Effectiveness of interactive workshops to raise awareness of the neurological harms associated with nitrous oxide use: a cross-sectional study.

BACKGROUND: The Royal London Hospital, East London, receives a case of nitrous oxide (N2O) myeloneuropathy roughly every 9 days. No formal education programme is widely available to warn young people of the risks of recreational N2O use. Our aim was to develop and evaluate the effectiveness of workshops focusing on the neurological risks of N2O, with the primary outcome to increase awareness of these risks among young people. METHODS: For this cross-sectional study, the workshop content was piloted with over 200 people at a community event, received input from a person with lived experience, and then piloted with a youth group, all in east London, UK. Between Oct 10, 2022, and April 11, 2023, 32 workshops were delivered to 984 young people in schools and youth groups in east London. The workshop included three interactive activities exploring how and why N2O causes neurological damage. An online anonymous questionnaire including free text and 5-point Likert scale answers was provided after each workshop. The HRA ethical toolkit and NIHR INVOLVE guidance were consulted, and NHS ethics approval was not required. FINDINGS: 396 (40%) of 984 workshop participants completed the questionnaire. The median age bracket of attendees was 13-15 years. 38 (10%) of 396 respondents reported past use of N2O, while 24 (6%) did not divulge use or non-use. Self-perceived likelihood of use was reduced after the workshop, with 261 (66%) very unlikely to use N2O before the session compared with 290 (73%) after the session. 238 (60%) respondents reported an increase in self-perceived knowledge of the risks after the session. When asked about their understanding of the risks of N2O, 206 (52%) relayed something related to N2O causing neurological damage. 327 (83%) respondents found the workshop useful. INTERPRETATION: This work highlights the feasibility of raising awareness among young people of N2O-myeloneuropathy in this workshop format. Limitations included difficulties involving many participants with lived experience in design, an absence of pre-existing interventions to compare against these workshops, and that data collection from young people required pragmatic, short questions. Overall, this work supports larger-scale preventive approaches to N2O-myeloneuropathy, such as a national education programme. FUNDING: Queen Mary Centre for Public Engagement Small Grant Fund.

Combined effects of mild hypothermia and nitrous-oxide-induced narcosis on manual and cognitive performance.

Divers are at enhanced risk of suffering from acute cognitive deterioration because of the low ambient temperatures and the narcotic action of inert gases inspired at high pressures. Yet, the behavioral effects of cold and inert gas narcosis have commonly been assessed in isolation and during short-term provocations. We therefore evaluated the interactive influence of mild hypothermia and narcosis engendered by a subanesthetic dose of nitrous oxide (N2O; a normobaric intervention analog of hyperbaric nitrogen) on cognitive function during prolonged iterative exposure. Fourteen men partook in two ∼12-h sessions (separated by ≥4 days), wherein they performed sequentially three 120-min cold (20°C) water immersions (CWIs), while inhaling, in a single-blinded manner, either normal air or a normoxic gas mixture containing 30% N2O. CWIs were separated by a 120-min rewarming in room-air breathing conditions. Before the first CWI and during each CWI, subjects performed a finger dexterity test, and the Spaceflight Cognitive Assessment Tool for Windows (WinSCAT) test assessing aspects of attention, memory, learning, and visuospatial ability. Rectal and skin temperatures were, on average, reduced by ∼1.2 °C and ∼8 °C, respectively (P < 0.001). Cooling per se impaired (P ≤ 0.01) only short-term memory (∼37%) and learning (∼18%); the impairments were limited to the first CWI. N2O also attenuated (P ≤ 0.02) short-term memory (∼37%) and learning (∼35%), but the reductions occurred in all CWIs. Furthermore, N2O invariably compromised finger dexterity, attention, concentration, working memory, and spatial processing (P < 0.05). The present results demonstrate that inert gas narcosis aggravates, in a persistent manner, basic and higher-order cognitive abilities during protracted cold exposure.

Factors affecting the topography of nitrous oxide-induced neurological complications.

