[The Lambert-Eaton myasthenic syndrome: a study of 110 Japanese cases]

This study was undertaken to analyse the clinical and immunological features in a large group of Lambert-Eaton Myasthenic Syndrome (LEMS) patients (n = 110). In the Japanese LEMS patients studied, there was a male predominance with a male to female ratio of 3:1. The age at onset of neurological symptoms ranged between 17 and 80 years with a mean of 62 years. Malignancy was detected in 69% of the patients, of whom 61% had small cell lung carcinoma (SCLC). Neurological symptoms preceded a diagnosis of malignancy in 84% of cases. The neurological findings were similar in all patients and consisted of lower limb weakness in 97%, upper limb weakness in 80%, hyporeflexia in 85%, autonomic dysfunction in 37% (dry mouth in 31%, constipation in 11%, impaired sweating, urinary disturbance, impotence, and blurred vision in less than 10%), blepharoptosis in 28% and ophthalmoplegia in 5%. Signs of cerebellar involvement are noted in 9% and all of these patients had SCLC. Of 110 patients with LEMS, 85% had detectable antibodies against P/Q-type voltage-gated calcium channel (P/Q-type VGCC). Seronegative patients (15%) had similar neurological findings, but a lower incidence of SCLC than seropositive patients. The clinical features of our patients were very similar to those observed in British LEMS patients (n = 50), but autonomic features in our study were less prevalent than reported in British patients.