Nitrous oxide inhalation among adolescents: prevalence, correlates, and co-occurrence with volatile solvent inhalation

Association of volatile substance, nitrous oxide and alkyl nitrate use with mental health in UK adolescents

BACKGROUND

'Inhalants' have been associated with poorer mental health in adolescence, but little is known of associations with specific types of inhalants.

AIMS

We aimed to investigate associations of using volatile substances, nitrous oxide and alkyl nitrates with mental health problems in adolescence.

METHOD

We conducted a cross-sectional analysis using data from 13- to 14-year-old adolescents across England and Wales collected between September 2019 and March 2020. Multilevel logistic regression examined associations between lifetime use of volatile substances, nitrous oxide and alkyl nitrates with self-reported symptoms of probable depression, anxiety, conduct disorder and auditory hallucinations.

RESULTS

Of the 6672 adolescents in the study, 5.1% reported use of nitrous oxide, 4.9% volatile solvents and 0.1% alkyl nitrates. After accounting for multiple testing, adolescents who had used volatile solvents were significantly more likely to report probable depressive (odds ratio = 4.59, 95% CI 3.58, 5.88), anxiety (odds ratio = 3.47, 95% CI 2.72, 4.43) or conduct disorder (odds ratio = 7.52, 95% CI 5.80, 9.76) and auditory hallucinations (odds ratio = 5.35, 95% CI 4.00, 7.17) than those who had not. Nitrous oxide use was significantly associated with probable depression and conduct disorder but not anxiety disorder or auditory hallucinations. Alkyl nitrate use was rare and not associated with mental health outcomes. Adjustment for use of other inhalants, tobacco and alcohol resulted in marked attenuation but socioeconomic disadvantage had little effect.

CONCLUSION

To our knowledge, this study provides the first general population evidence that volatile solvents and nitrous oxide are associated with probable mental health disorders in adolescence. These findings require replication, ideally with prospective designs.

"Burnout syndrome" in anesthesiologists and remedial measures- A narrative review

Anesthesiology, as an occupation, has its own unique sets of challenges, problems, issues, and circumstances, all leading to "occupational stress," which by now should be unequivocally accepted as a well-established fact. It is futile to continue pursuing research questions like, if there "really" is stress existing among practicing anesthesiologists/trainees, by conducting questionnaire-based surveys and doing meta-analyses. A significantly high incidence of existence of occupational stress in anesthesiologists is an undisputable and practical reality, which, when longstanding, gets culminated into "burnout syndrome" with its disastrous outcomes. Rather than pursuing the often-trodden path of finding the incidence, sources, and other superficial issues, an in-depth study of available literary evidence in relation to burnout has been carried out. Objectifying it as a "syndrome," its etiopathogenesis, pathophysiology inclusive of the prevalent theories of its causality, typology, and progression into various stages of/continuum of the process as an evolving clinical entity have been described. The preventive measures and "coping strategies" have been discussed at length in the end. It is the fervent hope and the desire of the authors that this discourse will sensitize all anesthesiologists, especially the younger and upcoming future generation, and help them avoid becoming a prey to this dreadful entity!

A Case of Fever, Impaired Consciousness, and Psychosis Caused by Nitrous Oxide Abuse and Misdiagnosed as Acute Meningitis

Nitrous oxide (N2O) is readily available, and its abuse for recreational purposes has become a social problem. In Japan, where N2O is strictly prohibited for non-medical use, abuse is often overlooked due to a lack of experience in the field. N2O abuse causes various long-term symptoms, including vitamin B12 deficiency, myelopathy, myeloneuropathy, subacute combined degeneration, mood changes, and psychosis. The diagnosis of N2O abuse is difficult due to the compound's short half-life and rapid elimination through the lungs. This report describes a case of fever and impaired consciousness in a patient with a history of N2O abuse.

A Case of Subacute Degeneration of the Spinal Cord Due to Vitamin B12 Deficiency Triggered by Nitrous Oxide Use

In this case report, we discuss a young female who presented to the emergency department with a recent onset of weakness, paraesthesia, and gait disturbance suggestive of peripheral neuropathy and gait ataxia. This was attributed to the occasional use of recreational nitrous oxide (N2O) over the past 10 months. Subacute combined degeneration of the spinal cord is a condition affecting the lateral and posterior columns of the spinal cord, mainly caused by demyelination. The use of recreational N2O depletes the levels of vitamin B12 thus leading to this demyelination of the nervous system. Physical examination revealed T6 and T7 and L3 and L4 sensory deficits bilaterally with hyporeflexia in bilateral knee and ankle reflexes with reduced power in the left lower limb as well as a spastic gait. Her vitamin B12 levels were low (98 g/dL). MRI spine showed a high signal in the posterior cord/ dorsal column. The patient made good recovery post-intramuscular B12 administration and physiotherapy with planned outpatient neurology rehabilitation.

