自己免疫性脳症のスペクトラムとびまん性脳障害の神経症候学

Differential Diagnosis of Immune-Mediated Encephalopathies: "Neurological Symptoms of Diffuse Brain Damage": A New Concept

多くの橋本脳症の患者がgive-way weaknessや解剖学的には説明しづらい異常感覚を呈していることをわれわれは見出した。それらは身体表現性障害（いわゆるヒステリー）で特徴的とされる身体症状に類似しており，脳梗塞のような局所的な障害で引き起こされる症状とは切り離されて考えられてきた。そのような神経症候が出現するためには，びまん性，多巣性に濃淡を持った微小病変を蓄積させることができる自己免疫性脳症のような病態を想定する必要がある。このような考え方で，われわれは「びまん性脳障害による神経症候」という新しい診断概念に到達し，実臨床では多くの患者を見出している。今回，抗ガングリオニックアセチルコリン受容体抗体関連脳症，子宮頸がんワクチン接種後に発生した脳症，またはスティッフ・パーソン症候群でも同様の症候がみられることを報告する。自己免疫性脳症の臨床では，抗体の存在だけでなく，自己免疫性脳症による「びまん性脳障害」という概念が重要であり，この新しい診断概念を用いることで診断が困難な自己免疫性脳症の軽症例であっても容易に診断が可能となる。

Abstract

In recent years, incidence of autoimmune encephalopathies has increased. The diagnosis of the severe form of autoimmune encephalopathy is not difficult; however, milder forms can be misdiagnosed as general encephalopathies. We often treat Hashimoto's encephalopathy, which has diverse clinical symptoms and is often misdiagnosed as a psychosomatic disease. We have found that the neurological findings and symptoms of patients with Hashimoto's encephalopathy are similar to those of psychogenic diseases, such as giveway weakness and atypical sensory disorder. To understand the mechanism underlying these symptoms, we propose a new concept: neurological symptoms of diffuse brain damage. This theory is based on the premise that etiologically, symptoms observed were caused by diffuse, spotty, and shaded brain damage due to autoimmune encephalopathies. We also found similar neurological conditions in patients with anti-ganglionic acetylcholine receptor antibody-related encephalopathy, encephalopathies that developed after injection of the cervical cancer vaccine, and encephalopathies associated with Stiff person syndrome.

In conclusion, the clinical features of autoimmune encephalopathy include the “neurological symptoms of diffuse brain damage” as well as the presence of antibodies. We could diagnose autoimmune encephalopathy more easily, using this new diagnostic concept.