N2O Abuse Research Articles

Spectrum of nitrous oxide intoxication related neurological disorders in Korea: a case series and literature review

Background: Nitrous oxide (N2O) is used in surgery and dentistry for its anesthetic and analgesic effects. However, neurological and psychiatric manifestations of N2O abuse have been increasingly reported among Korean adults. The aim of this study was to demonstrate laboratory findings of N2O abuse in Korean patients.Methods: Patients diagnosed with N2O-induced neuropathy or myelopathy from August 2018 to December 2019 were enrolled. Their clinical presentations and laboratory and imaging findings were analyzed.Results: Sensory changes and limb weakness were present in nine of the enrolled patients. The laboratory findings revealed that seven patients had high homocysteine levels and five had high methylmalonic acid levels in their blood. Nerve conductions studies indicated that axonal neuropathy was present in four cases and longer F-wave and Hoffman’s-reflex latencies were present in two cases. Signal changes in cervical spine imaging occurred in five patients, while two had normal results.Conclusions: Chronic N2O abuse can cause neurological damage or psychiatric problems. Because N2O is illegal for recreational use in Korea, patients tend to hide their history of use. Even though the spinal imaging results were normal, clinicians should consider the possibility of N2O use, and further electrophysiological tests should be applied for precise evaluations.

Neurological consequences of recreational nitrous oxide abuse during SARS-CoV-2 pandemic.

IntroductionRecreational use of nitrous oxide (N2O) is a growing practice in France and all around the world and is often associated with neurological complications. We report detailed clinical and paraclinical presentations of 12 patients with combined degeneration of the spinal cord and peripheral neuropathies in relation to N2O consumption, possibly favored by lockdowns due to SARS-CoV-2 pandemic.ResultsWith variable levels of consumption, the 12 patients presented spinal cord and/or peripheral nerve damage, with mostly motor and ataxic symptoms, motor axonal nerve damage, and medullary T2-weighted hyperintensities on MRI. There was a clear improvement in symptoms after vitamin B12 substitution, although some sequelae remained, particularly sensory.DiscussionWe report detailed clinical, electrophysiological, radiological, and biological consequences of N2O abuse in 12 patients. Our data support the clinical and paraclinical observations reported in the literature. The mechanisms of neurological N2O toxicity are still debated. There is currently no precise recommendation on the therapeutic management. The clinical evolution after vitamin B12 substitution seems sufficient but could depend on early management. Effective messages targeting at risk population, but also the health professionals involved, seem crucial as does a better legal framework for this growing practice.

Nitrous Oxide Abuse Associated with Severe Thromboembolic Complications

Nitrous oxide (N2O) is gaining popularity as a party drug because of its hallucinogenic effects and low cost. Previous case reports found an association between N2O abuse and vascular complications.1,2 This might be caused by the accumulation of homocysteine induced by the oxidation of N2O to methylcobalamine vitamin B12 (Met-B12). Three patients with severe thromboembolic complications associated with N2O abuse are presented, all treated in our hospital in 2020.

Nitrous Oxide-Induced Neuropathy among Recreational Users in Vietnam.

Nitrous oxide (N2O) commonly referred to as laughing gas, has significant medical uses. This study aims to describe the neurological disorders associated with N2O. We conducted across-sectional study that enrolled patients with nitrous oxide toxicity admitted to Vietnam Poison Control Center, Bach Mai Hospital, Hanoi, Vietnam from June 2018 to July 2019. The questionnaire included demographic characteristics, characteristics of using N2O, signs and clinical symptoms, neuroimaging findings, injury on electromyography (EMG) and the Total Neuropathy Score clinical version (TNSc) criteria. A total of 47 participants were included with mean age: 24.38 ± 6.20 years. The number of balloons used per week was 130.59 ± 117.43. The mean duration of N2O exposure was 8.79 ± 7.1 months. Multivariate linear logistic regression revealed that the number of N2O balloons used per week was significantly associated with TNSc point (Beta: 0.315; 95% CI: 0.001–0.022). We found that myeloneuropathy and peripheral neuropathy were the main neurological disorders related to N2O abuse, which should improve the awareness of the appearance of neurological disorders associated with N2O abuse.

Key Characteristics of Nitrous Oxide-Induced Neurological Disorders and Differences Between Populations.

