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

BACKGROUND: Nitrous oxide (N(2)O) is an increasingly popular recreational drug. N(2)O irreversibly disturbs the metabolism of vitamin B(12), resulting in a functional deficiency. Vitamin B(12) is vital for myelin synthesis and its deficiency primarily produces neurological complications. Inhaling N(2)O is more common and neurological complications are more evident than before. CASE PRESENTATION: We report a young man who developed progressive limb numbness and unsteady walking after N(2)O 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 B(12) treatment, symptoms significantly improved. CONCLUSION: Clinicians need to understand the presentation and treatment of SCD caused by N(2)O abuse. When symptoms progress despite conventional vitamin B(12) therapy, the combination of methylprednisolone and vitamin B(12) may be considered.