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Neurological picture
Recreational nitrous oxide-associated neurotoxicity
  1. Kate Johnson1,
  2. Philopatir Mikhail1,2,
  3. Myong Gyu Kim2,
  4. Annmarie Bosco2,
  5. William Huynh1,2,3
  1. 1Institute of Neurological Sciences, Prince of Wales Hospital, Sydney, New South Wales, Australia
  2. 2Prince of Wales Clinical School, University of New South Wales, Sydney, New South Wales, Australia
  3. 3Brain and Mind Centre, University of Sydney, Camperdown, New South Wales, Australia
  1. Correspondence to Dr William Huynh, Institute of Neurological Sciences, Prince of Wales Hospital, Sydney, New South Wales 2747, Australia; w.huynh{at}

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A previously healthy 21-year-old woman presented with subacute onset of confusion and gait ataxia. She reported habitual inhalation of nitrous oxide (N2O) purchased online over the past year, with increased consumption over the preceding weeks of up to 300 canisters/week. Examination revealed pale skin with diffuse hyperpigmented macular patches over the trunk (figure 1) and atrophic glossitis. Cognitive impairment was evident with impaired insight, orientation, short-term memory and attention. She had impaired limb proprioception with sensory ataxia and positive Romberg’s test. Distal limb power was significantly reduced with milder weakness proximally and globally depressed reflexes.

Figure 1

(A) Hyperpigmented maculopapular rash distributed diffusely over the back and neck. (B) Sagittal and (C) axial T2-weighted images demonstrating hyperintensity in the cervical cord region with an ‘inverted V sign’ classical of subacute combined degeneration of the spinal cord.

Laboratory testing demonstrated low …

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  • Contributors KJ, PM and MGK: patient management, manuscript preparation, editing and revision. AB: patient management and manuscript revision. WH: patient management, supervision, manuscript preparation and editing.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Detail has been removed from this case description/these case descriptions to ensure anonymity. The editors and reviewers have seen the detailed information available and are satisfied that the information backs up the case the authors are making.

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