TITLE: Laryngeal Trauma
SOURCE: Grand Rounds Presentation, UTMB, Dept. of Otolaryngology
DATE: March 28, 2007
RESIDENT PHYSICIAN: Jean Paul Font, MD
FACULTY PHYSICIAN: Francis B. Quinn, MD
SERIES EDITORS: Francis B. Quinn, Jr., MD and Matthew W. Ryan, MD
"This material was prepared by resident physician= s in partial fulfillment of educational requirements established for the Postgraduate Training Program of the UTMB Department of Otolaryngology/Head= and Neck Surgery and was not intended for clinical use in its present form. It = was prepared for the purpose of stimulating group discussion in a conference setting. No warranties, either express or implied, are made with respect to= its accuracy, completeness, or timeliness. The material does not necessarily re= flect the current or past opinions of members of the UTMB faculty and should not = be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion."
Introduction
Blunt and penetrating injury to the anterior nec= k may produce life-threatening injuries involving airway, major vascular structur= es, the cervical esophagus and the cervical spine. Along with cervical spine immobilization, airway injuries take paramount in the assessment and manage= ment of the acute trauma patient. Although many associated injuries may appear m= ore impressive, correct management of the neck injury with immediate attention = to securing the airway is always the first priority. Acute laryngotracheal trauma is unc= ommon presenting acutely to the otolaryngologist. This is because (1) the injury = is uncommon due to protection of the larynx superiorly by the mandible (particularly when the head is flexed), inferiorly by the sternum and later= ally by the sternomastoid muscle; (2) when such an injury occurs, it is not infrequently associated with multiple other life-threatening injuries, associated loss of airway and immediate death at the accident scene may ens= ue; (3) when such patients arrive in casualty they are often acutely managed by= a Trauma team.
Although these injuries are rare, occurring in o= ne percent of patients sustaining blunt neck trauma and account for approximat= ely 1 in every 30,000 emergency room visits, their initial management has a tremendous impact on the immediate probability of survival of the patient a= nd the patient's long-term quality of life.. In penetrating trauma to the neck, especially zone II, laryngotracheal injuries are seen in 31 to 69 percent of patients. Although these injuries are rare, their initial management has a tremendous impact on the immediate probability of survival of the patient a= nd the patient's long-term quality of life. Vocal dysfunction, while certainly= of secondary importance in terms of preservation of life, could be a consequen= ce of ineffective of the initial management of laryngotracheal injuries.
Laryngeal embryology
The larynx develops from the fourth and fifth branchial arches. At the third week of gestation, the respiratory primordiu= m is derived from the primitive foregut to later form the lung bud and later the bronchial bud which will eventually develop into the tracheobronchial tree. At the fourth and fifth= week of gestation the tracheoesophageal folds fuse to form the tracheoesophageal septum leading to the separation of the tracheal airway lumen from the esophageal digestive tract. <= /p>
The laryngotracheal groove is the primitive open= ing of the larynx during development. This structure will develop into the primitive laryngeal aditus which is formed = by three eminences. The hypobran= chial eminence is the most cephalad of these structures and will later develop in= to the epiglottis. The other two eminences will form the arythenoid cartilages. The laryngeal lumen obliterates and later recanalyzes by the tenth week of gestation.
There are certain difference between the adult a= nd the newborn larynx. The diameter of the subglottic and glottis are narrower whi= ch leads to increased propensity for airway obstruction and compromise. In the infant the narrowest portio= n of the airway is the subglottis in contrast to the glottis in the child and adult. The subglottic region = is about 4 to 5 millimeters in diameter. The epiglottis is also narrower in infants and is tubular and omega = in shape. The larynx lies at the= level of the fourth cervical vertebrae at birth.= By fifteen years of age it descends to the level of the six to seven= th vertebrae. Blunt laryngotracheal injury is uncommon in the pediatric popula= tion because the mandible, the elasticity of the cartilaginous support of the ai= rway, and the mobility of the supporting tissues collectively act to protect the laryngotrachea.
