SHM Converge Scientific Abstract ePoster Gallery-Not Just a Laugh: Hidden Danger of Nitrous Oxide Abuse

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This case report describes a 17-year-old male with longstanding nitrous oxide (“laughing gas”/“whippits”) use who presented with 4 days of bilateral lower-extremity numbness and paresthesias, sudden ataxia, gait instability, and genital sensory loss. Extensive infectious and neurologic evaluation for conditions such as Guillain-Barré syndrome and transverse myelitis was negative. MRI of the cervical spine showed bilaterally symmetric posterior medial cord abnormalities consistent with subacute combined degeneration (SCD). Although serum vitamin B12 was low, the report emphasizes that nitrous oxide can cause a functional B12 deficiency even when serum levels appear normal. This occurs because nitrous oxide irreversibly oxidizes and inactivates vitamin B12, impairing myelination and other B12-dependent metabolic pathways. Elevated methylmalonic acid and homocysteine supported the diagnosis.<br /><br />The patient was treated with intramuscular cyanocobalamin 1000 mcg every 48 hours for 6 weeks, then oral B12 daily, along with intensive physical therapy. He improved slowly in sensation and ambulation during hospitalization.<br /><br />The authors highlight that SCD from nitrous oxide abuse should be considered in adolescents with neurologic symptoms, even if serum B12 is normal. The case underscores the importance of asking about substance use, using a HEADSS assessment, and providing counseling about nitrous oxide’s neurologic risks.

Asset Subtitle

Dalia Breziner

Meta Tag

Author List Adrienne Tran, Claire Godenzi, Dalia Breziner, Laura Henkle, Sheila Nguyen

Category Clinical Vignettes

Concept Nitrous Oxide Abuse

Concept Functional Vitamin B12 Deficiency

Concept Subacute Combined Degeneration

Concept Vitamin B12 Inactivation

Concept Neurologic Symptoms

Distinguished Non-Finalist

Presenter Organization UC Irvine School of Medicine

Presenting Author Dalia Breziner

Track Pediatric

Keywords

nitrous oxide abuse

subacute combined degeneration

vitamin B12 deficiency

adolescent neurologic symptoms

methylmalonic acid

homocysteine elevation

cervical spine MRI

paresthesias

ataxia

functional B12 deficiency

Nitrous Oxide Abuse

Functional Vitamin B12 Deficiency

Subacute Combined Degeneration

Vitamin B12 Inactivation

Neurologic Symptoms