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.
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