What are the other Names for this Condition? (Also known as/Synonyms)

• Congenital Tracheobronchomegaly
• Mounier Kuhn Syndrome

What is Mounier-Kuhn Syndrome? (Definition/Background Information)

• Mounier-Kuhn Syndrome is a lung disorder that causes the respiratory tract to dilate or enlarge. People with this condition develop frequent respiratory tract infections and recurrent cough
• The condition can be diagnosed by lung function tests, bronchoscopy, and a chest CT scan
• The cause of Mounier-Kuhn Syndrome is unknown, although cigarette smoke and air pollutants may act as irritating factors
• Some cases are associated with connective tissue diseases such as Ehlers-Danlos syndrome, Marfan syndrome, and cutis laxa, and may be inherited
• The treatment of Mounier-Kuhn Syndrome typically involves chest physical therapy and antibiotics to treat infections

(Source: Mounier-Kuhn Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Mounier-Kuhn Syndrome? (Age and Sex Distribution)

• Mounier-Kuhn Syndrome is a rare lung disorder, with less than 300 cases reported in the medical literature
• The onset of symptoms can occur at any age
• Although both genders can be affected, the condition is more prevalent in males

What are the Risk Factors for Mounier-Kuhn Syndrome? (Predisposing Factors)

The risk factors for Mounier-Kuhn Syndrome may include the following:

• A family history of Mounier-Kuhn Syndrome 
• Connective tissue disorders, such as Ehlers-Danlos syndrome (EDS) and Marfan syndrome, or cutis laxa (a skin condition)
• Smoking
• Exposure to air pollutants

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Mounier-Kuhn Syndrome? (Etiology)

The exact genetic cause of Mounier-Kühn Syndrome is not known at the present time.

• The disorder may be associated with connective tissue disorders such as Ehlers-Danlos syndrome, Marfan syndrome, and cutis laxa, and may be inherited
• The condition is caused by atrophy of elastic fibers in the trachea and main bronchi, which lead to thinning of the smooth muscle layer and subsequent tracheobroncheal flaccidity, dilatation and collapse

(Source: Mounier-Kuhn Syndrome; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

What are the Signs and Symptoms of Mounier-Kuhn Syndrome?

The signs and symptoms of Mounier-Kuhn Syndrome may include:

• Abnormality of the skeletal system
• Bronchiectasis
• Diverticulosis of trachea

Based on the frequency of symptoms observed, the following information may be noted:

Very frequently present symptoms in 80-99% of the cases:

• Bronchitis
• Pneumonia
• Recurrent bronchopulmonary infections
• Tracheal stenosis
• Tracheobronchmegaly

(Source: Mounier-Kuhn Syndrome; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Mounier-Kuhn Syndrome Diagnosed?

Mounier-Kuhn Syndrome is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Pulmonary function tests to check for airflow obstruction
• Imaging studies, such as plain chest radiography or computed tomography, to measure the coronal and the sagittal diameters of the trachea, with the diameter measuring more than 25 mm and 27 mm, respectively, in males, and greater than 21 mm and 23 mm in females (being indicative Mounier-Kuhn Syndrome)
• Biopsy of bronchial and tracheal wall tissue
• Differential diagnosis to rule out conditions that may present with similar symptoms

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Mounier-Kuhn Syndrome?

The complications of Mounier-Kuhn Syndrome may include:

• Respiratory infections
• Tracheomalacia
• Pulmonary fibrosis
• Pneumothorax
• Pulmonary obstructive diseases
• Respiratory failure

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Mounier-Kuhn Syndrome Treated?

The treatment for Mounier-Kuhn Syndrome is usually given to manage the signs and symptoms and any complication that develops. The treatment methods may include:

• Antibiotics for infections
• Chest physiotherapy to improve obstruction
• Positive pressure ventilation
• Tracheal or tracheobronchial stent placement
• Double lung transplantation

How can Mounier-Kuhn Syndrome be Prevented?

If Mounier-Kuhn Syndrome is inherited or associated with a connective tissue disorder with a genetic basis, it may not be preventable.

• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Controlling certain factors, such as air pollution and chronic smoking, may help in mitigating the risk
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Mounier-Kuhn Syndrome? (Outcomes/Resolutions)

• The prognosis of Mounier-Kuhn Syndrome is dependent upon the severity of the signs and symptoms and associated complications, if any
• At the present time, no data are available regarding life expectancy
• The prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Mounier-Kuhn Syndrome:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/