Epilepsy Centre, Department of Human Neurosciences, "Sapienza" University of Rome, Viale dell'Università, 30, 00185, Rome, Italy.
Neurology Unit, Ospedale "San Camillo de' Lellis", Rieti, Italy.
J Neurol. 2022 May;269(5):2762-2768. doi: 10.1007/s00415-022-10959-6. Epub 2022 Jan 10.
Despite being long neglected, olfaction has recently become a focus of intense research in neuroscience, as smell impairment has been consistently documented in both neurodegenerative and neuroinflammatory diseases. Considering the close anatomo-functional correlations between the limbic system and the central olfactory structures, we investigated olfaction in a population of patients with autoimmune encephalitis (AE).
Nineteen adult subjects (14 males, median age 64 years) diagnosed with definite (14/19) or possible (5/19) AE and followed for ≥ 6 months were enrolled. The Brief Smell Identification Test (B-SIT), a 12-item, forced-choice, scratch-and-sniff measure, was used to assess the patients' olfactory function in comparison with a group of sex- and age-matched healthy controls (HC). According to the B-SIT score, subjects were classified as anosmic (< 6), hyposmic (6-8) and normal (≥ 9). Electro-clinical, laboratory and neuroimaging findings were reviewed.
Smell impairment was revealed in 15/19 patients (9 hyposmic, 6 anosmic), compared with 5/19 HC (p = 0.0029). Age, gender and smoking habits did not affect the participants' performance at B-SIT. Olfactory dysfunction appeared more common among patients with definite AE (p = 0.0374), regardless of autoantibody status. Subjects with higher modified Rankin Scale (mRS) scores at AE onset more likely presented hyposmia/anosmia (p = 0.033), and so did those with bilateral ictal/interictal EEG abnormalities (p = 0.006).
We found olfaction to be impaired in a significantly large proportion of AE cases. Smell deficits appeared more common in subjects with severe AE (as indicated by both definite diagnosis and higher mRS score), and might represent an additional feature of immune-mediated encephalitis.
尽管嗅觉长期以来一直被忽视，但它最近已成为神经科学研究的焦点，因为嗅觉障碍在神经退行性和神经炎症性疾病中均有记录。考虑到边缘系统与中枢嗅觉结构之间存在密切的解剖功能相关性，我们对自身免疫性脑炎（AE）患者的嗅觉进行了研究。
纳入了 19 名成年患者（男 14 例，中位年龄 64 岁），这些患者均被诊断为明确（14/19）或可能（5/19）AE，随访时间≥6 个月。使用 12 项、强制选择、刮擦和嗅探的简短嗅觉识别测试（B-SIT）来评估患者的嗅觉功能，并与一组性别和年龄匹配的健康对照者（HC）进行比较。根据 B-SIT 评分，将受试者分为嗅觉丧失（<6）、嗅觉减退（6-8）和正常（≥9）。回顾了电临床、实验室和神经影像学发现。
与 19 名 HC 中的 5 名相比（p=0.0029），19 名患者中有 15 名（9 名嗅觉减退，6 名嗅觉丧失）出现嗅觉障碍。年龄、性别和吸烟习惯均未影响 B-SIT 测试的结果。在明确的 AE 患者中，嗅觉功能障碍更为常见（p=0.0374），无论是否存在自身抗体。AE 发病时改良 Rankin 量表（mRS）评分较高的患者更有可能出现嗅觉减退/丧失（p=0.033），双侧发作期/发作间期脑电图异常的患者也更有可能出现嗅觉减退/丧失（p=0.006）。
我们发现 AE 患者中嗅觉受损的比例显著增加。嗅觉缺陷在 AE 严重程度较高的患者中更为常见（既表现在明确诊断中，也表现在更高的 mRS 评分中），这可能是免疫介导性脑炎的另一个特征。