BACKGROUND: The factors underlying the topography of nitrous oxide (N2O)-induced neurological complications are unknown. METHODS: We included all consecutive patients admitted to the university hospital of Marseille for N2O-induced neurological complications in a prospective observational study. Patients underwent neurological examination, spinal cord magnetic resonance imaging, and nerve conduction studies within the first 4 weeks after admission. RESULTS: In total, 61 patients were included: 45% with myeloneuropathy, 34% with isolated myelopathy, and 21% with isolated neuropathy. On multivariable analysis, the odds of myelopathy were associated with the amount of weekly N2O consumption (~600 g cylinder per week, odds ratio [OR] = 1.11, 95% confidence interval [CI] = 1.001-1.24). The extent of the myelopathy (number of vertebral segments) was correlated with the number of ~600-g cylinders consumed weekly (ρ = 0.40, p < 0.005). The odds of neuropathy were associated with the duration of consumption (per month; OR = 1.29, 95% CI = 1.05-1.58). Mean lower-limb motor nerve amplitude was correlated with the duration of consumption (in months; ρ = -0.34, p < 0.05). CONCLUSIONS: The odds of myelopathy increased with the amount of N2O consumption, and the odds of neuropathy increased with the duration of N2O exposure, which suggests distinct pathophysiological mechanisms underlying these two neurological complications.

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.

Is ethyl chloride the new nitrous oxide? A case report.

BACKGROUND: Over the last decade, there has been an emerging trend of recreational misuse of several drugs and inhaled solvent including ethyl chloride. This case report follows CARE guidelines and highlights, with supporting video, the neurological features of ethyl chloride intoxication. CASE PRESENTATION: A 48-year-old man was seen for the sudden occurrence of an unsteady gait with dizziness. His only medical history was a chronic and treated HIV infection without any complications. Clinical examination revealed a cerebellar syndrome associated with impairment of short-term memory. Biological and radiological workups were normal. After several days, the patient recalled ethyl chloride inhalation. He fully recovered after being discharged from hospital. CONCLUSION: Clinicians should recognise the clinical features and neurological manifestations of ethyl chloride intoxication due to the potential fatal cardiovascular complications of this intoxication.

Longitudinal follow-up and prognostic factors in nitrous oxide-induced neuropathy.

BACKGROUND AND AIM: Recreational use of nitrous oxide (N2O) has been associated with the development of severe nitrous oxide-induced neuropathy (N2On). Follow-up of these patients poses challenges, and their clinical progression remains largely unknown. The identification of prognostic factors is made difficult by the lack of standardized longitudinal assessments in most studies. The objective was to document the course of neuropathy through systematic follow-up assessments in N2On patients to identify prognostic factors for persistent disability after 6 months. METHODS: We gathered demographic, clinical, biological, and electrophysiological data from N2On patients hospitalized in the Referral center in Marseille, both at baseline and during a standardized follow-up assessment at 6 months. RESULTS: We retrospectively included 26 N2On patients (mean age 22.6 ± 4.4). Significant improvements were observed in all main clinical scores including Rankin, ONLS, and MRC testing (p < .01). Electrophysiological studies (EDX) revealed a predominantly motor neuropathy with marked reduction in CMAP in the lower limbs at baseline, and no significant improvement in motor parameters (p = .543). Rankin score at 6 months correlated with the initial weekly N2O consumption (r = .43, p = .03) and the CMAP sum score in the lower limbs at the first EDX (r = -.47, p = .02). Patients with and without myelitis showed similar Rankin and ONLS score after 6 months. INTERPRETATION: The clinical course generally improved favorably at 6 months with notable amelioration in the primary disability scores, sensory deficits, and ataxia. However, distal motor impairment associated with peripheral neuropathy persisted, with distal axonal loss emerging as the main prognostic factor for long-term disability in these young patients.

A recent surge of nitrous oxide misuse around London which merits a public health warning.

BACKGROUND: Use of nitrous oxide (N2O) gas for recreational purposes by young people is increasingly recognized as a public health hazard in the UK. METHODS: We looked at the hospital records of patients admitted over the last 4 years to a single neurological centre in Essex to determine the demographics, presentation, and management of patients presenting with symptoms of N2O toxicity from its recreational use. RESULTS: Of the 17 patients (mean age = 22.9 ± 3 years) admitted between September 2018 and October 2022, 70% were admitted between January and October 2022. All patients reported limb paraesthesiae and 16/17 reported (95%) imbalance; 11/17 (65%) showed objective limb weakness. Serum B12 concentration was low in 9/17 (53%). Plasma methylmalonic acid (n = 7) and homocysteine (n = 8) levels were elevated in all patients tested. Spinal cord Magnetic Resonance Imaging (MRI) imaging was abnormal in 10/17 (59%) patients. Nerve conduction studies were abnormal in 10/13 (77%) patients, with evidence of a symmetric, length-dependent, large fibre neuropathy. CONCLUSIONS: There has been a recent surge of cases with neurological complications of recreational N2O abuse in the UK, with a relatively greater rate in 2022. Greater awareness of this condition amongst clinicians and health regulators is urgently required to prevent harm from N2O misuse in young people.

