新型冠状病毒感染相关嗅觉障碍的流行现状、机制和康复

COVID-19-related Olfactory Dysfunction:Prevalence,Mechanism and Recovery

新型冠状病毒感染(coronavirus disease 2019,COVID-19),下简称“新冠”,是由严重急性呼吸综合征冠状病毒2(severe acute respiratory syndrome coronavirus 2,SARS-CoV-2)引发的全球流行传染病。鉴于嗅觉障碍是其主要神经症状,明确相关流行现状、机制和康复对促进公共健康非常重要。文献报道的新冠相关嗅觉障碍的发生率存在差异,与评估工具、人群以及变异毒株3个因素有关。其中,不同毒株之间嗅觉障碍发生率的差异可能源于刺突糖蛋白和侵入方式的变异。在外周嗅觉系统,SARS-CoV-2主要引发嗅裂炎症、支持细胞死亡和宿主免疫反应,而关于SARS-CoV-2入侵中枢的途径和机制仍存争议。部分“长新冠”患者存在持续的嗅觉障碍,SARS-CoV-2诱发慢性炎症反应和对嗅上皮再生的破坏是其潜在的病理基础。根据嗅觉媒介假说,SARS-CoV-2可能借由嗅觉系统影响中枢功能并最终诱发神经退行性变。嗅觉训练、药物等方法可帮助新冠相关嗅觉障碍的康复。

Coronavirus disease 2019(COVID-19)is a global pandemic caused by the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Since olfactory dysfunction is the main neurological symptom of COVID-19,it is important to examine the prevalence,underlying mechanisms,and recovery trajectories of COVID-19-related olfactory dysfunction for the promotion of public health.Reported prevalence rates of COVID-19-related olfactory dysfunction vary widely across studies due to differences in the assessment of olfactory function,demographic background,and the predominant SARS-CoV-2 strains around the time of data collection.Specifically,different SARS-CoV-2 strains differ in the stability of spike glycoproteins and the host-cell infection pathways and thus efficacy in infecting the olfactory epithelium.In general,SARS-CoV-2 has been shown to cause inflammatory obstruction of the olfactory cleft,death of supporting cells,and host immune responses in the olfactory epithelium.Whether and how it invades into the central olfactory system remain controversial.Some individuals with“long COVID”suffer from chronic olfactory loss.The pathological mechanisms likely involve persistent inflammation in the olfactory epithelium and disruption of its regeneration triggered by SARS-CoV-2 infection.Based on the olfactory vector hypothesis,SARS-CoV-2 may affect central nervous system function by way of the olfactory system and could potentially induce neurodegeneration in the long term.Available interventions for managing olfactory dysfunction from SARS-CoV-2 infection include olfactory training and pharmacotherapy.