries in the anterior triangle, which also contains the aerodigestive tract and cranial nerves VII, IX, X, XI, and XII. The internal jugular vein, as well as the vagus and hypoglossal nerves, are contained within the anterior triangle.

  
  
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  The posterior triangle is bordered by the sternocleidomastoid anteriorly, the clavicle inferiorly, and the anterior border of the trapezius muscle posteriorly. The spinal cord is the most significant structure in the posterior triangle of the neck.

  
  
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  For the management of penetrating trauma, the anatomy of the neck has historically been divided into three zones, which will be described in the section on penetrating injuries.

  
  
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  The neck can also be divided anatomically into facial planes. The platysma muscle stretches from the facial muscles to the thorax, and anatomically divides superficial from deep wounds. Wounds that do not penetrate the platysma do not generally lead to significant morbidity or mortality. The superficial fascia lies anterior to the platysma, while the deep fascia lies posteriorly.

Penetrating Injuries

Penetrating injuries are most commonly stab wounds or gunshot wounds but can be other types of projectile injuries as well. Historically, penetrating injuries to the neck have been described in one of three zones (Figures 12.1–12.4). While the particular zone involved no longer guides the management to the same degree, understanding the zones is still useful when communicating these injuries to consultants.

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  Zone I begins at the sternal notch and clavicles and extends superiorly to the cricoid cartilage.

  
  
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  Zone II involves the area between the cricoid cartilage and the angle of the mandible.

  
  
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  Zone III extends from the angle of the mandible to the base of the skull.

Figure 12.1 Anatomical zones of the neck. Zone I is confined between the clavicle and the cricoid cartilage, zone II between the cricoid and the angle of the mandible, and zone III between the angle of the mandible and the base of the skull

(illustration by Alexis Demetriades, reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 12.2 Zone I penetrating injury

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

(A) Knife wound.

(B) Gunshot wound

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 12.3 Zone II penetrating injuries.

Figure 12.4 Zone III stab wound to the neck

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

These zones have been used to help guide management, as injuries in zone II are most accessible to surgical intervention. In what has been called the “selective approach,” zone II injuries underwent surgical exploration in the operating room, while patients with injuries in zone I and zone II underwent endoscopy and angiography. More current technology using Multi-Detector Computed Tomographic Angiography (MDCTA) has allowed the safe and non-invasive evaluation of the critical neck structures and is now the gold standard for evaluating stable injuries in any zone that are causing symptoms.²

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  In unstable patients or those who have clear evidence (hard signs) of vascular or aerodigestive injuries, surgical exploration is indicated. Hard signs of vascular or aerodigestive injury include:

  
  
  
  
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    Active hemorrhage

    
    
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    Expanding or pulsatile hematoma

    
    
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    Bruit or thrill in the area of injury

    
    
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    Massive hemoptysis

    
    
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    Stridor or airway compromise

    
    
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    Hematemesis

    
    
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    Air bubbling through the injury site.

  
  
  
  
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  Soft signs of penetrating neck trauma include:

  
  
  
  
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    Minor hemoptysis

    
    
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    Dysphonia

    
    
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    Dysphagia

    
    
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    Subcutaneous or mediastinal air

    
    
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    Non-expanding hematoma

  
  

In stable patients with penetrating neck trauma, a reasonable approach is to perform a complete physical exam including an evaluation of the neck. Stable patients exhibiting soft signs of neck injury should undergo MDCTA (64 slice or higher). Stable patients with no hard or soft signs of neck injury can be managed with observation.³

Blunt Injuries

Blunt injuries to the neck will commonly occur from motor vehicle accidents but can occur from assaults or falls as well. The primary concerns in blunt injury to the neck include spinal fracture, spinal cord injury, and blunt cerebrovascular injury (BCVI). Cervical spine injuries have a reported incidence of 2% to 15%, with 10% to 20% of those incidents including injury to the spinal cord.⁴ Failure to diagnose unstable fractures and/or ligamentous injury may result in permanent neurologic damage; therefore, a great deal of effort has gone into determining the most effective way to evaluate blunt trauma patients for cervical spine injury.⁵

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  Two decision rules have been described and validated for determining the need for radiographic evaluation of the cervical spine in victims of blunt trauma. The National Emergency X-Radiography Utilization Study (NEXUS) has demonstrated that clinical evaluation can be sufficient to rule out injury.⁶ The NEXUS criteria for clearing the cervical spine include:

  
  
  
  
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    No midline spinal tenderness

    
    
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    No focal neurologic deficit

    
    
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    No altered level of consciousness

    
    
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    No intoxication

    
    
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    No painful distracting injury

  
  
  
  
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  An alternative decision rule is the Canadian Cervical Spine Rule, which involves a 3-step process.⁷ The process is as follows:

  
  
  
  
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    Step 1: Is there any high risk factor that mandates radiography?

    
    
    
    
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       – Age over 65

       
       
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       – Mechanism of injury considered dangerous

       
       
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       – Numbness or tingling present in the extremities

    
    
    
    

    Dangerous mechanisms include a fall from an elevation of 3 feet or higher; a bicycle collision; an axial load to the head; or a motor vehicle collision involving high speed, rollover, or ejection. If the answer is no to the existence of a high risk factor, then proceed to step 2.

