MRI findings in autoimmune encephalitis.

in Revue neurologique by T J Hartung, F Bartels, J Kuchling, S Krohn, J Leidel, M Mantwill, K Wurdack, S Yogeshwar, M Scheel, C Finke

TLDR

  • This study is about understanding the MRI changes in different types of autoimmune encephalitis.
  • The study found that different types of autoimmune encephalitis have different MRI changes.
  • The study suggests that MRI is important for diagnosing autoimmune encephalitis and managing long-term complications.

Abstract

Autoimmune encephalitis encompasses a spectrum of conditions characterized by distinct clinical features and magnetic resonance imaging (MRI) findings. Here, we review the literature on acute MRI changes in the most common autoimmune encephalitis variants. In N-methyl-D-aspartate (NMDA) receptor encephalitis, most patients have a normal MRI in the acute stage. When lesions are present in the acute stage, they are typically subtle and non-specific white matter lesions that do not correspond with the clinical syndrome. In some NMDA receptor encephalitis cases, these T2-hyperintense lesions may be indicative of an NMDA receptor encephalitis overlap syndrome with simultaneous co-existence of multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Encephalitis with leucine-rich glioma-inactivated 1 (LGI1)-, contactin-associated protein-like 2 (CASPR2)- or glutamic acid decarboxylase (GAD)- antibodies typically presents as limbic encephalitis (LE) with unilateral or bilateral T2/fluid attenuated inversion recovery (FLAIR) hyperintensities in the medial temporal lobe that can progress to hippocampal atrophy. Gamma aminobutyric acid-B (GABA-B) receptor encephalitis also often shows such medial temporal hyperintensities but may additionally involve cerebellar lesions and atrophy. Gamma aminobutyric acid-A (GABA-A) receptor encephalitis features multifocal, confluent lesions in cortical and subcortical areas, sometimes leading to generalized atrophy. MRI is unremarkable in most patients with immunoglobulin-like cell adhesion molecule 5 (IgLON5)-disease, while individual case reports identified T2/FLAIR hyperintense lesions, diffusion restriction and atrophy in the brainstem, hippocampus and cerebellum. These findings highlight the need for MRI studies in patients with suspected autoimmune encephalitis to capture disease-specific changes and to exclude alternative diagnoses. Ideally, MRI investigations should be performed using dedicated autoimmune encephalitis imaging protocols. Longitudinal MRI studies play an important role to evaluate potential relapses and to manage long-term complications. Advanced MRI techniques and current research into imaging biomarkers will help to enhance the diagnostic accuracy of MRI investigations and individual patient outcome prediction. This will eventually enable better treatment decisions with improved clinical outcomes.

Overview

  • The study reviews the literature on acute MRI changes in autoimmune encephalitis variants, focusing on NMDA receptor encephalitis, LGI1-antibody encephalitis, GABA-B receptor encephalitis, GABA-A receptor encephalitis, and IgLON5-disease.
  • The hypothesis being tested is that different autoimmune encephalitis variants have distinct MRI findings.
  • The methodology used for the experiment includes a review of the literature on acute MRI changes in autoimmune encephalitis variants. The study does not include any experimental procedures or tests conducted.

Comparative Analysis & Findings

  • In NMDA receptor encephalitis, most patients have a normal MRI in the acute stage. When lesions are present, they are typically subtle and non-specific white matter lesions that do not correspond with the clinical syndrome. In some NMDA receptor encephalitis cases, these T2-hyperintense lesions may be indicative of an NMDA receptor encephalitis overlap syndrome with simultaneous co-existence of multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).
  • Encephalitis with LGI1-antibodies typically presents as limbic encephalitis (LE) with unilateral or bilateral T2/fluid attenuated inversion recovery (FLAIR) hyperintensities in the medial temporal lobe that can progress to hippocampal atrophy. Gamma aminobutyric acid-B (GABA-B) receptor encephalitis also often shows such medial temporal hyperintensities but may additionally involve cerebellar lesions and atrophy. Gamma aminobutyric acid-A (GABA-A) receptor encephalitis features multifocal, confluent lesions in cortical and subcortical areas, sometimes leading to generalized atrophy.
  • MRI is unremarkable in most patients with IgLON5-disease, while individual case reports identified T2/FLAIR hyperintense lesions, diffusion restriction and atrophy in the brainstem, hippocampus and cerebellum.

Implications and Future Directions

  • The study highlights the need for MRI studies in patients with suspected autoimmune encephalitis to capture disease-specific changes and to exclude alternative diagnoses.
  • Ideally, MRI investigations should be performed using dedicated autoimmune encephalitis imaging protocols.
  • Longitudinal MRI studies play an important role to evaluate potential relapses and to manage long-term complications. Advanced MRI techniques and current research into imaging biomarkers will help to enhance the diagnostic accuracy of MRI investigations and individual patient outcome prediction. This will eventually enable better treatment decisions with improved clinical outcomes.
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