Laryngeal Trauma (May 1997

TITLE: LARYNGEAL TRAUMA
SOURCE: UTMB Dept. of Otolaryngology Grand Rounds
DATE: May 21, 1997
RESIDENT PHYSICIAN: Rusty Stevens, MD
FACULTY: Brian Driscoll, MD
SERIES EDITOR: Francis B. Quinn, Jr., M.D., F.A.C.S.

"This material was prepared by physicians in partial fulfillment of educational requirements established for Continuing Postgraduate Medical Education activities and was not intended for clinical use in its present form. It was prepared for the purpose of stimulating group discussion in a interactive computer mediated conference setting. No warranties, either express or implied, are made with respect to its accuracy, completeness, or timeliness. The material does not necessarily reflect the current or past opinions of subscribers or other professionals and should not be used for purposes of diagnosis or treatment without consulting appropriate literature sources and informed professional opinion."

General Information

Laryngeal injury is a rare entity with an estimated incidence of 1 in every 22,900 emergency room visits.(1) However, it must be recognized and treated appropriately to ensure an optimal outcome. Securing the airway is the most important immediate concern to preserve life. The effectiveness of the initial management will also likely determine the final airway and voice. For these reasons the otolaryngologist must be familiar with the presentation and treatment of this rare injury.

The mechanism of injury usually involves either blunt or penetrating trauma. While relatively protected by the mandible above and the sternum below, the larynx may be crushed between a blunt object and the cervical spine. Strangulation type injuries result mainly in cartilage fracture while high speed injuries such as motor vehicle or sports related accidents often have both cartilage injury as well as soft tissue injuries related to endolaryngeal shearing forces. Arytenoid cartilage dislocation and recurrent laryngeal nerve injury may also be present. Cervical spine injury must always be suspected and excluded with this type of trauma. Penetrating injuries usually result from gun shot or knife wounds. Gun shot wounds may result in massive injury and tissue loss not only in the path of the bullet but also in adjacent structures. The degree of peripheral injury is directly related to the velocity of the bullet and therefore hunting or military weapons are especially damaging. Knife wounds tend to cause damage primarily in the path of the blade however, it is important not to underestimate the depth of the injury. With any penetrating injury to the anterior neck, associated injuries to the surrounding vascular structures must be considered and evaluated.(2)

History and Physical Exam

The history of blunt or penetrating trauma to the anterior neck should always raise the question of laryngeal injury. While severe injuries usually have obvious findings, less severe but equally important injuries may present with more subtle signs and symptoms. Hoarseness or change in the patient’s voice should alert the physician to the possibility of laryngeal injury. Other symptoms include dysphagia, odynophagia and anterior neck pain.

On physical exam, findings of stridor, subcutaneous emphysema, hemoptysis and laryngeal tenderness are common findings. Additionally, loss of thyroid cartilage prominence and ecchymosis in the overlying skin may be noted.(2,3) In cases where the airway is stable, flexible fiberoptic laryngoscopy can provide important information. True vocal cord mobility, soft tissue injuries including edema, lacerations and hematomas as well as the patency of the airway can be evaluated. Again, associated injuries including cervical spine and vascular injuries must be excluded in this initial evaluation.

Diagnostic Imaging

Computer tomography has replaced other forms of laryngeal imaging as the radiographic tool of choice in cases of laryngeal trauma. The integrity of the laryngeal skeleton and cricoarytenoid joints as well as associated cervical injuries can be accurately assessed. It is especially useful in evaluating the extent of injury when the flexible fiberoptic exam is limited by edema. While some authors utilize CT scanning in almost all cases, others have recommended its use only when the results may change the treatment plan. (3,4) These authors do not scan patients with obvious injuries that will require open exploration or cases of minimal trauma and no physical findings.(4) Other radiographic techniques including angiography, cervical spine radiographs and barium esophagrams may be indicated in select cases.

Airway Management

As with any trauma patient, airway evaluation and management is of primary importance. If it is determined to be stable, the work up as described above may proceed. If at any point the airway is believed to be unstable, it must be secured. Although some controversy exist, many authors recommend local tracheotomy as the safest and least traumatic method of securing the airway in an adult patient who has suffered laryngeal trauma. An emergency cricothyrotomy may be performed if time does not permit a formal tracheotomy. If oral endotracheal intubation is attempted, it should be performed by an experienced physician with direct visualization and a small diameter endotracheal tube. Concerns related to endotracheal intubation in this setting include further iatrogenic injury and possible complete loss of an already marginal airway.(2) Special consideration must be given to pediatric patients with laryngeal injuries and an unstable airway because local tracheotomy is not usually a viable option. It has been suggested that these patients be managed in a manner similar to epiglottitis using inhalation anesthesia with spontaneous respirations followed by rigid endoscopic intubation. Once the airway has been evaluated and secured in this manner, tracheotomy can be performed if needed.(5)

