Persistent cognitive functioning deficits in operating rooms: two cases

Case report: Subacute combined degeneration of the spinal cord due to nitrous oxide abuse

Background

Nitrous oxide (N₂O) is an increasingly popular recreational drug. N₂O irreversibly disturbs the metabolism of vitamin B₁₂, resulting in a functional deficiency. Vitamin B₁₂ is vital for myelin synthesis and its deficiency primarily produces neurological complications. Inhaling N₂O is more common and neurological complications are more evident than before.

Case presentation

We report a young man who developed progressive limb numbness and unsteady walking after N₂O abuse. The dominant diagnosis was subacute combined degeneration of the spinal cord (SCD). The patient was admitted to the hospital and given adenosylcobalamin treatment, but his symptoms progressed significantly from before and he developed acute cognitive impairment. After methylprednisolone combined with vitamin B₁₂ treatment, symptoms significantly improved.

Conclusion

Clinicians need to understand the presentation and treatment of SCD caused by N₂O abuse. When symptoms progress despite conventional vitamin B₁₂ therapy, the combination of methylprednisolone and vitamin B₁₂ may be considered.

Effect of hyperbaric oxygen therapy on cognitive dysfunction induced by nitrous oxide abuse: protocol of a randomised, double-blinded, placebo-controlled trial

INTRODUCTION

The cognitive dysfunction associated with nitrous oxide abuse is gradually becoming a major global public health concern. Despite the increasing prevalence of nitrous oxide abuse, there are currently no authorised/approved treatment options. Hyperbaric oxygen therapy (HBOT) has been proven to be an efficient method to improve cognitive function. The current randomised, double-blinded, placebo-controlled trial will explore the effect of HBOT on cognitive dysfunction induced by nitrous oxide abuse.

METHODS AND ANALYSIS

Eighty participants who abuse nitrous oxide and have cognitive dysfunction, including memory decline, disorientation, attention deficits, slower reactions and learning disabilities, will be included in the trial. They will be randomly assigned to receive either HBOT or sham-HBOT 90-120 min once daily for 5 days per week for 2 weeks. The primary outcome will be the improvement in the total score of the MATRICS Consensus Cognitive Battery, which will measure comprehensive cognitive function between the two groups. Additionally, attention will be measured by integrated visual and auditory continuous performance tests, executive function will be measured by the Wisconsin card sorting test, intelligence will be measured by Raven's standard progressive matrices and cognitive control will be measured by the Stroop colour word interference test.

ETHICS AND DISSEMINATION

This protocol was approved by the West China Hospital of Sichuan University Biomedical Research Ethics Committee. The report of the study will be disseminated via scientific forums including peer-reviewed publications and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry (ChiCTR2100047111).

Acute cognitive disorder as the initial manifestation of nitrous oxide abusing: a case report

Nitrous oxide (N₂O) is a colorless, odorless gas used as an anesthetic and analgesic. It is also abused as a recreational drug, and such abuse is associated with neurological disorders and psychiatric complications such as myelopathy and, rarely, cognitive impairment. Its abuse has not been associated with acute cognitive decline. Here, we report a young girl who presented with acute cognitive impairment after excessive recreational inhalation of nitrous oxide and who recovered completely after vitamin B₁₂ supplementation. We conclude that nitrous oxide abuse can cause acute cognitive impairment, and that this diagnosis should be considered if a patient initially presents with acute cognitive decline.