A 25-year-old male presented with sudden onset neck and chest pain after a single episode of dry heaving followed by stifling a forceful sneeze. Examination revealed a reduced range of motion at the neck in all planes and odynophagia. Vital signs were unremarkable, and blood tests revealed raised inflammatory markers.
Initial Chest Radiograph PA view demonstrated linear lucencies along bilateral hilar and paratracheal regions with extension into the subcutaneous tissues of the neck, more evident on the left side. Appearances are suspicious for pneumomediastinum with associated subcutaneous emphysema (Figure 1).
Selected axial CT images confirm pneumomediastinum and associated surgical emphysema. (Figure 2a, 2b).
To rule out oesophageal rupture, CT chest with oral gastrografin contrast was conducted. 6 hours after the initial study, the subsequent CT does not display any extravasation of contrast into the mediastinum to suggest an active leak. The pneumomediastinum and surgical emphysema remain unchanged (Figure 3a, 3b).
The source of the pneumomediastinum was unclear and was eventually attributed to alveolar rupture; however, due to clinical uncertainty, the patient was admitted, kept nil by mouth, and received broad-spectrum antibiotics to cover an oesophageal source.
Pre-discharge chest radiograph shows interval resolution of the pneumomediastinum after five days (Figure 4).
Pneumomediastinum is defined as free air within the mediastinum and was first described by Laennec in 1829 . Spontaneous pneumomediastinum (SPM) is used to describe pneumomediastinum with no apparent cause such as trauma, infection or iatrogenesis. It is commonly linked to sudden increases in intrathoracic pressure such as through coughing and vomiting or Valsalva manoeuvre . SPM is a relatively rare presentation, with one study noting an incidence of 1 in 44511 patients that presented to an emergency department .
Common symptoms of a pneumomediastinum include chest pain and dyspnoea . Given the overlap with numerous pathologies, pneumomediastinum must remain a differential in patients presenting with cardiopulmonary complaints. In the case of our patient, the initial assessing clinician decided on discharge with a diagnosis of muscle spasm in the neck following the internalised sneeze. It was only after the patient sought a second opinion that a chest radiograph was organised, drawing attention to the extraluminal gas. This emphasises the importance of early imaging in detecting pneumomediastinum, especially in instances of diagnostic uncertainty.
Chest radiography may demonstrate subcutaneous emphysema and lucencies outlining mediastinal structures such as the pulmonary artery and major aortic branches which may prompt further imaging [4,5]. In our case, the patient experienced some chest discomfort following an initial dry heave which was then significantly worsened by the sneeze. As such, there was clinical suspicion that the gas may have originated from the oesophagus. In such instances, imaging with oral contrast agents becomes prudent . Contrast extravasation into the mediastinum may demonstrate oesophageal perforation, a potential source of mediastinitis, which has been associated with mortality rates of approximately 30% . In the absence of any oesophageal leak being identified, SPM commonly originates from the lungs through alveolar rupture, usually dissecting surrounding peribronchial/perivascular sheaths, and is treated conservatively as a benign and self-limiting condition. Other potential sources may include bowel and airways . If however, an active oesophageal breach is identified, the patient in question will likely require emergency surgical repair .
Written informed patient consent for publication has been obtained.
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