Up: The rise of nitrous oxide abuse. An international survey of contemporary nitrous oxide use

Subacute combined degeneration from nitrous oxide abuse

Nitrous oxide is an anesthetic medication which can also be recreationally abused in the form of whippet canisters. Its prolonged abuse can interfere with Vitamin B12 metabolism and lead to its functional deficiency. We report a case of a 30-year-old male who presented with generalized weakness and was found to have subacute combined degeneration (SCD) of the spinal cord. His laboratory workup showed low Vitamin B12 with elevated homocysteine and methylmalonic Co-A levels, and further questioning revealed prolonged nitrous oxide abuse. Nitrous oxide causes functional inactivation of methylcobalamin by rendering it unable to function as a coenzyme for methionine synthase enzyme. This leads to the decreased production of methionine and subsequent production of myelin. This case describes nitrous oxide abuse as an important etiology to be considered in patients presenting with weakness and myeloneuropathy and describes important imaging findings.

High lifetime prevalence of regular nitrous oxide use in French medical students

Background: Although nitrous oxide (N₂O) is increasingly misused recreationally, its use and risks among medical students who have professional access to it are rarely explored.Objectives: To investigate the recreational use of N₂O among medical students in Paris Region (France).Methods: This cross-sectional study used an online questionnaire distributed in 2022 through social networks, to all medical students (undergraduate student from the 2nd year of medical studies to residents until the end of the residency) from the six medical universities in Paris Region. We collected demographic characteristics, patterns of N₂O consumption, co-consumptions, and N₂O training (academic course or self-training). Factors associated with N₂O consumption and complications were analyzed using multivariable logistic regressions.Results: The questionnaires of 444 students (mean age: 25.9 years (SD = 2.69), 75.5% female, and 63.74% residents) were analyzed. Recreational N₂O consumption was reported by 71.85% of students and 20.50% consumed at least monthly. N₂O consumption was associated with being a resident (versus undergraduate student) (adjusted OR (aOR) = 3.07[1.45-6.72]; p < .01), receiving training on N₂O (aOR) = 3.13[1.84-6.24]; p < .01), and consumption of cannabis (aOR = 18.21[3.47-104.26]; p < .01), ecstasy (aOR = NA, p = .048) and poppers (aOR = 13.9[2.64-77.94]; p < .01). Complications (mainly dizziness, paresthesia and burns) were reported in 8.15% of students consuming N₂O. They were associated with consuming more than 10 balloons per intake (aOR = 6.04[1.32-25.00); p < .01) and inversely associated with receiving training (aOR = 0.35[0.14-0.86]; p = .01).Conclusions: Almost three-quarters of medical students experienced recreational N₂O consumption, particularly with poly-drug use. Given that complications were associated with high consumption and lack of education, risk training and screening for N₂O consumption could be beneficial.

Acute psychotic and vitamin B12 deficiency in patient with nitrous oxide misuse: A case report

Nitrous oxide, also called nitrous monoxide, or nitrous oxide, is a colorless and odorless gas, without toxicological effect, but it can be asphyxiating at high concentration, its misuse is increasing especially among young people. Chronic use of N2O may cause psychiatric complications, including depression, hypomania, and paranoid psychosis with visual and auditory hallucinations. We present a case of nitrous oxide abuse "laughing gas" in 25 years old woman with bizarre behavior delusions and hallucinations with a normal neurological examination. The patient had low levels of vitamin B12 (135 pmol/L). Treatment with antipsychotics and vitamin B12 (cobalamin) resolved her psychosis. In addition to the hematological and neurological effects, rare cases of acute psychosis, especially in young people with or without psychiatric history, use varies from 1 month to years. Clinicians are increasingly in need of knowledge regarding the misuse of nitrous oxide.

Treatment Seeking Nitrous Oxide Users in Addiction Care: A Comparison with Cocaine Users on Clinical and Treatment Characteristics

INTRODUCTION

Over the past decade, frequent use of large quantities of nitrous oxide (N2O) has become more common in the Netherlands. Although N2O poses several negative health consequences for a subgroup of problematic N2O users, there is a lack of knowledge on what characterizes these intensive users. This study therefore aims to provide the demographic and substance use characteristics and experiences during treatment of treatment seeking problematic N2O users and to compare this with a matched group of treatment-seeking problematic cocaine users.

METHODS

A retrospective chart review was performed of patients who were referred for treatment of problematic N2O use at a large Dutch addiction care facility from January 2020 to September 2022, extracting demographics, pattern of use and follow-up data. Additionally, a subgroup of N2O users was propensity-score matched (1:1) with a subgroup of treatment seeking problematic cocaine users, both groups excluding users with substance use disorders or frequent use of substances other than N2O and cocaine, respectively.

RESULTS

128 patients with a N2O use disorder were included in the total sample and a subgroup of 77 N2O-only users was propensity-score matched on age and sex to 77 cocaine-only users. N2O users were typically young (mean age 26.2 years), male (66.4%), unmarried (82.9%), with a low education level (59.0%) and born in the Netherlands (88.2%), with parents born in Morocco (45.3%). N2O was used intermittently (median 10 days/month, IQR 4.0-17.5 days) and often in very large quantities (median 5 kg [ca. 750 balloons] per average using day, IQR 2-10 kg). Compared to the patients with a cocaine use disorder, matched N2O users were lower educated, more often from Moroccan descent, and less likely to be alcohol or polysubstance users. Despite receiving similar treatments, N2O users were twice as likely to discontinue treatment before completion compared to cocaine users (63 vs. 35%, p = 0.004).

CONCLUSION

Treatment-seeking problematic N2O users are demographically different from treatment-seeking problematic cocaine users and are much more likely to dropout from psychological treatment. Further research is needed into the needs and other factors of problematic N2O users that relate to poor treatment adherence in problematic N2O users.

Nitrous oxide tank cold burn to the forearm: a case study and discussion of the literature

Nitrous oxide (N 2 O) has become one of the most popular recreational drugs in Europe. While N 2 O is often used in medical settings as an analgesic and anaesthetic agent, its recreational use was documented many years before its introduction into clinical practice. The desired effects from inhaling N 2 O for recreational purposes include rapid feelings of relaxation, calmness and euphoria, which can be accompanied by giddiness and laughter. There are various adverse effects associated with N 2 O use, including headache, nausea, vomiting, drowsiness and the development of permanent neurological damage. Furthermore, its use is associated with cold burns and road accidents. This article details the case of a patient who sustained an N 2 O tank burn to his forearm from recreational use. It also discusses the prevalence, legal status and adverse effects of N 2 O use as well as the pathophysiology and management of cold burn injuries.

