Laryngeal Fracture

Etiology

A laryngeal fracture requires considerable impact force. Almost 80 to 90% of laryngeal injuries, fracture/dislocations, and separation usually result from significant high-velocity blunt trauma.[8] The most common cause of laryngeal trauma is motor vehicle accident or sports injury, followed by penetrating neck injuries.[9][10] 

Schaefer reported 97% for laryngeal trauma was due to blunt trauma, and only one case had laryngeal trauma related to penetrating gunshot injury. Approximately 39% of blunt laryngeal trauma is caused by a sports injury, while physical assault comprises 33 % of blunt trauma.[11] Hanging is another common cause of laryngeal trauma.[12][10] Non-traumatic cause for laryngeal trauma is exceedingly rare.[13]

Epidemiology

Laryngeal trauma is rare. The incidence of laryngeal trauma ranges between 1 in 14000 and 1 in 30000 of emergency visits.[9][5][7][14] Less than 1% of all cases seen at major trauma centers are diagnosed with laryngotracheal trauma and accounts for approximately one patient in 131,000 hospital admission.[7][10] Laryngeal trauma is exceedingly rare in childhood compared to adulthood. Adult incidence is approximately 1 per every 30000 of emergency visits.[15][16] The incidence of laryngeal cartilage fracture ranges from 0 to 67%.[17]

The mortality rate is approximately 1% with a hospital stay of 13 days or longer if an injury is severe enough to warrant surgical intervention.[10] Injuries involving the cricoid cartilage can have a mortality rate of as high as 40% because of asphyxia from airway obstruction. There is rapid airway obstruction as cricoid cartilage is a complete ring that cannot accommodate any degree of swelling or hematoma.[18]

In literature, the average age of patients with laryngeal trauma is reportedly approximately 34 to 37 old, but the range is wide from 14 to 84.[10][11]

Pathophysiology

Following trauma to the larynx, swelling usually occurs within 6 hours post-trauma. Swelling can compromise the airway.[19]

Anterior direct trauma appears to cause the most severe injury to larynx. In the younger age group, the elastic nature of cartilage may result in damage to the soft tissue rather than cartilage itself. The isolated fracture of the thyroid cartilage is the most frequent injury encountered, while fracture of the cricoid alone is very unusual. Almost 85% of the cricoid cartilage trauma cases are associated with tracheal cartilage involvement.[8][20] 

Bloom, Carvalho, and Kearns explained the difference between the mechanism of laryngeal trauma in adults and children. Laryngeal trauma is exceedingly rare in children due to anatomical and behavioral variation.[21] Anatomically, the pediatric larynx is at the level of C4, thus protected by the mandible. Children also have relatively elastic cartilage and lack of ossification compared to an adult, which make it less likely to fracture. There are four varieties of laryngeal fractures described:

1. Supraglottic laryngeal fracture causing posterior displacement of the epiglottis and laryngeal inlet
2. Cricotracheal separation: usually fatal
3. Vertical midline fracture which will damage the anterior commissure and separate the thyroid alae
4. Comminuted fracture: usually common in older, calcified, and rigid larynx[22]

History and Physical

In all major trauma patients, especially MVA, assault, and sports injury, the clinician should be highly suspicious because there is a very high chance of missing laryngeal injury.[22] The most common presenting symptoms are stridor, respiratory distress, dysphonia, dysphagia, odynophagia, and hemoptysis.

The most common presentation is hoarseness (85%), followed by dysphagia (52%).[11] The common signs of laryngeal injury/fracture are edema, crepitations, subcutaneous emphysema, loss of thyroid prominence, open neck wound, and palpable cartilage fracture.[21] The most commonly used classification of laryngeal trauma in literature is Schaefer–Fuhrman classification; this is mainly based on clinical findings and comprises five groups.[11][7][16]:

1. Group I: minor laryngeal edema or lacerations
2. Group II: demonstrable edema or hematomas without exposed cartilage
3. Group III: massive edema or mucosal lacerations with exposed cartilage or displaced cartilaginous fractures or vocal fold immobility
4. Group IV: destabilization of laryngeal structure, including the disruption of the anterior commissure, more than two unstable displaced fracture or severe mucosal injury
5. Group V complete laryngotracheal separation.

Another classification system based on anatomical site, mode, the structure involved, and degree is as follows:[2] 

1. Supraglottic: epiglottic hematoma/ avulsion, hyoid bone fracture, thyroid cartilage fracture, arytenoid dislocation or degloving, endolaryngeal edema, and airway obstruction.
2. Glottic injuries: hoarseness generally associated with fracture of thyroid cartilage resulting in vocal cords edema, endolaryngeal lacerations, avulsion of vocal cord from the anterior commissure
3. Subglottic: Cricoid cartilage and cervical trachea involved causing profound airway compromise. Complete cricotracheal disruption with acute airway obstruction can cause rapid death unless the airway stabilizes rapidly.

