Sign/symptom
Significance
Stridor
Stridor is a sign of upper airway obstruction caused by compression of the trachea from a large hematoma, soft tissue swelling, direct laryngeal injury, or bilateral recurrent laryngeal nerve injury. It warrants immediate attention to the airway, usually in the form of endotracheal intubation
Odynophagia
Pain with swallowing is suggestive of an injury to the oropharynx or esophagus
Horner’s syndrome
The sympathetic fibers that innervate the pupil, eyelid, and skin surrounding the eye travel to these locations along the course of the common carotid and internal carotid arteries; thus Horner’s syndrome (ptosis, miosis, and anhydrosis) may indicate injury to these vessels in the neck on the basis of anatomical proximity
Thrill/bruit
Damage to the subclavian or carotid artery and adjacent vein can create an arteriovenous fistula; turbulent blood flow causes the vein to vibrate, leading to a palpable rumble or a whooshing sound on auscultation
Crepitus
Crepitus is a sign of subcutaneous emphysema (air trapped under the skin) secondary to injury of the aerodigestive tract (trachea, bronchus, or esophagus) or lungs
Hoarse voice
Dysfunction of the vocal cord either because of direct trauma or damage to the vagus or recurrent laryngeal nerve causing ipsilateral vocal cord paralysis
What Is the Diagnosis in This Patient?
The patient has a penetrating neck injury in Zone 2 of the neck (see discussion below), without hard signs of injury. Despite the lack of hard signs, injury to critical structures needs to be ruled out if the injury penetrates the platysma.
Anatomy
What Are the Zones of the Neck and What Are Their Borders?
In the setting of penetrating trauma, the neck is divided into three anatomic zones (Fig. 44.1) in order to summarize structures that are at risk for potential injury.
Fig. 44.1
Zones of the neck (With kind permission from Springer Science + Business Media: Handbook of Cerebrovascular Disease and Neurointerventional Technique, Extracranial Cerebrovascular Occlusive Disease, 2009, p 670, Harrigan MR., Fig. 18.3)
Watch Out
Remember that zones are numbered in the direction of carotid blood flow.
What Key Anatomic Structures are Contained Within the Three Zones of the Neck?
Watch Out
The three structures located in the carotid sheath include common carotid artery, internal jugular vein, and vagus nerve.
Zone | Lower border | Upper border | Anatomic structures within zone |
|---|---|---|---|
1 | Clavicles and sternal notch | Cricoid cartilage | Great vessels, common carotid and vertebral arteries, lung apices, thymus, thoracic duct, distal trachea, esophagus, cervical spine, and brachial plexus |
2 | Cricoid cartilage | Angle of the mandible | Mid-carotid and vertebral arteries, jugular veins, esophagus, vagus nerve, recurrent laryngeal nerve, phrenic nerve, cervical spine, larynx, and trachea |
3 | Angle of mandible | Base of skull | Proximal internal and external carotid arteries, vertebral arteries, uppermost segments of jugular vein, oropharynx, and cervical spine |
Pathophysiology
What Is the Significance of Whether or Not the Injury Has Penetrated the Platysma (Superficial Neck Muscle)?
Injuries that do not penetrate the platysma are by definition nonpenetrating neck injuries. As these injuries do not place the vital structures of the neck in harm’s way, they do not require any further diagnostic workup or surgical exploration.
What Types of Arterial Injuries Can Result from a Bullet Wound?
A bullet wound may cause a complete transection of the artery, pseudoaneurysm, intimal injury, dissection, or arteriovenous fistula. If a large artery is completely transected, the patient may quickly exsanguinate. Conversely, the ends of the severed artery may retract and vasoconstrict resulting in thrombus formation which may aid with temporary hemostasis.
What Is a Pseudoaneurysm? How Does It Differ from a Hematoma?
A pseudoaneurysm develops when an artery sustains a focal full-thickness injury that is temporarily tamponaded by the surrounding soft tissue (it is not surrounded by the media or adventitia). This differs from a hematoma, in which there is no active or ongoing hemorrhage from an injured vessel. Blood continues to be pumped into the pseudoaneurysm cavity, creating a pulsatile quality that can be felt on exam as a pulsatile mass on palpation of the overlying skin.
What Is an Arterial Intimal Injury? How Is It Managed? What About a Dissection?
The concussive or blast effect of a bullet may disrupt the intima of an artery. If the intimal injury is minor, it can be managed nonoperatively. A large intimal injury can occlude the lumen, leading to thrombosis. A large intimal injury can also create a false lumen. If blood enters the false lumen, a dissection occurs, which can also lead to occlusion of the artery. If the dissection extends high up into the intracranial carotid artery, it is generally managed nonoperatively with anticoagulation.
Watch Out
Know the differential diagnosis of a pulsating mass: AV fistula, aneurysm, and pseudoaneurysm.
What Nerve Would Be Injured if This Patient Presented with Vocal Cord Paralysis?
The recurrent laryngeal nerves, which supply the vocal cords, are both branches of the vagus nerve on their respective sides. They innervate all of the intrinsic muscles of the larynx except the cricothyroid (innervated by the external branch of the superior laryngeal nerve). Injury to the vagus nerve prior to the takeoff of the recurrent laryngeal nerve or damage to the recurrent laryngeal nerve itself leads to ipsilateral vocal cord paralysis. Normally the vocal cords are contracted to keep the airway open; paralysis of one vocal cord causes it to become fixed in a paramedian position and results in a hoarse voice. Bilateral paralysis of the vocal cords may result in complete upper airway obstruction.
Watch Out
Damage to the phrenic nerve causes ipsilateral hemidiaphragm paralysis which may be seen on chest x-ray as an elevation of the diaphragm on the affected side.
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