Quantitative determination of nitrous oxide in human blood by HS-GC-MS: forensic application of two fatal poisoning cases

Nitrous oxide (N2O), also known as laughing gas, has a euphoric effect and is becoming increasingly popular as a recreational inhalant drug. Deaths caused by recreational nitrous oxide abuse are rare, but may still occur. Although some methods for the quantification of N2O by GC-MS have been reported, elimination of carbon dioxide interference and the choice of a suitable internal standard remain current limitations to accurate N2O quantification. Here, a validated method using headspace-gas chromatography-mass spectrometry (HS-GC-MS) is described that allows the quantification of N2O in human blood samples: sodium hydroxide is used to remove carbon dioxide, and n-pentane is chosen as a suitable internal standard. Collectively, the validation results show a good linear relationship of N2O in blood within the concentration range of 0.02 ∼ 0.5 mL/mL and an LOD of 0.005 mL/mL. Subsequent application of the validated method to two real mortality cases due to N2O intoxication provided reference values for blood concentrations in forensic cases. Other biological specimens (gaseous samples and tissues) of the deceased were also analyzed to demonstrate that the deaths were caused by asphyxia due to the inhalation of N2O.

Multidisciplinary rehabilitation following recreational nitrous oxide (N2O) misuse: evaluating service provision and rehabilitation outcomes in a cohort with serious disability

Purpose: Recreational nitrous oxide (N2O) misuse is increasing globally. Chronic misuse can cause neurological impairments that require rehabilitation, though literature characterising rehabilitation is limited. This study aimed to evaluate rehabilitation service provision for impairments resulting from N2O misuse. Methods: A retrospective audit of hospitalised patients referred for rehabilitation for N2O toxicity was conducted between 2015 and 2022 at a single metropolitan hospital. Data were collected via medical record audit and analysed via descriptive and non-parametric statistics. Results: 16 eligible cases were identified, aged 18-43 years (50% female/male), with increasing case frequency. 12 cases received inpatient rehabilitation episodes for multifactorial sensorimotor, cognitive and psychosocial impairments. Cases articulated diverse rehabilitation goals and received intervention from a median of 6 clinical disciplines. All cases required assistance to mobilise or perform self-care activities on admission. Functional Independence Measure (FIM) scores significantly improved with rehabilitation (median FIM 84[75-93] to 117[112-123], p < .001). Despite gains in independence, all cases required referral for ongoing rehabilitation post-discharge. Conclusions: Demand for inpatient rehabilitation for disabling N2O toxicity appears to be increasing. In this series, cases were young, exhibited serious impairments, and had multidisciplinary rehabilitation needs. Inpatient rehabilitation led to significant functional improvements, though ongoing disability was evident post-discharge.

Nitrous oxide abuse in a 21-year-old female: a case report and review of literature

The abuse of nitrous oxide (N2O) poses a substantial public health challenge. In many countries, including China, regulations governing the utilization and accessibility to N2O remain ambiguous, particularly within the food industry. Here, we report a case of a 21-year-old female who presented with symptoms of subacute combined degeneration (SCD) of the spinal cord due to N2O abuse. The patient exhibited bilateral lower limb numbness and weakness, low serum vitamin B12 levels with elevated homocysteine levels, and lumbar spine magnetic resonance imaging (MRI) revealed abnormal signals of the spinal cord. Following cessation of N2O and comprehensive therapy including methylcobalamin and nerve growth factor, the symptoms significantly improved. A follow-up examination 3 months later showed good progress in gait stability. At a 5-year follow-up, the patient's previous clinical symptoms had completely disappeared, and her quality of life had returned to normal. This case underscores the urgency of raising awareness and prevention of N2O abuse, emphasizing the importance of timely diagnosis and comprehensive treatment for patient recovery. Clear formulation and enforcement of relevant regulatory measures are equally crucial in reducing instances of abuse.

Marked increase in severe neurological disorders after nitrous oxide abuse: a retrospective study in the Greater Paris area

BACKGROUND

Recreational nitrous oxide (N2O) use has become more widespread worldwide, leading to an increase in myelopathies and peripheral neuropathies. The aim of this study was to describe clinical and socioeconomical characteristics of severe N2O-induced (NI) neurological disorders (NI-NDs), to determine its incidence in the Greater Paris area and to compare it with that of similar inflammatory neurological disorders.

METHODS

We performed a retrospective multicentric cohort study of all adult patients with severe NI-NDs in the neurology and general internal medicine departments of the Greater Paris area from 2018 to 2021. The incidence was compared with that of non-NI-myelitis and Guillain-Barré syndrome (GBS) using a sample of 91,000 hospitalized patients sourced from health insurance data.

RESULTS

Among 181 patients, 25% had myelopathy, 37% had peripheral neuropathy and 38% had mixed disease. Most were aged between 20 and 25 years, lived in socially disadvantaged urban areas, and exhibited high rates of unemployment (37%). The incidence of NI-NDs increased during 2020 and reached a peak mid-2021. The 2021 incidence in 20-25-year-olds was 6.15 [4.72; 8.24] per 100,000 persons for NI-myelopathy and 7.48 [5.59; 9.37] for NI-peripheral neuropathy. This was significantly higher than for non-NI-myelitis (0.35 [0.02; 2.00]) and GBS (2.47 [0.64; 4.30]). The incidence of NI-NDs was two to three times higher in the most socially disadvantaged areas.

CONCLUSION

The recent increase in recreational N2O use has led to a rise in the incidence of severe NI-NDs, particularly in young adults with low socioeconomic status for whom NI-NDs strongly outweigh similar neurological disorders.

An Episode of Psychosis After Nitrous Oxide Abuse During a Pandemic: A Case Report

The abuse of inhalants like nitrous oxide (N2O), readily available worldwide, has remained a prominent public health problem during the last few decades. Literature reveals increased use during the previous pandemic, particularly regarding recreational use. There is limited evidence-based data available to relate the abuse of N2O with psychosis. Therefore, this case report of a 22-year-old adult with no previous psychiatry history, reportedly abusing 75-100 canisters of N2O per day during the last pandemic COVID-19 lockdown, highlights the relationship between (N2O) abuse and the symptoms evolved including delusions, auditory hallucinations, and disorganized cognition. All the laboratory findings and results from imaging modalities were inconsistent for any organic cause of the symptoms. The case then underwent treatment with antipsychotic medications and a multidisciplinary model, which improved the symptoms gradually. The case, in particular, discusses N2O abuse, which is widespread in European Union countries, including the UK and the Republic of Ireland, and its chronic use puts one at a higher risk of developing psychosis, personality changes, affective lability, anxiety, depression, cognitive impairment, and myeloneuropathy. The sale of N2O for its psychoactive properties is prohibited in many countries, including the Republic of Ireland, as per legislation. However, N2O is not a controlled drug, meaning it is not a crime to possess N2O. This case report manifests the psychopathy caused by abuse of N2O, which would further attract specialists in the field to conduct epidemiological studies for prevention at the primary level.