Perspectives on sustainable practices in the use of nitrous oxide for labour analgesia: A patient and staff survey.

BACKGROUND: Climate change has emerged as the single biggest global health threat of the twenty-first century. Nitrous oxide accounts for the largest carbon footprint amongst our use of anaesthetic gas. It is a potent greenhouse gas possessing a global warming potential of approximately 265 times that of carbon dioxide. Despite recent curtailment of its use, it remains extensively employed as an analgesic for women in labour. OBJECTIVES: Assessment of the opinions of post-natal women and staff on nitrous oxide use and to investigate whether knowledge of its environmental harm would influence their choice of labour analgesia. DESIGN: Postnatal women and healthcare staff were invited to participate in a survey of nitrous oxide use as a labour analgesic and knowledge of its effect of the environment. SETTING: A single-centre study in a major obstetric tertiary referral centre in Ireland in 2021. MAIN OUTCOME MEASURES: To evaluate the awareness and perceptions of postnatal women and staff regarding the environmental impact of nitrous oxide and if it would affect their decision to use it in the future. RESULTS: One hundred postnatal women and 50 healthcare staff completed the survey. One hundred and six post-natal women were invited to complete the survey, resulting in a response rate of 94%. Knowledge of nitrous oxide's environmental impact was low. After receiving information, 46% of patients were more inclined to seek epidural or request it earlier (54%) to limit their nitrous oxide use, while 51% would choose an alternative analgesia to avoid nitrous oxide altogether. Overwhelmingly, 99% believed they had the right to know about these harmful effects when choosing an analgesic option. CONCLUSIONS: Patients should be informed of the environmental impact of nitrous oxide antenatally, empowering them to make informed decision on a climate friendly analgesic option if they wish.

Nitrous Oxide-induced Myeloneuropathy Due to Recreational Abuse.

BACKGROUND: The recreational use of nitrous oxide (N2O) has increased in recent years with a noticeable surge in the incidence of nitrous oxide-related myeloneuropathy. OBJECTIVES: To raise awareness of increasing myeloneuropathy due to recreational nitrous oxide misuse in Israel. METHODS: We conducted a case series documenting the clinical and investigative features of eight patients presenting with nitrous oxide-induced myeloneuropathy who were admitted to our departments. RESULTS: Paresthesia was the chief complaint in all patients, with sensory gait ataxia being a common feature, which was often accompanied by Romberg's sign and mild lower limb weakness. Vitamin B12 levels were below the normal range in seven patients, accompanied by elevated homocysteine and methylmalonic acid levels. Magnetic resonance imaging scans revealed hyperintense signals in the dorsal columns of the cervical spine. All patients improved following vitamin B12 injections. CONCLUSIONS: Enhancing awareness, prompting the use of appropriate investigations, and advocating for timely treatment are needed to overcome the risks associated with nitrous oxide misuse.

Nitrous oxide-induced myeloneuropathy: a case series.

BACKGROUND: Nitrous oxide (N2O) is the second most common recreational drug used by 16- to 24-year-olds in the UK. Neurological symptoms can occur in some people that use N2O recreationally, but most information comes from small case series. METHODS: We describe 119 patients with N2O-myeloneuropathy seen at NHS teaching hospitals in three of the UK's largest cities: London, Birmingham and Manchester. This work summarises the clinical and investigative findings in the largest case series to date. RESULTS: Paraesthesia was the presenting complaint in 85% of cases, with the lower limbs more commonly affected than the upper limbs. Gait ataxia was common, and bladder and bowel disturbance were frequent additional symptoms. The mid-cervical region of the spinal cord (C3-C5) was most often affected on MRI T2-weighted imaging. The number of N2O canisters consumed per week correlated with methylmalonic acid levels in the blood as a measure of functional B12 deficiency (rho (ρ)=0.44, p=0.04). CONCLUSIONS: Preventable neurological harm from N2O abuse is increasingly seen worldwide. Ease of access to canisters and larger cylinders of N2O has led to an apparent rise in cases of N2O-myeloneuropathy in several areas of the UK. Our results highlight the range of clinical manifestations in a large group of patients to improve awareness of risk, aid early recognition, and promote timely treatment.

