Spontaneous Pneumomediastinum: An Underdiagnosed Condition in Young Adults

Introduction:

Spontaneous pneumomediastinum (SPM) is a rare entity affecting younger males that is not associated with any possible triggering factor. The condition occurs due to trapped air in the mediastinum. The first case was described by Louis Hamman in 1939, and hence, the condition is also referred to as Hamman’s syndrome. Young males with asthmatic disorders and pulmonary diseases are more prone to develop the condition. People suffering from spontaneous pneumomediastinum (SPM) can recover faster with effective management. However, patients with underlying respiratory illness require hospitalization for several weeks until the patient becomes completely stable.

What Is Spontaneous Pneumomediastinum?

Spontaneous pneumomediastinum is caused by the entrapped interstitial air in the mediastinum and is associated with chest pain, dyspnea, and subcutaneous emphysema. This occurs due to alveolar rupture owing to increased intrathoracic pressure associated with no possible precipitating factors. It commonly affects males under the age group of 20 to 40 years of age and is usually self-limiting.

What Happens in Spontaneous Pneumomediastinum?

• SPM occurs as a result of the existence of a pressure gradient between the alveoli and the lung interstitium.

• The increased intrathoracic pressure is caused due to factors such as smoking, bronchial asthma, respiratory infections, and interstitial lung disease.

• Increased airway pressure causes alveolar rupture, which in turn leads to dissection of air through the bronchovascular sheath involving mediastinum, then further extending through the cervical subcutaneous tissue, pleura, pericardium, peritoneal cavity, and epidural spaces.

What Causes Spontaneous Pneumomediastinum?

• Alveolocapillary membrane abnormalities.

• Interstitial lung diseases.

• Smoking.

• Bronchial asthma.

• Vomiting and sneezing.

• Vigorous exercises.

• Respiratory infections.

• Coughing.

• Drug abuse (consumption of marijuana, cocaine).

• Increased tobacco consumption.

• Occupational exposure to varnish fumes.

• Performing valsalva (forced expiration) procedure.

• Chronic obstructive pulmonary disease.

• Bronchiectasis (a condition in which the small tubules of the lungs through which the air is inspired and expired are damaged, causing difficulty in breathing).

• Bullae (fluid-filled blisters seen on the surface of the skin).

• Thoracic neoplasms (cancer involving the thyroid gland).

• Cystic disease (a lung disease that is associated with abnormal growth and development of fluid-filled cysts replacing normal lung tissue).

What Are the Clinical Features of Spontaneous Pneumomediastinum?

• Cough.

• Dyspnea (difficulty in breathing).

• Dysphagia (difficulty in eating).

• Odynophagia. (pain on swallowing).

• Neck pain.

• Chest pain.

• Subcutaneous emphysema (accumulation of air beneath the subcutaneous layers of the skin: a clue to the underlying pathology.

• Back pain.

• Abdominal pain.

• Acute retrosternal pleuritic pain (pain occurring behind the sternum).

• Presence of Hamman’s sign (heartbeat against air-filled spaces).

How Is Spontaneous Pneumomediastinum Diagnosed (SPM)?

• Posteroanterior and lateral chest radiography serves as an important diagnostic aid.

• A lateral view is used as an adjunct in diagnosing SPM, as many cases remain undiagnosed by obtaining only a posteroanterior view.

• A hyperlucency (radiolucent band) is seen when the air is entrapped in the retrosternal region in the case of pneumomediastinum.

• Radiological imaging is the mainstay of diagnosis in the case of SPM, which reveals radiographic features like multiple bands of hyperlucency with a fine radiopaque line showing elevated mediastinal pleura and entrapped air appear as radiolucent lines in the mediastinum extending towards the neck and surrounding mediastinal structures such as the aorta, trachea, esophagus or thymus gland.

• The chest CT (computed tomography) scan is referred to as the gold standard of all radiological studies in detecting pneumomediastinum, even in cases of negligible amounts of mediastinal air.

What Are the Complications of Spontaneous Pneumomediastinum?

Spontaneous pneumomediastinum can rarely cause life-threatening complications which need immediate medical care. The complications include:

• The area around one of the lungs can collapse, leading to pneumothorax due to an increased buildup of air.

• The entrapped air may become free and may get embolized between the heart and pericardium, causing pneumopericardium.

• Extreme pressure buildup occurs due to the entrapped air and can cause discomfort around the chest area, making breathing difficult and impairing cardiovascular function as the heart and blood vessels are also affected.

How Can One Prevent Spontaneous Pneumomediastinum?

Spontaneous pneumomediastinum is relatively rare and usually a self-limiting condition.

• Avoiding smoking and other deleterious habits like drug abuse reduces the risk.

• Bronchial asthma and other respiratory conditions should be treated and monitored at regular intervals, which may predispose to SPM.

• Vigorous exercises should be avoided.

• Using protective masks to prevent occupational exposure to various poisonous fumes is critical.

Differential Diagnoses Of Spontaneous Pneumomediastinum

• Musculoskeletal disorders.

• Acute coronary syndrome.

• Pericarditis (inflammation of the pericardium, a fibrous fluid-filled connective tissue sac covering the heart).

• Pneumothorax (accumulation of air in the cavity between the lungs and chest, causing the lung to collapse).

• Pulmonary embolism (presence of blood clot in the blood vessels of the lungs).

• Tracheobronchial tree rupture (a part of the respiratory tract that helps in the exchange of air and damage to it causes respiratory complications).

• Boerhaave’s syndrome (rupture of the esophagus due to increased stress caused by vomiting or due to increased intraesophageal pressure).

How Is Spontaneous Pneumomediastinum Treated?

• The mainstay of the treatment for spontaneous pneumomediastinum includes rest, oxygen therapy, and administering analgesia.

• The patient should be kept under continuous observation.

• Oxygen therapy is instituted to reduce dyspnea by enabling the body to absorb oxygen faster.

• Medications like painkillers are given to relieve the pain.

• Cough suppressants are administered to relieve cough and discomfort.

• Needle aspiration is advised when the entrapped air causes pressure on the surrounding tissues, causing discomfort and making breathing difficult. This involves removing or draining the entrapped air through a needle prick.

Conclusion:

SPM is often left undiagnosed as it presents its clinical features similarly to other respiratory diseases. SPM usually is a self-limiting condition and resolves on its own without requiring any treatment in most cases. The prognosis is relatively good and seldom turns into complications until the underlying predisposing factors (respiratory diseases) trigger the process. A young male patient with a history of smoking and a strong clinical inclination towards SPM should undergo complete and detailed radiological imaging to rule out SPM, as it can lead to further complications. SPM should be included in differential diagnoses along with other important medical emergencies requiring immediate care, such as cardiac tamponade (increased pressure on the heart due to fluid accumulation in the pericardium), angina pectoris (chest pain), dissecting aortic aneurysm(a tear in the aorta causing diversion in the blood flow, that forms a bulge in the aortic wall), mediastinitis (inflammation of the mediastinum), and pulmonary embolism.