Does nitrous oxide addiction exist? An evaluation of the evidence for the presence and prevalence of substance use disorder symptoms in recreational nitrous oxide users

BACKGROUND

Prevalence of nitrous oxide (N2 O) use appears to be increasing in numerous countries worldwide, and excessive use has been associated with physical and mental problems. Because there currently is no consensus whether N2 O has addictive potential, we aimed to evaluate the evidence for the presence and prevalence of DSM-5 substance use disorder (SUD) symptoms in N2 O users.

ANALYSIS

A literature search was conducted to assess the evidence for the presence of any of the 11 DSM-5 SUD symptoms in N2 O users and the prevalence experiencing those symptoms. A substantial part of the studied N2 O users use more than intended (i.e. 46% to 98%) and spend a substantial amount of time using N2 O. At least some of the studied N2 O users experience interpersonal problems (i.e. 13% to 80%) and use N2 O in risky situations, such as driving under the influence. Evidence for the other criteria is either insufficient or inconclusive.

CONCLUSIONS

The literature base for the presence and prevalence of DSM-5 substance use disorder (SUD) symptoms in nitrous oxide (N2 O) users is limited and largely consists of qualitative studies and case studies, but it provides consistent evidence for the presence of at least four SUD criteria in heavy N2 O users. N2 O could well be addictive and should be treated as a potentially addictive substance until systematic assessments can provide evidence-based guidance to users, healthcare professionals and legislators.

Substance use disorder of equimolar oxygen-nitrous oxide mixture in French sickle-cell patients: results of the PHEDRE study

BACKGROUND

In many countries, nitrous oxide is used in a gas mixture (EMONO) for short-term analgesia. Cases of addiction, with significant misuse, have been reported in hospitalized patients. Patients suffering from sickle cell disease (SCD) could represent a high-risk population for substance use disorder (SUD) due to their significant pain crisis and repeated use of EMONO. The objective of the PHEDRE study was to assess the prevalence of SUD for EMONO in French SCD patients.

RESULTS

A total of 993 patients were included. Among 339 EMONO consumers, only 38 (11%) had a SUD, with very few criteria, corresponding mainly to a mild SUD due to a use higher than expected (in quantity or duration) and relational tensions with the care teams. Almost all patients (99.7%) were looking for an analgesic effect, but 68% of patients were also looking for other effects. The independent risks factors associated with at least one SUD criterion were: the feeling of effects different from the expected therapeutic effects of EMONO, at least one hospitalization for vaso occlusive crisis in the past 12 months and the presence of a SUD for at least one other analgesic drug.

CONCLUSIONS

The use of EMONO was not problematic for the majority of patients. Manifestations of SUD that led to tensions with healthcare teams should alert and lead to an evaluation, to distinguish a true addiction from a pseudoaddiction which may be linked to an insufficient analgesic treatment related to an underestimation of pain in SCD patients.

TRIAL REGISTRATION

Clinical Trials, NCT02580565. Registered 16 October 2015, https://clinicaltrials.gov/.

Nitrous oxide induced subacute combined degeneration of the spine cord: A case report

RATIONALE

In recent years, recreational use of inhaled nitrous oxide (N2O) is on the increase among young people, accompanied by a corresponding rise in reports about its toxicity. Subacute combined degeneration of the spine cord (SCD) is the typical clinical picture of the nervous system disorder caused by N2O intoxication, as a result of metabolic disturbance of vitamin B12.

PATIENT CONCERNS, DIAGNOSES, INTERVENTIONS AND OUTCOMES

We report a 28-year-old female of SCD due to prolonged use of N2O, presented with paresthesia and unsteady in walking progressing within 1 month. Symptoms gradually improved with the treatment of intramuscular injections of hydroxocobalamin combined with N2O abstinence, and the patient recovered completely with normal neurological examination after 4 months of follow-up.

LESSONS

Clinicians should be aware of the clinical features and pathogenesis of SCD caused by N2O intoxication in order to lead effective treatment as soon as possible. Recreational N2O use should always be considered as an etiology when dealing with patients presented with myelopathy and/or neuropathy suspected of vitamin B12 deficiency.

Physiologic Effects of Substance Use

Physiologic and psychological effects of substance use are common occurrences. They may be the proximate purpose of the exposure or related to an unintended complication. Acute short-term exposure effects may not be the same as long-term effects. These effects are mediated by different receptors they act on and the homeostatic changes that occur due to repeat exposure. We review in this article the physiologic and psychological effects from exposure to commonly encountered drugs, ethanol, sedative hypnotics, cocaine, amphetamines, marijuana, opioids, nicotine, hydrocarbons (halogenated and non-halogenated), and nitrous oxide.

Nitrous-oxide-induced polyneuropathy and subacute combined degeneration of the spine: clinical and diagnostic characteristics in 70 patients, with focus on electrodiagnostic studies

BACKGROUND AND PURPOSE

Nitrous oxide (N2 O) induced neurological symptoms are increasingly encountered. Our aim is to provide clinical and diagnostic characteristics with a focus on electrodiagnostic studies.

METHODS

Patients with neurological sequelae due to N2 O presenting in our hospital between November 2018 and December 2021 reporting clinical and diagnostic data were retrospectively reviewed.

RESULTS

Seventy patients (median 22 years) were included. Median N2 O usage was 4 kg/week during 12 months. Patients' history revealed a higher rate of sensory symptoms compared to motor (97% vs. 57%) and 77% walking difficulties. Clinical diagnosis was polyneuropathy (PNP) in 44%, subacute combined degeneration (SCD) of the spine in 19%, both in 37%. Median vitamin B12 level was low (159 pmol/L), normal in 16%. The median methylmalonic acid was increased (2.66 μmol/L). Electrodiagnostic abnormalities were observed in 91%, with 72% fulfilling axonal PNP criteria, 20% showing mild to intermediate slowing. One patient fulfilled demyelinating PNP criteria not related to N2 O abuse (Charcot-Marie-Tooth type 1a). More prominent motor nerve conduction abnormalities were found; lower limbs were more affected. In 64% with normal conduction, myography showed signs of axonal loss. Magnetic resonance imaging showed cervical myelopathy in 58% involving generally five to six segments.

CONCLUSIONS

Nitrous oxide (N2 O) leads to neurological symptoms by causing PNP and/or SCD primarily involving the legs. Distinguishing PNP and SCD clinically was shown to be insufficient. Electrodiagnostic studies showed axonal PNP. Demyelinating PNP due to N2 O abuse was not present in our cohort. Therefore, further diagnostic work-up is warranted if demyelinating features are present.