Laryngeal Anatomy
The larynx can be divided into three areas: supraglottis, glottis and
subglottis. Support is mainta=
ined
by the hyoid bone, thyroid cartilage and cricoid cartilage. The supraglottis is less dependent=
on
external support and contains abundant soft tissue and redundant mucosa.
The anatomy of the larynx and the relation to ad= jacent structures are key to the rarity of injury. The inferior projection of the mandible affords significant protection from anterior blows. Inferiorly the larynx is protected = by the sternum and laterally by the sternomastoid muscle. Posteriorly, the larynx = is protected by the cervical spine.
Laryngeal Function
The larynx has an array of functions including breathing passage, airway protection, clearance of secretions, and vocalization. To maintain the= se functions, the skeletal framework and its underlying soft tissue must be in= tact. The framework includes the thyroid cartilage, cricoid cartilage and the tracheal rings. In laryngeal injuries, symptoms are commonly direct manifestation of the malfunction of the coordinated activities within the larynx. Reduction in the size= of the laryngeal airway can produce symptoms of airway obstruction ranging from mild stridor, to increased work of breathing associated to retractions, nas= al flaring and tachypnea, apnea, cyanosis and even sudden death.
Damage to the cricoarytenoid joint or damage to = the recurrent laryngeal nerves with resultant impaired vocal cord mobility may = lead to aspiration and dysphonia. These symptoms persist after resolution of acu= te life threatening period affecting the patient's long-term quality of life.<= /p>
Mechanism of Injury
The mechanisms of laryngeal injury can be divide= d into blunt trauma, including clothesline, crushing, and strangulation injuries; penetrating trauma; inhalation injuries; and injuries caused by caustic ingestions.
Anterior blunt injuries are most commonly the re= sult of motor vehicle accidents. This can be a car driver, which on forward thru= st during rapid deceleration the neck is extended impacting against the steeri= ng wheel. The laryngeal skeleton= is compressed between a foreign object (i.e., steering wheel or dashboard) and= the anterior aspect of the cervical spine. Hyperextension of the neck removes t= he mandibular barrier, exposing the larynx to anterior crushing forces. With t= he increasing use of seatbelts and airbags, the number of laryngeal fractures arising from motor vehicle accidents is likely to decrease, although seat b= elt harness and air bags injuries of the larynx have been described. Blunt pediatric neck injuries are more o= ften life-threatening, because relatively minor direct trauma to the larynx or trachea may result in significant injury, including laryngotracheal disrupt= ion. . Also, the relative smaller cross-sectional area of the pediatric populati= on predisposed them to higher risk of airway compromised.
Other less common blunt injuries can be caused b= y the motorcyclist or snowmobile who suddenly encounters a fixed horizontal barri= er at the level of the neck suffering a clothes-line type injury. This type of injury imparts a large amount of energy over a relatively small area, resul= ting in massive trauma and a high probability of sudden death by crushing the la= rynx or separating the cricoid from the larynx or trachea. Assault accounts for a small proportion of cases. St= rangulation by assault or during a suicidal attempt may lead to immediate airway obstru= ction or delayed laryngeal with airway compromised.
Sport-related injuries occur most frequently in = high velocity sports such as cycling, motorcycle racing and ice hockey or in the= martial arts. The incidence is dependent on the popularity of the particular sport.=
Penetrating trauma to the larynx most commonly o= ccur secondary to knife or bullet wounds. In gunshot wounds, the extent of injury could be the result of direct penetration or indirectly by the blast effect which varies with the type of assault weapon.
Initial Evaluation
Initial management should follow ATLS principles=
. Securing an airway takes precedenc=
e over
other problems and injury to the cervical spine is assumed until proven
otherwise. In laryngeal trauma there is controversy about the method of
securing the airway. The
Special considerations exist in the pediatric pa= tient population. The option of loc= al tracheotomy is not feasible in a frightened, injured child. The time margin= of error is also less because the arterial oxygen saturation drops more quickly than in an adult. In this instance, rigid bronchoscopy is performed to secu= re the airway under direct visualization. A tracheotomy can then be performed = over the bronchoscope.
