Recreational nitrous oxide abuse related subacute combined degeneration of the spinal cord in adolescents – A case series and literature review

Background: Nitrous oxide (N ₂ O) is a commonly used inhaled anesthetic in outpatient dental procedures. However, the increasing recreational use of N ₂ O may result in vitamin B ₁₂ deficiency-related neurologic and psychiatric symptoms. The aim of this study was to demonstrate the clinical features of chronic N ₂ O abuse in pediatric patients. Methods: Patients under 20 years of age who were diagnosed with N ₂ O-induced subacute combined degeneration of the spinal cord from 2012 to 2018 were enrolled in this study. Clinical presentations, laboratory, imaging, ancillary studies, treatments and outcomes were analyzed. Results: Nine patients were included, all of whom presented with symptoms of myeloneuropathy including limb numbness, limb weakness or unsteady gait. Six patients had low or low-normal vitamin B ₁₂ (cyanocobalamin) levels. Eight patients had evidence of subacute combined degeneration of the spinal cord via neuroimaging studies. All of the patients received vitamin B ₁₂ supplementation as treatment. All had full recovery of muscle power within 2 months. Five patients had persistent sensory deficits. Conclusion: Chronic N ₂ O abuse can cause permanent neurological damage if not treated promptly. Clinical staff should be aware of the various presentations of neurotoxicity related to N ₂ O abuse.