The use of nitrous oxide whippets as a recreational drug: Hidden health risks

Whipped cream canisters, also known as nitrous oxide whippets, are traditionally used in the culinary arts to prepare food foams. In recent years, however, these gas canisters have been cracked open and inhaled to produce a "legal" high. Users of these whippets have reported the presence of an oily residue containing metallic particles. This contamination was investigated using liquid chromatography-, gas chromatography- and inductively coupled plasma-mass spectrometry (ICP-MS) and optical emission spectrometry (ICP-OES). The particulate matter was also analyzed by scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectroscopy (EDX). The presence of cyclohexyl isothiocyanate was confirmed at a maximum concentration of 67 μg per whippet. ICP-MS and ICP-OES analysis revealed the presence of mainly iron and zinc, but also, traces of aluminum, chromium, cobalt, nickel, and lead were found. STEM-EDX analysis confirmed the presence of nano-sized particles containing iron and zinc. When simulating inhalation, using the multiple path particle dosimetry model, it was confirmed that these nano-sized particles can reach the deeper parts of the lungs. Most users assume that inhaling a food-grade nitrous oxide whippet for a "legal" high poses no risks. However, this research shows that users are exposed to cyclohexyl isothiocyanate, a substance classified as a respiratory sensitizer. The presence of zinc in the particulate matter could potentially be linked to lung lesions.

Nitrous Oxide Inhalant Abuse: Preliminary Results from a Cross-Sectional Study on Knowledge, Attitudes, and Practices of Italian Physicians (2023)

Background and Objectives: Nitrous oxide (N2O) has recently emerged as a cheap alternative to other recreational substances. Although legally available, its chronic use is associated with severe neurological and hematological complications due to the irreversible inactivation of vitamin B12. While no reliable data on abuse of N2O in Italy have been provided to date, we assessed the knowledge, attitudes, and practices of Italian medical professionals on the management of N2O abuse cases. Materials and Methods: A cross-sectional study was performed as a web-based survey through a series of Facebook discussion groups (targeted medical professionals: 12,103), and participants were specifically asked about their previous understanding of N2O abuse and whether they had or not any previous experience in this topic. Results: A total 396 medical professionals participated in the survey. Overall, 115 participants had previous knowledge about N2O abuse (29.04%), with higher odds for professionals with a background in emergency medicine (adjusted odds ratio (aOR) 3.075; 95% confidence intervals (95%CI) 1.071 to 8.828) and lower for specialists in psychiatry (aOR 0.328; 95%CI 0.130 to 0.825). Knowledge status on N2O abuse was largely unsatisfying, as knowledge status, reported as a percent value, was estimated to 45.33% ± 24.71. Having previously managed a case of N2O abuse was associated with higher risk perception of the actual severity of this condition (aOR 5.070; 95%CI 1.520 to 16.980). Conclusions: Our study suggests that N2O poisoning cases are occurring in Italian settings but are not reasonably reported to national authorities. As substantial knowledge gaps of Italian medical workforces were identified, we cannot rule out that the actual abuse of N2O in the population may be far larger than currently suspected.

Imaging Aspects of Toxic and Metabolic Myelopathies

Metabolic and toxic myelopathies usually occurs due to several different causes. Metabolic myelopathy usually occurs due to deficiency of a nutrient, such as vitamin B12. Toxic myelopathy occurs secondary to the exposure to an external toxic agent. Although they may have a difficult diagnosis, determination of the specific cause of myelopathy is of utmost importance, because many causes are amenable to treatment. Although they have many clinical, electrophysiologic, and neuropathologic similarities, imaging may aid in the suspicion of toxic or metabolic myelopathy. The aim of this article, is to review the imaging features of the main toxic and metabolic myelopathies.

Hereditary Neuropathy With Liability to Pressure Palsy Detected During the Use of Recreational Drugs

Background: Nitrous oxide (N2O) has been an increasingly popular recreational drug over the past few years. Abuse is associated with severe neurological complications and even fatal outcomes. Purpose: Here we present a case of chronic nitric oxide abuse in a teenager presenting with rapidly progressive mixed sensory and motor polyneuropathy. Results: The initial diagnostic workup excluded electrolyte derangement, heavy metal intoxication, autoimmune neuropathy, myopathy, hematological disorders, and thyroid disease. On further questioning, patient reported 8-months of inhalation of nitrous oxide, commonly known as "whippets". Subsequent tests revealed low Vitamin B12 and elevated homocysteine level. Eventual genetic test demonstrated a heterozygous deletion in the gene that encodes the peripheral myelin protein 22 (PMP22), consistent with a diagnosis of Hereditary Neuropathy with Liability to Pressure Palsies (HNPP). Conclusion: The association of neurologic and genetic findings with the timeline of nitrous oxide inhalation suggests a multifactorial etiology of her symptoms, with the N2O acting as a trigger to the axonal degeneration and demyelination detected on electrodiagnostic studies.

The efficacy and tolerability of inhaled nitrous oxide in major depressive disorder: a systematic review and meta-analysis

BACKGROUND

Nitrous oxide (N2O) has been initially confirmed by clinical trials to benefit to patients with major depressive disorder (MDD). However, there needs to be a meta-analysis to compare the efficacy and tolerability of N2O in MDD.

METHODS

PubMed, EMBASE, and Cochrane Library were searched for relevant studies up to Jan 1st, 2023. The meta-analysis mainly compared the outcome of the change in depression severity scores, response, remission, and adverse events in patients with MDD receiving 50% N2O and placebo.

RESULTS

Four studies with 133 patients were eventually identified. We found that the N2O group and control group showed an overall significant difference in the change in depression severity score for patients at 2 h, 24 h, and 2 weeks or more (2 h, SMD =  - 0.64, 95% CI - 0.01 to - 0.28, p < 0.0001) (24 h, SMD =  - 0.65, 95% CI - 1.01 to - 0.29, p < 0.0001) (2 weeks, SMD =  - 0.76, 95% CI - 1.16 to - 0.36, p < 0.0001). For the response and remission rate, the long-term effect of N2O was also statistically significant (for the response, RR = 2.33, 95% CI 1.23 to 4.44, p = 0.01) (for the remission, RR = 4.68, 95% CI 1.49 to 14.68, p = 0.008). For safety outcomes, patients treated with N2O had higher odds of nausea or vomiting (RR = 10.15, 95% CI 1.96 to 52.59, p = 0.009).

CONCLUSION

Our study suggested that N2O has a rapid and long-lasting antidepressant effect in patients with MDD. However, the efficacy of lower or titrated concentration of N2O should be further investigated.