Neurologic and Thrombotic Complications in the Setting of Chronic Nitrous Oxide Abuse

Nitrous oxide is a commonly used inhaled anesthetic for medical procedures, as well as a drug of abuse throughout the world. Excessive nitrous oxide inhalation has been shown to cause a functional vitamin B12 deficiency and hyperhomocysteinemia, which can lead to peripheral neuropathy and hypercoagulability, respectively. While the development of neurologic toxicity from chronic nitrous oxide abuse (i.e., encephalopathy, myelopathy, and neuropathy) has been previously described, the thrombotic potential of chronic nitrous oxide abuse is less known. The authors report two cases of nitrous oxide abuse leading to both neurologic and thrombotic complications.

Electrophysiologic Characteristics of Nitrous-Oxide-Associated Peripheral Neuropathy: A Retrospective Study of 76 Patients

BACKGROUND AND PURPOSE

The electrophysiologic characteristics of peripheral neuropathy secondary to nitrous oxide (N₂O) abuse remain unclear. The paper therefore aimed to summarize the electrophysiologic characteristics of N₂O-associated peripheral neuropathy and identify the risk factors of severe nerve injury.

METHODS

The electrophysiologic results and clinical data of patients with peripheral neuropathy secondary to N₂O abuse at our hospital between 2018 and 2020 were analyzed retrospectively, and their electrophysiologic changes were summarized.

RESULTS

Most patients exhibited decreased sensory and motor nerve conduction velocities (75% and 76%), decreased sensory nerve and compound motor action potentials (57% and 59%), and prolonged distal motor latency (59%), while a response was absent in 36%. These findings indicate that N₂O abuse can result in generalized injury to sensory and motor nerves. Electrophysiologic results indicated axonal neuropathy in 37 cases (49%), demyelinating peripheral neuropathy in 4 (5%), and mixed neuropathy in 12 (16%). Peripheral nerve injury was more common in the lower limbs (72%) than in the upper limbs (42%, p<0.0001). The upper and lower limbs were primarily affected by sensory nerve demyelination (35%) and motor axonal injury (67%), respectively. Subgroup analysis indicated that longer N₂O exposure and longer disease course were associated with more-severe motor axonal injury in the lower limbs.

CONCLUSIONS

N₂O-associated peripheral neuropathy can lead to sensory and motor nerve injury, with axonal injury being the most common. Injuries were more severe in the lower limbs. Prolonged N₂O exposure and disease course increased the severity of motor axonal injury in the lower limbs.

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.

The Clinical Presentations of Nitrous Oxide Users in an Emergency Department

Today, the concomitant abuse of nitrous oxide (N₂O) and illicit drugs is evident and problematic. However, there are few reports regarding the clinical manifestations of N₂O users when they present to the emergency department (ED). The purpose of this study was to describe the clinical presentations, the associated illicit substances used in combination, and the outcomes in N₂O users visiting the ED. This was a retrospective observational cohort study. All N₂O adult users admitted to the ED at Linkou Chang Gung Memorial Hospital between 2012 and 2020 were included. Demographic variables, clinical symptoms, and examination results were collected from medical records. Univariate comparisons were conducted between pure N₂O users and combined illicit drug users. A total of 40 patients were included, 24 of which were pure N₂O users. Limb weakness and numbness accounted for the majority of chief complaints. Neurologic symptoms were the most common clinical manifestations (90%). A more severe ED triage level, faster heart rate, greater agitation, and cardiovascular symptoms were significantly noted in combined illicit drug users. In ED, limb numbness/weakness should arouse physicians’ awareness of patients using N₂O. Combined use of N₂O and illicit drugs can cause great harm to health.

Prognostic indicators of subacute combined degeneration from B12 deficiency: A systematic review

OBJECTIVE

A systematic review was conducted on published data of subacute combined degeneration (SCD) from B12 deficiency to investigate potential prognostic indicators of final ambulatory function in affected patients. TYPE: Systematic review.

