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• Response
  Alexis Demas
  Published on: 2 September 2023

• Published on: 2 September 2023

  Response

  • Alexis Demas, Neurologist Groupe Hospitalier du Havre

  I read the article by Alvar Paris et al. with great interest. The consumption of nitrous oxide (N2O) has recently surfaced as an exponentially growing form of recreational abuse, particularly among students, due to its euphoric effects and accessibility. The European Monitoring Centre for Drugs and Drug Addiction has expressed concern in a recent report about the recreational use of N2O in Europe. 1
  The most common neurological complications associated with N2O consumption are toxic polyneuropathy and subacute combined degeneration of the spinal cord (N2O-SACD), which may occur concurrently— a critical aspect that should not be overlooked. Initial clinical descriptions of N2O-SACD were reported in 2015 and complicated episodic use mediated through canisters. 2 Recently, the market for N2O distribution has expanded with diverse consumption accessories. The introduction of larger cylinders facilitates the consumption of significant amounts of N2O, posing younger individuals at an elevated risk of early and severe Vitamin B12 deficiency along with systemic complications. Consequently, new complications associated with N2O intoxication have been described, and their wide-ranging effects are regularly emphasized in the literature.
  Beyond psychiatric symptoms like hallucinations, cognitive impairments including Gayet-Wernicke's encephalopathy have been recently reported. 3 These deficiencies are mediated by Vitamin B1 levels, suggesting a risk of broader deficie...

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  I read the article by Alvar Paris et al. with great interest. The consumption of nitrous oxide (N2O) has recently surfaced as an exponentially growing form of recreational abuse, particularly among students, due to its euphoric effects and accessibility. The European Monitoring Centre for Drugs and Drug Addiction has expressed concern in a recent report about the recreational use of N2O in Europe. 1
  The most common neurological complications associated with N2O consumption are toxic polyneuropathy and subacute combined degeneration of the spinal cord (N2O-SACD), which may occur concurrently— a critical aspect that should not be overlooked. Initial clinical descriptions of N2O-SACD were reported in 2015 and complicated episodic use mediated through canisters. 2 Recently, the market for N2O distribution has expanded with diverse consumption accessories. The introduction of larger cylinders facilitates the consumption of significant amounts of N2O, posing younger individuals at an elevated risk of early and severe Vitamin B12 deficiency along with systemic complications. Consequently, new complications associated with N2O intoxication have been described, and their wide-ranging effects are regularly emphasized in the literature.
  Beyond psychiatric symptoms like hallucinations, cognitive impairments including Gayet-Wernicke's encephalopathy have been recently reported. 3 These deficiencies are mediated by Vitamin B1 levels, suggesting a risk of broader deficiencies beyond Vitamin B12. Physicians should be vigilant about potential cognitive and psycho-behavioral deficiencies. Neuropsychological assessments and proactive identification of cognitive sequelae are crucial.
  To physical health risks, one must also consider the risks of co-addiction to psychoactive substances, as well as psychosocial risks like anxiety and depression that may complicate N2O consumption. The risk of road accidents should also be highlighted.
  Radiologically, the described MRI findings appear to be related to a higher density of myelinated fibers in the fasciculus gracilis in the cervical area. This can explain the patients' sensory disorders like numbness and ataxia. However, muscle weakness and pyramidal signs often accompany these sensory disorders, pointing to a close association with pyramidal tract fibers. Frequent signal abnormalities in the lateral corticospinal tracts on axial MRI series have been noted. This emerging neuroradiological pattern aligns with recent descriptions of frequent motor disorders and warrants further analysis.
  Physicians must be aware of the evolving spectrum of neurological complications associated with N2O intoxication, as well as their radiological characteristics. A surge in case incidence is anticipated due to its rapidly growing utilization.

  References
  1. https://www.emcdda.europa.eu/publications/rapid-communication/recreation...
  2. Ernst LD et al. Longitudinally Extensive Myelopathy With Novel Radiographics Features. JAMA Neurology. 2015 Nov;72(11):1370-1
  3. Amir Garakani et Al. Neurologic, psychiatric, and other medical manifestations of nitrous oxide abuse: A systematic review of the case literature. Am J Addict. 2016 Aug;25(5):358-69.

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  Conflict of Interest:
  None declared.

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