Nitrous oxide recreational abuse presenting with myeloneuropathy and mimicking Guillain-Barre syndrome

The recreational use of nitrous oxide (N₂O) is increasing in festivals, university parties, clubs, private residences, and parks. The abuse of N₂O has serious complications of the central and peripheral nervous system. In this article, we report a case of a 28-year-old previously healthy man who presented with a three-day history of rapidly progressive leg numbness, tingling, and weakness with gait instability and frequent falls. He had a history of marijuana use and daily inhalation of N₂O (approximately 20 whippets daily over 2-3 years). He was admitted with a presumptive diagnosis of Guillain-Barre syndrome and was started on intravenous immunoglobulin. Three days after admission, paresthesia ascended to the level of nipple line, and his weakness in the lower limb increased significantly. MRI of the cervical spine showed focal non-enhancing lesions extending from C4 to C6. Serum analysis showed low vitamin B12 level, elevated methylmalonic acid, and elevated homocysteine level. Supplemental 1000 μg/day of vitamin B12 intramuscular injections and 15 mg of folic acid tablets were given. The patient showed gradual improvement. This is a rare case of N₂O recreational abuse presenting with myeloneuropathy and mimicking Guillain- Barre syndrome. This case highlights the importance of detailed history and physical examination in patients who arrive at the hospital with clinical features of Guillain-Barre syndrome. This is especially true if there are red flags such as drug abuse or discrepancy between clinical and para-clinical (investigations) parameters. Neuroimaging of the brain and spinal cord might be necessary to score the final diagnosis in such cases.