Hänsel Martin, Schmitz-Peiffer Henning, Hähner Antje, Reichmann Heinz, Schneider Hauke
Department of Neurology, University of Dresden, Dresden, Germany.
Department of Internal Medicine, GZO - Zurich Regional Health Center, Wetzikon, Switzerland.
Front Neurol. 2023 Aug 25;14:1225975. doi: 10.3389/fneur.2023.1225975. eCollection 2023.
Patients' olfactory function after autoimmune encephalitis (AE) involving limbic structures may be impaired. This study aimed to characterize olfactory function in patients after autoimmune encephalitides.
A case-control study was performed including 11 AE patients with antibodies against NMDAR ( = 4), GAD ( = 3), VGKC ( = 3) and antibody-negative AE ( = 1) and a control group of 12 patients with pneumococcal meningo-encephalitis (PC). In subgroup analyses, AE patients with and without NMDAR-antibodies were compared. Olfactory function was assessed using the Sniffin Sticks test and the resulting TDI-score (threshold, discrimination, identification). Involvement of limbic structures was evaluated on imaging data (MRI). Statistical analyses were performed to test for correlations of TDI-score and MRI results.
The overall olfactory function of the AE-group and the PC-group was comparable (mean TDI 32.0 [CI 27.3-36.7], 32.3 [CI 28.5-36.0)]. The proportions of hyposmic patients were similar compared to the general population. However, AE patients of the non-NMDAR group had significantly lower TDI-scores (28.9 ± 6,8) than NMDAR patients (37.4 ± 3.5) ( = 0.046) and a significantly lower discrimination capability than the NMDAR patients (9.9 ± 2.0 vs. 14.5 ± 0.6) ( = 0.002). The non-NMDAR patients had significantly more limbic MRI pathologies (6/7) compared to the NMDAR patients (0/4) ( = 0.015). Furthermore, a correlation between limbic MRI pathologies and worse capability of smelling discrimination was found ( = 0.016, = -0.704, = 11).
Our results indicate that patients with NMDAR autoimmune encephalitis have normal long term olfactory function. However, patients with non-NMDAR autoimmune encephalitis appear to have a persistently impaired olfactory function, probably mediated by encephalitic damage to limbic structures.
自身免疫性脑炎（AE）累及边缘系统结构后患者的嗅觉功能可能受损。本研究旨在描述自身免疫性脑炎患者的嗅觉功能特征。
进行了一项病例对照研究，纳入11例抗NMDAR（n = 4）、抗GAD（n = 3）、抗VGKC（n = 3）抗体阳性及抗体阴性的AE患者（n = 1），以及12例肺炎球菌性脑膜脑炎（PC）患者作为对照组。在亚组分析中，比较了有和没有NMDAR抗体的AE患者。使用嗅觉棒测试评估嗅觉功能，并得出TDI评分（阈值、辨别力、识别力）。根据影像学数据（MRI）评估边缘系统结构的受累情况。进行统计分析以检验TDI评分与MRI结果之间的相关性。
AE组和PC组的总体嗅觉功能相当（平均TDI分别为32.0 [CI 27.3 - 36.7]，32.3 [CI 28.5 - 36.0]）。嗅觉减退患者的比例与一般人群相似。然而，非NMDAR组的AE患者的TDI评分（28.9±6.8）显著低于NMDAR患者（37.4±3.5）（p = 0.046），且辨别能力显著低于NMDAR患者（9.9±2.0对14.5±0.6）（p = 0.002）。与NMDAR患者（0/4）相比，非NMDAR患者有更多的边缘系统MRI病变（6/7）（p = 0.015）。此外，发现边缘系统MRI病变与嗅觉辨别能力较差之间存在相关性（p = 0.016，r = -0.704，n = 11）。
我们的结果表明，NMDAR自身免疫性脑炎患者的长期嗅觉功能正常。然而，非NMDAR自身免疫性脑炎患者似乎存在持续受损的嗅觉功能，可能是由边缘系统结构的脑炎损伤介导的。
