THE CLINICAL CHALLENGE
The human neck is a highly complex anatomic region containing vital vascular, neurologic, and aerodigestive structures within a relatively small space. The structures of the neck are also relatively unprotected and therefore susceptible to traumatic injury. As a result, evaluation and management of trauma to this region is challenging.
Penetrating neck trauma is relatively rare, with 5% to 10% of traumas presenting with injury to the neck and representing only 1% of all trauma admissions in the United States.1
Although penetrating neck trauma has a low incidence, the mortality rate can be as high as 10%.2
A comprehensive understanding of the anatomy of the neck, injury patterns of the region, and current recommendations on management is critical for clinicians to adequately manage these patients.
By definition, a penetrating trauma to the neck is any injury that violates the platysma muscle,2
which is a broad thin sheet of muscle covering most of the anterior and lateral neck and extending from below the clavicle to above the angle of the jaw. The depth of the neck wound is an important part of the initial evaluation. Wounds superficial to the platysma muscle do not warrant further investigation, but wounds penetrating the platysma are at high risk for violating deeper vital structures (Figure 22.1
The anterior and posterior neck are defined by the sternocleidomastoid muscle, which originates at the clavicle/manubrium and inserts at the mastoid tip. The triangle anterior to the sternocleidomastoid muscle contains anatomically critical structures, including the larynx, pharynx, trachea, esophagus, carotid artery, and jugular vein. The triangle posterior to the sternocleidomastoid muscle contains the spinal accessory nerve and the spinal column.
The neck has classically been divided into three zones to aid in the evaluation and management of traumatic injury3,4
). Zone I encompasses the area between the clavicle and sternum inferiorly to the cricoid superiorly. Zone II transverses the space from the cricoid cartilage to the angle of the mandible. Zone III is the area of the neck ranging from the angle of the mandible, extending superiorly to the skull base. Zone classification can be useful to determine which structures are at risk for injury (Table 22.1
and Figure 22.3
), but caution should be taken when relying solely on these zones, because penetrating injuries can traverse zones.5,6
APPROACH/THE FOCUSED EXAM
Patients with penetrating neck injuries have the potential to rapidly decompensate. Therefore, evaluation should be prompt and follow a systematic approach to cover all critical aspects of care, immediately assessing airway, breathing, and circulation.
Figure 22.1: Deep structures of the neck. (From The Anatomical Chart Company. ACC Atlas of Human Anatomy. Wolters Kluwer; 2002.)
Regardless of the zone of injury, unstable patients exhibiting “hard signs” indicate the need for emergent surgical management. These signs include airway compromise, expanding or pulsatile hematoma, active brisk bleeding, hemorrhagic shock, hematemesis, signs of stroke or cerebral ischemia, massive subcutaneous emphysema, unilateral pulse deficit, and air bubbling through the wound.7
Presence of at least one hard sign is associated with a 90% rate of major injury.1
However, absence of hard signs does not exclude injury to the underlying structures of the neck, so in their absence, clinical assessment should guide decisions for further testing.
In penetrating neck wounds, evaluation and management of the airway is particularly critical. The provider should first assess whether the airway is protected or whether the patient requires immediate airway intervention. A careful evaluation of the oral, pharyngeal, laryngeal, and tracheal structures will usually reveal whether airway intervention is needed. Some clinical signs that
suggest an airway injury include vocal hoarseness, stridor, dysphonia, subcutaneous emphysema, bubbling from the wound, and large volume hematemesis.6
Zones of the neck as defined for purposes of trauma. (From Helling KD, Pelaez CA. Neck Exploration for Trauma. In: Scott-Conner CE, ed. Scott-Conner & Dawson: Essential Operative Techniques and Anatomy
. 4th ed. Wolters Kluwer; 2014:98-104. Figure 13.1
TABLE 22.1 Critical Structures by Zone
Clavicle/sternum to cricoid cartilage
Cricoid cartilage to angle of mandible
Angle of the mandible to base of skull
Critical anatomic structures
Figure 22.3: Cervical structures contained in Zones I, II, and III: (1) facial artery; (2) esophagus; (3) internal carotid artery; (4) external carotid artery; (5) thyroid cartilage; (6) sympathetic trunk; (7) vagus nerve; (8) cricothyroid membrane; (9) cricoid cartilage; (10) thyroid cartilage; (11) common carotid artery; (12) subclavian artery; (13) right innominate vein; (14) superior vena cava; (15) ascending aorta; (16) descending aorta; (17) pulmonary artery; (18) subclavian vein; (19) clavicle; (20) brachial plexus; (21) internal jugular vein; (22) vertebral artery; (23) phrenic nerve; (24) submandibular gland; (25) lingual artery; (26) hypoglossal nerve; (27) parotid gland and duct; (28) facial nerve and its branches; (29) maxillary artery; (30) sternal manubrium. The thoracic duct is not shown in this figure. (Adapted from Ordog GJ, Albin D, Wasserberger J, et al. 110 bullet wounds to the neck. J Trauma 1985; 25:238-46; inset reproduced with permission from Baker RJ, Fischer JE. Mastery of Surgery. 4th ed. Lippincott Williams & Wilkins; 2001.)
If indicated, the method of airway intervention depends on the clinical setting, resource availability, and provider skill and experience. Methods that allow direct visualization of the airway are preferred, because blind techniques can exacerbate injuries. The team should prepare with multiple backup options, double suction, and supplies for surgical airway. Bag valve mask ventilation should be performed with caution owing to risk of air dissection into injured tissue planes.
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