Postoperative Pulmonary Complications in the ENIGMA II Trial: A Post Hoc Analysis.

BACKGROUND: Nitrous oxide promotes absorption atelectasis in poorly ventilated lung segments at high inspired concentrations. The Evaluation of Nitrous oxide In the Gas Mixture for Anesthesia (ENIGMA) trial found a higher incidence of postoperative pulmonary complications and wound sepsis with nitrous oxide anesthesia in major surgery compared to a fraction of inspired oxygen of 0.8 without nitrous oxide. The larger ENIGMA II trial randomized patients to nitrous oxide or air at a fraction of inspired oxygen of 0.3 but found no effect on wound infection or sepsis. However, postoperative pulmonary complications were not measured. In the current study, post hoc data were collected to determine whether atelectasis and pneumonia incidences were higher with nitrous oxide in patients who were recruited to the Australian cohort of ENIGMA II. METHODS: Digital health records of patients who participated in the trial at 10 Australian hospitals were examined blinded to trial treatment allocation. The primary endpoint was the incidence of atelectasis, defined as lung atelectasis or collapse reported on chest radiology. Pneumonia, as a secondary endpoint, required a diagnostic chest radiology report with fever, leukocytosis, or positive sputum culture. Comparison of the nitrous oxide and nitrous oxide-free groups was done according to intention to treat using chi-square tests. RESULTS: Data from 2,328 randomized patients were included in the final data set. The two treatment groups were similar in surgical type and duration, risk factors, and perioperative management recorded for ENIGMA II. There was a 19.3% lower incidence of atelectasis with nitrous oxide (171 of 1,169 [14.6%] vs. 210 of 1,159 [18.1%]; odds ratio, 0.77; 95% CI, 0.62 to 0.97; P = 0.023). There was no difference in pneumonia incidence (60 of 1,169 [5.1%] vs. 52 of 1159 [4.5%]; odds ratio, 1.15; 95% CI, 0.77 to 1.72; P = 0.467) or combined pulmonary complications (odds ratio, 0.84; 95% CI, 0.69 to 1.03; P = 0.093). CONCLUSIONS: In contrast to the earlier ENIGMA trial, nitrous oxide anesthesia in the ENIGMA II trial was associated with a lower incidence of lung atelectasis, but not pneumonia, after major surgery.

How to distinguish Guillain-Barré syndrome from nitrous oxide-induced neuropathy: A 2-year, multicentric, retrospective study.

BACKGROUND: Recreational use of nitrous oxide (N2 O) has dramatically increased in recent years, resulting in numerous cases of acute sensorimotor tetraparesis secondary to nitrous oxide-induced neuropathy (N2 On). Challenging clinical features can mimic Guillain-Barré syndrome (GBS), the main differential diagnosis upon admission. The most sensitive biomarkers for distinguishing between these two conditions remain to be determined. METHODS: Fifty-eight N2 On patients from three referral centers were retrospectively included over a 2-year period and compared to GBS patients hospitalized during the same timeframe (47 patients). Collected demographic, clinical, biological, and electrophysiological data were compared between the two groups. RESULTS: The typical N2 On clinical pattern included distal sensorimotor deficit in lower limbs with absent reflexes, proprioceptive ataxia, and no cranial involvement (56.7% of our cohort). Misleading GBS-like presentations were found in 14 N2 On patients (24.1%), and 13 patients (22.4%) did not report N2 O use during initial interview. Only half the N2 On patients presented with reduced vitamin B12 serum levels upon admission. A slightly increased cut-off (<200 pmol/L) demonstrated 85.1% sensitivity and 84.5% specificity in distinguishing N2 On from GBS. Only 6.9% of N2 On patients met the criteria for primary demyelination (p < 0.01), with only one presenting conduction blocks. A diagnostic algorithm combining these two biomarkers successfully classified all GBS-like N2 On patients. CONCLUSIONS: Vitamin B12 serum level < 200 pmol/L cut-off and conduction blocks in initial electrophysiological study are the two most sensitive biomarkers for rapidly distinguishing N2 On from GBS patients. These two parameters are particularly useful in clinically atypical N2 On with GBS-like presentation.

