Table_3_Magnetic resonance imaging in acute meningoencephalitis of viral and unknown origin: frequent findings and prognostic potential.DOCX

BackgroundMagnetic resonance imaging (MRI) findings in meningoencephalitis have mainly been described in terms of their diagnostic value rather than their prognostic potential, except for herpes simplex virus (HSV) encephalitis. The aims of our study were to describe frequency and anatomic locations of MRI abnormalities specific to limbic, circadian and motor systems in a cohort of meningoencephalitis patients, as well as to investigate the prognostic value of these MRI findings. MethodsA secondary, selective analysis of a retrospective database including all meningitis, meningoencephalitis and encephalitis cases treated between 2016 and 2018 in the University hospital of Bern, Switzerland was performed. Patients with meningitis of any cause, bacterial or autoimmune causes of encephalitis were excluded. ResultsMRI scans and clinical data from 129 meningoencephalitis cases found that the most frequent causes were tick-borne encephalitis (TBE, 42%), unknown pathogens (40%), VZV (7%), and HSV1 (5%). At discharge, median modified Rankin Score (mRS) was 3 (interquartile range, IQR, 1), 88% of patients had persisting signs and symptoms. After a median of 17 months, median Glasgow Outcome Score (GOS) was 5 (IQR 1), 39% of patients still had residual signs or symptoms. All patients with HSV, 27% with TBE and 31% of those with meningoencephalitis of unknown etiology had fluid-attenuated inversion recovery (FLAIR) and to a lesser extent diffusion-weighted imaging (DWI) lesions in their initial MRI, with highly overlapping anatomical distribution. In one fifth of TBE patients the limbic system was affected. Worse outcome was associated with presence of DWI and/or FLAIR lesions and lower normalized apparent diffusion coefficient (ADC) signal intensities. ConclusionPresence of FLAIR lesions, restricted diffusion as well as the extent of ADC hypointensity in initial MRI are parameters which might be of prognostic value regarding the longterm clinical outcome for patients with meningoencephalitis of viral and of unknown origin. Although not described before, affection of limbic structures by TBE is possible as shown by our results: A substantial proportion of our TBE patients had FLAIR signal abnormalities in these regions.研究背景：除单纯疱疹病毒（Herpes Simplex Virus, HSV）脑炎外，脑膜脑炎患者的磁共振成像（Magnetic Resonance Imaging, MRI）表现既往多聚焦于其诊断价值，而非预后潜力。本研究旨在明确脑膜脑炎患者队列中，累及边缘系统、昼夜节律系统与运动系统的MRI异常的发生率及解剖分布，并探讨此类MRI表现的预后价值。 研究方法：本研究对瑞士伯尔尼大学医院2016至2018年间收治的所有脑膜炎、脑膜脑炎及脑炎病例的回顾性数据库进行二次选择性分析。本研究排除了任何病因的脑膜炎患者，以及细菌感染或自身免疫性病因导致的脑炎患者。 研究结果：本研究纳入129例脑膜脑炎患者的MRI扫描结果与临床数据，发现最常见的病因依次为蜱传脑炎（Tick-borne Encephalitis, TBE，42%）、病原体未知（40%）、水痘带状疱疹病毒（Varicella-Zoster Virus, VZV，7%）及单纯疱疹病毒1型（HSV1，5%）。出院时，患者的改良Rankin量表（Modified Rankin Scale, mRS）中位数为3（四分位距IQR=1），88%的患者仍存在持续的体征与症状。随访中位数时长为17个月时，格拉斯哥预后评分（Glasgow Outcome Scale, GOS）中位数为5（四分位距IQR=1），39%的患者仍存在残留体征或症状。所有HSV感染患者、27%的TBE患者及31%的病因不明脑膜脑炎患者，在初始MRI中均出现液体衰减反转恢复序列（Fluid-Attenuated Inversion Recovery, FLAIR）病灶，且伴有一定程度的弥散加权成像（Diffusion-Weighted Imaging, DWI）病灶，两者的解剖分布高度重叠。五分之一的TBE患者存在边缘系统受累。不良预后与DWI和/或FLAIR病灶的存在，以及归一化表观扩散系数（Apparent Diffusion Coefficient, ADC）信号强度降低显著相关。 研究结论：对于病毒性及病因不明的脑膜脑炎患者，初始MRI中FLAIR病灶的存在、弥散受限以及ADC低信号的范围，可作为预测其长期临床结局的潜在指标。本研究结果显示，尽管此前尚无相关报道，但TBE确实可能累及边缘系统结构：本研究中相当比例的TBE患者在该区域存在FLAIR信号异常。