Loss of consciousness, a generalized tonic-clonic seizure, rightside weakness, and pneumomediastinum developed suddenly in a 13-year-old boy who had inhaled helium directly from a pressurized helium tank. His condition improved dramatically with hyperbaric oxygen treatment, and he had apparently regained complete neurologic function by the time of follow-up 2 weeks later. On the basis of the boy’s clinical presentation and his response to hyperbaric oxygen therapy, we diagnosed a cerebral gas embolism.

Pao, Hayden, , , , , , , (1996). Cerebral gas embolism resulting from inhalation of pressurized helium. Annals of emergency medicine, 1996 Sep;28(3):363-6. https://www.ncbi.nlm.nih.gov/pubmed/8780487