Síndrome de Mounier-Kühn

Tracheobronchomegaly (Mounier-Kuhn Syndrome) with CT and bronchoscopic correlation: A case report

Tracheobronchomegaly, or Mounier-Kuhn syndrome, is a clinical and radiological entity characterized by marked dilatation of the trachea and bronchi as a result of severe atrophy of the elastic fibers, with thinning of the muscularis, and the formation of diverticula between the cartilaginous rings. The etiopathogenesis is uncertain and may be congenital or acquired. The clinical signs are not specific and are frequently revealed by recurrent respiratory infections and chronic cough. The diagnosis of Mounier-Kuhn syndrome is based on well-documented measurements of the trachea and main bronchi performed on a chest computed tomography scan. The management of patients is based on symptomatic treatment and may require, in severe cases, the use of endoscopic treatment by stent placement or surgical tracheobronchoplasty. We present a case of a 59yearold patient with recurrent respiratory infections that required several hospitalizations. Diagnosed with Mounier Kuhn syndrome, the thoracic computed tomography scan demonstrated a dilated trachea until the bifurcation and focal points of bronchial dilatation. Bronchoscopic examination showed a dilated and deformed trachea with the presence of diverticula on the tracheal anterior wall. The diameter of the trachea was reduced by more than 50% during expiration and coughing. For this reason, Mounier-Kuhn syndrome should be considered in cases of recurrent respiratory infection or persistent respiratory symptoms.

Improving Airways Patency and Ventilation Through Optimal Positive Pressure Identified by Noninvasive Mechanical Ventilation Titration in Mounier-Kuhn Syndrome: Protocol for an Interventional, Open-Label, Single-Arm Clinical Trial

BACKGROUND

Mounier-Kuhn syndrome or congenital tracheobronchomegaly is a rare disease characterized by dilation of the trachea and the main bronchi within the thoracic cavity. The predominant signs and symptoms of the disease include coughing, purulent and abundant expectoration, dyspnea, snoring, wheezing, and recurrent respiratory infection. Symptoms of the disease in some patients are believed to be pathological manifestations arising due to resident tracheobronchomalacia. Although treatment options used for the management of this disease include inhaled bronchodilators, corticosteroids, and hypertonic solution, there is no consensus on the treatment. The use of continuous positive airway pressure (CPAP) has been reported as a potential therapeutic option for tracheobronchomalacia, but no prospective studies have demonstrated its efficacy in this condition.

OBJECTIVE

The purpose of this is to identify the presence of tracheobronchomalacia and an optimal CPAP pressure that reduces the tracheobronchial collapse in patients with Mounier-Kuhn syndrome and to analyze the repercussion in pulmonary ventilation. In parallel, we aim to evaluate the prevalence of obstructive sleep apnea/hypopnea syndrome.

METHODS

This interventional, open-label, single-arm clinical trial will enroll patients who are diagnosed Mounier-Kuhn syndrome. Patient evaluation will be conducted in an outpatient clinic and involve 3 visits. Visit 1 will involve the collection and registration of social demographic, clinical, and functional data. Visit 2 will entail polysomnography, bronchoscopy for the evaluation of tracheobronchomalacia, titration of the optimal pressure that reduces the degree of collapse of the airway, and electrical impedance tomography. In visit 3, patients exhibiting a reduction in collapse areas will be requested to undergo chest computed tomography during inspiration and forced expiration with and without positive pressure (titrated to determine optimal CPAP pressure).

RESULTS

This protocol is a doctorate project. The project was submitted to the institutional review board on January 24, 2017, and approval was granted on February 2, 2017 (Brazilian Research database number CAAE 64001317.4.000.0068). Patient evaluations started in April 2018. Planned recruitment is based on volunteers' availability and clinical stability, and interventions will be conducted at least once a month to finish the project at the end of 2020. A preliminary analysis of each case will be performed after each intervention, but detailed results are expected to be reported in the first quarter of 2021.

CONCLUSIONS

There is no consensus on the best treatment options for managing Mounier-Kuhn syndrome. The use of positive pressure could maintain patency of the collapsed airways, functioning as a "pneumatic stent" to reduce the degree of airflow obstruction. This, in turn, could promote mobilization of thoracic secretion and improve pulmonary ventilation.

TRIAL REGISTRATION

ClinicalTrails.gov NCT03101059; https://clinicaltrials.gov/ct2/show/NCT03101059.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/14786.

An Unusual Cause of Spontaneous Pneumomediastinum: The Mounier-Kuhn Syndrome

Mounier-Kuhn syndrome is a rare clinical and radiologic condition. It is characterized by tracheal and bronchial dilation. Diagnosis is made by computed tomography and bronchoscopy. An 81-year-old man presenting with an acute chest pain was referred to the pulmonology department. His chest computed tomographic scan showed a tracheobronchomegaly with an increase in the diameter of both the trachea and right and left main bronchi, associated with pneumomediastinum and fibrosis. Fiberoptic bronchoscopy revealed enlarged trachea and both main bronchi. These findings are consistent with a diagnosis of Mounier-Kuhn syndrome. Besides considering this long-neglected "orphan disease" when diagnosing spontaneous pneumomediastinum, clinicians should also be aware of an underlying Mounier-Kuhn syndrome in patients with recurrent respiratory infections, in order to avoid complications associated with the disease.

