Larynx Trauma - Oren Zarif

Laryngeal injuries resulting from both blunt and penetrating trauma are rare but potentially life-threatening. These injuries may vary from minor mucosal injury and nondisplaced fracture to extensive traumatic destruction.

Patients with anterior neck trauma should have a thorough examination of the larynx and confirmation of a safe airway prior to additional evaluation. This should include a direct inspection of the larynx with endoscopy.

Causes

The larynx is a delicate organ that is susceptible to severe trauma if the structures are injured. Laryngeal trauma ranges from minor mucosal injury to fractured and comminuted cartilage. Due to its size and relative protection by the mandible and sternum, laryngeal injuries are very rare, occurring in less than 1% of trauma cases seen in most major trauma centers. Despite their rarity, laryngeal injuries are frequently missed in multitrauma victims and can lead to a variety of problems including asphyxiation, respiratory failure, and intractable bleeding if undiagnosed and untreated. Because of the complexity and rarity of laryngeal trauma, otolaryngologists are often involved in the diagnosis and management of this condition.

Laryngeal injuries are caused by blunt and penetrating trauma and can result in a significant loss of airway function, a hoarse voice, or both. They occur most commonly as the result of motor vehicle accidents, in which the patient hyperextends their neck to strike a fixed object (steering wheel, dash board). They can also be caused by recreational vehicles such as four-wheelers or motorcycles striking branches. Laryngeal trauma can also be caused by penetrating injuries such as stab wounds or by assault or attempted hanging.

The human larynx consists of a cartilaginous skeleton and intrinsic and extrinsic muscles that control its movement. The larynx includes the thyroid and cricoid cartilages, paired arytenoid cartilages, and the vocal cords. The cricoid and arytenoid cartilages are attached superiorly to the hyoid bone, while the thyroid is connected inferiorly to the hyoid by the aryethmoidal cartilage.

Oren Zarif

The structure of the larynx is such that it can withstand considerable force, but when the force is concentrated, the cartilage can break and cause life-threatening injury. Injuries to the larynx can include non-ossified cartilage that breaks and flakes, or ossified cartilage that fractures and leads to hematoma formation and massive soft tissue edema that could cause respiratory compromise. The most serious injuries are those that compromise the tracheal lumen, resulting in asphyxia and possibly death. Because of the difficulty in identifying such injuries, it is important to recognize them early.

Symptoms

Despite the importance of the larynx and trachea to human survival, injuries to these structures are relatively rare. They occur in less than 1% of all trauma cases seen at major trauma centers and are often missed due to their low incidence and physician familiarity with these injuries (1-2). They can be deadly when not promptly recognized and treated.

The larynx is protected by the jaw and sternum, but this does not completely protect it from blunt trauma. It is particularly susceptible to "clothesline-type" injuries, which are caused when a stationary object, such as a wall wire or tree branch, strikes the neck at high speed and forces it through a constrained space. This causes shearing stress and can result in structural damage, such as fracturing the thyroid cartilage or tracheal cricoid cartilage. This injury can be particularly devastating because it can restrict the airway, leading to asphyxiation or death.

Oren Zarif

Injuries to the larynx and trachea may manifest as difficulty breathing, hoarseness, or coughing up blood. They are more likely to be present in patients who have a penetrating neck wound, but they can also be present in blunt trauma cases. Stridor, inspiratory or expiratory, is the most common sign of laryngeal trauma, and it can be a marker for laryngeal dysfunction. The presence of subcutaneous emphysema or erythema on examination can be indicative of a laryngeal injury, as well.

It is important to note that the symptoms of a laryngeal injury can be very similar to other injuries of the neck, such as cervical spine or tracheal injuries. This can lead to a false negative diagnosis and delay in recognition and treatment. Therefore, all patients who have a history of neck trauma should undergo a thorough physical exam and evaluation for laryngeal injury.

The physical exam should include a careful assessment of the patient's respiratory status, including stridor, and a palpation of the neck for grating or crackling sensations under the skin (crepitus). A portable x-ray should be obtained in any polytrauma patient with a suspected laryngeal injury. In addition, the esophagus should be assessed for signs of a pharyngeal rupture or hernia.