Background: Nitrous oxide (N2O), commonly known as laughing gas, is inhaled recreationally because it produces the feelings of euphoria and freedom from pain. The risk of neurological dysfunction secondary to N2O abuse and its clinical diagnosis are, however, not yet sufficiently recognized, especially in China. Here, we have summarized the key clinical characteristics of N2O-induced neurological disorders.Materials and Methods: We recruited 20 patients with N2O-induced neurological disorders and analyzed their clinical features, laboratory data, magnetic resonance imaging and electromyography. We also carried out a literature review and compared 99 previously reported patients with our case series to confirm our results. Subgroup analysis was performed to explore the difference in demographical and clinical characteristics of N2O abuse between Asian and non-Asian patients.Results: The most common initial symptoms of N2O-induced neurological disorders were weakness and/or paresthesia. Most patients presented with myelopathy and/or peripheral neuropathy. The most commonly involved segment of the spinal cord was the cervical spinal cord, extending over 4–6 vertebral levels, but more than half of the patients with myelopathy had no sensory change at the corresponding spinal level. Homocysteine was found to be the most sensitive and practical indicator for diagnosis. Subgroup analysis showed that the Asian patients (median: 22.0 years old, Q1–Q3:19.0–26.0 years old) with N2O abuse were younger than non-Asian patients [26.0 (22.3–31.0) years old, P = 2.8 × 10−4]. The incidence of myelopathy combined with peripheral neuropathy was significantly higher in Asian patients than in non-Asian patients, who had myelopathy or peripheral neuropathy (P = 2 × 10−5).Conclusions: Key clinical characteristics of N2O abuse are longitudinally extensive cervical myelopathy and peripheral neuropathy. Recognition of these traits in young people in the age group of 20–30 years will provide important guidance for accurate diagnosis of neurological disease associated with N2O abuse. The clinical manifestations differ in Asian patients and non-Asian patients.

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.

Plaque erosion causing ST-elevation myocardial infarction after consumption of cannabis and N2O in a 27-year old man: a case report

BackgroundThe recreational drugs cannabis and nitrous oxide (N2O) are known for pro-atherogenic effects and are associated with an elevated risk of myocardial infarction. These cardiovascular effects might be underestimated by the public. Culprit-lesion composition of myocardial infarctions associated with cannabis and N2O has been unknown so far. This case report aims to raise the awareness of the adverse cardiovascular effects of cannabis and N2O and reports, for the first time, optical coherence tomography (OCT) findings of the culprit lesion.Case presentationThis is a case report of a 27-year old man with anterior ST-segment-elevation myocardial infarction (STEMI) after intoxication with cannabis and N2O. Coronary angiography and OCT revealed plaque erosion with subsequent subtotal thrombotic occlusion of the left anterior descending artery that was successfully treated with 1 drug-eluting stent. The patient was symptom free at 6 months follow-up and had been able to abstain from drug consumption.ConclusionsThis is the first case to demonstrate the association between cannabis and N2O abuse and plaque erosion on OCT in a young man with STEMI. In contrast to smoking, whose adverse effects are well-known, the cardiovascular effects of cannabis and N2O might be underestimated. These adverse effects should gain more awareness in the public to prevent early vascular events in young adults.

Appearance of hypersegmented neutrophils in the peripheral blood associated with subacute combined degeneration of the spinal cord due to nitrous oxide abuse

A 25-year-old man following 1 year of recreational nitrous oxide (N2O) use presented with quadriplegia and decreased sensation in a glove and stocking distribution. The weakness distally was 2/5 and proximally 2–3/5. The spinal cord lesions showed an increased signal in a V-shape within the posterior column on T2-weighted magnetic resonance imaging (MRI) extending posteriorly from the C1–C2 level to the C5 level. Laboratory tests showed: white cell count 4.39 × 109/l, red cell count 3.95 × 109/l, haemoglobin concentration 133 g/l, haematocrit 0.39 l/l, mean corpuscular volume 99.4 fl (normal range 82–100), mean corpuscular haemoglobin 33.8 pg, mean corpuscular haemoglobin concentration 340 g/l, red cell distribution width 16.2% (9.0–17.0), platelet count 175 × 109/l, serum folate 22.82 ng/ml (5.90–24.80), homocysteine 11.3 μmol/l (0.0–20.0), methylmalonic acid 296 nmol/l (73–376), vitamin B12 312 pg/ml (180–914) and thiamine 165.3 nmol/l (66.5–200). The differential white cell count was normal but a peripheral blood film showed hypersegmented neutrophils, 19% having 6 lobes (normal 1–5) (images, ×100 objective, Wright–Giemsa stain). Neutrophil alkaline phosphatase was normal. The morphology of mature red blood cells showed no obvious abnormality. The patient received intensive physiotherapy and vitamin B12 therapy. At outpatient review 6 weeks later, his symptoms had improved considerably. Neurological examination was normal apart from a mild hyporeflexia of the lower limbs. His peripheral blood film no longer showed neutrophil hypersegmentation. The clinical diagnosis of nitrous oxide abuse causing subacute combined degeneration of the spinal cord mainly depends on a history of N2O inhalation. However patients who are generally young men may conceal the N2O abuse history. Hence, clinical staff should be aware not only of the various presentations of neurotoxicity, but also the peripheral blood features related to N2O abuse.

