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Inhaled nitrous oxide-induced functional B12 deficiency
  1. Yorissa Padayachee,
  2. Chris Richards and
  3. Owen Morgan
  1. Emergency Medicine, Imperial College Healthcare NHS Trust, London, UK
  1. Correspondence to Dr Yorissa Padayachee; yorissap5{at}


Recreational nitrous oxide (N2O) is commonly used among young people partly due to its low cost and accessibility, and awareness of its potential adverse effects is poor in this group. One such adverse effect is degeneration of the spinal cord due to its disruption of DNA synthesis by inactivating cobalamin (B12).

A 19-year-old man presented to the emergency department with a 4-week history of worsening paraesthesia in his fingers and lower limbs, and weakness in the hands and lower limbs for 2 weeks. On examination, he had an ataxic gait, reduced power of grip strength and ankle movements, and impaired sensation in the lower limbs. An MRI brain and spine revealed myelopathy of the cervical and thoracic cord.

On further questioning, he reported recreational N2O inhalation. His symptoms improved after stopping this and he was treated with supplementation of B vitamins. Education strategies regarding the risks of N2O misuse are indicated.

  • vitamins and supplements
  • drug misuse (including addiction)
  • drugs misuse (including addiction)
  • spinal cord

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  • Contributors YP wrote the background, introduction, parts of the discussion, inserted and labelled the figures, edited the manuscript and added information to the other two author’s sections. CR wrote the case presentation, follow up and the learning points. OM wrote the rest of the discussion and the summary and obtained consent from the patient. All three authors contributed to the summary, reference list, layout and final editing of the report. YP was also responsible for submitting the case report and making changes to the returned manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.