    
    
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    Step 2: Are there any low risk factors that indicate safe assessment of range of motion? Low risk factors include:

    
    
    
    
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       – Simple rear-end motor vehicle collision

       
       
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       – Patient was ambulatory at any time since the injury

       
       
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       – Delayed onset of neck pain

       
       
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       – Patient is in a sitting position in the emergency department

       
       
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       – Absence of midline cervical spine tenderness

    
    
    
    

    If any low risk factors are present, proceed to Step 3.

    
    
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    Step 3

    
    
    
    
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       – Is the patient able to actively rotate his or her neck 45° left and right?

    
    
    
    

    If yes, radiography is not performed.

  
  

In patients who do not meet criteria for clearance, imaging is indicated. Some patients may need a period of observation to allow metabolization of alcohol or other intoxicants before they can be clinically cleared. There are over 3 million patients with spinal trauma every year, with an imaging cost of over $3.4 billion.⁸ In patients where radiographic evaluation is needed, there is some debate over the best modality.

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  While some have argued there is still a role for plain x-rays in the evaluation of neck trauma patients,^{8, 9} others say the superiority of multislice CT scan makes it the modality of choice for all patients.^{10, 11}

  
  
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  In high risk patients, such as those with neurologic symptoms, significant midline tenderness, or the elderly, CT is clearly superior to plain radiographs.

  
  
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  For patients with an abnormal neurologic exam, there is a small but clinically significant incidence of missed injury with CT scans, and, in these patients, magnetic resonance imaging (MRI) is warranted.¹² Based on the current literature, a reasonable algorithm would be:

  
  
  
  
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    No risk: Nothing

    
    
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    Low risk: Plain radiographs and re-evaluate

    
    
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    Higher risk (unable to evaluate [altered], concerning exam, elderly): CT scan

    
    
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    Persistent or progressive neurologic deficit not completely explained on the CT: MRI

  
  

Alcohol and drug intoxication are common in trauma patients and can result in significant delays to cervical spine clearance. In these patients, CT scans are highly reliable for identifying all clinically significant cervical spine injuries. Spine clearance based on a normal CT scan among intoxicated patients with no gross motor deficits appears to be a safe option that avoids prolonged observation and unnecessary immobilization.⁴ Computed tomography also appears to be effective in ruling out other injuries, including ligamentous injuries, in blunt trauma patients.¹³

One of the most widely accepted strategies when evaluating patients with possible cervical spine injuries involves cervical spine immobilization using a hard cervical collar. It is important to note that, like immobilization on a hard board, this practice is not based on randomized, controlled trials. Like long boards, hard cervical collars may cause harm. They can result in abnormal distraction within the upper cervical in the presence of a severe injury.¹⁴ Motion is generated when cervical collars are applied and removed,¹⁵ and they do not effectively reduce motion in the unstable cervical spine.¹⁶ The cervical collar may not result in any decrease in motion during extrication.¹⁷ In fact, self-extrication without a collar may result in less deviation of the cervical spine from the neutral position than extrication using the cervical collar.¹⁸ While not providing adequate protection from motion, the hard cervical collar may also cause harm. There is a high incidence of category 1 pressure ulcers and indentation marks associated with hard cervical collars, and the pain due to the application of the cervical collar and head blocks may cause undesirable movement and bias the clinical examination.^{19, 20} Application of the cervical collar raises intracranial pressure (ICP) in head injured patients,²¹ reduces venous return,²² and complicates airway management.²³ While still considered standard, the current practice of cervical spine immobilization needs to be re-evaluated and revised to ensure the proper care of blunt trauma patients.

While once considered rare, BCVI has been found in 1% to 2% of blunt trauma patients.²⁴ The diagnosis of this injury is important as the incidence of stroke is 25% and mortality is as high as 13% if left untreated.²⁵ The internal carotid artery is the most frequently injured artery, followed by the vertebral artery (Figures 12.5 and 12.6). The Western Trauma Association recommends screening for BCVI in patients who have experienced a high-energy transfer mechanism with:

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  Displaced mid-face fracture (LeFort II or III)

  
  
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  Basilar skull fracture with carotid canal involvement

  
  
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  Closed head injury consistent with diffuse axonal injury and GCS <6

  
  
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  Cervical vertebral body or transverse foramen fracture, subluxation, or ligamentous injury at any level

  
  
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  Any fracture at C1–C2

  
  
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  Near hanging with anoxia

  
  
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  Clothesline type injury or seatbelt abrasion with significant swelling, pain, or altered mental status²⁶

(A) A “seatbelt” sign on the neck should increase suspicion for vascular injury.

(B) The intraoperative findings show the carotid contusion and underlying thrombosis of the internal and external carotid arteries (arrows)

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 12.5 Patient with seatbelt sign on the right side of the neck and unexplained hemiplegia.

