[How to Diagnose Lambert-Eaton Myasthenic Syndrome Patients Early: A Systematic Review of Japanese Case Reports].

A systematic review was conducted on case reports of Lambert-Eaton myasthenic syndrome (LEMS) in Japanese patients published prior to 2023, focusing on clinical features. Particular attention was paid to the interval from LEMS onset to diagnosis, examining the clinical question (CQ): 'How can the time to diagnosis be shortened?' Patient profiles showed a male predominance, with 76 males and 21 females among the total 97 cases, yielding a male-to-female ratio of 3.6:1. The median age of onset (mean±standard deviation) across all cases was 62.0 (59.3±11.7) years, with the age distribution peaking in the 70s. For cases with tumour involvement (n=84), the median age at onset (mean±SD) was 62.5 (60.2±10.8) years, and the median duration of illness prior to LEMS diagnosis (mean±SD) was 3.0 (4.9±5.7) months. Conversely, for cases without tumour involvement (n=13), the median age at onset (mean±SD) was 52.0 (53.5±15.8) years, and the median duration of illness (mean±standard deviation) was 6.0 (21.1±25.7) months. Based on the above CQ responses, LEMS should be actively suspected and electrophysiological testing considered when neurological symptoms include lower limb muscle weakness combined with ocular symptoms such as ptosis and diplopia, and further autonomic symptoms such as dry mouth. Furthermore, it was considered that P/Q-type VGCC antibody testing could potentially be utilised prior to diagnosis by electrophysiological testing. (Received August 12, 2025; Accepted October 3, 2025; Published February 2, 2026).