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Objective Limbic encephalitis (LE) is an inflammatory condition of the limbic system that has an acute or subacute onset. Several types of antibodies are related to the onset of LE, including anti-N-methyl D-aspartate receptor (NMDAR) antibodies and voltage-gated potassium channel (VGKC)-complex antibodies. However, the characteristics and prevalence of LE remain unclear, especially in Asian cohorts, due to the rarity. We aimed to survey their characteristics. Materials and Methods Data of 30 cases clinically defined as "definite autoimmune LE" (based on the standard criteria) were retrospectively collected. These patients were categorized into four subtypes: NMDAR (+) (n=8), VGKC (+) (n=2), antibodies related to paraneoplastic syndrome (n=2), and an antibody-negative group (uncategorized) (n=18). Results LE is rare in Japan, and affected only 30 of 16,759 hospital patients (0.2%) over a ten-year period. The NMDAR (+) group showed distinctive symptoms, while the other three groups had similar indications. Brain MRI indicated significant medial temporal lobe atrophy at one year follow up after discharge. The prevalence of cognitive dysfunction as a complication was 64% (9/14). First-line immunotherapy resulted in a good outcome. A drastic improvement was seen from 4.0±1.1 to 1.1+ on the modified Rankin Scale. A good treatment outcome was observed in all groups (NMDAR, VGKC, and uncategorized), suggesting the importance of an early clinical diagnosis and the early initiation of treatment. Furthermore, we reviewed 26 cases that were clinically diagnosed as definitive autoimmune LE in previous case reports. Conclusion Our findings show that the establishment of a clinical diagnosis based on the clinical criteria of definitive autoimmune LE is important for the initiation of immunotherapy.

A variety of anti-neuronal cell membrane antibodies such as voltage-gated potassium channel antibody, N-methyl-D-aspartate-2B-antibody, and glutamic acid decarboxylase antibody, are correlated with limbic encephalitis (LE). In this study on patients with LE, the clinical manifestations, psychology Wechsler Adult Intelligence Scale, cerebrospinal fluid, electrophysiology, magnetic resonance imaging, and anti-immune therapy were studied and immunological determination was conducted; it was found that patients of Chinese Han nationality showed 2 types of clinical manifestations: simple and complex. Lesions could also be divided into focal and scalable lesions, and the clinical manifestations and lesions scopes were associated with various antibodies and antibody types. The prognosis may improve if early diagnosis is conducted and early anti-immune therapy is implemented in LE patients.