Oxford Autoimmune Neurology Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
Department of Neurology, John Radcliffe Hospital, Oxford University Hospitals, Oxford, United Kingdom.
JAMA Neurol. 2024 May 1;81(5):525-533. doi: 10.1001/jamaneurol.2024.0126.
Rapid and accurate diagnosis of autoimmune encephalitis encourages prompt initiation of immunotherapy toward improved patient outcomes. However, clinical features alone may not sufficiently narrow the differential diagnosis, and awaiting autoantibody results can delay immunotherapy.
To identify simple magnetic resonance imaging (MRI) characteristics that accurately distinguish 2 common forms of autoimmune encephalitis, LGI1- and CASPR2-antibody encephalitis (LGI1/CASPR2-Ab-E), from 2 major differential diagnoses, viral encephalitis (VE) and Creutzfeldt-Jakob disease (CJD).
DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study involved a retrospective, blinded analysis of the first available brain MRIs (taken 2000-2022) from 192 patients at Oxford University Hospitals in the UK and Mayo Clinic in the US. These patients had LGI1/CASPR2-Ab-E, VE, or CJD as evaluated by 2 neuroradiologists (discovery cohort; n = 87); findings were validated in an independent cohort by 3 neurologists (n = 105). Groups were statistically compared with contingency tables. Data were analyzed in 2023.
MRI findings including T2 or fluid-attenuated inversion recovery (FLAIR) hyperintensities, swelling or volume loss, presence of gadolinium contrast enhancement, and diffusion-weighted imaging changes. Correlations with clinical features.
Among 192 participants with MRIs reviewed, 71 were female (37%) and 121 were male (63%); the median age was 66 years (range, 19-92 years). By comparison with VE and CJD, in LGI1/CASPR2-Ab-E, T2 and/or FLAIR hyperintensities were less likely to extend outside the temporal lobe (3/42 patients [7%] vs 17/18 patients [94%] with VE; P < .001, and 3/4 patients [75%] with CJD; P = .005), less frequently exhibited swelling (12/55 [22%] with LGI1/CASPR2-Ab-E vs 13/22 [59%] with VE; P = .003), and showed no diffusion restriction (0 patients vs 16/22 [73%] with VE and 8/10 [80%] with CJD; both P < .001) and rare contrast enhancement (1/20 [5%] vs 7/17 [41%] with VE; P = .01). These findings were validated in an independent cohort and generated an area under the curve of 0.97, sensitivity of 90%, and specificity of 95% among cases with T2/FLAIR hyperintensity in the hippocampus and/or amygdala.
In this study, T2 and/or FLAIR hyperintensities confined to the temporal lobes, without diffusion restriction or contrast enhancement, robustly distinguished LGI1/CASPR2-Ab-E from key differential diagnoses. These observations should assist clinical decision-making toward expediting immunotherapy. Their generalizability to other forms of autoimmune encephalitis and VE should be examined in future studies.
快速准确的自身免疫性脑炎诊断有助于及时启动免疫治疗，从而改善患者的预后。然而，仅凭临床特征可能不足以缩小鉴别诊断的范围，等待自身抗体的结果可能会延迟免疫治疗。
确定简单的磁共振成像（MRI）特征，可准确区分两种常见的自身免疫性脑炎，LGI1 和 CASPR2 抗体脑炎（LGI1/CASPR2-Ab-E）与两种主要鉴别诊断，病毒性脑炎（VE）和克雅氏病（CJD）。
设计、地点和参与者：这是一项回顾性、盲法分析英国牛津大学医院和美国梅奥诊所的 192 名患者的首份脑 MRI（2000-2022 年采集）的横断面研究。通过 2 名神经放射科医生（发现队列；n=87）评估这些患者为 LGI1/CASPR2-Ab-E、VE 或 CJD；结果由 3 名神经病学家（验证队列；n=105）在独立队列中验证。通过列联表对各组进行统计学比较。数据在 2023 年进行分析。
MRI 结果包括 T2 或液体衰减反转恢复（FLAIR）高信号、肿胀或体积损失、钆对比增强的存在以及弥散加权成像的变化。与临床特征的相关性。
在 192 名接受 MRI 检查的参与者中，71 名为女性（37%），121 名为男性（63%）；中位年龄为 66 岁（范围，19-92 岁）。与 VE 和 CJD 相比，在 LGI1/CASPR2-Ab-E 中，T2 和/或 FLAIR 高信号更不可能超出颞叶（42 名患者中的 3 名 [7%]与 18 名 VE 患者中的 17 名 [94%]；P<0.001，和 4 名 CJD 患者中的 3 名 [75%]；P=0.005），肿胀不常见（55 名患者中的 12 名 [22%]与 LGI1/CASPR2-Ab-E 相比，22 名 VE 患者中的 13 名 [59%]；P=0.003），没有弥散受限（0 名患者与 22 名 VE 患者中的 16 名 [73%]和 10 名 CJD 患者中的 8 名 [80%]；均 P<0.001）和罕见的对比增强（20 名患者中的 1 名 [5%]与 17 名 VE 患者中的 7 名 [41%]；P=0.01）。这些发现在独立队列中得到了验证，并在海马和/或杏仁核的 T2/FLAIR 高信号的情况下产生了 0.97 的曲线下面积、90%的敏感性和 95%的特异性。
在这项研究中，局限于颞叶的 T2 和/或 FLAIR 高信号，没有弥散受限或对比增强，可有力地区分 LGI1/CASPR2-Ab-E 与关键鉴别诊断。这些观察结果应有助于临床决策，加快免疫治疗的开展。在未来的研究中应检验其在其他形式的自身免疫性脑炎和 VE 中的泛化能力。
