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

Background: Nitrous oxide (N2O) is a commonly used inhaled anesthetic in outpatient dental procedures. However, the increasing recreational use of N2O 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 N2O abuse in pediatric patients. Methods: Patients under 20 years of age who were diagnosed with N2O-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 N2O abuse can cause permanent neurological damage if not treated promptly. Clinical staff should be aware of the various presentations of neurotoxicity related to N2O abuse. (C) 2018 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.