Pneumomediastinum after inhalation of helium gas from party balloons.

A previously healthy 16-year-old boy presented to the Emergency Department with a 2-day history of hoarseness, sore throat, and chest tightness. The physical examination was significant for diffuse neck and chest subcutaneous emphysema. A computed tomography (CT) scan of the neck and chest revealed pneumomediastinum after a plain chest X-ray study failed to uncover this finding. The patient reported that 5 days before presentation he forcefully inhaled helium gas directly from multiple party balloons in an attempt to alter his voice. The patient fully recovered over the next 2 days. Spontaneous pneumomediastinum developed in this patient with no underlying lung disease, presumably from air leakage secondary to the excessive elevation of intra-thoracic pressure due to repetitive inhalation of helium gas. Spontaneous pneumomediastinum remains largely underdiagnosed clinically, especially in young, healthy patients.