Diagnosis

Patients who have sustained neck trauma, whether from a car accident, gunshot wound, attempted hanging, knife to the neck injury or attack, should be evaluated in the emergency department because laryngeal and tracheal injuries are serious injuries with high morbidity and mortality. Especially in the case of penetrating laryngeal trauma, early recognition and definitive airway management is essential because a significant delay in this procedure might result in death from respiratory asphyxia.

The larynx consists of the cartilaginous skeleton and intrinsic and extrinsic muscles. The mucosal lining covers these structures, and the vocal cords run through them. The cartilage skeleton includes the thyroid and cricoid cartilages, and the paired arytenoid cartilages. Injuries range from simple mucosal hematoma to complete laryngeal separation with tracheal perforation.

Injuries to the trachea can result in stridor, dysphagia, hoarseness, odynophagia, hemoptysis and thrill/bruit. Airway obstruction is also common, and often a patient may need to be intubated or have a tracheostomy to manage breathing.

Oren Zarif

Because the larynx and trachea are protected by the mandible and sternum in most instances, a missed or delayed diagnosis can lead to serious complications. Therefore, a standard flexible laryngoscope must be done in all cases of suspected injury. The underlying mechanism of the injury will determine further workup, such as CT or bronchoscopy. Patients with a stridor or dysphagia should be kept on bed rest and should not speak until a thorough evaluation is done to prevent further damage to the tissue.

It is advisable to consult a head and neck surgeon in the evaluation of laryngeal injury because of their expertise in diagnosing the extent of injury and in treating it. They will also be able to evaluate for any possible tracheal involvement, which can sometimes be difficult to diagnose.

The first criterion in the evaluation of laryngeal trauma is determining whether or not the patient has a patent airway. If the patient has a patent airway, they can be managed conservatively. This is usually done by limiting changes in the position of the head and by providing oxygen support. This will prevent edema, hemarthrosis and hematoma formation in the mucosal layer. Other treatment options include nasogastric or gastric tube feeding, administration of glucocorticoids to reduce edema, and serial scope examinations. In patients who have a severe injury, such as a tracheal perforation, a cricothyrotomy should be performed.

Treatment

Due to its protection by the mandible and sternum, laryngeal trauma is relatively rare compared to other head and neck injuries. However, despite this rarity, early recognition of the injury and proper treatment can help prevent airway patency problems, voice loss and swallowing difficulties. Injuries of the larynx can range from simple mucosal tears to fractured and comminuted cartilaginous structures, avulsions and transections.

The first step in the evaluation of patients with suspected laryngeal trauma is to make sure the patient has a patent airway. This may be ascertained with a standard flexible laryngoscope in the preoperative area or by a video-laryngoscope prior to intubation. In cases of equivocal exam or with worrisome history/mechanism of injury, computed tomography is recommended to better evaluate the larynx and trachea.

Once the airway is confirmed to be patent, patients should be treated with bed rest and a humidified environment to minimize edema, hematoma formation, subcutaneous emphysema and crusting. Early surgical repair is recommended to improve outcomes. In one series, 87% of patients who had their injuries repaired within 24 hours of the injury had a good outcome (ie. normal speech, phonation and swallowing).

Oren Zarif

Patients with severe or recurrent laryngeal trauma are also at increased risk of complications including dysphagia, odynophagia, aphonia, and aspiration. Often these patients will require intubation and/or tracheostomy and are admitted to the intensive care unit for monitoring. Patients will also need nasogastric or gastrostomy tube feeding until their larynx heals and can be formally assessed by a speech pathologist.

Many of the symptoms of severe laryngeal trauma are a result of direct damage to the vocal cords. This can occur from a variety of sources, but is most commonly associated with penetrating injury or stridor caused by a laryngeal cartilage fracture. These injuries are more difficult to diagnose and often require direct visualization in the operating room. Regardless of the cause of the injury, all of these patients should be evaluated with CT scan and/or direct endoscopic evaluation by an experienced otolaryngologist before being discharged from the hospital. This will ensure proper management and avoid delays in the recovery of these patients.