In patients with no acute breathing difficulties= , a detailed history and careful physical examination can be obtained. Observat= ion without tracheotomy or endotracheal intubation may be indicated.
Diagnosis
Presenting symptoms of laryngeal trauma may incl= ude a change in the quality of voice, pain, dyspnea, Subcutaneous emphysema, dysp= hagia, odynophagia, hemoptysis and/or stridor. Inability to tolerate the supine position is a concerning symptom with regard to airway stability. On physic= al exam the vitals signs including respiratory rate and saturations are closely monitored. The skin of the neck may reveal contusions or abrasions in blunt trauma or a line pattern indicative of a strangulation injury. Some obvious signs of injury are tracheal deviation, open wound with air bubbles or trac= heal cartilage. Any penetrating injury is examined for an entrance and exit woun= d, and the most likely path of travel of the projectile is determined. Open wo= unds are not explored with instruments, nor are they probed for fear of dislodgi= ng a hematoma and initiating further bleeding.
In stable patients, flexible fiberoptic laryngos= copy in the emergency room should be performed.= CT scan, direct laryngoscopy, bronchoscopy and esophagosopy are used selectively based on initial fiberoptic exam findings. It has become increasingly important to categorize patients by the severity of trauma according to fiberoptic exam and CT findings in order to aid with the management of their injuries. CT allows evaluation of the laryngeal skeletal framework in a noninvasive manner, thus avoiding unnecessary operative explorations by selecting patients who should do well without surgical intervention. Optimal imaging is performed using spiral technique and subse= cond scan times, particularly when using two-dimensional sections for multiple projections or three-dimensional reconstructions. CT should be reserved for patients in whom laryngeal injury is suspected by history and physical examination without obvious surgical indications.
Laryngotracheal Injury Classification
Group I injuries include minor endolaryngeal hem= atoma, edema or laceration without detectable fracture. Group II injuries have edema, hema= toma, minor mucosal disruption without exposed cartilage, and nondisplaced fractu= res noted on CT scan. Massive ede= ma, mucosal disruption, displaced fractures, exposed cartilage and/or cord immobility qualify as Group III injuries.&= nbsp; Group IV injury is the same as group III with the addition of two or more fracture lines, skeletal instability or significant anterior commissure trauma. The group V category includes complete laryngotracheal separation.
Medical Management
The purpose of the extensive physical and radiol= ogic evaluation is to identify the patients with injury and to select patients w= ho are likely to do well without surgical intervention. A patient can be treated medically with close observation if = the injury will resolve without surgical intervention and the airway is stable. Group I injuries can = be safely managed with a minimum of 24 hours of close observation, head of bed elevation, voice rest and humidification of inspired air. Antibiotics are recommended with d= isruption of the laryngeal mucosa. Trea= tment with anti-reflux medication is also initiated. Nasogastric tube feedings should be considered if significant mucosal lacerations are present. Serial flexible fiberoptic examinations should be performed to evaluate the airway and healing prior to discharge. Although not proven, early systemic steroids therapy are often g= iven to reduce laryngeal edema. There was one randomized controlled trial on the use of intravenous dexamethasone in preventing traumatic laryngeal edema in pediatric bronchoscopy. This study showed no reduction in postbronchoscopy laryngeal oedema with the use of intravenous dexamethasone.
Surgical Management
The principles of surgery are hemostasis, evacua= tion of hematoma, reconstruction of the laryngeal framework and coverage of de-epithelialized surfaces. Group II through group V patients will usually require some form of surgical intervention. Surgical options fall into one = of three categories: endoscopy a= lone, endoscopy with exploration, and endoscopy with exploration and stenting. If there is any doubt about the extent of injury endoscopy should be performed. Indications for su= rgical exploration include: large mu= cosal lacerations, exposed cartilage, multiple or displaced cartilaginous fractur= es, vocal cord immobility, fractured cricoid, disruption of the cricoarytenoid joint, and lacerations involving the free margin of the vocal cord or anter= ior commisure.