Verschueren, Bell, et al. modified Schaefer's classification to add endoscopic and imaging findings and create a management guideline.[23]

Evaluation

Clinical evaluation should always include an endoscopic examination of the larynx using fiberoptic endoscopy, or direct laryngoscopy under general anesthesia in addition to imaging modalities such as a CT scan and ultrasound.[1][2][23][11] Early endoscopic evaluation can guide the clinician in securing the airway and establishing a surgical plan. A systematic approach of clinical suspicion, followed by flexible laryngoscopy to assess grading of injury and status of the airway, and then reconstructive computed tomography (CT) to assess the laryngeal framework, avoids missing laryngeal fracture and long-term co-morbidities.[24]

In literature, the recommendation is to perform CT within 24 hours of trauma is suggested as laryngeal fractures are frequently underdiagnosed. Schaefer has suggested a CT scan for all patients with a potential laryngeal fracture, while others have recommended selective use of CT scans.[11][25] According to Taku et al., it is imperative to perform a CT scan after laryngeal trauma as a clinical examination may not reveal the underlying fracture. Various clinical findings might include swelling, hematoma, or normal at times. Hence CT scan can change the course of treatment; this will allow early surgical intervention to fix the laryngeal fracture.[26] Ultrasound can be useful to diagnose thyroid cartilage fracture.[11][26]

Treatment / Management

The optimal timing of surgical intervention is controversial, but many proposed that early reconstruction of larynx post-trauma gives a better prognosis for phonation and decannulation.[7][11][15][24][7][14] In contrast, some authors proposed that delay in treatment can provide a comparable outcome to early treatment in laryngeal trauma.[27][28](B2)

Securing the airway is the primary goal of early management. Intubation can be difficult and might lead to losing the airway if not performed with caution. Tracheostomy under local anesthesia is recommended if airway obstruction is severe.[22] [24] management of laryngeal trauma based on Schaefer–Fuhrman classification can categorize according to the following [15]:(B2)

1. Nonsurgical/conservative (minor edema, hematoma, and mucosal laceration): Observation, delivery of humidified air, voice rest for group 1
2. Surgical options: group 2 through 5, which includes endoscopy, endoscopy with exploration, and endoscopy with exploration with stenting

1. Endoscopy alone: (if there is doubt in a degree of injury post-physical) Fiberoptic examination and CT.
2. endoscopy with exploration: large mucosal laceration, exposed cartilage, multiple displaced cartilaginous fractures, vocal cord immobility, fractured cricoid cartilage, laceration of anterior commissure or free margin of vocal cord and disruption of cricoarytenoid joint
3. Endoscopy with exploration and stenting: comminuted laryngeal fractures, massive mucosal injuries, and disruption of anterior commissures.

The literature has recommended keeping a patient under close observation for at least 24 hours as airway edema can occur several hours after the trauma.[7] Most of the literature in the past 20 years has recommended early exploration and reconstruction of the laryngeal framework.[7][9][14][29] This approach will help to preserve laryngeal function, especially the sphincteric, airway, and phonatory function, as even a minimal displacement of fractures can disrupt normal phonation.[30](B2)

Conservative management consists of observation, head of the bed elevation, steam inhalation, voice rest, and IV corticosteroid.

Tracheostomy is always the recommended intervention if a patient needs surgical exploration. Disruption of the laryngeal framework is an indication for surgical intervention. As per Hwan et al., an average timing of reconstruction suggested in the literature is 5.6 days (3 to 10 days). 

Surgical exploration and correction of fractures are possible using different materials such as mini-plates, 3-D plates, or bioresorbable plates, and Montgomery intralaryngeal stent.[31] Other various types of materials used for internal fixation post laryngeal fracture reduction are thread, steel wires, and titanium plates.[32][4][5][6][33][34] (B2)

Whenever a conventional method of titanium mini-plates fails, especially in unossified cartilage because of the lack of uniformity, Titanium mesh may merit consideration as a safe and reliable method to fix fractured laryngeal unossified cartilage. Titanium mesh can be adjusted freely into various shapes, sizes, and positions, even with the complicated types of fractures.[26] The adaptation plates have replaced wire fixation techniques of the laryngeal framework reconstruction.[30][4] Likewise, mini plates have been suggested over wire fixation by Lynkins and Pinczower.[34] (B2)

Other modalities of treatment include resorbable plates.[4] Various indications for endolaryngeal stent include failure of primary repair of the mucosa, disruption of the anterior commissure, and comminuted fractures.[14][9][10][11](B2)

Differential Diagnosis

• Neck soft tissue trauma
• Neck vascular injury
• Pneumothorax
• Penetrating lung apex injury

Prognosis

Literature has reported relatively good outcomes and has used functional parameters to assess prognosis. In 62 to 85% of cases, there is a good voice outcome, with good airway outcomes achieved in 76 to 97% of cases.[7][25][35] The better outcome occurred in people who were treated early compared to those who received delayed treatment.[35]

Age has a direct influence on prognosis as an older patient tends to have poor outcomes, especially if over 70 years of age.[10]

Complications

Complications subdivide into acute and chronic. Acute complications are upper airway obstruction and asphyxia, Recurrent laryngeal nerve injury, hematoma, infection, and death. Chronic complications are vocal cord paralysis, hoarseness, recurrent granulation formation, supraglottic stenosis, glottic stenosis, subglottic or tracheal stenosis, Recurrent laryngeal nerve dysfunction, and chronic aspiration.[36][37] 

Most patients achieve decannulation and stable airway without stenosis or granulation tissue.[9] Some cases result in deglutition disorder.