Rewarding Subjective Effects of the NMDAR Antagonist Nitrous Oxide (Laughing Gas) Are Moderated by Impulsivity and Depressive Symptoms in Healthy Volunteers.

BackgroundNitrous oxide (N2O) is an anesthetic gas with both therapeutic and abuse potential. Because N2O is an NMDA receptor (NMDAR) antagonist, its effects are expected to resemble those of the prototypical NMDAR antagonist, ketamine. In this study, we examined the subjective rewarding effects of N2O using measures previously employed in studies of ketamine. We also tested for moderation of these effects by bipolar phenotype, depressive symptoms, and impulsivity.MethodsHealthy volunteers were randomly assigned to either 50% N2O (n = 40) or medical air (n = 40). Self-reported rewarding (liking and wanting), and alcohol-like effects were assessed pre-, peri- and post inhalation.ResultsEffect sizes for the various rewarding/alcohol-like effects of N2O were generally similar to those reported in studies of moderate-dose ketamine. Impulsivity moderated the subjective reinforcing (liking) effects of inhaled gas, while depressive symptoms moderated motivational (wanting [more]) effects. However, depression and impulsivity had opposite directional influences, such that higher impulsivity was associated with higher N2O liking, and higher depression, with lower N2O wanting.ConclusionTo the extent that static (versus longitudinal) subjective rewarding effects are a reliable indicator of future problematic drug use, our findings suggests that impulsivity and depression may predispose and protect, respectively, against N2O abuse. Future studies should examine if these moderators are relevant for other NMDAR antagonists, including ketamine, and novel ketamine-like therapeutic and recreational drugs. Similarities between moderate-dose N2O and moderate-dose ketamine in the intensity of certain subjective effects suggest that N2O may, at least to some extent, serve as substitute for ketamine as a safe and easily implemented experimental tool for probing reward-related NMDAR function and dysfunction in humans.

Systematic Review of Vitamin B12 Regimen for Patient with Subacute Combined Degeneration of the Spinal Cord Following Nitrous Oxide Abuse

Purpose: The purpose of this study is to evaluate the effectiveness of vitamin B12 treatment in subacute combined degeneration (SCD) caused by nitrous oxide (N2O) abuse. Methods: Relevant literature was accessed through PubMed, EMBASE, Scopus, and KoreaMed. All the literature that was relevant to human use of vitamin B12 treatment for SCD caused by N2O abuse was included. Case reports were excluded if the treatment regimens were not precisely described. The literature search was conducted by two investigators during September 2019 for the final publication period. The languages of the publications were restricted to English and Korean. Results: Twenty-three published articles that contained 24 cases were included. Sixteen cases among them were treated with intramuscular vitamin B12 of 1 mg/day and the rest received different doses or routes. Although most cases described significant clinical improvements, one case showed no beneficial effect due to the patient's noncooperation. Another case showed adverse events, including spinal myoclonus, following vitamin B12 therapy. Conclusion: Vitamin B12 has been broadly used for the treatment of SCD caused by N2O abuse. However, most of the relevant studies were case reports that reported various regimens of vitamin B12 administration. Further studies are needed to establish a standard regimen of vitamin B12 because the incidence of N2O abuse may increase in South Korea.

