Tracheobronchomalacia

Tracheobronchomalacia or TBM is a condition characterized by flaccidity of the tracheal support cartilage which leads to tracheal collapse. This condition can also affect the bronchi. There are two forms of this rare condition: primary TBM and secondary TBM. Primary TBM is congenital and starts as early as birth. It is mainly linked to genetic causes. Secondary TBM is acquired and starts in adulthood. It is mainly developed after an accident or chronic inflammation.

On 28 May 2013, it was reported that a cure had been developed via a 3D printed windpipe. This cure has currently saved the lives of at least 3 infants.

Signs and symptoms

Initially symptoms asymptomatic or some patients do not experience symptoms at all. In a progressive TBM case symptoms include:

• shortness of breath
• a cough
• mucus build up
• wheezing
• difficulty in breathing
• bluish coloration to skin around the nose and mouth

Symptoms may become worse if the patient is stressed, sick, lying down, or forcing a cough.

• Chronic cough

Cause

The cause of tracheobronchomalacia (TBM) varies depending on whether a person has primary TBM (also called congenital TBM) or acquired TBM (also called secondary TBM). Most cases of primary TBM are caused by underlying genetic conditions that weaken the walls of the airway (the trachea and bronchi). For example, primary TBM has been reported in people with mucopolysaccharidoses (such as Hunter syndrome and Hurler syndrome), Ehlers-Danlos Syndrome, and a variety of chromosome abnormalities. Primary TBM can also be idiopathic (unknown cause) or associated with prematurity and certain birth defects (such as a tracheoesophageal fistula). A small proportion of adults with TBM have the primary form but are not diagnosed until adulthood. Acquired TBM is generally caused by the degeneration (break down) of cartilage that typically supports the airways. In most adults with acquired TBM, the underlying cause of this cannot be identified. Many adults diagnosed with acquired TBM have common respiratory conditions such as asthma, chronic bronchitis and emphysema. Acquired TBM may be associated with inflammatory conditions (such as relapsing polychondritis), exposure to toxins (e.g. mustard gas), enlargement of structures near the airway (such as goiter or a tumor), and complications from medical procedures (such as endotracheal intubation).

Inheritance

Primary tracheobronchomalacia (TBM) is often associated with certain genetic conditions. In some cases, an affected person inherits the condition from an affected parent. Other cases may result from new (de novo) gene mutations. These cases occur in people with no history of the disorder in their family. When TBM is part of a genetic condition, it can be passed on to future generations. Secondary TBM (also called acquired TBM) is not inherited. It generally occurs incidentally due to trauma, chronic inflammation and/or prolonged compression of the airways.

Diagnosis

Diagnosis is conducted according to the severity of the symptoms. Initially pulmonary function tests are administered. These tests include the lungs' capability of air intake and outtake, and gas flow of oxygen and carbon dioxide between the body and environment. Following these function tests a CT scan or bronchoscopy will be ordered. The results to the scan and bronchoscopy will display the status of the rare condition. A mild case of tracheobronchomalacia would be if the patient's trachea condenses 50% of its normal space when exhaling. Moderate tracheobronchomalacia would be 25% of the normal trachea space constricting and a severe case would be if the walls touch each other.

Treatment

To properly treat a patient with tracheobronchomalacia, the subtype must be determined (primary or secondary). After the type is named, the cause must be identified, whether it is from genetics, a trauma accident, or chronic tracheal illness. If a trauma case or chronic tracheal illnesses were the cause, the first steps of treatment would be to fix or help these underlying issues. If the cause is genetic or the previous underlying issues could not be fixed, other treatments would be assessed. More severe treatments include silicone stenting to prevent tracheal constriction, surgery to strengthen or attempt to rebuild the walls, continuous positive airway pressure that has a machine blow small amounts of air into the trachea to keep it open (mainly at night), or a tracheostomy, which is surgically put into your neck that leads to your trachea to help with breathing. People with tracheobronchomalacia who do not experience symptoms do not need treatment and are often undiagnosed.

See also

• Bronchomalacia
• Tracheomalacia

External links

Classification	ICD-10: J39.8

• Tracheobronchomalacia in Children on Medscape
• Tracheobronchomalacia on Genetic and Rare Diseases Information Center (GARD)