未来へつなぐ神経治療学　自己免疫性脳炎の発展

抄録

Encephalitis/Encephalopathy is a life–threatening disease with many causes. In the last 15 years the continual discovery of newly identified forms of autoimmune encephalitis (AE) associated with antibodies to cell–surface or synaptic proteins has changed the paradigms for diagnosing and treating disorders. AE is one of the most common causes of non–infectious encephalitis. It can be triggered by tumors, infections, or it may be cryptogenic. These disorders can occur in patients with or without cancer―often children or young adults who develop psychosis, catatonic or autistic features, memory problems, abnormal movements, or seizures that were previously considered idiopathic. We review here the process of discovery, the symptoms, and the target antigens of AE including our previous published research data. Anti–N–methyl–D–Aspartate receptor (NMDAR) encephalitis, several subtypes of limbic encephalitis, and other AEs that result in psychosis, seizures, or abnormal movements are described. We also discussed their recent diagnostic approach and treatment in AE.

This recent advances in AE research led to the identification of syndromes and biomarkers. Existing criteria for AE are too reliant on antibody testing. Since antibody test results are not available at onset, a practical, syndrome–based diagnostic approach is required. It is possible to proceed through a logical differential diagnosis of AE using criteria based on conventional clinical neurological assessment and standard diagnostic tests (MRI, EEG, and CSF studies). Through this approach, levels of evidence of probable and definite AE can be achieved early and therapies implemented quickly, with the possibility of fine–tuning the diagnosis and treatment when antibody results become available. Notably, most treatment recommendations in AE are based on the experience of experts in the field. However, there is a need for clinical trials to identify clinically meaningful cut–off values of autoantibody titres which provide a clear indication for immunotherapy and to compare the efficacy of different immunotherapeutic strategies more objectively. A task for the future is moving these strategies to the clinics.