Systematic Review of Vitamin B12 Regimen for Patient with Subacute Combined Degeneration of the Spinal Cord Following Nitrous Oxide Abuse

Purpose: The purpose of this study is to evaluate the effectiveness of vitamin B12 treatment in subacute combined degeneration (SCD) caused by nitrous oxide (N2O) abuse. Methods: Relevant literature was accessed through PubMed, EMBASE, Scopus, and KoreaMed. All the literature that was relevant to human use of vitamin B12 treatment for SCD caused by N2O abuse was included. Case reports were excluded if the treatment regimens were not precisely described. The literature search was conducted by two investigators during September 2019 for the final publication period. The languages of the publications were restricted to English and Korean. Results: Twenty-three published articles that contained 24 cases were included. Sixteen cases among them were treated with intramuscular vitamin B12 of 1 mg/day and the rest received different doses or routes. Although most cases described significant clinical improvements, one case showed no beneficial effect due to the patient's noncooperation. Another case showed adverse events, including spinal myoclonus, following vitamin B12 therapy. Conclusion: Vitamin B12 has been broadly used for the treatment of SCD caused by N2O abuse. However, most of the relevant studies were case reports that reported various regimens of vitamin B12 administration. Further studies are needed to establish a standard regimen of vitamin B12 because the incidence of N2O abuse may increase in South Korea.

Literature review of nitrous oxide-induced disease

Nitrous oxide (N2O) is an anesthetic which is also known to have abuse potential. Nitrous oxide-induced disease is occasionally encountered in the clinic, and there have been only several case reports about nitrous oxide-induced disease. In this article we review the reported cases of severe nerve injury following N2O abuse. Key words: Nitrous oxide; Neurotoxicity syndromes

The sharp rise of neurological disorders associated with recreational nitrous oxide use in China: a single-center experience and a brief review of Chinese literature.

In recent years, there has been a sharp increase in the number of patients with neurological disorders associated with recreational use of nitrous oxide (N2O) in China. Here, we summarize the clinical characteristics of patients with neurological disorders associated with N2O abuse diagnosed in our Hospital. Further, we conducted a literature search on recent cases reported in mainland China to improve the awareness of the outbreak of neurological disorders associated with N2O abuse. We retrospectively collected data of patients diagnosed with neurological disorders associated with recreational use of N2O in Shengjing Hospital of China Medical University from January 2018 to June 2019, and performed a literature search using the "nitrous oxide" and "neurological disorder" as keywords in the Chinese literature databases of WANFANG and CNKI and the English literature databases of Pubmed and Web of Science RESULTS: We enrolled 43 patients (average age: 21.9 ± 3.3years). The main clinical manifestations were weakness and paresthesia in the four extremities and unsteady gait. Further, most patients showed significantly lower levels of serum vitamin B12 (169.4 ± 79.1pg/mL) and increased homocysteine levels (78.1 ± 32.2μmol/L). MRI of the spinal cord showed longitudinal high T2 signal lesions in the dorsal spinal cord in some patients. Moreover, electromyography showed sensory and motor nerve axonal damage combined with demyelination, which was relatively more severe in the lower limbs. There was rapid improvement of the symptoms after treatment with intramuscular injections of vitamin B12 and the overall prognosis was good. The literature search indicated that the number of published papers and related patients showed a rapid annual increase since the first Chinese case reported in 2016 CONCLUSION: Recreational use of N2O is an emerging public health problem in China that needs prompt action from the society and government. Early diagnosis and treatment allow a good overall prognosis.

Skin hyperpigmentation: a rare presenting symptom of nitrous oxide abuse

Context: Recreational nitrogen oxide (N2O) abuse can cause nervous system damage. There was a sharp increase in the number of patients with neurological disorders associated with recreational N2O use in China, as recreational N2O use became popular in young people nationwide. Among cases with neurological disorders caused by N2O abuse, a few showed skin hyperpigmentation, which has rarely been reported. We explored the characteristics of hyperpigmentation in N2O abusers to draw the attention of clinicians to this rare cutaneous symptom related to N2O abuse.Methods: We retrospectively collected data of patients with neurological disorders related to recreational N2O abuse in Shengjing Hospital of China Medical University from January 2014 to June 2019. Detailed clinical data were gathered from patients who manifested skin pigmentation, including the history of N2O abuse and characteristics of neurological lesions and skin pigmentation.Results: In total, 66 patients (average age: 22.7 ± 4.5 years, 36 males) with neurological disorders due to N2O abuse were included; four of them (17–23 years old, 1 male) manifested skin hyperpigmentation. The duration of N2O abuse of the four patients ranged from 2 to 24 months, and they all had peripheral neuropathy; the two patients also had subacute combined degeneration of the spinal cord. One patient exhibited significant hyperpigmentation throughout the body (trunk, limbs, and face), with no abnormalities in cortisol and other biochemical tests. One patient presented with punctuate pigmentation throughout the trunk. Two patients presented with finger skin pigmentation, especially in the distal phalanxes. Pigmentation after N2O use remitted slowly with vitamin B12 supplementation.Conclusion: Skin hyperpigmentation is a rare symptom in N2O abusers, which can distribute locally in hands or diffusely throughout the body. Therefore, attention should be paid to a history of N2O abuse and serum vitamin B12 level should be tested.