When laryngeal exploration is indicated, it shou= ld be performed within 24 hours of the injury in order to maximize airway and phonation results. A horizontal skin incision is made at the level of the cricothyroid membrane and subplatysmal flaps are elevated. The strap muscles are then divided= in the midline and the laryngeal skeleton is exposed to the level of the hyoid superiorly and sternal notch inferiorly. The larynx can then be explored vi= a a midline thyrotomy or via a vertical fracture within 2 to 3 mm of the midlin= e. Simple nondisplaced fractures can be repaired by suturing the outer perichondrium with nonabsorbable sutures. Primary closure is almost always possible and debridement should be minimized. All mucosal lacerations are meticulously repaired using fine absorbable sutures. Closure is performed w= ith knots outside the laryngeal lumen to prevent granulation. Displaced aryteno= id cartilages should be reduced. The anterior commissure should be reconstituted by using 4.0 sutures to suspend= the anterior true vocal cords to the outer perichondrium of the thyroid cartila= ge. Fractures of the cartilages are reduced and can be stabilized using a varie= ty of materials, including stainless steel wires, nonabsorbable suture, and miniplates. If the fracture is comminuted, small fragments of cartilage with no intact perichondrium are removed to prevent chondritis. The thyrotomy can then be reapproximated with nonabsorbable suture, wire or rigid miniplates.
There may be a need for endolaryngeal stenting. = Stents that have reportedly been used include cut portions of an endotracheal tube= as well as finger cots filled with gauze or foam to commercially manufactured polymeric silicone stents. Endolaryngeal stenting is reserved for wounds involving disruption of the anterior commissure, massive mucosal injuries a= nd comminuted fractures of the laryngeal skeleton. Stenting reestablishes the normal scaphoid shape of the anterior commissure, stabilizes severely comminuted fractures and prevents web formation and stenosis. The stent should extend = from the false vocal fold to the first tracheal ring to add stability and prevent endolaryngeal adhesions. The stent should be secured in such a manner as to= be easily removed using endoscopic techniques. The stents should be removed in= a period of 10 to 14 days to prevent mucosal damage, even in the case of seve= re injury.
In the case of laryngotracheal separation, surgi= cal repair requires permanent sutures between the cricoid and second tracheal r= ing for airway support. Bilateral recurrent laryngeal nerve injury and subglottic stenosis are common with th= is injury. If the recurrent lary= ngeal nerve is severed by the injury, a neurorrhaphy of the severed ends should be performed.
Severe wounds involving extensive tissue and fra= mework loss of the supraglottic or hemilarynx can be managed using various partial laryngectomy procedures to restore function. Total laryngectomy is a last resort and is reserved for situations where the basic elements of the laryn= geal skeleton and investing soft tissue are not usable for repair.
Outcomes
The outcome after laryngeal trauma depends on the extent of the
original injury and the quality of subsequent repairs. The ultimate quality=
of
airway, voice and swallowing are important considerations following repair =
of
external laryngeal trauma. Ai=
rway
status is poor if the patient remains cannulated, fair with mild aspiration=
or
exercise intolerance and good if it resembles preinjury status. Voice can be considered poor if it
represents aphonia or whisper, fair if it is functional but changed (hoarse=
),
and good if normal. Swallowin=
g function
is either normal or abnormal from the subjective reports of the patient.
Conclusion
Although laryngeal trauma is an uncommon injury,= it is life-threatening. Recognizing any airway compromise and need for immediate intervention could prevent immediate death as well as acute and long term m= orbidity. Initial management should follow ATLS principles. In laryngeal trauma there is contr= oversy about the most appropriate method of securing the airway in certain scenari= os, but most authors agree that tracheotomy should be performed on patients exh= ibiting respiratory distress. In patients with no acute breathing difficulties, a detailed history, careful physical examination and appropriate diagnostic t= ools should be use to differentiate the need for medical from surgical managemen= t.
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