ABSTRACT

Human bornavirus encephalitis is an emerging disease caused by the variegated squirrel bornavirus 1 (VSBV-1) and the Borna disease virus 1 (BoDV-1). While characteristic brain magnetic resonance imaging (MRI) changes have been described for BoDV-1 encephalitis, only scarce diagnostic data in VSBV-1 encephalitis exist. We systematically analysed brain MRI scans from all known VSBV-1 encephalitis patients. Initial and follow-up scans demonstrated characteristic T2 hyperintense lesions in the limbic system and the basal ganglia, followed by the brainstem. No involvement of the cerebellar cortex was seen. Deep white matter affection occurred in a later stage of the disease. Strict symmetry of pathologic changes was seen in 62%. T2 hyperintense areas were often associated with low T1 signal intensity and with mass effect. Sinusitis in three patients on the first MRI and an early involvement of the limbic system suggest an olfactory route of VSBV-1 entry. The viral spread could occur per continuitatem to adjacent anatomical brain regions or along specific neural tracts to more distant brain regions. The number and extent of lesions did not correlate with the length of patients’ survivals. The overall pattern closely resembles that described for BoDV-1 encephalitis. The exact bornavirus species can thus not be deduced from imaging results alone, and molecular testing and serology should be performed to confirm the causative bornavirus. As VSBV-1 is likely of tropical origin, and MRI investigations are increasingly available globally, imaging techniques might be helpful to facilitate an early presumptive diagnosis of VSBV-1 encephalitis when molecular and/or serological testing is not available.

摘要

人博尔纳病毒脑炎是由杂色松鼠博尔纳病毒 1 (VSBV-1) 和博尔纳病病毒 1 (BoDV-1) 引起的一种新发疾病。虽然已经描述了 BoDV-1 脑炎的特征性脑磁共振成像 (MRI) 变化，但 VSBV-1 脑炎的诊断数据很少。我们系统地分析了所有已知 VSBV-1 脑炎患者的大脑 MRI 扫描。初始和后续扫描显示边缘系统和基底神经节中的特征性 T2 高信号病变，其次是脑干。未见小脑皮质受累。疾病晚期出现深部白质病变。62% 的病理变化严格对称。T2 高信号区域通常与低 T1 信号强度和质量效应相关。首次 MRI 显示三名患者的鼻窦炎和边缘系统的早期受累提示 VSBV-1 进入的嗅觉途径。病毒传播可能发生每个连续到相邻的大脑解剖区域或沿着特定的神经束到更远的大脑区域。病变的数量和范围与患者的存活时间长短无关。总体模式与针对 BoDV-1 脑炎所描述的非常相似。因此，不能仅从影像学结果推断出确切的博纳病毒种类，应进行分子检测和血清学以确认致病博纳病毒。由于 VSBV-1 很可能起源于热带，并且 MRI 检查在全球范围内越来越多地可用，因此当分子和/或血清学检测不可用时，成像技术可能有助于促进 VSBV-1 脑炎的早期推定诊断。