Imaging the Invisible: The Macklin Effect in Cannabinoid Hyperemesis Syndrome

Spontaneous pneumomediastinum is a rare, typically benign condition characterized by the presence of air in the mediastinum, often resulting from alveolar rupture due to elevated intrathoracic pressures. The Macklin effect, air dissection along bronchovascular sheaths following alveolar injury, is central to its pathophysiology. Cannabis use, particularly in cases of cannabinoid hyperemesis syndrome, may precipitate this via forceful vomiting. Though uncommon, especially in young adults, recognizing psychoactive substance use as a potential trigger is crucial for accurate diagnosis and management. We present the case of a previously healthy 25-year-old man with a history of cannabis use disorder who developed spontaneous pneumomediastinum most likely secondary to the Macklin effect.