Functional vitamin B12 deficiency is a consistent feature in hospital admissions for neurological disorders due to the use of nitrous oxide

Introduction: Misuse of inhaled nitrous oxide is a growing concern in France. It is known to alter concentrations of vitamin B12, which is required as a cofactor for methionine synthase and methylmalonyl-CoA mutase activity. Hence, measurement of the concentrations of cobalamin metabolism biomarkers, including vitamin B12, homocysteine, and methylmalonic acid, could assist in the management of patients with a complex clinical presentation or in those who deny the consumption of nitrous oxide.Methods: We retrospectively collected clinical and biological data in patients hospitalized for nitrous oxide use in a university hospital in southern France between January 2020 and October 2022.Results: Thirty-one patients were identified during 34 months; 79% were men with a median age of 23.7 years. Most (97%) presented with peripheral polyneuropathy and/or myelopathy. The median vitamin B12 concentration was 134.6 pmol/L, with 17 of 31 patients having values less than 145 pmol/L (the lower limit of the normal range). The median plasma folate concentration was 20.1 nmol/L, which is within the normal range. The median plasma homocysteine concentration was 87.7 µmol/L (normal range <15 µmol/L), and the median plasma methylmalonic acid concentration was 3.8 µmol/L (normal range <0.5 µmol/L).Conclusion: Nitrous oxide use is an emerging public health problem in France, as shown by the number of patients admitted to our hospital. The presence of a functional vitamin B12 deficiency was a consistent feature that could be helpful in diagnosis in complex cases.

From Medical Analgesic to Recreational Use: A Rare Case of Acute Myelitis Caused by Laughing Gas Abuse

Nitrous oxide, commonly known as laughing gas, which is originally intended to be used in various industries as well as for legitimate medical purposes, has unfortunately come to be used recreationally. However, it is crucial to recognize that the seemingly innocent recreational use of nitrous oxide can have serious repercussions on one's health. When consumed in excessive quantities and for prolonged periods, this substance can lead to serious adverse effects. In this article, we shed light on the abuse potential of the substance by discussing a distressing case of a young nitrous oxide user who developed severe myelitis.

Pushing boundaries or adding a gimmick to the party? Young people's experiences of nitrous oxide use in Denmark

Nitrous oxide (N₂O) use for intoxication among young people has increased in many parts of the Western world, including Denmark. The literature, however, primarily focusses on harms related to N₂O use, and not on other aspects, for example modes of administration or effects such as different forms of pleasure or fun. Therefore, despite this increase, we still know very little about how and why young people use nitrous oxide for intoxication, including their experiences of N₂O intoxication. Based on 45 qualitative interviews with young Danes age 18-25 years, who all were former or present N₂O users, we explore their experiences of N₂O intoxication. We do this by analyzing in-depth descriptions of where, how and with whom they use N₂O. When analyzing these descriptions in relation to different modes of administration, intensity of use, combination with other substances (e.g. alcohol, cannabis), and use in different settings, we argue that N₂O intoxication is experienced differently by the young participants. Some of the participants also searched for particular intoxication experiences with N₂O. We unfold the participants' various descriptions of intoxication by differentiating between moderate and intensive use. Overall, our study shows that these differences in N₂O use for intoxication are not equally risky or harmful. In general, young people's own perspectives and experiences with (illegal) drug use is increasingly emphasized as important to include when developing preventive interventions. Our analysis of the young participants' differing experiences with N₂O for intoxication can inform future prevention initiatives in relation to harms of N₂O intoxication.

Severe length-dependent peripheral polyneuropathy in a patient with subacute combined spinal cord degeneration secondary to recreational nitrous oxide abuse: A case report and literature review

Nitrous oxide abuse can have detrimental effects on the central and peripheral nervous systems. This case study report aims to demonstrate a combination of severe generalized sensorimotor polyneuropathy and cervical myelopathy related to vitamin B₁₂ deficiency following nitrous oxide abuse. We present a clinical case study and literature review examining primary research-published between 2012 and 2022-reporting nitrous oxide abuse affecting the spinal cord (myelopathy) and peripheral nerves (polyneuropathy); 35 articles were included in the review with a total of 96 patients, where the mean "patients" age was 23.9 years and were in a 2:1 male/female ratio. Of the 96 cases, within the review, 56% of patients were diagnosed with polyneuropathy, most commonly impacting the nerves of the lower limb (62%), while 70% of patients were diagnosed with myelopathy, most commonly impacting the cervical region (78%) on the spinal cord. In our clinical case study, a 28-year-old male underwent a multitude of diagnostic investigations for bilateral "foot drop" and sense of lower limb stiffness as ongoing complications of a vitamin B₁₂ deficiency secondary to recreational nitrous oxide abuse. Both the literature review and our case report emphasize the dangers of recreational nitrous oxide inhalation, colloquially termed "nanging" and the risks it presents to both the central and peripheral nervous systems, which is erroneously considered by many recreational drug users to be less harmful than other illicit substances.

Use of the Rehabilitation Treatment Specification System (RTSS) in the management of nitrous oxide (N2O)-induced spinal cord injury

Nitrous oxide (N₂O) is an inhaled anaesthetic gas and a popular intoxicant. Excessive recreational use can cause spinal cord myelopathy. Previous studies have discussed the medical management. However, none have specified the sensorimotor rehabilitation management. This case report documents the investigations, physical rehabilitation and functional outcomes in two cases of N₂O-associated myelopathy. Both presented with lower limb strength and sensorimotor integration impairments resulting in ataxic ambulation. Dorsal column signal abnormality was observed on T2-weighted MRI in one case. Myelopathy was diagnosed based on clinical presentation and both were treated with vitamin B₁₂ Rehabilitation was conceived and specified using the Rehabilitation Treatment Specification System (RTSS). Both cases achieved independent indoor gait on hospital discharge, and full function at 9 months in one case. Appropriate and timely medical management and reasoned rehabilitation provided excellent functional outcomes for N₂O-related myelopathy. By using the RTSS, reasoned rehabilitation efficacy can be tested in the future.

Nitrous oxide abuse leading to extreme homocysteine levels and thrombosis in young adults: a case series

BACKGROUND

Neurologic complications from recreational use of nitrous oxide (N₂O), which are attributed to vitamin B12 deficiency, have been well documented. With increasing dosages and frequency of N₂O use, an additional association with thromboembolisms is becoming apparent.

OBJECTIVES

To assess thrombotic complications of recreational N₂O use.

METHODS

All medical charts at the largest hospital in Amsterdam were searched for N₂O use and subsequent neurologic and/or thrombotic events. For patients with thrombotic events, we extracted data on the risk factors for arterial and venous thrombosis as well as serum vitamin B12 and homocysteine concentrations.

RESULTS

Between January 2015 and May 2021, 326 patients who reported recreational use of N₂O were identified; of these, 17 (5%) patients presented with severe thrombotic events associated with N₂O (71% men; median age, 26 years [range, 18-53 years]), 5 patients presented with arterial thrombosis (3 with acute coronary syndrome, 1 with femoral artery thrombosis, and 1 with middle cerebral artery thrombus), and 12 patients presented with venous thromboembolisms (10 with pulmonary embolisms, 1 with portal vein thrombosis and 1 with cerebral vein thrombosis). Additionally, homocysteine were concentrations severely increased (median, 125 μmol/L [range, 22-253 μmol/L]; reference, <15 μmol/L). Patients reported use of 400 to 6000 g (ie, 50-750 balloons) of N₂O in 1 day. Fifty percent of these patients had experienced neurologic symptoms before the thrombotic event.

