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

Abstract

Introduction: 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.

Methods: 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 ± 3.3 years). 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 ± 79.1 pg/mL) and increased homocysteine levels (78.1 ± 32.2 μmol/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.

Keywords: Laughing gas; Neurological disorders; Neuropathy; Nitrous oxide; Vitamin B12.