Case report: Subacute combined degeneration of the spinal cord due to nitrous oxide abuse

Nitrous oxide (N₂O) is an increasingly popular recreational drug. N₂O irreversibly disturbs the metabolism of vitamin B₁₂, resulting in a functional deficiency. Vitamin B₁₂ is vital for myelin synthesis and its deficiency primarily produces neurological complications. Inhaling N₂O is more common and neurological complications are more evident than before.

We report a young man who developed progressive limb numbness and unsteady walking after N₂O abuse. The dominant diagnosis was subacute combined degeneration of the spinal cord (SCD). The patient was admitted to the hospital and given adenosylcobalamin treatment, but his symptoms progressed significantly from before and he developed acute cognitive impairment. After methylprednisolone combined with vitamin B₁₂ treatment, symptoms significantly improved.

Clinicians need to understand the presentation and treatment of SCD caused by N₂O abuse. When symptoms progress despite conventional vitamin B₁₂ therapy, the combination of methylprednisolone and vitamin B₁₂ may be considered.