Tracheal diverticulum is a defect of the tracheal wall in the form of protrusion, which has a message with the lumen of the organ. This pathology may be asymptomatic or manifest as cough with sputum, shortness of breath, hoarseness of voice, dysphagia. Diverticula are diagnosed using videotracheobronchoscopy, radiography, multispiral CT. Conservative and surgical methods are used for treatment. Drug therapy includes taking anti-inflammatory, restorative drugs, mucolytics during periods of exacerbation of inflammation. Surgical treatment is carried out for complicated forms of the disease and consists in resection of the diverticulum.
Q32.1 Other malformations of the trachea
Tracheal diverticulum is a congenital or acquired defect in the structure of the tracheal wall in the form of its karman-like bulging. It is a rather rare find in pulmonology: posthumously, this pathology is detected in 1-2% of autopsies; in vivo, during CT examination – in 3.7% of patients. The disease was first described in 1838 by the Austrian pathologist K. von Rokitansky. In the medical literature, this pathology is found under the names: air cyst, paratracheal diverticulum, tracheocele, bronchogenic cyst. However, unlike cysts, diverticula have an inner layer of the ciliated epithelium. Acquired diverticula are more often diagnosed in men – this is due to the higher prevalence of smoking and COPD among the male population.
Tracheal diverticulum causes
Congenital defects of the tracheal wall can develop due to the effect of adverse factors on the fetus at almost any stage of pregnancy. More often, this is the period from 3-4 weeks, when the process of laying the breathing tube is underway, and up to 6-8 months, corresponding to the formation of the alveoli. The most dangerous effect of carcinogens, viruses and other agents on the respiratory system of the fetus in the early stages of gestation. Another cause of anomalies in the development of the respiratory tube are chromosomal and gene rearrangements.
Acquired diverticula are formed due to increased pressure in the tracheal lumen with prolonged and severe cough accompanying chronic bronchitis, whooping cough, bronchial asthma, tuberculosis, and other respiratory diseases. The situation is aggravated by the weakness of the layers of the tracheal wall (muscle, elastic fibers, connective tissue structures), especially in its membranous part.
Congenital diverticula usually retain the histological structure of the trachea: from the inside they consist of atrial fibrillation, muscle and cartilage elements and are usually smaller than acquired. They are formed as a result of local underdevelopment of tracheal cartilages. At the same time, mucosal invagination occurs where the cartilaginous framework is thinned or absent. If a valve mechanism operates at the mouth of such a defect, air enters through the channel into its lumen. There is a kind of “pumping” of the sac formation, its walls stretch with the formation of a tracheocele.
Diverticula of acquired genesis are macroscopically similar to enlarged lymph nodes, from which, when pressed, a mucopurulent secret flows out. The walls are lined from the inside with a cylindrical multilayer epithelium and a fibrous base, cartilaginous and smooth muscle fibers are absent. The ducts that connect the diverticula with the trachea may have a wide or narrow lumen, which determines the degree of emptying of the diverticulum and the severity of the symptoms of the disease. These cavities are filled with air or mucus.
In the early stages of diverticulum formation, duct expansion and hyperplastic changes of the mucous glands occur. In the future, atrophy of the glands develops. All these phenomena are observed against the background of chronic inflammation of the trachea. The condition is aggravated by a constant increase in pressure in the tracheal lumen due to strong coughing jerks. The changes progress against the background of atrophic phenomena in the tracheal wall, especially its membranous part, weakness of elastic fibers and muscle tissues, chronic infection. There is a further expansion of the duct, its cyst-like deformation and, as the final result of pathological changes, the formation of a diverticulum.
There is no single classification of tracheal diverticula. Below is an interpretation of this pathology according to some criteria.
1. By origin:
- Congenital diverticula. They are located to the right of the trachea, 4-5 cm below the vocal cords. Their position corresponds to the level of 1-2 thoracic vertebrae. They reach 15-20 mm in diameter. They have a cylindrical, oval, round, baggy or fusiform shape.
- Acquired diverticula. They can develop at any level of the trachea, most often on the posterior-lateral wall between the cervical and thoracic sections in the spaces between the tracheal rings.
2. By localization:
- Diverticula of the cervical trachea. Anatomically located from the level of the sixth cervical vertebra to the second thoracic. The cervical part of the trachea has from 6 to 8 cartilaginous rings, within which pathological protrusions can form.
- Diverticula of the thoracic trachea. Their upper border corresponds to the projection of the sternum tenderloin, the location is between the pleural sacs in the upper mediastinum.
3. By size:
- Small (up to 2 cm). They are usually characterized by a low-symptomatic course, manifested by a slight cough with moderate sputum discharge. Well drained, rarely accompanied by the development of infection.
- Large (more than 2 cm). The patient is often disturbed by cough with mucus of a mucous or mucopurulent nature, sometimes in large quantities, voice disorders.
4. By quantity:
Single: in the presence of 1-2 bay-shaped protrusions of the tracheal wall. They are more often located at the level of the collarbones and are fused with the surrounding tissues.
Multiple: there are two or more diverticula, characterized by a more pronounced clinical picture.