CONCLUSION

We describe an alarming incidence of serious thrombotic events among young adults after excessive recreational use of N₂O, accompanied by extremely high homocysteine concentrations. The upward trend in the recreational use of N₂O warrants more awareness of its dangers among both users and medical professionals. Furthermore, these findings could reopen the discussion on possible associations between hyperhomocysteinemia and thrombosis mediated through N₂O.

A Case Report of Subacute Combined Degeneration Due to Nitrous Oxide-Induced Vitamin B12 Deficiency

Nitrous oxide, also known as "laughing gas," is a naturally occurring gas that is colorless, odorless, nonflammable, and nontoxic. It has been used as an inhalant anesthetic in the medical field for more than 150 years for dental and surgical procedures. Due to its wide availability and ability to cause euphoria, its recreational use is on the rise. We present a case of subacute combined degeneration (SCD) due to nitrous oxide-induced vitamin B12 deficiency. The patient presented with bilateral lower extremity paresthesia, weakness, and ataxic gait. The patient was found to have vitamin B12 deficiency. An MRI of the cervical spine revealed an abnormal T2 signal within the cervical spinal cord extending from the level of C2-C6 affecting only the posterior column. On the fifth day of hospitalization, the patient reported that he had been inhaling nitric oxide from whipped cream cans for recreational use. According to his clinical presentation and laboratory and imaging findings, we concluded that the patient had SCD. The patient slowly improved after receiving vitamin B12 supplementation therapy. Patients presenting with paresthesia, weakness, and laboratory studies indicating vitamin B12 deficiency should be questioned about nitrous oxide recreational use since the incidence is increasing.

A man in his twenties with weakness and numbness in his legs

Neuropathy can have many causes, some less well known than others. In this article, we present the case of a young man with progressive neurological deficit over several months. The cause was found to be an increasing social problem.

The Inverse Lhermitte Phenomenon Suggests Nitrous Oxide-Induced Myelopathy: Case Report and Review of the Literature

Nitrous oxide-induced myelopathy is a relatively well-known clinical entity. Less well-known, however, is the rare inverse Lhermitte phenomenon, where neck flexion elicits an ascending, rather than descending, electric shock-like sensation. This is a characteristic symptom and sign that may occur in nitrous oxide toxicity. In this article, we present the case of a patient who was admitted to our hospital with suspected Guillain-Barré syndrome due to her ascending numbness and unsteady gait. We describe her examination and laboratory features leading to the correct diagnosis, along with a historical review of the various subtypes of the Lhermitte phenomenon and the pathophysiology of nitrous oxide-induced myelopathy.

A cross-sectional study: Nitrous oxide abuse in Parisian medical students

BACKGROUND AND OBJECTIVES

Nitrous oxide (N₂ O) has euphoric properties, which are associated with an alarming increasing misuse. A lack of data exists regarding medical students. The objectives are: (i) evaluate the prevalence of N₂ O use and N₂ O use disorder (NUD) among French medical students, (ii) assess whether education about addictions has an impact on consumption, (iii) draw up clinical profiles of N₂ O users with or without NUD, (iv) identify factors associated with use and NUD.

METHODS

A cross-sectional study among medical students at Université de Paris, using an online questionnaire.

RESULTS

Out of the 981 medical students (29% of the total medical students) who completed the questionnaire, 80% had used N₂ O. 19% had a mild use disorder, 4% moderate, and 1% severe. N₂ O use was significantly associated with the use of poppers (p < .0005), alcohol (p < .0005), and cocaine (p = .004). Factors significantly associated with NUD were alcohol use disorder (p = .017), male gender (p = .006), and being part of a student association (p = .0130).

DISCUSSION AND CONCLUSION

This survey shows a high prevalence of N₂ O use and NUD among medical students. It could be explained by the N₂ O pharmacokinetic profile or by a perception of "harmlessness." We also identified associated risk factors that may be useful to better identify and treat students seeking help.

SCIENTIFIC SIGNIFICANCE

This is the first study to evaluate the use of this product among medical students. The evaluation of factors impacting use and dependence is also new in this population, which is at risk of misuse of substances.

Nitrous oxide: a unique official French addictovigilance national survey

Introduction

Nitrous oxide has become over the last few years a public health problem in many countries. France has a dedicated health monitoring system dedicated to the surveillance of the abuse, dependence and consequences associated with the use of psychoactive substances coordinated by the French National Agency for the Safety of Medicines and Health Products.We present the French national survey of nitrous oxide.

Materials and methods

We analyzed all the cases with nitrous oxide from 2012 to 2021: number of notifications, characteristics of the subjects and consumption, consequences reported and their evolutions over time. In addition, we have made a special focus on the four main complications reported.

Results

A total of 525 cases were received with an exponential increase since 2019. We observed changes in the characteristics of the notifications with an increase in the proportion of women [42.7% in 2021 vs. 30.8% in 2020 (p = 0.02)]; an increase in the quantities consumed (use of cylinders); a negative evolution of the contexts of use with a search for self-therapeutic effects and use in violent contexts; an increasing trend of the severity of cases [78.1% in 2021 vs. 70.0% in 2020 (p = 0.07)].The main effects were substance use disorders and/or associated criteria (82.5%), neurological disorders (75.4%), psychiatric symptoms (15.4%) and cardiovascular events (8.6%). In terms of evolution, we observed a significant increase in cases with a use disorder and an increase in neurological complications. Moreover, new serious effects, notably cardiovascular events were reported.

Discussion

The combination of high availability, varied effects from euphoria to relief of discomfort in a stressful global pandemic context and the development of dependence could explain the rapid growth of consumption and the seriousness of the cases.It must now be taken into account that (i) Substance use disorders are associated with nitrous oxide consumption; (ii) clinicians must consider "nitrous oxide" in young subjects presenting different types of manifestations; and (iii) stopping consumption is imperative and is the first treatment. In this context, an addictological assessment must also be carried out.

Nitrous oxide intoxication: systematic literature review and proposal of new diagnostic possibilities

Background

Nitrous oxide (N2O), also called “laughing gas,” is the most commonly used inhalation anesthetic in dentistry. The N2O is no longer used, because of the long-term neurologic and cardiovascular sequelae. Due to its sedative and euphoric properties, N2O is often used for recreational use or in some erotic activities. Accidental deaths are mainly associated with the uses of N2O: death can occur from sudden cardiac arrhythmia or, most commonly, acute asphyxiation due to hypoxia. This paper aims to study the literature concerning deaths due to N2O intoxication and highlight pathological findings useful for diagnosis when the crime scene investigation does not reveal any evidence.