Medical management

Select patients with stable airways and certain, minimal injuries can be expected to heal with good results and no further surgical intervention. These include patients with minor endolaryngeal lacerations that do not involve the free margin of the vocal cords or anterior commissure and those with single nondisplaced thyroid cartilage fractures. Appropriate medical management in these patients includes a minimum of twenty-four hours of airway observation, voice rest, head elevation, and humidification of inspired air. Antibiotic prophylaxis is used when the laryngeal mucosa is disrupted and many authors also recommend H2 blockers to reduce further injury from reflux of gastric acid.(2,3,6) Although unproven, systemic steroids are often given to reduce laryngeal edema. When used they should be initiated as early as possible.

Surgical management

Patients with more significant injuries should be taken to the operating room as soon as possible for direct laryngoscopy, bronchoscopy and esophagoscopy. Tracheotomy is also performed if indicated and not already done. If at this point the patient is found to have only laryngeal edema, small hematomas with intact mucosal coverage, or minimal lacerations as described above, no further surgical intervention is indicated. Adjuvant medical management is employed and the airway is maintained via the tracheotomy until the patient tolerates prolonged plugging.

When the initial work up and endoscopy indicate an intact endolarynx with a displaced thyroid cartilage fracture, open reduction and internal fixation is indicated. Many forms of fixation have been described including nonabsorbable suture, wire, and miniplates. Austin et al have described a wire-tube technique that involves passing a stainless steel wire around the fracture and submucosally on the medial surface of the cartilage.(7) On the lateral aspect of the cartilage, the wire is passed through a blunted 18-gauge needle. This helps prevent wire pull-through and maintains fixation of the cartilage in a more normal position with less angulation or blunting. For vertical fractures, a wire-tube device is placed both above and below the true vocal cord.

In cases with large mucosal lacerations, small lacerations involving the anterior commissure or free margin of the true vocal cords, exposed cartilage, multiple fractures, or true vocal cord immobility, open laryngeal exploration is indicated in addition to ORIF of the fractures. This should be carried out within 24 hours of the injury and is accomplished through a midline thyrotomy or via a vertical fracture if it is located within 2-3 mm of the midline. A horizontal skin incision is made at the level of the cricothyroid membrane and subplatysmal flaps are elevated. The strap muscles are separated and the larynx exposed. An oscillating saw is used to make the midline thyrotomy if no nearby fracture is available. The cricothyroid membrane is then incised and a vertical incision is carried superiorly through the anterior commissure to the thyrohyoid membrane. The thyroid laminae can then be retracted laterally exposing the endolarynx. Afrin soaked pledgetts are placed to achieve hemostasis and the endolarynx is carefully evaluated.

The goals at this point is to return all remaining tissue to its appropriate location and to cover all cartilage. Primary closure is usually possible because most injuries do not involve significant tissue loss and debridment should be kept to a minimum. All lacerations are carefully and meticulously closed using 5.0 or 6.0 absorbable suture. Occasionally, minimal undermining of adjacent mucosa is required to achieve closure. If primary closure is still not possible, mucosal flaps can be rotated from the epiglottis or pyriform sinuses.(3,8) Skin or mucosal grafts are rarely needed. If dislocated, the arytenoid cartilages should be reduced and the overlying mucosa repaired. The normal scaphoid shape of the anterior commissure is then reconstituted by using 4.0 absorbable suture to approximate the anterior true vocal cords to the outer perichondrium.(1) The thyrotomy is then close with nonabsorbable suture, wire or wire-tube techniques. ORIF of associated fractures is then carried out as described above.

Patients with anterior commissure injury, comminuted laryngeal fractures, or massive mucosal injuries require stenting in addition to the techniques mentioned above. With anterior commissure injury, the stent is used to prevent webbing and to maintain its scaphoid shape. In comminuted fractures and massive mucosal injuries, the stent is used to provide support during the healing process and to prevent adhesions. The use of a stent should be viewed as a compromise between the above benefits and the inherent further injury caused by the stent. For this reason, stents should be removed as soon as possible, usually after about two weeks. There are many types of stents available including home-made finger cots, modified endotracheal tubes (Portex), and commercial silastic stents. The ideal stent should extend from the false vocal folds to the first tracheal ring, should be relatively soft and should be able to be secured inside the larynx in a manner that allows movement with the larynx during swallowing. Additionally, its shape should resemble the shape of the larynx as closely as possible being scaphoid shaped at the level of the true cords and round in the subglottis.(9)

Special Considerations

Laryngotracheal separation is an injury that requires special consideration. Often this injury results in immediate death but occasionally a mucosal attachment may remain. Tracheotomy is again the preferred method of airway management but if not possible, bronchoscopic intubation may be successful.(1) The mucosa is repaired using absorbable suture with permanent sutures between the cricoid and the second tracheal ring to provide support.(2) Bilateral recurrent nerve injury and subglottic stenosis are common complications with this injury.