Elucidating Unique Axonal Dysfunction Between Nitrous Oxide Abuse and Vitamin B12 Deficiency.

Introduction: Abuse of nitrous oxide (N2O) has an unusually high lifetime prevalence in developed countries and represents a serious concern worldwide. Myeloneuropathy following the inhalant abuse is commonly attributed to the disturbance of vitamin B12 metabolism, with severe motor deficits are often noted. The present study aims to elucidate its underlying pathophysiology.Methods: Eighteen patients with N2O abuse or vitamin B12 deficiency were recruited. Comprehensive central and peripheral neuro-diagnostic tests were performed, including whole spine MRI, and thermal quantitative sensory testing (QST). Specifically, paired motor and sensory nerve excitability tests were performed in order to obtain a complete picture of the sensorimotor axonal damage.Results: The mean duration of N2O exposure for the N2O abuse patients was 17.13 ± 7.23 months. MRI revealed T2 hyperintensity in 87.5% of the N2O abuse patients and 50% of the vitamin B12 deficiency patients. In N2O abuse patients, the motor nerve excitability test showed decreased in peak response (7.08 ± 0.87 mV, P = 0.05), increased latency (7.09 ± 0.28 ms, P < 0.01), increased superexcitability (−32.95 ± 1.74%, P < 0.05), and decreased accommodation to depolarizing current [TEd (40–60 ms) 56.53 ± 0.70%, P < 0.05]; the sensory test showed only decreased peak response (30.54 ± 5.98 μV, P < 0.05). Meanwhile, motor test in vitamin B12 deficiency patients showed only decreased accommodation to depolarizing current [TEd (40–60 ms) 55.72 ± 1.60%, P < 0.01]; the sensory test showed decreased peak response (25.86 ± 3.44 μV, P < 0.05) increased superexcitability (−28.58 ± 3.71%, P < 0.001), increased subexcitability (8.31 ± 1.64%, P < 0.05), and decreased accommodation to depolarizing current [TEd (peak) 67.31 ± 3.35%, P < 0.001].Conclusion: Compared to vitamin B12 deficiency, N2O abuse patients showed prominent motor superexcitability changes and less prominent sensory superexcitability changes, hinting a unique pathological process different from that of vitamin B12 deficiency. N2O abuse might cause axonal dysfunction not only by blocking methionine metabolism but also by toxicity affecting the paranodal region.

Recreational nitrous oxide abuse related subacute combined degeneration of the spinal cord in adolescents – A case series and literature review

BackgroundNitrous oxide (N2O) is a commonly used inhaled anesthetic in outpatient dental procedures. However, the increasing recreational use of N2O may result in vitamin B12 deficiency-related neurologic and psychiatric symptoms. The aim of this study was to demonstrate the clinical features of chronic N2O abuse in pediatric patients. MethodsPatients under 20 years of age who were diagnosed with N2O-induced subacute combined degeneration of the spinal cord from 2012 to 2018 were enrolled in this study. Clinical presentations, laboratory, imaging, ancillary studies, treatments and outcomes were analyzed. ResultsNine patients were included, all of whom presented with symptoms of myeloneuropathy including limb numbness, limb weakness or unsteady gait. Six patients had low or low-normal vitamin B12 (cyanocobalamin) levels. Eight patients had evidence of subacute combined degeneration of the spinal cord via neuroimaging studies. All of the patients received vitamin B12 supplementation as treatment. All had full recovery of muscle power within 2 months. Five patients had persistent sensory deficits. ConclusionChronic N2O abuse can cause permanent neurological damage if not treated promptly. Clinical staff should be aware of the various presentations of neurotoxicity related to N2O abuse.

