Isolated Pneumomediastinum in an Adult: A Case Report

Abstract

Turkish Abstract

Introduction

Pneumomediastinum (PM) and subcutaneous emphysema are the clinical findings of air in the mediastinum and under the skin, which usually occur after an esophageal or chest trauma, or sometimes can be spontaneously ¹. Spontaneous pneumomediastinum (SPM) is a rare but clinically benign finding especially in young patients with no history of precipitating condition. There is no absolute data but only case series, point to an incidence of 1/7000-45000 ². It is more common in young males. Causes include asthma exacerbations, dental extraction, barotrauma, infection and  esophageal rupture ³. It can also spontaneously occur due to vomiting, Valsalva maneuver, coughing, forceful straining during exercise ^1,4. However, recreational illicit drug use is a very rare cause of PM and subcutaneous emphysema, there are only a few reported cases in literature ⁵.

Case Report

A 22-year-old man with no past medical history presented to emergency department with a neck swelling and pain for 2 days. His vitals were normal and had no concomitant complaint. He was an exillicit drug user but he denied any illicit drug use at presentation. There was no history of trauma or vigorous exercise. He described no history of vomiting or coughing. However, the patient remembered a history of trauma while wrestling with his friend 3 days ago.

His examination revealed crepitus under the skin of his neck but normal air entry on chest auscultation. His blood tests and ECG were normal. His chest radiography (Figure 1) showed extensive emphysema under the skin of neck and shoulders.

Figure 1 Chest X-ray, showed extensive emphysema under the skin of neck

Computed tomography (CT) was performed and CT showed extensive pneumomediastinum, a small pneumopericardium and dissecting air in the deep spaces of the neck and chest wall (Figures 2,3 and 4). No rib fractures were detected.

Figure 2 CT of the chest, axial view, revaling pneumomediastinum free air around the pericardium

Figure 3 CT of neck, axial view, showing emphysema in the deep spaces of the neck and the right shoulder

Figure 4 CT of the chest, coronal view, showing pneumomediastinum around the heart and in the deep spaces of the neck and the right shoulder

The patient, was then  admitted to the Thoracic Surgery Ward for observation, no intervention was performed.  He was treated with supplemental oxygen, bronchodilators and analgesics. His symptoms relieved and control chest X-ray was stable. He was discharged in good condition after 2 days. 

Discussion

PM and subcutaneous emphysema are often a consequence of bronchial or esophageal rupture ⁶. Also, peptic ulcus, or perforations secondary to diverticulitis, intestinal perforation or abdominal surgical interventions may be the reason of air dissecting through the diaphragm into the mediastinum. Alveolar rupture may occur usually during positive pressure ventilation in patients with infections, aspiration, acute respiratory distress syndrome, emphysema, interstitial lung disease or Valsalva maneuver, vomiting, coughing, illicit drug inhalation, childbirth, seizure, forceful straining during exercise and diving ⁷. However, PM can occur spontaneously, which is a rare condition with an incidence of 1/30000 presenting to ED ⁸. It can also be  harbinger to severe injury of mediastinal structures and should be further evaluated ⁹.

Traumatic PM was first described by Laennec in 1819 ¹⁰. The most commonly accepted pathophysiology of PM was first described by Macklin and Macklin, the underlying factor was alveolar rupture secondary to increased alveolar pressure or overdistention or decreased interstitial perivascular pressure ^11-13. The most common presenting complaint is chest pain, other presenting complaints consist of coughing, neck pain and dyspnea ^6,8. The most common clinical finding is the crunching sound in time with the heartbeat ¹⁴. Subcutaneous emphysema is the most common clinical finding which has a low sensitivity and high specificity in diagnosis of pneumothorax ¹⁵. In our case, chest pain was the presenting complaint as in other series ^2,6,8, and subcutaneous emphysema was the presenting finding on physical examination.

There have been reports of PM case series after barotrauma during pulmonary function tests and inflation of party balloons ⁸.  A history of asthma and illicit drug use, especially inhalational drugs, also have been reported ¹ . The etiology of our case was thought to be increased alveolar pressure and terminal alveolar rupture secondary to trauma to the neck or chest while wrestling.

Plain chest radiography or CT are the most common investigations performed for the diagnosis of PM. Kaneki et al. ¹⁶ reported in their case series that plain chest radiography has 30% sensitivity in detection of PM cases and chest X-ray should be combined with a CT scan. Also,  Caceres et al. ¹⁷ showed in their case series that only 69% of cases were diagnosed by plain films and the remaining 31% were discovered by CT scan. Ryoo et al. ⁷ reported that CT is the most reliable diagnostic modality in PM patients. CT scan is important to exclude or diagnose other pathologies and has become the gold standard for diagnosing PM. In our case, we primarily performed a chest X-ray, proceeding to a CT scan of the thorax.

PM and subcutaneous emphysema usually follow a self-limiting and benign course, and the required treatment is bed rest, oxygen therapy and analgesics. Patients with PM should be observed for a period to exclude the complications. Antibiotics are not needed unless suspicion of viscus perforation ¹⁷.

What makes this case remarkable are despite the late presentation, the clinical findings and symptoms of the patient are milder than expected. This case report serves to emphasize the importance of the thorough clinical examination and the fact that detailed history may be the cornerstone of the etiology.

A recent history of drug use in a PM patient could be misleading and cause the overlook of further severe injuries. CT is a useful tool in diagnosing PM and quantifying the amount of free air. All these patients should be observed for at least for 24 hours. 

References

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