Spontaneous pneumomediastinum: time for consensus.

Pneumomediastinum (PM) is defined as the presence of free air in the mediastinal cavity. It is often regarded as a revealing sign of a more serious medical condition. PM is broken down into two categories, one, with an instigating event, referred to as secondary PM. The other is when free air is discovered in the mediastinal cavity without a clear etiology, referred to as spontaneous pneumomediastinum (SPM). Often misdiagnosed due to the vague nature of presenting symptoms, SPM must be part of the differential diagnosis of a chest pain patient to expedite discovery and if necessary, management. A MedLine/PubMED search was performed identifying all relevant articles with "SPM" in the title. Six case series were reviewed to determine what clinical scenario constitutes a possible case of SPM. Results showed that almost all patients with SPM exhibited some chest pain, but Hamman's crunch was present in only one-fifth of patients. Patients with certain pre-existing pulmonary diseases showed a greater propensity for the presence of free air in the mediastinal cavity. SPM must be diagnosed and managed promptly due to rare, but serious complications and any chest pain with an unknown etiology should contain SPM in the differential diagnosis.