This page considers all aspects of plain film imaging of pneumomediastinum.

Pneumomediastinum refers to the presence of air in the mediastinum.

Pneumomediastinum is commonly associated with asthma and ruptured oesophagus.

	This 22 year old male presented to the Emergency Department with a history of difficulty breathing and subcutaneous emphysema most evident around the soft tissues of the neck. He was referred for chest radiography. There is pneumomediastinum and subcutaneous emphysema
	The pneumomediastinum is usually most evident in the upper mediastinum (white arrows). The mediastinal air often tracks through soft tissue planes and is demonstrated as subcutaneous emphysema on plain film chest imaging (black arrow)
	Ther lateral projection can be important in the diagnosis of pneumomediastinum when the PA findings are subtle.
	The mediastinal air mainfests as lucent striations around the cardiac shadow.
	CT imaging shows the air within the mediastinum (white arrows) and associated subcutaneous emphysema (black arrows)