Intrinsic Lesions Which Deform the Trachea

A number of conditions largely display gross deformation of the trachea in several characteristic patterns. These changes appear to be intrinsic to the trachea rather than being due to compression by adjacent structures or masses. Included are saber-sheath trachea, tracheopathia osteoplastica, and tracheobronchomegaly.

Saber-Sheath Trachea

A normal adult trachea has an essentially oval cross section, with the coronal diameter greater than that of the sagittal, although in many it is nearly circular (see Chapter 1, "Anatomy of the Trachea"). With increasing age, the configuration of the lower third of the trachea may be altered by the left lateral impression of an enlarging aorta. "Saber-sheath" trachea, however, describes a coronal narrowing of the entire intrathoracic trachea from both sides, with a corresponding increase in the sagittal diameter, usually affecting about the lower two-thirds of the trachea. The proximal cervical segment retains a normal shape (Figure 14-21). Saber-sheath trachea is identified most often in older patients, particularly in males over 50 years of age. Ninety-five percent of patients appear to suffer chronic obstructive pulmonary disease (COPD).53,54 Not all patients with COPD, however, show saber-sheath deformity. In most patients, it is an incidental finding. However, with extreme progression of the deformity, a large part of the posterior lateral walls of the trachea approximate to one another on coughing and on increased respiratory effort, especially expiratory. As the cross-sectional area of the trachea is reduced, the rate of airflow is also reduced.54 The patient finds it increasingly difficult to generate a cough sufficiently forceful enough to clear tenacious secretions, which are characteristic of the pulmonary disease.

Greene and Lechner described 13 patients with such narrowing, recalling the original use of the term in 1905.53 Patients' ages ranged from 52 to 75 years, and clinical diagnoses were varied. All the patients had a history of heavy smoking, 10 had a diagnosis of chronic bronchitis, and 7 suffered from primary chronic obstructive pulmonary disease. The coronal intrathoracic tracheal diameters ranged from 7 to 13 mm with a mean of 10.5 mm; in contrast, the sagittal diameters showed a mean of 23.5 mm. The extrathoracic trachea was normal, with a coronal diameter of 20.6 mm. Ten of the 13 patients demonstrated calcification in the tracheal rings, which was probably age related.

The mechanical forces that lead to this deformation of the intrathoracic trachea are not understood. It should be emphasized that the cartilages are not malacic. It is the change in shape and approximation on respiratory and tussive efforts that can lead to clinical problems. In a very rare case, I found it necessary to splint the trachea externally (using specially made polypropylene rings), in order to allow the patient to clear secretions adequately. A large bore tracheal T tube or inlying stent could also provide a means for maintaining an open airway during expiration and cough in these few critical patients. Definition of the extent to which the airway is obstructed by the process is obtained by bronchoscopic examination in the awake patient, flow volume curves, and inspiratory and expiratory thin-section CT scans of the trachea. Patients who have this deformity, but who are not symptomatic from it, and who require tracheal resection between the differently shaped proximal and distal portions of the trachea, do not present any difficulties in anastomosis. Sutures are placed proportionally. The tracheal ends are sufficiently flexible to permit easy anastomotic accommodation.

figure 14-21 Saber-sheath trachea. A, Anteroposterior (left) and lateral (right) roentgenograms, showing normal appearing cervical trachea with side-to-side narrowing of the intra-thoracic trachea. Near the carina, the trachea begins to widen again.

Tracheopathia Osteoplástica

In tracheopathia osteoplástica (TPO), multiple submucosal osseocartilaginous nodules are present in the trachea, subglottic larynx, and bronchial tree (see Figures 42 and 43 [Color Plate 16]). An alternative name, tracheobronchopathia osteochondroplastica, is more completely descriptive, lacking only "laryngo"—but is excessively long and something of a tongue twister. The nodules are distributed only over underlying cartilages and not over the membranous wall. The most prominent nodules are usually seen in the trachea and the next most prominent in the main bronchi. Some are tiny and scattered like seeds. Others grow to considerable size (4 to 6 mm). The nodules are of hyaline cartilage with foci of ossification and lie sub-mucosally, essentially forming a partial intratracheal osseocartilaginous cylinder (except over the membranous wall). Bridges of bone, cartilage, and collagen connect the inner tracheal cylinder formed by the pathologic bone and cartilage with the perichondrium of the regular tracheal cartilages. These findings led Young and colleagues to support ecchondrosis of the tracheal cartilages as the pathological process.55 An often present saber-sheath configuration in these patients may commence just below the cricoid cartilage, rather than being confined to the intrathoracic trachea, as it is in isolated saber-sheath tracheal deformation. Portions of the trachea may be more severely affected by TPO than others, and occasionally involve only part of the trachea. The etiology is unknown. Earlier suggestions that TPO is an end stage of amyloidosis have not held up.56 Other theories relate the calcifications to chronic purulent tracheitis or abnormalities in tracheal elastic tissue.56,57 This rare condition is seen in older adults and is often asymptomatic. Fifteen patients were diagnosed with TPO over 36 years at the Mayo Clinic.56 A number of cases reported were discovered incidentally at postmortem examination.55 TPO may, however, progress insidiously to produce respiratory symptoms, including dyspnea, cough, sputum production and retention, wheezing, hoarseness, and hemoptysis.56 A long history of exertional dyspnea and respiratory infection may be elicited. As obstruction worsens, the patient has progressive difficulty in raising viscid secretions.