Materials and methods

The authors conducted the literature search by PubMed and Scopus databases, searching for articles from 1 January 1970 to 1 March 2020 using the key terms: “Nitrous oxide,” “Laughing gas,” “Hypoxic damage,” “Nitrous oxide anesthesia,” and “Nitrous oxide death.”

Results and discussion

A total of 244 articles were collected. Only 26 articles were included in the systematic review. Most of the deaths from intoxication are due to asphyxiation; the diagnosis is often difficult and immunohistochemistry could be helpful. Nitrous oxide increases the intracellular adhesion molecule expression, E- and P-Selectin (markers of the early inflammatory response), and HIF-1 α (indicative of oxidative stress during ischemia-reperfusion).

Conclusion

The macroscopic and microscopic signs of N2O intoxication are non-specific, but N2O has been proven to cause hypoxic damage to the brain. The suspicion of the presence of the gas in the environment should guide the pathologist. Tissue analyzes provide important information; immunohistochemical stains can confirm hypoxic damage through the use of markers such as HIF-1 α, E-Selectin, and P-Selectin.

Co-Occurring Subacute Combined Degeneration and Guillain-Barré Syndrome Resulting From Nitrous Oxide Abuse: A Case Report

Growing in prevalence as a recreational drug of abuse across a broad scope of people, nitrous oxide (N₂O) has proven to be a public health concern. Side effects of its abuse have a great degree of variation among people ranging from neurologic, psychiatric, and medical symptoms. We present a rare case of a 23-year-old female with a history of N₂O abuse, who presented with symptoms of both subacute combined degeneration syndrome (SCD) and Guillain-Barré syndrome (GBS). She presented with three weeks history of progressive bilateral lower extremity weakness, burning and tingling sensation, difficulty walking, and falls. This patient underwent an extensive medical workup upon hospitalization. Notable findings of the magnetic resonance imaging (MRI) of her cervical spine showed an abnormal cervical cord signal intensity pattern typical for vitamin B₁₂ deficiency and her lumbar puncture showed albuminocytological dissociation, which confirmed the diagnosis of GBS. For these conditions, this patient was successfully treated with weekly vitamin B₁₂ injections and five treatments of plasmapheresis. Her condition was additionally complicated by worsening anxiety and depression, which were treated with gabapentin, escitalopram, trazodone, hydroxyzine, and melatonin. She demonstrated great clinical improvement with almost complete resolution of her symptoms at the time of her hospital discharge. This case highlights the easy accessibility, addiction potential, and adverse consequences related to N₂O abuse.

Mechanisms Involved in the Neurotoxicity and Abuse Liability of Nitrous Oxide: A Narrative Review

The recreational use of nitrous oxide (N₂O) has increased over the years. At the same time, more N₂O intoxications are presented to hospitals. The incidental use of N₂O is relatively harmless, but heavy, frequent and chronic use comes with considerable health risks. Most importantly, N₂O can inactivate the co-factor cobalamin, which, in turn, leads to paresthesia's, partial paralysis and generalized demyelinating polyneuropathy. In some patients, these disorders are irreversible. Several metabolic cascades have been identified by which N₂O can cause harmful effects. Because these effects mostly occur after prolonged use, it raises the question of whether N₂O has addictive properties, explaining its prolonged and frequent use at high dose. Several lines of evidence for N₂O's dependence liability can be found in the literature, but the underlying mechanism of action remains controversial. N₂O interacts with the opioid system, but N₂O also acts as an N-methyl-D-aspartate (NMDA) receptor antagonist, by which it can cause dopamine disinhibition. In this narrative review, we provide a detailed description of animal and human evidence for N₂O-induced abuse/dependence and for N₂O-induced neurotoxicity.

Case report: Recreational nitrous oxide abuse triggered peripheral neuropathy possibly through the immune-mediated pathogenesis

Nitrous oxide (N2O), commonly known as laughing gas, is widely used in clinical practice and food industry. However, an increasing number of young people have been abusing N2O for recreational purpose, resulting in many functional disorders and sometimes irreversible nerve damage. We present the case of a 20-year-old N2O abuser who gradually developed peripheral neuropathy after continuously inhaling N2O for 2 months. The neurological symptoms of the patient had kept exacerbation for the next 2 months until she came for medical care sitting in a wheelchair. We suggested the patient halting N2O intake and supplementing methylcobalamine according to the standardized protocol. Her symptoms had partly recovered during the following 2 weeks but remained unchanged in another 2 weeks. Antibodies against ganglioside complexes were detected and anti-GM1 IgM antibodies were positive in both cerebrospinal fluid and serum. Intravenous immunoglobulin was given as an additional treatment and the patient's symptoms had significantly recovered further. The patient discharged walking by herself. Then she has been continuously followed up in outpatient department for the next 4 months and taking steroid hormone as well as methylcobalamine. Her symptoms gradually disappeared and all the electrophysiological parameters significantly improved. With this case we were able to show that N2O-related peripheral neuropathy is not only a metabolic disorder but also an immune-mediated disease. N2O intake can trigger a mimic Guillain-Barré syndrome.

Strukturelle Gehirnveränderungen und Läsionen durch den Konsum illegaler Drogen und Psychedelika

Drogen können sowohl die Funktion wie auch die Struktur des Gehirns verändern. Gelegentlicher oder regelmäßiger Drogenkonsum ist in der Bevölkerung weit verbreitet. Daher ist die Kenntnis möglicher Nebenwirkungen und charakteristischer Bildbefunde bei Untersuchungen des Gehirns für den klinischen Alltag wichtig. Dieser Artikel beschreibt die für die am weitesten verbreiteten Substanzen typischen Komplikationen und morphologisch-radiologischen Veränderungen. Zu den möglichen Pathomechnismen gehören neurotoxische Effekte, die zu Leukenzephalopathie oder Hirnatrophie führen können, und vaskuläre Komplikationen wie Vasokonstriktion, Vaskulitis oder Hypertonus, durch die es zu intrazerebralen Blutungen oder Infarkten kommen kann. Da die klinische Präsentation oft unspezifisch ist, und die betroffenen Patienten ihren Drogenkonsum häufig verschweigen, ist das Erkennen typischer Bildbefunde essentiell für eine zuverlässige Diagnosestellung und zielgerichtete Therapie.

Becoming a nitrous oxide user on social media: Learning to maximise pleasures and minimise harms

BACKGROUND

In his classic work 'Becoming a marihuana user', Howard Becker (1953) showed how drug use learning occurred in social interactions and settings, which in turn shape drug use. Today, social media offers people opportunities to learn about drugs without physical proximity. In this paper, we identify nitrous oxide (N₂O) users' key concerns about how to maximise pleasures and minimise harms, as expressed on the social media platform Reddit. In doing so, we consider what learning about N₂O online might mean for the provision of drug education in an era of internet technology.