LITERATURE SURVEY

Records published from 1999 through 2018 were searched on the electronic databases MEDLINE, PUBMED, and SCOPUS. The publication language was restricted to English and French.

METHODOLOGY

Records that described cases of SCD from B12 deficiency in patients ≥16 years of age at onset were included. From a final total of 66 cases of SCD identified, ambulation scores were assigned based on the clinical descriptions reported. Patient characteristics, clinical manifestations, and ambulatory function were reported descriptively. Subanalyses on potential prognostic indicators were performed.

SYNTHESIS

Greater ambulatory function at diagnosis was associated with recovery of normal ambulatory function at follow-up (P < .001). Nearly 90% of patients walking unsupported at diagnosis made a complete recovery regardless of etiology. For patients initially walking with support, 22% of cases from impaired B12 digestion/absorption made a complete recovery compared with ≥50% of cases from other etiologies. For patients initially requiring a wheelchair, 33% of cases from impaired digestion/absorption were able to walk with support compared with ≥50% of cases from other etiologies. The total B12 administered over the course of treatment was correlated with improved ambulation (P = .024) for all patients, with a higher B12 replacement regimen associated with better outcomes in patients who were unable to walk unsupported at diagnosis (number needed to treat = 4).

CONCLUSIONS

Initial ambulatory function may be a useful clinical marker of the severity of spinal cord dysfunction and final functional outcome. Etiological risk factors influenced both clinical manifestations and final walking ability in SCD, suggesting a distinct pathophysiological mechanism among the causes. In addition, a more intensive B12 replacement regimen may improve ultimate ambulatory function in advanced cases of SCD.

Recreational Nitrous Oxide Abuse: Prevalence, Neurotoxicity, and Treatment

Nitrous oxide (N₂O), also known as "laughing gas," is a colorless, nonirritating gas. Clinically, it is widely used as an inhaled anesthetic, analgesic, and anxiolytic. In recent years, recreational abuse of N₂O has become increasingly common, especially among young adults and adolescents, but many of them lack awareness of the possible side effects associated with this drug. N₂O abuse can damage multiple systems, especially the nervous system, but the exact mechanism of N₂O toxicity remains controversial. At present, an increasing number of cases of nervous system damage caused by N₂O abuse have been reported both at home and abroad. Discontinuation of N₂O use and timely supplementation with vitamin B12 are essential for a good prognosis. Long-term abuse without timely treatment will eventually lead to irreversible neurological damage. In this article, we discuss the epidemiology of N₂O abuse, neurotoxicity mechanisms, clinical manifestations, relevant auxiliary examinations, treatments, and prognosis to improve social awareness of N₂O exposure risk, especially among users and clinicians.

Nitrous oxide use among young people – new trends, policy challenges, and knowledge gaps

Purpose

Nitrous oxide (N2O) use for recreational purposes appears to have increased among young people in several countries, including Denmark, Australia, The Netherlands and the UK. This increase has prompted concern among health authorities and politicians. The purpose of this paper is to map out findings in the available literature about N2O use among young people to better understand current trends and contextualize the public concerns and the new policy responses to it.

Design/methodology/approach

The authors draw here on a range of sources, including research literature, reports and policy documents in English and Danish. Given the broad aim, the authors used a scoping study approach (Arksey and O’Malley, 2005).

Findings

The authors found literature on prevalence of use, health effects and policy regulations. The literature suggests that health harms associated with N2O use are generally associated with intensive and long-term use, and death is more likely where the means of administration entails a risk of suffocation. Overall, however, the analysis shows that substantial gaps exist in the available literature. The authors lack detailed knowledge on several issues, including comparable prevalence data of N2O use; the extent to which N2O is used with other drugs; how one can distinguish between harmful and non-harmful use in terms of both quantity inhaled and mode of administration; and on intended and unintended consequences of policy responses to this use.

Originality/value

The current increase and trend in inhaling N2O for intoxication among young people is under researched. This general review maps out what kind of knowledge would be valuable to have for prevention, harm reduction and policy interventions.

