Objective: Anosmia has been listed as a key-symptom associated with the COVID-19 infection. Because it often occurs without any sign of rhinitis, lesions of the central olfactory system have been suspected. To date, however, there is no evidence that anosmia caused by SARS-CoV2 could be the result of brain damage. Methods: We conducted a case-series on 10 consecutive COVID-19 patients who reported anosmia. Each patient prospectively underwent a validated olfactory test (Sniffin Sticks test) and a brain MRI. Results: Hypersignal intensity lesions of the central olfactory system were found in 3 subjects on 3D T2 FLAIR and 2D T2 High Resolution images with a lesion involving the olfactory bulbs and/or the orbitofrontal cortex. These 3 subjects showed a severe and persistent loss of smell on the olfactory test. Mucosal hyperplasia of the upper nasal cavities was found in two other subjects with significant smell disorders. There was no MRI anomaly in two subjects with good smell restoration. Conclusions: Anomalies of the central olfactory system could be responsible for anosmia in patients with COVID-19 infection. Further studies are needed to assess the impact on long-term functional prognosis of these lesions.

中文翻译：

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COVID-19失眠患者脑部MRI确诊的中央嗅觉系统病变：病例系列

目的：厌食症已被列为与COVID-19感染相关的关键症状。由于它经常在没有任何鼻炎迹象的情况下发生，因此怀疑中央嗅觉系统有病变。然而，迄今为止，尚无证据表明由SARS-CoV2引起的失眠可能是脑损伤的结果。方法：我们对连续10例报告失眠的COVID-19患者进行了病例系列研究。每位患者均接受了有效的嗅觉测试（Sniffin Sticks测试）和脑部MRI。结果：在3D T2 FLAIR和2D T2高分辨率图像上的3位受试者中发现了中央嗅觉系统的高信号强度病变，其病变涉及嗅球和/或眶额皮质。这三名受试者在嗅觉测试中表现出严重且持续的嗅觉丧失。在另外两个患有严重嗅觉障碍的受试者中发现了上鼻腔的粘膜增生。气味恢复良好的两名受试者没有MRI异常。结论：中央嗅觉系统异常可能是导致COVID-19感染的患者失眠的原因。需要进一步的研究来评估这些病变对长期功能预后的影响。