Department of Medicine, Northern Health, Melbourne, Victoria, Australia.
Department of Emergency Medicine, Northern Health, Melbourne, Victoria, Australia.
Emerg Med Australas. 2022 Aug;34(4):492-503. doi: 10.1111/1742-6723.13997. Epub 2022 Jun 13.
Recreational nitrous oxide (N O) use is widespread, and complications associated with its use are increasingly common. We sought to identify risk factors, clinical features and outcomes in individuals presenting with effects of chronic N O abuse to develop an approach to clinical assessment and management. A systemic literature review was completed with searches conducted across EMBASE, MEDLINE, PSYCINFO and Cochrane databases. Our search strategy identified 612 studies, 105 met inclusion criteria, and 10 were added via hand search. Subjects from 24 case series and 91 case reports were typically in their 20s, using over 100 bulbs daily for several months. Neurological presentations, including sensory change, gait disturbance or weakness, were characteristic. Serum Vitamin B12 was normal or raised in 133 out of 243 case series subjects and 37 out of 84 reports. Serum homocysteine and methylmalonic acid were usually raised. Macrocytosis and anaemia were not commonly seen. MRI findings were abnormal with dorsal column change where specified, typically involving the cervical spine. Nerve conduction studies mostly reported a sensorimotor polyneuropathy. B12 replacement was the treatment of choice and partial recovery was most reported. This review highlights the dose-dependent nature of chronic N O toxicity and recognises functional B12 deficiency as the cause. As B12 is often normal, homocysteine and methylmalonic acid are important biomarkers of disease. An approach to diagnosis is offered but requires validation in prospective studies. Research exploring B12 and methionine therapy is required to refine management.
娱乐性一氧化二氮（N O）的使用非常普遍，与使用相关的并发症也越来越常见。我们试图确定患有慢性 N O 滥用的个体出现的影响的风险因素、临床特征和结局，以制定临床评估和管理方法。通过对 EMBASE、MEDLINE、PSYCINFO 和 Cochrane 数据库进行搜索，完成了系统文献综述。我们的搜索策略确定了 612 项研究，其中 105 项符合纳入标准，另外通过手动搜索添加了 10 项。来自 24 项病例系列研究和 91 项病例报告的研究对象通常在 20 多岁，每天使用超过 100 个灯泡，持续数月。神经系统表现，包括感觉改变、步态障碍或无力，是特征性的。133 项病例系列研究中有 243 项血清维生素 B12 正常或升高，84 项报告中有 37 项血清同型半胱氨酸和甲基丙二酸升高。巨细胞性贫血和贫血并不常见。MRI 发现异常，有指定的背柱改变，通常涉及颈椎。神经传导研究大多报告为感觉运动性多发性神经病。B12 替代治疗是首选，大多数报告为部分恢复。本综述强调了慢性 N O 毒性的剂量依赖性，并认识到功能性 B12 缺乏是其病因。由于 B12 通常正常，同型半胱氨酸和甲基丙二酸是疾病的重要生物标志物。提出了一种诊断方法，但需要前瞻性研究验证。需要探索 B12 和蛋氨酸治疗的研究来改进管理。
