Spontaneous mediastinal emphysema, also known as spontaneous pneumomediastinum, is defined as radiologically detected free air in the mediastinum, without preceding trauma. It is a rare condition, mainly affecting young adults. It can be caused by coughing, strenuous sports or cocaine inhalation, however, 40% are idiopatic. Common symptoms are chest pain and dyspnoea. 75-90% can be diagnosed with a chest X-ray, and 100% with a computed tomography. Treatment is symptomatic and complications are rare, however, pneumothorax and pneumorrachis have been reported.