Metabolic encephalopathy caused by nitrous oxide ('laughing gas') induced hyperammonaemia.
BMJ case reports November 25, 2019 Marissa Ginette Danielle Vive, Galia Valentinova Anguelova, Sjoerd Duim et al.
A 26-year-old man arrived at the emergency department confused and with decreased consciousness after several days of vomiting. For the preceding six months, he had used a 2-liter tank of nitrous oxide weekly. His metabolic encephalopathy was caused by hyperammonaemia, probably resulting from nitrous-oxide-induced vitamin B12 deficiency interfering with ammonia degradation. A catabolic state may have contributed. After treatment with vitamin B12 and lactulose, both his consciousness and hyperammonaemia improved. He reported no residual complaints after three months of follow-up. The authors recommend considering hyperammonaemia as a cause of metabolic encephalopathy in cases of nitrous oxide use and altered mental status.