Laughing Gas-Induced Funicular Myelopathy

A young adult presented to the emergency department with progressive dysesthesia and weakness in both arms and legs. The patient had no bladder disorders, infections, or relevant pre-existing conditions and did not follow a vegetarian diet. There was a 6-month history of weekly laughing-gas use (recreational drug), totaling around 150 instances of use. From a clinical perspective, the patient presented with transverse myelopathy, weakness predominantly in the legs and a sensory level at T8. Spinal magnetic resonance imaging (T2w) showed a long segment of hyperintensity (C2–C5), with an inverted V-sign in the posterior funiculi on axial imaging. There was no peripheral nerve demyelination. Serum vitamin B12 (122.9 pmoL/L) and folic acid levels (13.74 μg) were normal, as were cerebrospinal fluid readings; homocysteine and methylmalonic acid levels were significantly elevated (40.3 μmoL/L and 330 μg/L, respectively), representing a vitamin B12 utilization disorder. N₂O oxidizes and inactivates vitamin B12. Methionine synthase activity is thus reduced and myelin protein damaged. Intensive laughing-gas use can cause severe funicular myelosis, which is reversible only in some cases, as in ours. Re-assessment of N₂O availability appears necessary.

Figure

Magnetic resonance imaging (MRI)

Alina Wolfowski, Dr. med. Max-Lorenz Hollweck, Prof. Dr. med. Helge Topka, Klinik für Neurologie, Klinische Neurophysiologie, Kognitive Neurologie und Stroke Unit, München Klinik Bogenhausen, München, [e-mail]

Conflict of interest statement: The authors declare that no conflict of interest exists.

Translated from the original German by Christine Rye.

Cite this as: Wolfowski A, Hollweck ML, Topka H: Laughing gas-induced funicular myelopathy. Dtsch Arztebl Int 2025; 122: 209. DOI: 10.3238/arztebl.m2024.0251