Psychiatric and Other Medical Manifestations of Nitrous Oxide Abuse: Implications From Case Series

BACKGROUND

Nitrous oxide (N2O), a commonly used anesthetic agent in dentistry, has emerged as a global public health threat in young population. Although N2O-related neurological sequelae such as spinal cord degeneration and sensorimotor peripheral neuropathy are well known, psychiatric manifestations of heavy N2O use remain unclear. Here, we presented 7 treatment-seeking patients with severe N2O use disorder to delineate the psychiatric profiles of N2O users in Asia.

METHODS

Seven patients with severe N2O use disorder who sought treatment in Taipei City Psychiatric Center between 2017 and 2018 were enrolled. We used chart review method to retrospectively collect their clinical information including sociodemographics, psychiatric and substance history, urine toxicology findings, and treatment course.

RESULTS

These N2O users all had diagnoses of severe N2O use disorder. They usually initiated N2O use in late adolescence and early adulthood. Six of them had histories of mood disorders; all of them reported other illicit substance use before using N2O. The main reasons for treatment seeking were irritability, psychotic symptoms, self-harm, or violent behaviors as four of them were given a diagnosis of substance-induced psychotic disorder. Urine drug screen showed negative for other illicit drug use except for 1 positive case for cannabis and 1 for amphetamine. Three of 7 cases were hospitalized because of the severity of their psychiatric symptoms and suicidal risk.

CONCLUSIONS

These cases with severe N2O use disorder showed high prevalence of psychotic symptoms and dangerous behaviors such as suicide or violence. This study highlights the addiction potential of N2O and its related adverse consequences in the psychiatric aspect.

Nitrous oxide causes peripheral neuropathy in a dose dependent manner among recreational users

BACKGROUND

Nitrous oxide (N₂O) has been used in clinical and recreational settings for over 150 years. Through inactivation of the Vitamin B12 dependent enzyme, methionine synthase, N₂O can lead to the development of peripheral neuropathy. This study sought to determine the relationship between the exposure and risk of neurological symptoms in the largest ever sample of users.

DESIGN

Data are drawn from the Global Drug Survey (GDS) over three consecutive years (2014-2016). The Global Drug Survey is an online, cross-sectional survey of substance use, translated into multiple languages.

PARTICIPANTS

Respondents to the Global Drug Survey who provided details on N₂O use and the experience of paraesthesia in the previous 12 months.

MEASUREMENTS

Questions relating to N₂O use, peripheral neuropathy, age and gender were explored among last year's users.

FINDINGS

Of 241,566 respondents, 41,181 (17.0%) indicated that they had ever used nitrous oxide; of these, 42.1% had used in the last 12 months. For the final model, data from 16,124 participants who had used N₂O in the last 12 months and had provided responses on age, dose, gender and paraesthesia were used. Of these, the number of respondents reporting persistent numbness/tingling (paraesthesia) in their hands or feet was 537 (3.3%). Although the risk was very low among infrequent users, there was a strong dose-response relationship. For people indicating one or two doses per session, the probability of reporting paraesthesia was approximately 0.018 by comparison; for people indicating 100 doses per session the probability was approximately 0.085. The association, between dose and paraesthesia was influenced by gender and age.

CONCLUSION

While infrequent, episodic users are not at risk, a minority of heavy users are at dose-dependent risk of developing serious neurological consequences. Better education and raised awareness of early symptoms are required.

Nitrous oxide recreational abuse presenting with myeloneuropathy and mimicking Guillain-Barre syndrome

The recreational use of nitrous oxide (N₂O) is increasing in festivals, university parties, clubs, private residences, and parks. The abuse of N₂O has serious complications of the central and peripheral nervous system. In this article, we report a case of a 28-year-old previously healthy man who presented with a three-day history of rapidly progressive leg numbness, tingling, and weakness with gait instability and frequent falls. He had a history of marijuana use and daily inhalation of N₂O (approximately 20 whippets daily over 2-3 years). He was admitted with a presumptive diagnosis of Guillain-Barre syndrome and was started on intravenous immunoglobulin. Three days after admission, paresthesia ascended to the level of nipple line, and his weakness in the lower limb increased significantly. MRI of the cervical spine showed focal non-enhancing lesions extending from C4 to C6. Serum analysis showed low vitamin B12 level, elevated methylmalonic acid, and elevated homocysteine level. Supplemental 1000 μg/day of vitamin B12 intramuscular injections and 15 mg of folic acid tablets were given. The patient showed gradual improvement. This is a rare case of N₂O recreational abuse presenting with myeloneuropathy and mimicking Guillain- Barre syndrome. This case highlights the importance of detailed history and physical examination in patients who arrive at the hospital with clinical features of Guillain-Barre syndrome. This is especially true if there are red flags such as drug abuse or discrepancy between clinical and para-clinical (investigations) parameters. Neuroimaging of the brain and spinal cord might be necessary to score the final diagnosis in such cases.