5. By the presence of cameras:
- Single-chamber. They are located in the membranous part between the cartilages of the trachea. In the presence of a narrow channel communicating the diverticulum with the trachea, they are accompanied by stagnation of mucous secretions and suppuration.
- Multi-chamber. They have the form of a “reservoir” with one or more partitions of connective tissue components. They are rare.
6. On the mechanism of development:
- Pulsating. The main cause of their occurrence is cough. There is a protrusion of the tracheal wall from the inside with a sharp increase in pressure in it due to coughing jerks.
- Traction. They develop with cicatricial and adhesive changes of the tracheal tube from the outside. As a result of the ongoing scarring processes, the tracheal wall is pulled in the appropriate direction, which leads to an increase in fibrous changes and its deformation. They have a funnel-shaped shape and are usually located in the lower parts between the tracheal cartilages.
Small sizes are more characteristic of congenital diverticula. Multiplicity, multicameration and differences in the mechanisms of formation are inherent in the pathology of acquired character.
Tracheal diverticulum symptoms
With small tracheocele sizes, there may be no clinical manifestations. In other cases, patients receive treatment for chronic tracheobronchitis for a long time. Signs of the disease appear with an increase in compression of the trachea and esophagus due to an increase in the diverticulum and the development of infection. The severity of symptoms is influenced by the localization of the cavity formation, its size. Sometimes diverticula can be visualized as swelling in the neck. Palpation is usually painless.
Patients complain of a constant cough of a vibrating nature with the discharge of mucous or mucopurulent sputum. Cough, in turn, contributes to a further increase in the size of the diverticulum. If the diverticulum reaches a large size, dysphagia may bother. With compression of the recurrent laryngeal nerve, hoarseness of voice, shortness of breath occurs. In addition, diverticula are a kind of “reservoir” that delays the mucous secretion in the trachea. This contributes to the development of infection, as well as its spread to the bronchi and lungs, and the chronization of the inflammatory process.
One of the most serious complications of a diverticulum is its suppuration. The result of abscessing may be the melting of the wall of the cavity formation and the breakthrough of its contents into the surrounding tissues, tissue of the cervical region or mediastinum. Cases of perforation of the tracheal diverticulum into the brachiocephalic artery involved in the blood supply to the face, neck, and brain are described.
Aspiration of infected mucus from the cavity formation with its penetration into the bronchi often causes the development of bronchitis and pneumonia. Hemoptysis can have serious consequences for the patient. The presence of diverticula can complicate the intubation of the trachea and ventilator during surgery, cause the development of mediastinal emphysema.
Of great importance is the collection of patient complaints and medical history data. The long “experience” of the disease, the corresponding clinical signs, a thorough examination and palpation of the lesion site give grounds for a deeper examination of the patient. A therapist, a pulmonologist, a radiologist, an otorhinolaryngologist, and an endoscopist take part in the diagnosis of the disease. The survey includes:
- Tracheography with contrast. Radiography of the trachea is currently rarely used. It is informative in cases when the diverticulum communicates with the tracheal lumen with a small diameter duct. The pictures show the protrusion associated with the lumen of the trachea by a narrow isthmus.
- Endoscopy of the trachea and bronchi. Tracheobronchoscopy is the main method in the diagnosis of tracheal diverticula. With endoscopic examination, it is easily possible to identify defects in the tracheal wall and concomitant mucosal changes (hyperemia, mucopurulent secretion, etc.).
- Multispiral tomography. On MSCT of the chest, the diverticulum is visualized as a single- or multi-chamber air formation located paratracheal and communicating with the tracheal lumen.
Tracheal diverticula must be differentiated from mediastinal emphysema, laryngocele, pharyngocele. The subject for differential diagnosis is the Cenker diverticulum (pharyngeal-esophageal), in which there are also symptoms of swallowing disorders and difficulty breathing, and compression of the recurrent nerve causes hoarseness of the voice. To exclude these diseases, OGC radiography, pharyngoscopy, laryngeal endoscopy, esophagoscopy are performed.
Tracheal diverticulum treatment
Therapeutic tactics in relation to this pathology can be conservative or surgical. The main principles of medical care are timeliness and rationality.
Conservative therapy. It is used in elderly patients or patients with a low-symptomatic or asymptomatic course of diverticulum. During periods of exacerbations, it includes taking anti-inflammatory drugs (NSAIDs, antibiotics), mucolytics, antioxidants (vitamins C, E), restorative drugs (vitamins, trace elements, adaptogens), physiotherapy (UHF, electrophoresis).
Surgical treatment. Involves resection of the diverticulum. It is produced in thoracic surgery departments. It is indicated for conditions complicated by compression of the surrounding diverticula of organs and tissues, abscessing. Radical methods are also used for conditions and complications that threaten the patient’s life (bleeding and hemoptysis, foreign body of the trachea, asphyxia, etc.).
Prognosis and prevention
Usually, tracheal diverticula have a low-symptomatic course and rarely cause complications. The outcome of treatment – both surgical and conservative – is favorable in most cases. Preventive measures include maintaining a healthy lifestyle, giving up smoking, walking in the fresh air, physical education and sports. Pregnant women should avoid contact with potentially harmful teratogenic substances. If symptoms of the disease appear, you should seek medical help in time, be examined and begin treatment.
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