Spontaneous pneumomediastium following an alcoholic binge

Clinical History

A 24 year old man presented with spontaneous chest pain and neck swelling after an alcoholic binge.

Imaging Findings

A 24 year old bricklayer presented the evening after a 28 unit alcohol binge during which he had vomited once with no immediate symptoms and had gone to bed three hours later. On waking, he complained of chest pain and a 'thickened neck'. He had no significant past medical history. Physical examination revealed surgical emphesema around his neck but no other abnormal signs. In particular he was afebrile and normotensive. Initial chest radiograph showed pneumomediastinum (Figure 1) but no other abnormal signs, and blood tests were unremarkable. On the suspicion of an oesophageal rupture he was commenced on broad spectrum antbiotics and a chest CT perfomed with the prior administration of 50mls of niopam 300 orally (Figure 2). The CT showed extensive mediastinal air seen from the level of the gastro-oesophageal junction up into the root of the neck, but no extraluminal leakage of contrast. The absence of oesophageal perforation was confirmed by the
performance of a gastrografin swallow in the erect, supine, left and right decubitus positions on the day subsequent to admission (Figure 3). The patients symptoms settled over the next few days and he was discharged to uneventful outpatient review.

Discussion

The causes of pneumodiastium separate naturally according to the origin of the mediastinal gas, whether from respiratory system, digestive tract, from outside the body, or generated in situ as a result of gas forming infection. Respiratory causes include spontaneous alveolar rupture (subsequent to coughing, vomiting or other rise in intrathoracic pressure - which may be associated with conditions such as asthma, croup, exercise, pneumonia, diabetic ketoacidosis, pulmonary fibrosis, parturition, mechanical ventilation and compressive chest trauma) [1]. The air leak tracks along
pulmonary interstitium to the mediastium via the hila, but is usually only visible on the chest radiograph if adjacent lung is opacified by some pathological process. Natural contrast against soft tissues makes the air visible once it reaches the mediastinum. On CT imaging, by contrast, air in the bronchovascular interstitium may often be seen as a dark line between aerated lung and bronchial/vascular walls. Occasionally other routes for air to access the mediastinum from the chest arise, for example subsequent to pneumothorax, chest drain insertion, mediastinoscopy or as a
sequel to bronchial laceration. Perforation of the pharynx, oesophagus, duodenum, colon or rectum can allow gas originating from the digestive tract to end in the mediastinum. The originating structures are usually either mediastinal themselves or retroperitoneal, allowing gas to track from retroperitoneum to mediastinum via the diaphragmatic hiatus. In our patient the differential diagnosis is between alveolar rupture and oesophageal rupture secondary to vomiting (Boerhaave's syndrome). As a complete oesophageal tear allows contaminated material into the mediastinum and
pleural space with likely mediastinitis, the early detection of a leak is of critical importance so that surgical repair can be contemplated without delay; the mortality of mediastinitis is 20-30% [2]. Alveolar rupture, by contrast is a benign self-limiting process that requires no specific therapy [3]. Fortunately for our patient it was the latter diagnosis that applied.

Differential Diagnosis List

Final Diagnosis

Spontaneous pneumomediastium following presumed alveolar rupture

URL:	https://eurorad.org/case/5060
DOI:	10.1594/EURORAD/CASE.5060
ISSN:	1563-4086