[Clinical features of long segmental myelopathy caused by nitrous oxide]

OBJECTIVE

To analyze the clinical and imaging characteristics of the neurological damage caused by nitrous oxide (N₂O).

METHODS

In the study, 10 patients in the Department of Neurology of China-Japan Friendship Hospital from October 2015 to February 2018 were retrospectively analyzed for the demographic data, the history of inhaled N₂O, clinical features, blood examination, electrophysiological examination, spinal magnetic resonance imaging and therapeutic efficacy profiles.

RESULTS

The male-to-female ratio was 4:6 and it presented with an age-of-onset 17-26 years [the average age: (20.80±3.12) years]. The time from inhaled N₂O to onset was 1 month to 1 year [the average time: (6.95±4.19) months]. Paralysis in all the patients and numbness in 9 patients were the main clinical features, while positive Lhermitte's sign in 3 patients, urinary and defecation disturbance in 4 patients were also found. Blood examination indicated anemia in 2 patients, giant cell anemia in 1 case and small cell hypochromic anemia in 1 case. 3 cases had been treated with vitamin B12 in an external hospital, and the other 7 cases had abnormal increase in homocysteine levels. Electrophysiological examinations showed sensory and motor nerve involvement in 9 patients, and motor nerve involvement in 1 patient. The severity of lower extremity lesion was significantly heavier than that of upper extremity. Spinal magnetic resonance imagings showed that long segmental lesions were present in the cervical spinal cord of all the patients, 3 cases with long segmental lesions of the thoracic cord and 2 cases with spinal cord swelling. In 6 cases, the horizontal axis had an "inverted V-type" T2 high signal, 1 case was classified as "crescent", and 3 cases were "eight-shaped". The symptoms in these 10 cases were alleviated in varying degrees after stopping the inhalation of nitrous oxide, actively supplementing high doses of vitamin B12 and doing early rehabilitation exercises.

CONCLUSION

Myelopathy with nitrous oxide presents as paralysis and numbness in limb extremities. In imaging, cervical spinal cord damage is common, accompanied by thoracic spinal cord damage. The horizontal axis is more common in the "inverted V-type". Treatment with high doses of vitamin B12 is effective.

The impact of conventional and nonconventional inhalants on children and adolescents

AIM

Inhalant abuse in the adolescent population is a growing concern for care givers, communities, physicians, and medical providers. The aim of this article is to provide a review of the literature about this new challenge. In addition, it raises awareness about recent health policy rulings.

METHODS

Review of the literature was done.

RESULTS

In this review article, the prevalence of different modes of inhalant use and abuse in children and young adults and their potential health implications will be examined: Cigarettes, ENDS (E Cigarettes), Hookah, Marijuana, and Huffing. Additionally, marketing and advertising tactics will be reviewed to understand how they target this population. A review of current health policy recommendations from the FDA, American Thoracic Society, and the American Academy of Pediatrics will also be discussed.

CONCLUSION

The rapid rise in e-cigarette and hookah use in school aged children should trigger a call to action in the medical and public health communities. Health policy recommendations need to be made to reduce the level of adolescent substance abuse.

Past, present, and future of nitrous oxide

INTRODUCTION

For a drug that has been omnipresent for nearly 200 years, nitrous oxide's (N2O) future seems less certain than its illustrious past. Environmental concerns are coming to the fore and may yet outweigh important clinical benefits.

SOURCES OF DATA

After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered.

AREAS OF AGREEMENT

The analgesic and anaesthetic advantages of N2O remain despite a plethora of newer agents.

AREAS OF CONTROVERSY

N2O greenhouse gas effect and its inhibition of key enzymes involved in protein and DNA synthesis have provided further fuel for those intent on eliminating its further clinical use.

GROWING POINTS

The use of N2O for treatment-resistant depression has gained traction.

AREAS TIMELY FOR DEVELOPING RESEARCH

Comparative studies for N2O role in combatting the prescription opioid analgesic epidemic may well provide further clinical impetus.