Sputum The Trachea Chest

figure 14-21 (continued) B, Computed tomography scans showing changes in tracheal configuration with progression, from the cervical (left upper image), to the upper thoracic (right upper and left lower image), to the lower thoracic (right lower image). The shape of a saber sheath is best exemplified in the right upper image. As the carinal branching is reached, the airway becomes more triangular.

When saber-sheath deformity is concurrent, as is often the case, the obstruction is worsened. Atrophic rhinitis and pharyngitis may be concurrent.57

Tomograms and CT scans show typical changes, with scalloped calcification in the nodules lining the lumen of the involved segments of the airway (Figure 14-22). These nodules are within the inner border of the cartilages, which are not themselves involved. Bronchoscopy is also diagnostic (Figure 14-23). The lesions may be seen extending from the subglottic larynx to distal bronchi. In advanced cases with marked airway constriction, it may not be possible to force an adult rigid bronchoscope very far into the trachea since the process is so rigid. Biopsy is extremely difficult due to the hardness of the nodules, and it is not usually productive or necessary.

Attempts to treat this condition by removal of the nodules either with bronchoscopic biopsy forceps or with laser have not been highly successful.56 The trachea may be impossible to dilate, so that per oral stent placement is not feasible. Segmental stenosis of the trachea by TPO is infrequent. Localized disease, although rare, can be resected.58,59 In 1 of our patients who had squamous cell carcinoma identified by biopsy in an obstructing localized segment of TPO, a resection gave complete relief. In 4 patients with severe and

figure 14-22 Images of tracheopathia osteoplastica (TPO). A, Chest roentgenogram of a 48-year-old woman with TPO so severe, she was incapacitated by dyspnea. Tracheal shadow shows saber-sheath configuration with suggestion of irregularities in lateral walls. Sternal wires and clips are from previous coronary artery surgery. B, Three-dimensional (computed tomography [CT] scan) reconstruction of the trachea in a 44-year-old man with obstructing TPO. Marked distortion and narrowing are evident. C, CT scan of the same patient in B. The saber-sheath tracheal shape and the irregular and calcified nodules facing the lumen are typical.

incapacitating airway obstruction due to disease involving the entire trachea (the more common presentation), relief was sought by reshaping the obstructed trachea over a silicone T or T-Y tube.60,61 The entire length of the trachea was divided vertically in the anterior midline from the cricoid to the carina (see Chapter 32,

Saber Sheath Trachea Bronch

figure 14-22 (continued) D, Lateral longitudinal reconstruction. The apparently posterior nodules are in the distorted lateral wall (see Figure 14-22C), not the membranous wall, which is not involved. E, CT scan 4 years after T tube tracheoplasty in the patient in Figure 14-22C. The patient had returned to all activities, including small game hunting.

figure 14-22 (continued) D, Lateral longitudinal reconstruction. The apparently posterior nodules are in the distorted lateral wall (see Figure 14-22C), not the membranous wall, which is not involved. E, CT scan 4 years after T tube tracheoplasty in the patient in Figure 14-22C. The patient had returned to all activities, including small game hunting.

"Surgery for Tracheomalacia, Tracheopathia Osteoplastica, Tracheal Compression, and Staged Reconstruction of the Trachea"). This permitted the rigid lateral walls to be hinged outward from the anterior midline incision, since the membranous wall is uninvolved. After placement of a T or T-Y tube, the anterior line of the incision was sutured closed. Pedicled strap muscles were interposed between the linear suture line and the brachiocephalic artery. After 4 to 6 months, when healing had occurred in the outwardly hinged position, the T tube was extracted. Airway patency was maintained in 3 patients long term (see Figures 14-22E, 14-23C). One patient continued to need a T tube, but was lost to follow-up. Viscid secretions, as expected, continue to be produced by the abnormal mucosa, but can be cleared through a now widely patent trachea. I have not, thus far, encountered a case where distal involvement also required surgical reshaping of the bronchi. This should be feasible with a custom-made T-Y tube. Kutlu and colleagues treated a single patient with narrowing of only the upper half of the trachea, by side to side slide tracheoplasty, with satisfactory follow-up at 15 months.62 See also Figures 3-62, 3-63, and 3-64 (Color Plate 8).

Tracheobronchomegaly

Tracheobronchomegaly (TBM), the Mounier-Kuhn syndrome, is characterized by a hugely dilated trachea and central bronchi and frequently associated with recurrent respiratory infection. Widening of the trachea transversely may reach 35 to 45 mm or greater. Mounier-Kuhn described the radiographic and broncho-scopic presentations of a number of these patients and gave the syndrome its current name.63 TBM is most likely of congenital origin.64-67 It has been identified in the neonate, but usually becomes clinically manifest in adult life.64 Katz and colleagues identified the condition in patients between the ages of 8 and 64 years, but found the majority to be in the fourth and fifth decades.64 The patient often finds it difficult to date the origin of symptoms exactly, since these have appeared insidiously over many years, sometimes being retrospectively identifiable in childhood. Longitudinal elastic fibers of the central airways are atrophic or absent.

Symptoms are progressive dyspnea on exertion, ineffective cough, and difficulty in raising secretions. Emphysema, respiratory infections, and bronchiectasis follow.64,65,67 The trachea appears hugely dilated on chest x-ray and on bronchoscopy. CT scan demonstrates the defects graphically (Figure 14-24). Cartilages

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