Gao Xing, Su Baihan, Sun Zhifu, Xu Lei, Wei Yongxiang, Wu Dawei
Department of Otorhinolaryngology-Head and Neck Surgery, Children's Hospital, Capital Institute of Pediatrics, Beijing, China.
Department of Otolaryngology, Smell and Taste Center, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
Front Neurol. 2022 Jul 4;13:690760. doi: 10.3389/fneur.2022.690760. eCollection 2022.
Traumatic brain injury is one of the major causes of human olfactory dysfunction and leads to brain structure alterations, mainly in the cortical olfactory regions. Our study aimed to investigate volume changes in the gray matter (GM) and white matter (WM) in patients with post-traumatic anosmia and then to explore the relationship between GM volume and olfactory function.
Ethics committee approved prospective studies which included 22 patients with post-traumatic anosmia and 18 age- and gender-matched healthy volunteers. Olfactory function was assessed using the Sniffin' Sticks. High-resolution 3-dimensional T1 MRIs of the participants were acquired on a 3T scanner and the data were collected for voxel-based morphometry (VBM) analysis. Furthermore, the GM and WM volumes of the whole brain regions were compared and correlated with olfactory function.
The analysis revealed significant GM volume reduction in the orbitofrontal cortex (OFC), gyrus rectus (GR), olfactory cortex, insula, parahippocampal, temporal pole, and cerebellum (all < 0.001) in patients. Besides, WM volume loss was also found in the OFC, GR, and insula (all < 0.001) in patients. All WM atrophy areas were connected to areas of GM volume loss spatially. Correlation analysis showed the olfactory scores were significantly positively correlated with the GM volume of the occipital cortex ( < 0.001, and < 0.05), while no significant correlation was found between the Sniffin' Sticks test scores and the WM volume in patients.
The reduction of GM and WM volume in olfactory-related regions was responsible for olfactory dysfunction in post-traumatic patients. The occipital cortex may play a compensation mechanism to maintain the residual olfactory function. To our knowledge, we report here for the first time on white matter volume alterations specifically in post-traumatic patients with anosmia.
创伤性脑损伤是人类嗅觉功能障碍的主要原因之一，会导致脑结构改变，主要发生在皮质嗅觉区域。我们的研究旨在调查创伤后嗅觉丧失患者的灰质（GM）和白质（WM）体积变化，进而探讨GM体积与嗅觉功能之间的关系。
伦理委员会批准了前瞻性研究，该研究纳入了22例创伤后嗅觉丧失患者以及18名年龄和性别匹配的健康志愿者。使用嗅觉棒评估嗅觉功能。在3T扫描仪上获取参与者的高分辨率三维T1 MRI，并收集数据用于基于体素的形态学测量（VBM）分析。此外，比较了全脑区域的GM和WM体积，并将其与嗅觉功能进行关联。
分析显示，患者的眶额皮质（OFC）、直回（GR）、嗅觉皮质、岛叶、海马旁回、颞极和小脑的GM体积显著减少（均P<0.001）。此外，患者的OFC、GR和岛叶也发现有WM体积减少（均P<0.001）。所有WM萎缩区域在空间上都与GM体积减少区域相连。相关性分析表明，嗅觉评分与枕叶皮质的GM体积显著正相关（P<0.001和P<0.05），而患者的嗅觉棒测试分数与WM体积之间未发现显著相关性。
嗅觉相关区域GM和WM体积的减少是创伤后患者嗅觉功能障碍的原因。枕叶皮质可能发挥补偿机制以维持残余嗅觉功能。据我们所知，我们首次在此报告了创伤后嗅觉丧失患者白质体积的特异性改变。
