Subcutaneous emphysema describes the presence of gas in subcutaneous tissue. It has several known causes, among them anaerobic infections, traumatic disruption of mucosal surfaces, and alveolar rupture. Diagnosis is characterized by the presence of crepitation on palpation over the affected area and radiographic evidence of gas in the subcutaneous tissues. The pathogenesis relates to the tracking of gas along fascial planes into the subcutaneous space of the neck, chest, or extremities. Therapy of subcutaneous emphysema itself is generally supportive and involves the treatment of the underlying condition, as subcutaneous emphysema is usually self-limited and benign. However, the appearance of subcutaneous emphysema often warrants a search for more serious underlying pathology such as pneumothorax, pneumomediastinum, or tracheobronchial or esophageal disruption.Subcutaneous emphysema limited to the surgical area is an expected and acceptable consequence of endoscopic neck procedures that involve the use of gas insufflation. The operative pocket is created within the potential spaces of the neck and maintained with carbon-dioxide insufflation. At the conclusion of the procedure, residual carbon dioxide in the operative pocket and carbon dioxide that has diffused into surrounding tissue will result in subcutaneous emphysema. In animal studies, the degree of subcutaneous emphysema was greater among those subjects who were operated on with higher insufflation pressures (i.e., ≥15 mm Hg), and it may have been the result of pneumomediastinum or simply the result of a greater passage of carbon dioxide into the subcutaneous tissues.