Spontaneous pneumomediastinum: A comparative study and review of the literature

Background. Spontaneous pneumomediastinum (SPM) is an unusual occurrence with few cases reported. It is seen after intrathoracic pressure changes leading to alveolar rupture and dissection of air along the tracheobronchial tree. This study was undertaken to provide a thorough clinical and radiologic analysis of this patient population. Methods. A retrospective comparative analysis was performed on patients with SPM over 12 years. Patient demographics, clinical presentation, and radiographic and diagnostic studies were recorded. A clinical and radiologic comparison was performed with secondary pneumomediastinum. Results. Seventy-four patients were identified with a diagnosis of pneumomediastinum. A total of 28 patients with SPM were identified. The major initial complaints were chest pain (54%), shortness of breath (39%), and subcutaneous emphysema (32%). The main triggering events were emesis (36%) and asthma flare-ups (21%). No apparent triggering event was noted in 21% of patients. Chest radiograph was diagnostic in 69%; computed tomography was required in 31%. Esophagram, esophagoscopy, and bronchoscopy were performed on an individual basis and were invariably negative. When compared with secondary pneumomediastinum, SPM is more likely to be discovered by chest radiography, has a lower incidence of pneumothorax and pleural effusion, requires a shorter hospital stay, and has no associated mortality. Conclusions. Spontaneous pneumomediastinum is a benign condition that often presents with chest pain or dyspnea. It can develop without a triggering event and with no findings on chest radiography. Treatment is expectant and recurrence is low. Secondary causes must be ruled out to avoid an unfavorable outcome.