An Atypical Case of Mounier-Kuhn Syndrome: Time to Change the Diagnostic Approach?

Mounier-Kuhn syndrome (MKS) is a rare disease of unknown etiology characterized by abnormal pathologic dilatation of tracheabronchial tree. The diagnosis of MKS is normally made on CT scan of chest on the basis of enlarged diameters of trachea and main stem bronchi. We are presenting histologically confirmed case of MKS, where the diameter of right main bronchus is below minimum diameter (mean+3 SD) required for the diagnosis. We suggest that the diagnosis of MKS should not be solely based on fixed criteria such as the diameter of airways, but on the basis of the overall clinical, pathologic, and radiologic profile.

Mounier-Kuhn syndrome or congenital tracheobronchomegaly: a literature review

Mounier-Kuhn syndrome or congenital tracheobronchomegaly is a chronic airway condition which for currently unknown reasons mostly affects males. It is commonly overlooked on conventional chest X-rays, and is considered to be rare, but the prevalence might be higher as commonly assumed. The hallmark of it is a dilatation of the main airways which frequently, but not always, causes marked, mainly respiratory, symptoms, and patients usually present with varying degrees of recurrent infections, breathlessness, haemoptysis, dyspnoea. Although at least 200 case reports have been published, there have been only a few attempts to review them, and none in the last 20 years. Due to the lack of clinical trials and wide variability of case-report format, a systematic review was deemed not feasible, therefore PubMed and Medline databases were searched using terms "Mounier-Kuhn syndrome", "tracheobronchomegaly", "tracheomegaly", and "bronchomegaly", without any time restrictions, to summarize currently known facts about the syndrome. To the authors' best knowledge, the result is currently the most comprehensive review of previously published literature about the congenital tracheobronchomegaly, and summarizes what's known about symptoms, prevalence, disease associations, and treatment options for this syndrome.

Case report: Mounier-Kuhn syndrome

Tracheobronchomegaly or Mounier-Kuhn syndrome is a rare disorder characterized by marked dilatation of the trachea and main bronchi, bronchiectasis, and recurrent respiratory tract infections. The etiology of this disorder is uncertain and the clinical presentation is variable. The diagnosis is usually made on the basis of the characteristic CT scan findings. We report a case in a 21-year-old man presenting with recurrent lower respiratory tract infections.

Airway stenting and tracheobronchoplasty improve respiratory symptoms in Mounier-Kuhn syndrome

BACKGROUND

Mounier-Kuhn syndrome (MKS) is a condition characterized by tracheobronchomegaly resulting from the loss or atrophy of musculoelastic fibers within the airway wall. Concomitant tracheobronchomalacia is seen in most patients with MKS, often leading to significant respiratory compromise due to bronchiectasis, increased dead space, and impaired secretion clearance.

METHODS

We report a series of 12 patients with MKS and tracheobronchomalacia who were evaluated at our institution for significant respiratory problems. Stent trials were conducted in 10 patients, with seven proceeding to operative tracheobronchoplasty (TBP) and one continuing with long-term stent placement. One patient underwent TBP without prior stent placement. Of the remaining three patients, two had no improvement with trials of stent placement, and a stent could not be placed in the third because of a large tracheal diameter.

RESULTS

Compared with baseline values, clinically significant improvements in health-related quality-of-life measures and pulmonary function testing were seen in patients who underwent central airway stabilization (n = 9). Complications of both stent placement and TBP were generally mild. However, one death was reported in the surgical group secondary to an exacerbation of preexisting interstitial pneumonia.

CONCLUSIONS

An aggressive approach that targets central airway stabilization may improve outcomes for patients with MKS.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00550602; URL: www.clinicaltrials.gov.

Alterações difusas da traquéia: aspectos na tomografia computadorizada

O objetivo deste ensaio pictórico foi apresentar as principais alterações tomográficas observadas em doenças que acometem a traquéia de forma difusa. As doenças estudadas foram amiloidose, traqueobroncopatia osteocondroplástica, traqueobroncomegalia, papilomatose laringo-traqueo-brônquica, linfoma, neurofibromatose, policondrite recidivante, granulomatose de Wegener, tuberculose, paracoccidioidomicose e traqueobroncomalácia. O principal aspecto observado na tomografia computadorizada foi o espessamento das paredes traqueais, com ou sem nodulações, calcificações parietais ou comprometimento da parede posterior. Embora a tomografia computadorizada permita a detecção e a caracterização das doenças das vias aéreas centrais, e a correlação com os dados clínicos reduza as possibilidades diagnósticas, a broncoscopia com biópsia continua sendo o procedimento mais importante no diagnóstico das lesões difusas da traquéia.