Pneumorachis and pneumomediastinum caused by repeated Müller's maneuvers: complications of marijuana smoking.

Pneumomediastinum may occur during marijuana inhalation but only rarely has pneumorachis (epidural pneumatosis or aerorachia) been reported. The usual mechanisms that produce pneumomediastinum include severe acute asthma, toxic-induced bronchial hyperreactivity, and barotrauma caused by Valsalva's maneuver (expiration through resistance). We report a case in which barotrauma resulted from repeated deep inspiration through a device with airflow resistance equivalent to Müller's maneuver. Inspiration occurred through a homemade apparatus resembling a narrow outlet bong with 2 piled compartments. Pneumomediastinum combined with subcutaneous emphysema and pneumorachis occurred, without identified pneumothorax. There were no neurologic complications. Because of the absence of bronchospasm, expiration either through the apparatus or actively against a closed glottis, or apnea, this phenomenon is likely a result of repeated Müller's maneuvers. Successive inhalation through resistance could have resulted in extreme negative intrathoracic pressure, which would have caused a transmural pressure gradient inducing barotrauma and release of extrarespiratory air. High-concentration oxygen therapy to achieve nitrogen washout was used.