Nitrous Oxide Use in Australian Health Care: Strategies to Reduce the Climate Impact.

Nitrous oxide is a useful inhaled analgesic. Due to its high global warming potential and ozone-depleting properties, the nitrous oxide emissions related to health care are being increasingly scrutinized. In this narrative review, we will discuss the clinical uses of nitrous oxide relevant to anesthetists, in addition to its contribution as a greenhouse gas. Using available data from Australia, we will explore potential strategies for reducing the impact of those emissions, which are likely to be applicable in other countries. These include destruction of captured nitrous oxide, minimizing nitrous oxide waste and reducing clinical use. Anesthesia clinicians are well placed to raise awareness with colleagues and consumers regarding the environmental impact of nitrous oxide and to promote cleaner alternatives. Reducing use is likely to be the most promising reduction strategy without large-scale changes to infrastructure and subsequent delay in action.

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.

High Incidence of Signs of Neuropathy and Self-Reported Substance Use Disorder for Nitrous Oxide in Patients Intoxicated with Nitrous Oxide.

INTRODUCTION: The number of patients with excessive nitrous oxide (N2O) use and neurological disorders has been rising, indicating an addictive potential of N2O. We studied the incidence of self-reported substance use disorder (SUD)-related symptoms, signs of neuropathy, and the patterns of use in N2O-intoxicated patients. METHODS: The Dutch Poisons Information Center (DPIC) provides information by telephone on the management of intoxications to healthcare professionals. Retrospective data on signs of neuropathy and patterns of use were collected for all N2O intoxications reported to the DPIC in 2021 and 2022. Frequent and heavy use were self-reported as "often/frequent/weekly use" and as "use of tanks or >50 balloons/session," respectively. From this cohort, we included patients with excessive N2O use or signs of neuropathy in a prospective observational cohort study. Online surveys were sent 1 week, 1 month, and 3 months after DPIC consultation. The survey included the drug use disorder questionnaire (validated to measure self-reported substance abuse [SA] and substance dependence [SD] based on Diagnostic and Statistical Manual of Mental Disorders [DSM]-IV-TR criteria) and questions on patterns of use and signs of neuropathy. DSM-IV-TR criteria were translated to DSM-V criteria to score for mild, moderate, or severe SUD, with 2-3, 4-5, or ≥6 symptoms, respectively. RESULTS: We included 101 N2O-intoxicated patients in the retrospective study. Of these, 41% showed signs of neuropathy (N = 41), 53% used N2O tanks to fill balloons (N = 53), 71% used them frequently (N = 72), and 76% used them heavily (N = 77). We included 75 patients in the prospective study and 10 (13%) completed the first survey. All 10 patients fulfilled the criteria for SA and SD (DSM-IV-TR, median number of questions answered "yes" = 10/12), all used N2O tanks to fill balloons, and 90% (N = 9) experienced signs of neuropathy. After 1 and 3 months, 6/7 and 1/1 patients, respectively, continued to fulfill SA and SD criteria. Translating to DSM-V criteria, 1/10 patients fulfilled the criteria for (self-reported) mild SUD, 1/10 patients for moderate SUD, and 8/10 patients for severe SUD, 1 week after consultation. CONCLUSION: The high proportion of N2O-intoxicated patients reporting frequent and heavy use of N2O indicates an addictive potential of N2O. Although follow-up rate was low, all patients fulfilled self-reported SA, SD (DSM-IV-TR), and SUD (DSM-V) criteria for N2O. Somatic healthcare professionals treating patients with N2O intoxications should be aware of possible addictive behavior in patients. The screening, brief intervention, and referral to treatment approach should be considered to treat patients with self-reported SUD symptoms.

Sedative and adverse effect comparison between oral midazolam and nitrous oxide inhalation in tooth extraction: a meta-analysis.