METHOD

Data are drawn from a Reddit page (subreddit) dedicated to N₂O use. We undertook thematic analysis of 655 threads contributed in late-2020. The subreddit is conceptualised as an internet-mediated social world that constitutes drug user knowledges, practices and identities, rather than simply reflecting them.

RESULTS

Our analysis uncovers practices not previously been reported in academic literature or health information on N₂O, such as breathing techniques to maximise the effects and use of filters to reduce exposure to oil residue. While education resources often describe effects as 'mild', users recounted intense pleasures including euphoria, anaesthesia, sensory distortion, hallucination and epiphanies, especially when N₂O was used with other drugs. Subreddit members were deeply concerned to minimise the risk of harms. Yet official health advice regarding N₂O was not referenced, some misinterpretation of scientific literature was apparent and drug treatment was almost never suggested when people recounted harms.

CONCLUSION

In contrast to official health resources, the subreddit offers members practical advice on harm reduction. It provides opportunities for users of N₂O to position themselves as playful, informed and caring curators of drug use pleasures. We highlight the need for those formulating drug education to engage with the knowledge, practices and identities that emerge within internet-mediated social worlds.

Clinical feature and sural biopsy study in nitrous oxide-induced peripheral neuropathy

Objective

The objective was to analyze the clinical characteristics and pathological characteristics of sural biopsy in nitrous oxide (N₂O) -induced peripheral neuropathy.

Methods

We recruited 18 patients with N₂O abuse-induced neurological disorders and reported their demographic data, clinical manifestations, laboratory examinations, and nerve conduction studies. Seven patients underwent sural nerve biopsy pathologic examination.

Results

All 18 patients had polyneuropathy, the nerve conduction results showed significant reductions in motor and sensory amplitudes, slowing of conduction velocities, and prolongation of latencies in most tested nerves compared to the controls. Toluidine blue staining of semi-thin sections of sural nerve biopsy showed decreased myelinated nerve fiber density, increased thin myelinated nerve fiber density, and axonal regeneration. Electron microscopy showed axonal degeneration and nerve regeneration.

Conclusion

The main manifestations of peripheral nerve damage caused by the abuse of N₂O are lower limb weakness and distal sensory disorder. The nerve conduction study results demonstrated that mixed axonal and demyelinating neuropathy was the most common type of neuropathy. Sural biopsy showed the main pathological change was chronic axonal degeneration.

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.

Peripheral polyneuropathy and acute psychosis from chronic nitrous oxide poisoning: A case report with literature review

RATIONALE

Nitrous oxide (NO) is a commonly used drug in medical practice, restoration, and the automobile industry. Recreational abuse is an emerging public health problem owing to its accessibility and drug properties.

PATIENT CONCERNS

A 25-year-old male was hospitalized with acute psychosis and lower-extremity sensorimotor proprioceptive ataxia due to nitrous oxide abuse.

DIAGNOSIS

Laboratory studies confirmed a vitamin B12 deficiency. Magnetic resonance imaging of the spinal cord showed normal findings. Electrophysiological testing confirmed length-dependent sensorimotor polyneuropathy, with a predominant motor component and axonal degeneration.

INTERVENTION AND OUTCOMES

Abstinence from toxic substances was suggested, and vitamin B12 substitution was introduced. The patient was lost to follow up.

LESSONS

Nitrous oxide toxicity is multisystemic and is thought to result from vitamin B12 inactivation. Recent case reports postulated direct paranodal lesions resulting from nitrous oxide consumption. Neurological, neuropsychiatric, and hematological toxicities are among those explored in this case report. Correction of the functional vitamin B12 status and nitrous oxide abstinence are essential in the treatment process.

Nitrous oxide for the treatment of psychiatric disorders: A systematic review of the clinical trial landscape

OBJECTIVE

To systematically review published research studies and ongoing clinical trials investigating nitrous oxide (N₂ O) in psychiatric disorders, providing an up-to-date snapshot of the clinical research landscape.

METHODS

A comprehensive literature search was conducted for studies published until June 2021 using the OVID databases (MEDLINE, Embase, APA PsycInfo) and the clinical trial registries (ClinicalTrials.gov, ICTRP).

RESULTS

In total, five relevant published articles were identified, among which four investigated N₂ O for depression. One single-dose randomized controlled trial (RCT) for treatment-resistant depression (TRD), one triple crossover RCT comparing 50% vs. 25% N₂ O for TRD, and one repeated-dose RCT for major depressive disorder (MDD) suggest that N₂ O has preliminary feasibility with rapid-acting effects on symptoms of depression. From the public registries, 10 relevant ongoing clinical trials were identified. They aim to explore the use of N₂ O for MDD, post-traumatic stress disorder, bipolar disorder, obsessive-compulsive disorder, and suicidal ideation. To date, the typical treatment protocol parameters were a single session of 50% N₂ O delivered for 60 min, although the concentration of 25% is also being explored. Projected enrolment numbers for ongoing trials (M = 55.0) were much higher than sample sizes for published studies (M = 13.0), suggesting that there potentially will be more large-scale RCTs published in the next few years.

CONCLUSION

Preliminary studies support the feasibility of administering N₂ O for depression; however, appropriate blinding is a critical challenge. Larger-scale RCTs with repeated doses of N₂ O and follow-up times beyond 1 month are needed to confirm the feasibility, therapeutic efficacy, and sustainability of response.

Increasing recreational nitrous oxide use: Should we worry? A narrative review

BACKGROUND

Since 2000, the prevalence of recreational nitrous oxide (N₂O) use has increased in the Western world. Although N₂O is a relatively safe drug, the overall increase in the use of N₂O has concomitantly also initiated a modest but important increase in the number of young excessive users. The recent introduction of large 2 kg N₂O tanks, allowing high and prolonged dosing, has facilitated this excessive use. This is of concern, because repeated exposure to high doses of N₂O for a prolonged time is known to induce neurological damage, such as (irreversible) neuropathy and paralysis due to N₂O-induced vitamin B₁₂ deficiency. The increasing trend of recreational users with N₂O-induced neurological damage at emergency departments confirms the urgency of this development.

OBJECTIVE/METHODS

This narrative review describes recent trends in N₂O use and misuse, the adverse health effects associated with excessive use and the risk factors of excessive use.

RESULTS

Considering the rising trend in N₂O use, particularly among young and other vulnerable people, we propose to take legislative action to limit the availability of N₂O, and also advocate for better and timely education of non-users, users and medical professionals about the serious side-effects associated with excessive N₂O use.

CONCLUSION

It is concluded that the increase in excessive N₂O use is of serious concern.