Repair of recurrent laryngeal nerve injuries is controversial. Although direct repair provides little chance of functional return, it may help maintain true vocal cord bulk and should be considered when transection of the nerve is identified.(2)

As mentioned above, most injuries do not involve significant tissue loss. In those cases where portions of the larynx are lost or completely destroyed, techniques similar to those used in various partial laryngectomy procedures can sometimes be utilized to restore function. In general, if the basic laryngeal skeletal and soft tissue elements remain, an attempt should be made at restoration.(9) In some cases however, the best final result may require total laryngectomy.

Pediatric laryngeal injuries also deserve special consideration because of several important differences when compared to adult injuries. First the proportionally smaller pediatric larynx tolerates much less edema before airway obstruction occurs. Second, the pediatric larynx is more flexible with more loose connective tissue. This results in a lower incidence of cartilage fracture but more soft tissue injury including edema, arytenoid dislocation, recurrent laryngeal nerve injury, and telescoping injuries where the cricoid becomes displaced under the thyroid cartilage. The third and only protective difference is the relatively high position of the pediatric larynx under the mandible. Except for the differences in airway management mentioned above, the medical and surgical treatment is similar to adult injuries. Finally, except in cases with a clear mechanism of injury ( i.e. MVA), the possibility of child abuse should be considered.(5)

Complications

Granulation tissue formation is the most common immediate complication. Prevention using the techniques of meticulous primary closure and cartilage coverage is the best treatment of this problem. Additionally, limiting the use of stents to selective cases and their early removal also lessens its occurrence. Once granulation tissue develops, careful laser excision offers the best chance of effective treatment.

Laryngeal and tracheal stenosis may also complicate the final result. This is often related to maturation of areas of granulation tissue. The management is site specific and may include laser excision, resection with mucosal coverage, stent placement, laryngotracheoplasty, or segmental tracheal resection.

True vocal cord immobility may be related to either recurrent laryngeal nerve injury or arytenoid fixation. Treatment is determined by whether one or both cords are involved and by whether the resulting functional problem involves airway patency or voice.

Conclusion

Recognition of laryngeal injury related to either blunt or penetrating trauma is important for both initial preservation of life as well as long term airway and vocal function. A history a cervical trauma coupled with signs and symptoms of hoarseness, pain, stridor, hemoptysis, or subcutaneous emphysema should prompt appropriate airway management and evaluation of laryngeal injury. This work up includes flexible fiberoptic laryngoscopy and computer tomograms and may include direct laryngoscopy, bronchoscopy and esophagoscopy. Associated cervical spine and vascular injuries must also be evaluated. Treatment varies according to the injury but may be as limited as medical management and observation or as extensive as open surgical treatment with or without stenting.

BIBLIOGRAPHY

1. Schaefer, S.D. The acute surgical treatment of the fractured larynx. Operative Techniques in Otolaryngology-Head and Neck Surgery. 1990;1(1):64-70

2. Bailey, B.J. Head and Neck Surgery-Otolaryngology. Laryngeal Trauma, J.B. Lippincott; Philadelphia. Ch 74 vol. 1. 1993

3. Bent, J.P., and Porubsky, E.S. The management of blunt fractures of the thyroid cartilage. Otolaryn Head Neck Surgery. 1994:110(2);195-202

4. Schaefer, S.D. Use of CT scanning in the management of the acutely injured larynx. Oto Clinics of North America. 1991:24 (1); 31-36

5. Myer, C.M., Orobello, P., Cotton,R.T., Bratcher, G.O. Blunt laryngeal trauma in children. Laryngoscope. 1987:97;1043-48

6. Austin, J.R., Stanley, R.B., and Cooper, D.S. Stable internal fixation of fractures of the partially mineralized thyroid cartilage. Ann Otol Rhinol Laryngol 1992:101;76-80

7. Olson, N.R. Laryngeal Trauma. Publication Am. Academy of Otol-Head and Neck Surgery. Washington, DC. 1982

8. Schaefer, S.D. The treatment of acute external laryngeal injuries "State of the Art". Arch Otolaryngol Head Neck Surg. 1991:117;35-39

TITLE: LARYNGEAL TRAUMA SOURCE: UTMB Dept. of Otolaryngology Grand Rounds DATE: May 21, 1997 RESIDENT PHYSICIAN: Rusty Stevens, MD FACULTY: Brian Driscoll, MD SERIES EDITOR: Francis B. Quinn, Jr., M.D., F.A.C.S.