Nitrous oxide-induced toxic leukoencephalopathy

Neuropsychiatric disorders associated with recreational nitrous oxide use

BACKGROUND

Recreational nitrous oxide use has grown in popularity among young people and has become a serious public health problem. Chronic use of nitrous oxide can lead to a functional vitamin B12 deficiency and neuropsychiatric complications.

PURPOSE

This study aimed to investigate the characteristics of neuropsychiatric complications associated with nitrous oxide use and to enhance clinicians' awareness of this public health problem.

METHODS

We retrospectively reviewed 16 patients with neuropsychiatric disorders related to nitrous oxide use who were treated in our hospital from June 2021 to October 2022. Their demographics, clinical features, investigations, treatments and outcomes were analyzed.

RESULTS

There were ten males and six females between the ages of 17 and 25 with a mean age of 20.5 ± 2.6 years. Thirteen patients sought medical help from the neurology clinic. Two patients presented to the psychiatric department and one patient presented to the emergency department with acute cognitive impairment. All 16 patients presented with neurological symptoms, such as paresthesia in four limbs or the lower limbs, unsteady gait and weakness. Twelve patients developed psychiatric symptoms, such as hallucinations, agitation, depression, emotional indifference and personality changes. Twelve patients had vitamin B12 deficiency. All 16 patients had hyperhomocysteinemia. Fourteen patients showed abnormal high signal on T2-weighted imaging and an inverted "V" sign in axial view, mainly involving the cervical cord. Neuropsychiatric symptoms improved with vitamin B12 treatment and cessation of nitrous oxide use in all cases.

CONCLUSION

Young adults are predominately involved in recreational use of nitrous oxide, which can cause neuropsychiatric complications. The clinical response to vitamin B12 supplementation and cessation of nitrous oxide use is generally good. Clinicians should recognize nitrous oxide use as a public health problem and a cause of a wide range of neuropsychiatric symptoms, particularly in younger patients.

A Systematic Review of Recreational Nitrous Oxide Use: Implications for Policy, Service Delivery and Individuals

BACKGROUND

Nitrous oxide (N₂O) is a dissociative anaesthetic that is sometimes used recreationally. The prevalence of N₂O use is difficult to quantify but appears to be increasing. Research on N₂O harms and application of harm reduction strategies are limited. The aim of this mixed method systematic review was to collate and synthesise the disparate body of research on recreational nitrous oxide use to inform harm reduction approaches tailored for young people.

METHODS

To identify publications reporting the recreational use of N₂O, a search of public health, psychology and social science databases was conducted. Databases included PubMed, CIHNAL, PsycINFO, Scopus and Web of Science. Grey literature and Google advanced search were also used. Due to limited published literature on the recreational use of N₂O, no limit was placed on publication date or study type. A thematic synthesis extracted descriptive and analytical themes from the selected studies. Quality appraisal was conducted using the CASP Tool for Qualitative studies and the Joanna Briggs Institute case report assessment tool.

RESULTS

The search retrieved 407 reports. Thirty-four were included in the final analysis, including sixteen case reports. The included studies were primarily concerned with raising awareness of the apparently increasing use and subsequently increasing harms of recreational N₂O use. There was limited reference to policy or legislative responses in any published studies, no suggestions for harm reduction strategies or application of service level responses. In general, individuals lack awareness of N₂O-related harms.

CONCLUSION

The review found three key areas that deserve further consideration including: (1) policy, (2) service delivery, and (3) harm associated with N₂O use. We recommend a top-down (policy) and bottom-up (services delivery/services users) approach to harm reduction for N₂O use which also includes further consultation and research with both groups. Future research could explore young people's experience of N₂O use including benefits and problems to inform contextually relevant harm reduction strategies.

Clinical epidemiological characteristics of nitrous oxide abusers: A single-center experience in a hospital in China

PURPOSE

This study investigated the clinical epidemiological characteristics of nitrous oxide (N₂ O) abusers in a hospital in China, which have not been systematically reported.

METHODS

The characteristics of patients abusing N₂ O who were examined and treated at the Affiliated Hospital of Xuzhou Medical University from January 2017 to December 2020 were analyzed.

RESULTS

A total of 61 patients (average age: 21.7 ± 3.2 years; 42 male and 19 female) were enrolled; 60.7% of the patients had an education level of high school or lower, and most (59.0%) had no stable occupation. The mean exposure time was 8.5 ± 7.7 months (range: 1-36 months). Only 52.5% of the abusers reported the physician of the relevant exposure history at the first time of visiting the doctor. The main clinical type was mixed (49.2%). The most common clinical manifestation was distal limb numbness (80.3%). The most frequent outcome was peripheral neuropathy (59%) and subacute combined degeneration (36%). Serum homocysteine level was elevated in 67.5% (27/40) of the patients, while 44.4% (20/45) showed reduced vitamin B12. Note that 61% (22/36) showed abnormal signals in the posterior or lateral funiculus of the spinal cord, and 97% (31/32) of the patients showed peripheral nerve damage by electromyography. In all cases, symptoms were alleviated after halting N₂ O intake and receiving nutritional neurotherapy.

CONCLUSIONS

N₂ O abuse can lead to nervous system damage, especially peripheral nerve and spinal cord damage. A full understanding of its clinical epidemiological characteristics is helpful for clinicians to make a timely and clear diagnosis.

A rise in cases of nitrous oxide abuse: neurological complications and biological findings

BACKGROUND

The recent lockdown due to the COVID-19 pandemic has been linked to a higher incidence of psychiatric manifestations and substance abuse. The recreative use of nitrous oxide is more and more widespread and neurological complications are frequent.

METHODS

We report clinical characteristics and biological findings of five consecutive patients presenting to our tertiary care center between April 2020 and February 2021 with various neurological symptoms occurring after recent nitrous oxide abuse.

RESULTS

Our patients presented with subacute combined degeneration of the spinal cord (4/5 patients) or with acute inflammatory demyelinating polyneuropathy (1/5 patients). No patient had reduced vitamin B-12 titer, but all had elevated blood levels of homocysteine and methylmalonic acid. This reflects the functional deficit in vitamin B-12 that can be linked to nitrous oxide consumption. After vitamin B-12 supplementation, clinical signs regressed at least partially in all 5 patients.

CONCLUSION

We report an elevated incidence of neurological complications of nitrous oxide abuse occurring during the recent COVID-19 lockdown. Nitrous oxide abuse should be tracked down in patients presenting with compatible neurological symptoms and elevated homocysteinemia. Vitamin B-12 should be supplemented as soon as the diagnosis is made.