PNEUMOMEDIASTINUM - OLD SIGNS AND NEW SIGNS

Pneumomediastinum, also known as mediastinal emphysema, represents ext raluminal gas in the mediastinum. Pneumomediastinum can lead to pneumo thorax, pneumopericardium, pneumoperitoneum, or pneumoretroperitoneum. There are many causes of pneumomediastinum (Table 1) and several radi ographic signs: pneumopericardium, continuous diaphragm sign, continuo us left hemidiaphragm sign, Naclerio's V sign, V sign at confluence of brachiocephalic veins, ring-around-the-artery sign, thymic spinnaker- sail sign, and extrapleural air sign. We review the common and uncommo n signs of pneumomediastinum and present some new signs. We also addre ss the problem of distinguishing pneumomediastinum from pneumothorax a nd pneumopericardium.