Objective: To retrospectively analysely the electrophysiological and imaging features of isolated congenital anosmia (ICA) and to assess the clinical phenotypic characteristics and classification of ICA. Methods: Clinical data of 30 ICA patients in Beijing Anzhen Hospital from 2012 to 2019 was retrospectively reviewed, including 13 males and 17 females, aged (35±19) years. The control group consisted of 30 healthy people from medical examination center, including 13 males and 17 females, aged (39±14) years. The clinical characteristics of ICA were analyzed using Sniffin' Sticks test, olfactory event-related potentials (oERPs), trigeminal event-related potentials (tERP) and olfactory pathway MRI. SPSS 17.0 software was used to compare the difference of olfactory function between the two groups. The correlation between olfactory bulb, olfactory sulcus structure and age was observed, and the clinical phenotype characteristics of ICA patients were analyzed. Results: The subjective olfactory function was completely lost in ICA patients. oERP was absent in all of the ICA patients, but showed normal N1 and P2 waves in controls. tERP could be evoked in 63.3% (19/30) of ICA patients, and signals in these patients showed higher amplitude in the N1 ((-10.33±6.93) μV vs (-5.11±2.71) μV, t=-10.113, P<0.01) and P2 ((+17.25±8.51) μV vs (+7.31±3.46) μV, t=5.443, P<0.01) waves than that of the controls. Olfactory bulbs were aplastic in 80.0% (24/30) of patients and hypoplastic in 20.0% (6/30) of patients. Fifty-six point seven percent (17/30) of patients had bilateral olfactory sulcus deletion while 43.3% (13/30) had dysplasia, and all of the patients exhibited a depth of olfactory sulcus less than 8 mm. Both the structure of olfactory bulbs and olfactory sulcus were not associated with age for ICA patients (r value was -0.174 and 0.325, respectively, all P>0.05). Conclusions: ICA patients show neurophysiologic deficits and some anatomic differences compared with healthy controls. The absence of oERP combining with a depth of olfactory sulcus less than 8 mm is the important indicator for clinical diagnosis of ICA. The structure of olfactory bulb may be a critical factor for clinical classification of ICA.
目的： 回顾性分析孤立型先天性失嗅（isolated congenital anosmia，ICA）患者嗅觉系统的电生理功能及影像学特点，探讨ICA的临床表型特征和分型方法。 方法： 收集2012—2019年就诊于北京安贞医院嗅觉味觉诊疗中心的30例ICA患者，男性13例，女性17例，年龄（35±19）岁。对照组为来自体检中心的健康成年人，包括男性13名，女性17名，年龄（39±14）岁。对受试者分别进行主观嗅觉功能检查（采用Sniffin′s Sticks嗅棒测试）、嗅觉诱发电位（olfactory event-related potentials，oERP）、三叉神经诱发电位（trigeminal event-related potentials，tERP）和嗅通路磁共振的检测。采用SPSS 17.0统计软件比较两组间嗅觉功能检测结果的差异，观察嗅球、嗅沟结构与年龄的相关性，分析ICA患者的临床表型特征。 结果： 30例ICA患者主观嗅觉功能完全丧失，oERP波形均缺失，提示嗅神经传导功能异常。36.7%（11/30）的患者tERP波形缺失，63.3%（19/30）的患者能够引出tERP波形，但与对照组相比，N1波［（-10.33±6.93）μV比（-5.11±2.71）μV，t=-10.113，P<0.01］和P2波［（+17.25±8.51）μV比 （+7.31±3.46）μV，t=5.443，P<0.01］的振幅均显著增加。80.0%（24/30）的患者双侧嗅球缺失，20.0%（6/30）的患者双侧对称或非对称性嗅球发育不良。56.7%（17/30）的患者双侧嗅沟缺失，43.3%（13/30）的患者嗅沟发育不良，双侧嗅沟深度均小于8 mm。嗅球体积和嗅沟深度均与年龄无相关性（r值分别为-0.174、0.325，P值均>0.05）。 结论： ICA患者的嗅觉系统在神经电生理功能和初级嗅中枢的影像学结构上均存在异常，oERP波形缺失、双侧嗅沟深度小于8 mm是ICA的重要特征，嗅球结构可能是区分ICA不同表型的关键因素。.