The effects of nitrous oxide on vitamin B12 and homocysteine levels in methyltetrahydrofolate reductase gene mutation

Whippets Causing Vitamin B12 Deficiency

On the rise due to its effects of euphoria, recreational use of nitrous oxide can cause severe neurologic symptoms caused by marked and rapid onset of vitamin B12 deficiency. This is a case of a young 34-year-old male who presented with an inability to walk and confusion caused by vitamin B12 deficiency in the setting of recreational nitrous oxide use.

Myelopathy Secondary to Vitamin B12 Deficiency Induced by Nitrous Oxide Abuse

Nitrous oxide (N₂O), a colorless gas known to have abuse potential, can induce vitamin B12 deficiency that eventually leads to peripheral neuropathy, central nervous demyelination, and myelopathy. N₂O abuse has rarely caused subacute combined degeneration of the spinal cord despite being reported in a few studies. Although numerous published studies have demonstrated the toxic effects of N₂O abuse, it is still a controversial topic of debate among neurologists. We outline a case of a patient presenting with acute onset of numbness who was ultimately diagnosed with myelopathy secondary to vitamin B12 deficiency induced by nitrous oxide abuse. This case report emphasizes the early diagnosis and management of vitamin B12 deficiency to prevent the severe complications associated with it.

Association between preoperative serum homocysteine and delayed neurocognitive recovery after non-cardiac surgery in elderly patients: a prospective observational study

BACKGROUND

Homocysteine, folate, and vitamin B₁₂ involved in 1-carbon metabolism are associated with cognitive disorders. We sought to investigate the relationships between these factors and delayed neurocognitive recovery (dNCR) after non-cardiac surgery.

METHODS

This was a prospective observational study of patients (n = 175) who were ≥ 60 years of age undergoing non-cardiac surgery. Patients were evaluated preoperatively and for 1 week postoperatively by using neuropsychological tests and were divided into dNCR or non-dNCR groups according to a Z-score ≤ - 1.96 on at least two of the tests. The relationship between the occurrence of dNCR and preoperative levels of homocysteine, folate, and vitamin B₁₂ was analyzed. Univariate and multivariable logistic regression analyses were conducted to identify factors associated with dNCR.

RESULTS

Delayed neurocognitive recovery was observed in 36 of 175 patients (20.6%; 95% confidence interval [CI], 14.5-26.6%) 1 week postoperatively. Patients who developed dNCR had significantly higher median [interquartile range (IQR)] homocysteine concentrations (12.8 [10.9,14.4] μmol/L vs 10.6 [8.6,14.7] μmol/L; P = 0.02) and lower folate concentrations (5.3 [4.2,7.3] ng/mL vs 6.9 [5.3,9.5] ng/mL; P = 0.01) than those without dNCR. Compared to the lowest tertile, the highest homocysteine tertile predicted dNCR onset (odds ratio [OR], 3.9; 95% CI, 1. 3 to 11.6; P = 0.02), even after adjusting for age, sex, education, and baseline Mini Mental State Examination.

CONCLUSIONS

Elderly patients with high homocysteine levels who underwent general anesthesia for non-cardiac surgery have an increased risk of dNCR. This knowledge could potentially assist in the development of preventative and/or therapeutic measures.

TRIAL REGISTRATION

NCT03084393 ( https://www.clinicaltrials.gov ).

Nitrous Oxide-Induced Vitamin B12 Deficiency Resulting in Myelopathy

Nitrous oxide, primarily used in the medical field and in the food industry, can cause symptoms of euphoria and analgesia. Recreational use of nitrous oxide is rising, as are reports of its adverse effects, including neurologic complaints secondary to an evoked vitamin B12 deficiency. We outline a case of a patient presenting with several neurologic symptoms and found to have myelopathy secondary to vitamin B12 deficiency in the presence of prolonged recreational nitrous oxide use. 

Complications caused by nitrous oxide in dental sedation

The first clinical application of nitrous oxide (N₂O) was in 1844, by an American dentist named Horace Wells who used it to control pain during tooth extraction. Since then, N₂O has shared a 170-year history with modern dental anesthesia. N₂O, an odorless and colorless gas, is very appealing as a sedative owing to its anxiolytic, analgesic, and amnestic properties, rapid onset and recovery, and, in particular, needle-free application. Numerous studies have reported that N₂O can be used safely and effectively as a procedural sedation and analgesia (PSA) agent. However, N₂O can lead to the irreversible inactivation of vitamin B12, which is essential for humans; although rare, this can be fatal in some patients.