Damage (trauma) of the larynx and trachea: causes and pathogenesis

Causes of injury (trauma) of the larynx and trachea

Trauma of the larynx and trachea can occur with a general neck injury. Causes of closed laryngotracheal injuries - punch or an object, auto-trauma, attempts of strangulation, a dull blow to the chest. Penetrating wounds are usually knife or bullet. As a rule, these are combined injuries.

Isolated lesions of the larynx and trachea occur with internal trauma. Internal trauma of the larynx and trachea is often iatrogenic (intubation, prolonged artificial ventilation of the lungs). The wound of the larynx and trachea is possible with any manipulation in the larynx, including during endoscopic examinations and surgical interventions. Another cause of internal trauma of the larynx and trachea is the ingress of a foreign body (fish bone, parts of dentures, pieces of meat, etc.). To internal trauma of the larynx and trachea also include burn injuries (thermal, chemical). Most often burns the respiratory tract with sodium hydroxide, the contents of batteries, ammonium used in the household, vehicles. In case of burn injury, the mucous membranes of high temperatures and chemical substances - combustion products - are directly affected.

Classification of injuries of the larynx and trachea

On the mechanism of action of the damaging factor, traumas and wounds of the larynx and trachea are divided into:

• external;
• internal;
• stupid;
•  sharp:
• chipped;
• cut.

By degree of damage:

• isolated;
• combined.

Depending on the involvement of the skin:

• closed;
• open.

On the fact of penetration into the hollow organs of the neck:

• penetrating:
• non-penetrating.

On the etiology:

• mechanical (including iatrogenic):
  • firearms:
  • cross-cutting;
  • blind;
• tangents:
  • knife;
  • chemical;
  • thermal.

Pathogenesis of lesions of the larynx and trachea

The larynx is protected by the lower jaw from above, the clavicles from below: a certain role is played by its lateral mobility. With a direct stroke, for example auto- or sports injury, the fracture of the larynx cartilage is caused by the mixing of the larynx and compression of it on the spine. It matters not only the strength of the impact, but also the previous state of the structures of the neck. Ossification of the larynx cartilage, previous surgical interventions on the neck. Postponed radiotherapy and other local factors also determine the outcome of traumatic effects. At a blunt trauma of a larynx the risk of occurrence of skeletal damages is more, than at a penetrating wound. The dull trauma of the larynx and cervical trachea may be accompanied by a fracture of the hyoid bone, cartilage of the larynx and trachea, larynx separation from the trachea or hyoid bone. Vocal folds can be torn, displacement of their or arytenoid cartilages, paresis of the larynx is possible. Develop hemorrhages in the subcutaneous tissue, muscles, formed hematomas, capable of squeezing the structure of the neck and lead to respiratory failure. Of great importance are traumatic injuries inside the larynx and trachea, submucous hemorrhages, linear ruptures of the mucosa, internal bleeding. Particularly severe injuries occur with the successive effects of several trauma agents.

External trauma, as a rule, leads to damage to the surrounding larynx and trachea of the tissues and organon of the esophagus, glottis, cervical spine, thyroid gland, and neurovascular bundles of the neck.

Analyzing the possible mechanism of trauma, conditionally distinguish three zones of the neck. The first extends from the sternum to the cricoid cartilage (high risk of trachea, lung injury, bleeding due to vascular damage); the second - from the cricoid cartilage to the edge of the lower jaw (the area of the larynx, esophagus, possible damage to the carotid arteries and veins of the neck, is more accessible for examination); the third - from the lower jaw to the base of the brain (zone of injury of large vessels, salivary gland, pharynx).

When through gunshot wounds are often damaged both walls of the larynx. In approximately 80% of the cases of laryngeal injuries, the inlet and outlet openings are located on the neck. In other cases, the inlet may be located in the front of the head. The difficulty in determining the passage of a wounded canal is due to the mobility of the larynx and trachea, their displacement after trauma. The cutaneous edges of the wound often do not coincide with the wound channel, and its course, as a rule, is tortuous. With blind injuries of the neck, accompanied by damage to the larynx and trachea, the outlet can be located in the lumen of the larynx and trachea.

The tangential wounds have a more favorable outcome due to the fact. That the skeleton of the larynx and the trachea is not damaged. However, it should be remembered that it is possible to injure neighboring organs and develop chondroperichondritis of the larynx and trachea or phlegmon of the neck at an early time after the injury.

Stitched and cut wounds are often more severe, as they are penetrating and are accompanied by wounding of blood vessels. If you get into the larynx or trachea of a foreign body, you can immediately develop asphyxia. If foreign matter is introduced into soft tissues, inflammation and edema develop, often bleeding. In the future, the process of inflammation can spread to surrounding tissue, lead to the development of mediastinitis, phlegmon neck. As with another trauma, penetrating wounds of the esophagus, development of subcutaneous emphysema are possible.

With burn lesions, external damage to the mucous membrane of the oral cavity and larynx may not reflect the true severity of damage to the esophagus and stomach. In the first 24 hours, edema of the mucous membranes builds up, then during ulceration, ulceration occurs. In the next 2-5 days, the inflammatory process continues, accompanied by vascular stasis (thrombosis). The rejection of necrotic masses occurs on the 5th-7th day. Fibrosis of the deep layers of the mucous membrane and the formation of scars and strictures begins with 2-4 weeks. Against the background of inflammation, hollow organs may be perforated, the appearance of tracheo-esophageal fistula, the development of pneumonia and mediastinitis. Sharply increases the risk of carcinoma of the esophagus. In the outcome of this inflammation, cicatricial narrowing of the hollow organs of the neck is often formed.

Pathogenetic process with intubation injury includes:

• hemorrhages in soft tissues, hematomas of the larynx;
• ruptures of the mucous membrane of the larynx and trachea;
• tearing of the voice fold;
• dislocation and subluxation of the finger joint;
• granulomas and ulcers of the larynx.

Outcomes of such damages are cicatricial deformation of the larynx and trachea, cysts of the vocal cords, post-indubation granulomas and paralysis of the larynx. Severe injuries can also be inflicted on the bougie of the narrowed larynx and trachea lumen for the purpose of widening their lumens with scar deformation. It is possible that the bougie penetrates into the paratracheal space with the subsequent development of mediastinitis and damage to adjacent organons and large vessels.

In some cases, traumatic damage to the larynx (haemorrhage in the vocal folds, granuloma, subluxation of the pustvitcherpalovodnogo joint) occurs with a sharp increase in underlaying pressure on screaming, a strong cough, against a background of constant overstrain of the voice apparatus with the use of a severe attack of sound. Predisposing factors consider the patient to have gastro-isophageal reflux, changes in microcirculation of the vocal folds, taking drugs containing acetylsalicylic acid.

In case of traumatic damage to any etiology, emphysema, hematoma and edema of the mucous membrane of the larynx can grow for two days and immediately lead to respiratory failure, stenosis of the larynx and trachea.

[1], [2], [3], [4], [5], [6], [7], [8], [9]