Neurologic, psychiatric, and other medical manifestations of nitrous oxide abuse: A systematic review of the case literature

BACKGROUND/OBJECTIVES

Nitrous oxide (N2 O) is known to have abuse potential, although debate regarding the toxic effects of such abuse continues. Our objective was to review the case literature and present the neurologic, psychiatric and medical consequences of N2 O abuse.

METHODS

A systematic literature review was completed for case reports using keywords "nitrous oxide" with "abuse/abusing" or "misuse/misusing" or "overuse/overusing" or "addiction." Non-English-language cases and cases not involving direct toxic effects of N2 O were excluded as were commentaries or personal essays. Clinical presentation, frequency of N2 O abuse, laboratory studies, imaging, ancillary tests, treatments and outcomes were collected from case reports.

RESULTS

Our review returned 335 Pubmed, 204 Web of Science, 73 PsycINFO, 6 CINAHL, 55 EMBASE and 0 Grey Literature results, and after exclusion and removal of duplicates, 91 individual cases across 77 publications were included. There were also 11 publications reporting 29 cases of death related to N2 O abuse. The majority of cases (N = 72) reported neurologic sequelae including myeloneuropathy and subacute combined degeneration, commonly (N = 39) with neuroimaging changes. Psychiatric (N = 11) effects included psychosis while other medical effects (N = 8) included pneumomediastinum and frostbite. Across all cases N2 O abuse was correlated with low or low-normal Vitamin B12 (cyanocobalamin) levels (N = 52) and occasionally elevated homocysteine and methylmalonic acid.

CONCLUSIONS/SCIENTIFIC SIGNIFICANCE

N2 O abuse represents a significant problem because of the difficulty involved with identification and the toxicity related to chronic abuse including possible death. Health professionals should be aware of the toxic effects of N2 O and be able to identify potential N2 O abuse. (Am J Addict 2016;25:358-369).

Subacute combined degeneration of the spinal cord in a patient abusing nitrous oxide and self-medicating with cyanocobalamin

PURPOSE

A case of subacute combined degeneration (SCD) of the spinal cord manifesting as severe ataxia and urinary retention in a patient with a history of heavy nitrous oxide abuse and self-supplementation with cyanocobalamin is reported.

SUMMARY

A 27-year-old woman was treated in the emergency department for complaints of abdominal pain and inability to urinate for about 12 hours. The patient also complained of worsening lower-extremity weakness for 10 days and a "pins and needles" sensation in the lower extremities for approximately 1 year. She reported nitrous oxide abuse over 3 years (an average of 100-200 "whippit" cartridges daily on 3 or 4 days per week), as well as long-term self-medication with oral and i.m. cyanocobalamin for the purpose of preventing nitrous oxide-induced neurologic symptoms. Results of magnetic resonance imaging (MRI) were highly suggestive of SCD, which is typically seen in primary vitamin B12 deficiency but has been reported in the context of chronic nitrous oxide exposure. Treatment was initiated with cyanocobalamin 1000 μg i.m. daily, to be continued for 5 days and followed by a four-week regimen of 1000 μg i.m. weekly. The patient was discharged after 3 days, despite continued symptoms, with instructions to obtain ongoing care but was lost to follow-up.

CONCLUSION

A patient who abused nitrous oxide chronically developed ataxia, paresthesia, and urinary retention while self-medicating with cyanocobalamin. A diagnosis of SCD was supported by MRI findings, symptoms, and the known relationship between nitrous oxide exposure and vitamin B12 deficiency.

