SHM Converge Scientific Abstract ePoster Gallery-Whippets Wreck the Spine: Case of a Reversible Cause of White Matter Lesions

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This case report describes nitrous oxide (“whippets”)-induced subacute combined degeneration (SCD), a reversible myelopathy caused by functional vitamin B12 inactivation. A 47-year-old woman presented with two months of progressive bilateral leg weakness, numbness, and gait instability. Her husband had recently developed similar neurologic symptoms, which raised concern for a shared toxic exposure.<br /><br />On examination, she had severe proximal lower-extremity weakness, sensory loss below the mid-thighs, impaired proprioception, positive Romberg sign, and abnormal reflexes. Her serum vitamin B12 was low at 71 pg/mL. Cervical spine MRI showed classic long-segment, symmetric dorsal column T2 hyperintensity from C1 to C6 without enhancement or cord compression, consistent with SCD.<br /><br />The initial differential diagnosis included nutritional neuropathy, alcohol-related neurotoxicity, demyelinating disease, and infection. Diagnosis was clarified only after a more complete social history revealed frequent recreational nitrous oxide use shared with her spouse. Nitrous oxide oxidizes and inactivates cobalamin, disrupting methionine synthase activity, myelin maintenance, and DNA synthesis. This produces clinical and MRI findings that can resemble ordinary B12 deficiency.<br /><br />The patient was treated with daily intramuscular cyanocobalamin, stopped nitrous oxide exposure, and began physical therapy. She showed meaningful neurologic improvement within three weeks, including better leg strength and gait stability.<br /><br />The report emphasizes that nitrous oxide use is an increasingly common and under-recognized cause of myelopathy. It highlights the importance of asking detailed substance-use and environmental exposure questions, especially when multiple household members present with similar neurologic complaints. Early recognition, B12 replacement, and exposure cessation can lead to substantial recovery.

Asset Subtitle

Brandon M. Block

Meta Tag

Author List Brandon M. Block, Cody Jinnette, Kevin Kessler

Category Clinical Vignettes

Concept Nitrous Oxide Abuse

Concept Vitamin B12

Concept Subacute Combined Degeneration

Concept Myelopathy

Concept Dorsal Column

Distinguished Non-Finalist

Presenter Organization Indiana University School of Medicine

Presenting Author Brandon M. Block

Track Adult

Keywords

nitrous oxide

subacute combined degeneration

vitamin B12 deficiency

myelopathy

dorsal column hyperintensity

cervical spine MRI

cobalamin inactivation

gait instability

neurologic symptoms

cyanocobalamin treatment

Nitrous Oxide Abuse

Vitamin B12

Subacute Combined Degeneration

Myelopathy

Dorsal Column