Imaging appearance of myelopathy secondary to nitrous oxide abuse: a case report and review of the literature

Purpose The abuse of nitrous oxide (N2O) can induce Vitamin B12 deficiency that subsequently leads to central nervous demyelination, myelopathy and peripheral neuropathy. Although myelopathy has been reported in the past, the specific locations and prognosis of the disease are still unclear.Materials and methods: We report the case of a 22-year-old male who presented with quadriplegia that began after a 3-month history of inhalation of N2O. We summarized the clinical data of this entity and performed a comprehensive literature review of various presentations and MRI features of myelopathy secondary to N2O abuse.Results: In combination with previous reports of 14 cases, we found that the onset of the disease was usually subacute, and the majority of patients (92.85%) were young men. There was no definite relationship between myelopathy and the amount or duration of N2O inhalation. The most common clinical manifestation was sensory ataxia, and the cervical spinal cord was the most frequently impaired area of the whole spinal cord. The spinal cord lesions had a high signal intensity on T2-weighted MRI and usually involved more than three spinal segments and impaired the posterior column more significantly. Most patients recovered well after vitamin B12 supplementation.Conclusions: Myelopathy secondary to N2O abuse is generally seen in young men. The clinical diagnosis mainly depends on a history of N2O inhalation and the characteristic imaging changes in the posterior cervical spinal cord. Early diagnosis and intervention are important for a satisfactory prognosis.

“Whippet” Into Your Differential

SESSION TITLE: Critical Care Case Report Posters SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 27, 2015 at 01:30 PM - 02:30 PM INTRODUCTION: The differential diagnosis of a patient presenting with confusion and neurologic abnormalities is broad. Recreational drug use is a common etiology while vitamin deficiency is more rare. Here we present a case of recreational drug abuse precipitating severe vitamin deficiency resulting in neurologic abnormalities. CASE PRESENTATION: A 60-year-old male presented with altered mental status and ataxia. He had a history of deteriorating mental status and progressive ataxia for several months. Notably he had been a chronically abusing nitrous oxide (N2O), known recreationally as “whippits”. In the ED the patient's mental status worsened, requiring intubation for airway protection. Physical exam was limited due to sedation. Diagnostic investigations revealed negative toxicology, pancytopenia, severely low vitamin B12 level with elevated methylmalonic acid and homocysteine levels. MRI of the spine revealed increased T2 signal intensity at the C3-C4 and C4-C5 levels. The patient was diagnosed with N2O induced severe vitamin B12 deficiency and neurotoxicity. He was treated with vitamin B12, leucovorin and thiamine, which yielded rapid improvement in hematologic abnormalities. He was discharged to inpatient rehabilitation with mild improvement in his neurologic abnormalities. DISCUSSION: N2O is used as an inhalational dissociative anesthetic and is available as a propellant in pressurized containers. N2O is a commonly abused inhalant. Abuse resulting in severe vitamin B12 deficiency and injury to the dorsal column of the spinal cord and peripheral nervous system has been described; however, it is uncommon likely due to a dose-response correlation. Mechanistically nitrous oxide irreversibly inactivates vitamin B12 leading to a functional deficiency ultimately inhibiting myelin formation in the spinal cord and peripheral nerves. Diagnostic imaging may reveal lesions on T2 weighted MRI. Treatment consists of vitamin B12 replacement and discontinuation of N2O use. Hematologic abnormalities normalize with vitamin supplementation; however, the neurologic prognosis varies. CONCLUSIONS: The clinician should consider N2O induced vitamin B12 deficiency when a patient presents with neurologic deficits, altered mental status and/or pancytopenia with a history of N2O abuse. Reference #1: Hsu C et al. Myelopathy and polyneuropathy caused by nitrous oxide toxicity:a case report. Am Jour of Emer Med.2012;30:1016.e3-e6 Reference #2: Baum VC.When Nitrous Oxide is No Laughing Matter. Pediatr Anessthesia.2007;17(9):824-830 DISCLOSURE: The following authors have nothing to disclose: Matthew Anderson, Trina Hollatz No Product/Research Disclosure Information

Polyneuropathy from inhalation of N 2 O cartridges through a whippedcream dispenser

A generalized toxic polyneuropathy was identified in a 23-year-old woman after excessive intentional inhalation of compressed N2O delivery from cartridges through a whipped-cream dispenser. The chronology of the patient's N2O abuse correlated clearly with two episodes of recurrent polyneuropathy. The toxic effects were limited to the nervous system, primarily involving the peripheral nerves, although some signs suggested a possible effect on the cerebellum or its connections. The findings on sural nerve biopsy were nonspecific, characterized principally by axonal degeneration. Gas chromatographic analysis of the N2O cartridges dispensed through the whipped-cream canister revealed an exposure to N2O and 26 other compounds. Three of these, trichloroethylene, toluene, and phenol, are known neurotoxins.