Recreational nitrous oxide use: Prevalence and risks

Nitrous oxide (N2O; laughing gas) is clinically used as a safe anesthetic (dentistry, ambulance, childbirth) and appreciated for its anti-anxiety effect. Since five years, recreational use of N2O is rapidly increasing especially in the dance and festival scene. In the UK, N2O is the second most popular recreational drug after cannabis. In most countries, nitrous oxide is a legal drug that is widely available and cheap. Last month prevalence of use among clubbers and ravers ranges between 40 and almost 80 percent. Following one inhalation, mostly from a balloon, a euphoric, pleasant, joyful, empathogenic and sometimes hallucinogenic effect is rapidly induced (within 10 s) and disappears within some minutes. Recreational N2O use is generally moderate with most users taking less than 10 balloons of N2O per episode and about 80% of the users having less than 10 episodes per year. Side effects of N2O include transient dizziness, dissociation, disorientation, loss of balance, impaired memory and cognition, and weakness in the legs. When intoxicated accidents like tripping and falling may occur. Some fatal accidents have been reported due to due to asphyxia (hypoxia). Heavy or sustained use of N2O inactivates vitamin B12, resulting in a functional vitamin B12 deficiency and initially causing numbness in fingers, which may further progress to peripheral neuropathy and megaloblastic anemia. N2O use does not seem to result in dependence. Considering the generally modest use of N2O and its relative safety, it is not necessary to take legal measures. However, (potential) users should be informed about the risk of vitamin B12-deficiency related neurological and hematological effects associated with heavy use.

N-methyl-D-aspartate receptor channel blocker-like discriminative stimulus effects of nitrous oxide gas

Nitrous oxide (N2O) gas is a widely used anesthetic adjunct in dentistry and medicine that is also commonly abused. Studies have shown that N2O alters the function of the N-methyl-d-aspartate (NMDA), GABAA, opioid, and serotonin receptors among others. However, the receptors systems underlying the abuse-related central nervous system effects of N2O are unclear. The present study explores the receptor systems responsible for producing the discriminative stimulus effects of N2O. B6SJLF1/J male mice trained to discriminate 10 minutes of exposure to 60% N2O + 40% oxygen versus 100% oxygen served as subjects. Both the high-affinity NMDA receptor channel blocker (+)-MK-801 maleate [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate] and the low-affinity blocker memantine partially mimicked the stimulus effects of N2O. Neither the competitive NMDA antagonist, CGS-19755 (cis-4-[phosphomethyl]-piperidine-2-carboxylic acid), nor the NMDA glycine-site antagonist, L701-324 [7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-2(1H)-quinolinone], produced N2O-like stimulus effects. A range of GABAA agonists and positive modulators, including midazolam, pentobarbital, muscimol, and gaboxadol (4,5,6,7-tetrahydroisoxazolo[4,5-c]pyridine-3-ol), all failed to produce N2O-like stimulus effects. The μ-, κ-, and δ-opioid agonists, as well as 5-hydroxytryptamine (serotonin) 1B/2C (5-HT1B/2C) and 5-HT1A agonists, also failed to produce N2O-like stimulus effects. Ethanol partially substituted for N2O. Both (+)-MK-801 and ethanol but not midazolam pretreatment also significantly enhanced the discriminative stimulus effects of N2O. Our results support the hypothesis that the discriminative stimulus effects of N2O are at least partially mediated by NMDA antagonist effects similar to those produced by channel blockers. However, as none of the drugs tested fully mimicked the stimulus effects of N2O, other mechanisms may also be involved.

Assessment of reinforcement enhancing effects of toluene vapor and nitrous oxide in intracranial self-stimulation

RATIONALE

Despite widespread abuse, there are few validated methods to study the rewarding effects of inhalants. One model that may have utility for this purpose is intracranial self-stimulation (ICSS).

OBJECTIVES

This study aims to compare and contrast the ICSS reward-facilitating effects of abused inhalants to other classes of abused drugs. Compounds were examined using two different ICSS procedures in mice to determine the generality of each drug's effects on ICSS and the sensitivity of the procedures.

METHODS

Male C57BL/6J mice with electrodes implanted in the medial forebrain bundle were trained under a three-component rate-frequency as well as a progressive ratio (PR) ICSS procedure. The effects of nitrous oxide, toluene vapor, cocaine, and diazepam on ICSS were then examined.

RESULTS

Concentrations of 1,360-2,900 parts per million (ppm) inhaled toluene vapor significantly facilitated ICSS in the rate-frequency procedure and 1,360 ppm increased PR breakpoint. A concentration of 40 % nitrous oxide facilitated ICSS in the rate-frequency procedure but reduced PR breakpoint. Doses of 3-18 mg/kg cocaine facilitated ICSS in the rate-frequency procedure, and 10 and 18 mg/kg increased PR breakpoint. Doses of 1 and 3 mg/kg diazepam facilitated ICSS in the rate-frequency procedure, and 3 mg/kg increased PR breakpoint.

