Spontaneous mediastinal emphysema: hamman's syndrome.

A case of spontaneous mediastinal emphysema (Hamman's syndrome) is described. The patient was a 21-year-old man, who had a sudden onset of substernal chest pain at rest associated with typical findings of Hamman's syndrome: subcutaneous emphysema of the neck, a precordial crunching sound synchronous with the heart beat and air in the mediastinum on chest x-ray. He recovered uneventfully. The pathogenesis and clinical picture of this rare condition are discussed.