Figure 12.6 Patient with seatbelt sign on the neck (A). Surgical exploration shows bruising and underlying thrombosis of the internal carotid artery (arrow) (B)

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Screening for BCVI should be done with 64 slice or greater MDCTA.²⁷ Treatment of BCVI will depend on the type and location of the injury, as well as the presence of other injuries. Treatment options include observation, anticoagulation, and surgery. Anticoagulation with either heparin or antiplatelet agents have comparable outcomes.²⁸ Surgical treatment may include ligation, resection, or endovascular stent therapy. Endovascular stents have typically been used for higher grade lesions, while low grade lesions are often managed with anticoagulation and/or antiplatelet therapy.²⁹ Appropriate treatment reduces the stroke rate from about 25% to just under 4%.³⁰

Laryngotracheal injuries are rare but can result in significant morbidity or mortality (Figure 12.7). Most laryngotracheal injuries occur as a result of motor vehicle accidents where an inadequately restrained driver’s neck contacts the steering wheel.³¹ Other mechanisms include clothesline injuries and assaults. A quiescent phase has been described with progressive subclinical airway edema or hematoma that can result in delayed airway obstruction.³² Computed tomography of the neck is the imaging modality of choice when there is concern for laryngotracheal injuries.³³ Airway compromise is the greatest concern in patients with laryngotracheal trauma, and these patients should be closely monitored. Awake fiberoptic intubation is likely the best route for securing the airway when available. Paralysis could precipitate a loss of the airway in the event a complete transection of the trachea has occurred and the musculature of the neck is stabilizing the trachea (clothesline injury). A surgical airway may be necessary. While small mucosal injuries and non-displaced fractures can be managed conservatively, more significant injuries require surgical repair.³¹

Figure 12.7

(A) Patient with blunt force trauma to the anterior neck.

(B) CT scan showing fracture of the larynx

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Strangulation and Hanging

Strangulation refers to external compression of the neck and tends to be either manual (hands) or ligature, but it can be positional.

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  The external force causes venous congestion and stasis of cerebral blood flow, resulting in loss of consciousness.

  
  
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  Once the victim loses consciousness, relaxation of the neck musculature allows complete arterial occlusion that can lead to permanent brain injury or death due to cerebral anoxia and ischemia. Obstruction of cerebral venous return rather than acute airway compromise is the more likely pathophysiologic mechanism.

  
  
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  Judicial hanging involves a fall distance of at least the height of the victim and results in a forceful distraction of the head from the neck and body.

  
  
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  These injuries lead to high cervical spine fractures and spinal cord transection. Non-judicial hangings typically involve falls from lesser heights and are often inadequate to injure the cervical spine other than in the elderly.³⁴

  
  
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  Near-hanging typically refers to survivors of attempted hangings. Ten percent of violent deaths in the United States are due to strangulation. Hanging is the second most common means of suicide death, so it is not uncommon to see these injuries in the ED.^{35, 36}

  
  
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  External trauma may or may not be evident in victims of strangulations or hangings. Petechial hemorrhages, sometimes referred to as Tardieu spots, can be seen in the conjunctiva, mucous membranes, and skin cephalad to the pressure point, and have been described in asphyxia deaths but can also be seen in otherwise uninjured patients.

  
  
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  Injuries associated with strangulation include laryngotracheal fractures and carotid artery injuries.³⁷

  
  
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  Dyspnea, dysphonia, or odynophagia is concerning for laryngeal or tracheal injury and should be evaluated with either laryngobronchoscopy or MDCTA of the neck. Any concern for carotid artery injury, including any neurologic deficit not explained on head CT, should undergo MDCTA.

  
  
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  Cervical spine fractures are uncommon in strangulation injuries and in hangings involving a fall of less than the patient’s height or strangulation injuries.³⁸ Patients with strangulation and hanging injuries, even when self-inflicted, are at risk for domestic abuse, and evaluation for abuse is warranted.³⁹

Airway Management

Airway management remains a critical priority in neck trauma patients. Situations such as hematomas, upper airway hemorrhage, subcutaneous emphysema, and voice changes are indications to consider early endotracheal intubation while the airway is still accessible. Expanding neck hematomas require early intervention.

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  Airway management in the setting of a possible unstable cervical spine should be handled with particular attention to avoid unnecessary spinal movement. Although the ideal method of airway management remains the subject of some debate, rapid sequence orotracheal intubation with video laryngoscopy has been shown to be safe and effective and may reduce the number of failed intubations.⁴⁰

  
  
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  Video laryngoscopy also has the advantage of less need for manipulation of the neck.^{41, 42}

  
  
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  When endotracheal intubation cannot be performed or is unsuccessful, surgical cricothyrotomy is indicated.

Pitfalls

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  Failure to diagnose unstable fractures and/or ligamentous injury in victims of blunt neck trauma.

  
  
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  Failure to recognize hard signs of vascular or aerodigestive injuries in victims of penetrating neck trauma.

  
  
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  Failure to remove patients from cervical spine immobilization in a timely manner when appropriate.

  
  
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  Failure to consider blunt cerebrovascular injury in appropriate patients.

  
  
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  Application of a hard cervical collar in penetrating neck trauma.

  
  
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  Forcing kyphotic elderly patients into a hard cervical collar.

  
  
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  Failure to recognize potential challenges of airway management in neck trauma and have a backup plan.