CONCLUSIONS

The reinforcement-facilitating effect of toluene in ICSS is at least as great as diazepam. By contrast, nitrous oxide weakly enhances ICSS in only the rate-frequency procedure. The data suggest that the rate-frequency procedure may be more sensitive than the PR schedule to the reward-facilitating effects of abused inhalants.

Megaloblastic hematopoiesis in a 20 year old pregnant female

Background:

Nitrous oxide can cause disordered blood cell proliferation and lead to pancytopenia and altered immune function.

Case Report:

A young pregnant female patient presented after binge nitrous oxide abuse with altered mental status and abnormal vital signs. From her initial assessment she was noted to have pancytopenia and was found to have megaloblastic, hyper-cellular changes in a subsequent bone marrow biopsy. This presentation was determined to be secondary to toxic effects after heavy use of nitrous oxide.

Conclusions:

Nitrous oxide exposure, including use as an inhalant, over 12 hours can lead to bone marrow abnormalities such as megaloblastic hematopoiesis.

Volatile substance misuse : clinical considerations, neuropsychopharmacology and potential role of pharmacotherapy in management

Volatile substance misuse is among the most prevalent and toxic forms of psychoactive drug use, and often results in highly deleterious social, psychological and medical consequences. The prevalence of this pernicious form of substance misuse owes in part to the fact that volatile substances of misuse are ubiquitous in the natural environment. Commonly misused commercial products include glue, shoe polish, nail polish remover, butane lighter fluid, gasoline and computer duster spray. National samples of volatile substance misusers tend to exhibit high rates of psychiatric problems and antisocial behaviour. In addition, cognitive impairments and affective dysregulation are often observed among these individuals. Volatile substances exert their complex neuropharmacological effects on dopaminergic, glutamatergic, GABAergic and serotoninergic receptor systems, as well as on cell membranes and ion channels. Concomitantly, pharmacotherapies for volatile substance abuse might profitably target a number of mechanisms, including reward circuitry in the brain, symptoms of craving and withdrawal, neuropsychiatric and emotional impairments that promote volatile substance abuse, and cognitive enhancement to rectify deficits in executive function. This review details the modes of use, subjective effects, epidemiology, adverse consequences, neuropsychopharmacology and drug treatment of volatile substance misuse, and discusses the potential role of novel forms of pharmacological intervention for this oft-overlooked public health threat of epidemic proportions.

Adolescents and inhalant abuse: how huffing affects the myelin sheath

As concern grows over the impact that accidental chemical exposures may have on the long term health of individuals, our young people are deliberately exposing themselves to the effect of neurotoxic chemicals with the intent of feeling high. Over time the result of inhaling these chemicals is often the development of symptoms and behavior that may suggest serious physiological damage. Research is being conducted to examine what the exact nature of the damage might be, especially the impact of inhaled lipophilic chemicals on structures in the brain and other parts of the nervous system. Healthcare professionals responsible for assessing adolescents in all settings need to be aware of the prevalence of inhalant abuse, as well as the chemicals, terminology, and potential symptomatology in order to intervene in the behavior and provide diagnosis and treatment as indicated. Some implications for nursing are included.

The effect of age, gender, diet and lifestyle on DNA damage measured using micronucleus frequency in human peripheral blood lymphocytes

Micronucleus (MN) frequency in cytokinesis-blocked peripheral blood lymphocytes (PBL) has become one of the best-established biomarkers for studying DNA damage occurring in vivo in humans. The application of this method in population biomonitoring studies requires a deep understanding of how lifestyle and common host variables may influence MN frequency in PBL. In this mini-review, an update is provided on results from studies reporting on the impact of age, gender, diet and lifestyle factors (e.g. exercise, alcohol, smoking and recreational drugs) on this biomarker. Evidence from these studies shows that each of these factors, either in isolation or in combination, can significantly influence MN frequency. Proper control for these factors is required to enable better measurement of the impact of other conditions, such as environmental exposure to genotoxins or a susceptible genetic background, on MN frequency in PBL.

Volatile substance misuse in the United States

Volatile substance misuse (VSM) is prevalent in the United States and associated with manifold deleterious outcomes. This review summarizes research on: (1) the prevalence of VSM in the United States and its trends since 1975, (2) population subgroups at an elevated risk for VSM, (3) key correlates of VSM, (4) psychosocial consequences of VSM, including emerging public health threats, and (5) etiological and contextual considerations of VSM use. Implications for future research and practice with volatile substance misusers in the United States are identified.