Jia Liu , Xing Gao , Xiaojun Zhan , Yingxia Lu , Linyin Yao , Xiaoli Yi , Qinglong Gu
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引用次数: 0
Abstract
Purpose
Isolated congenital anosmia (ICA) is a relatively rare condition characterized by a complete lack of olfactory perception dating from birth or early childhood. Congenital deficits in sensory systems appear to have distinct effects on brain function and nervous system pathway, but little is known about ICA. The study aims to explore the neural basis of ICA through measuring brain activation in response to olfactory stimuli and cerebral processing in patients with ICA.
Methods
Retrospective review of medical records of 11 ICA patients from two smell and taste centers. All patients who were diagnosed ICA thorough interview and medical investigation. We used olfactory pathway magnetic resonance imaging (MRI) to evaluate the structural change of olfactory system, and functional MRI (fMRI) to observe the brain's response to pleasant and unpleasant olfactory stimuli (phenethyl alcohol and isovaleric acid) in 11 patients with ICA and 11 age- and sex-matched controls. Additionally, we measured EEG signals using olfactory and trigeminal event-related potentials (oERP and tERP) in response to phenethyl alcohol and CO2 stimuli, respectively. The Sniffin' Sticks test was used to evaluate the participants' subjective olfactory function.
Results
ICA patients showed the smaller olfactory bulb and shallower olfactory sulcus than controls. Healthy subjects showed brain activity in multiple regions associated with olfactory processing. Subjects with ICA exhibited reduced or no activation in the olfactory cortex, which is responsible for olfactory processing. Nevertheless, these subjects had activation outside the olfactory cortex, indicating functional compensation. In the case of ICA, oERP was missing in all patients while it was present in all control subjects. tERP was detected in 8 patients with anosmia, and these patients displayed higher amplitude signals in the N1 and P2 waves than the controls (p < 0.001, p < 0.05).
Conclusion
Congenital anosmia patients exhibit functional inactivation in the olfactory cortex and neurophysiologic deficits throughout the olfactory pathway. Our findings support the concept of distinct central nervous system abnormalities in ICA.
目的孤立性先天性嗅觉缺失(ICA)是一种相对罕见的疾病,其特征是从出生或儿童早期就完全缺乏嗅觉知觉。感觉系统的先天性缺陷似乎对脑功能和神经系统通路有明显的影响,但对ICA知之甚少。本研究旨在通过测量ICA患者对嗅觉刺激的脑激活和大脑加工,探讨ICA的神经基础。方法回顾性分析来自两个嗅觉和味觉中心的11例ICA患者的病历。所有诊断为ICA的患者均进行了彻底的访谈和医学调查。我们使用嗅觉通路磁共振成像(MRI)评估了11例ICA患者嗅觉系统的结构变化,并使用功能磁共振成像(fMRI)观察了大脑对愉快和不愉快的嗅觉刺激(苯乙醇和异戊酸)的反应,以及11例年龄和性别匹配的对照组。此外,我们分别使用嗅觉和三叉神经事件相关电位(oERP和tERP)测量脑电信号对苯乙醇和二氧化碳刺激的反应。用嗅探棒测试来评估参与者的主观嗅觉功能。结果与对照组相比,ica患者嗅球变小,嗅沟变浅。健康受试者在与嗅觉处理相关的多个区域表现出大脑活动。患有ICA的受试者表现出负责嗅觉处理的嗅觉皮层的激活减少或没有。然而,这些受试者在嗅觉皮层外有激活,表明功能补偿。在ICA病例中,所有患者均未出现oERP,而所有对照受试者均出现oERP。在8例嗅觉缺失患者中检测到tERP,这些患者在N1和P2波中表现出比对照组更高的振幅信号(p <;0.001, p <;0.05)。结论先天性嗅觉缺失患者表现为嗅觉皮质功能失活和整个嗅觉通路的神经生理缺陷。我们的发现支持了ICA中明显中枢神经系统异常的概念。
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