OBJECTIVE: Oral midazolam and nitrous oxide inhalation were commonly used sedative and analgesic techniques during tooth extraction. It is still controversial whether oral midazolam can replace the nitrous oxide inhalation for sedative and analgesic treatment of tooth extraction. Therefore, we conducted this study in order to provide a reference for doctors to choose effective sedative and analgesic treatment in tooth extraction. METHODS: We searched the Chinese and English databases including PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure, Wanfang and VIP information databases. RESULTS: Through this meta-analysis, we found that the success rate of sedation and analgesia treatment with oral midazolam during tooth extraction was 75.67% and the incidence of adverse reactions was 21.74%. The success rate of sedation and analgesia treatment using nitrous oxide inhalation during tooth extraction was 93.6% and the incidence of adverse reactions was 3.95%. CONCLUSION: The use of nitrous oxide inhalation for sedation and analgesia during tooth extraction is very effective, and oral midazolam can be used as an alternative to nitrous oxide inhalation.

Nitrous oxide-induced subacute combined degeneration of the cord: diagnosis and treatment.

Recreational use of nitrous oxide (N2O) has increased rapidly in recent years and is now the second most commonly used recreational drug among young people in the UK. There has been a corresponding rise in cases of nitrous oxide-induced subacute combined degeneration of the cord (N2O-SACD), a pattern of myeloneuropathy usually associated with severe vitamin B12 deficiency. This can cause serious and permanent disability in young people but, if recognised early, may be effectively treated. All neurologists should be aware of N2O-SACD and its treatment; however, there are currently no agreed guidelines. Based on our experience in East London, an area of high N2O use, we provide practical advice on its recognition, investigation and treatment.

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.

[Burns caused by nitrous oxide cylinder misuse]. / Brûlures par l'usage détourné du protoxyde d'azote en bonbonne.

In recent years, we have seen an increase in the frequency of the misuse of nitrous oxide as a narcotic. The risks associated with its use are now well-known, such as neurological and psychiatric risks. In this study, we report our experience with specific thigh burns when using nitrous oxide canisters for narcotic purposes. PATIENTS AND METHODS: Between November 2021 and August 2022 we treated 4 patients burned during a nitrous oxide use accident. RESULTS: We report the cases of three women and one man with an average age of 28. Two of them were treated in addictology. We observed an average delay before consultation of a healthcare professional of 7days. The burns were all rounded and deep, localized at the level of the thighs. For three of the patients (one having been lost to sight), a split thickness skin graft was performed within an average of 32days. CONCLUSIONS: The non-medical use of nitrous oxide represents a real public health problem in addition to the adverse effects of the substance itself. Prevention and health security measures seem to be becoming essential.

Myeloneuropathy induced by recreational nitrous oxide use with variable exposure levels.

BACKGROUND AND PURPOSE: Although several case series have described nitrous-oxide-associated neurological disorders, a comprehensive assessment of exposure characteristics (e.g., time to onset, level of exposure) in substance abusers has not been performed. The aim of this study was to describe the onset patterns of recreational use of nitrous-oxide-induced neurological disorders. METHODS: All cases of neurological disorders related to nitrous oxide recreational use reported to the Hauts-de-France addictovigilance center between January 2019 and August 2020 were selected. Only cases requiring hospitalization with informative data to perform the nitrous oxide causality assessment were included. RESULTS: A total of 20 cases from five hospitals were included. The male-to-female ratio was 6:1 and the median age was 19 years (range 16-34). The neurological presentation (myeloneuropathy 64%, 7/11; sensorimotor neuropathy 36%, 4/11) included for all patients gait disorders due to proprioceptive ataxia and limb hypoesthesia. The median dose used per occasion was 100 cartridges (range 5-960; n = 19). The median time from the start of nitrous oxide use to the onset of neurological symptoms was 6 months (range 0.7-54; n = 16). The cumulative dose was significantly higher in patients with damage to all four limbs than in patients with lower limb symptoms only (p = 0.042). CONCLUSIONS: A low intermittent exposure may be sufficient to cause neurological damage in some subjects, suggesting that, at the population level, there is no safe exposure to nitrous oxide in recreational settings. The severity of neurological impairment could increase once used at high doses and for prolonged durations of nitrous oxide.