Abstract

Ocular and childhood myasthenia gravis (MG) cases appear relatively more common in Oriental than in Caucasian populations, but there have been no comprehensive serological studies on patients from mainland China. We studied 391 unselected cases of MG attending Tongji Hospital in WuHan (the largest in the province of HuBei) during a one year period. The male to female ratio was 0.8. 50% of the patients were children (under 15 years), and age at onset showed a single peak at between 5 and 10 years of age. 64% of the children and 66% of the adults were positive for acetylcholine receptor (AChR) antibodies but the antibody titres were lower than in similar Caucasian studies, although this was partly due to the high incidence of ocular MG. Of the 43 patients with generalized MG without AChR antibodies, only one had MuSK antibodies (2.5%) and two had VGCC antibodies indicating probable Lambert Eaton myasthenic syndrome. 94/126 (75%) of the children had pure ocular MG whereas only 24/85 (28%) of the adults had ocular MG. Thymoma was evident by MRI in 1.5% of children and 20% of adults. Despite most patients receiving prednisone, very few obtained full clinical remission. The results of thymectomy were more striking but were compounded by concurrent prednisone. The study emphasises the frequency of early childhood onset with ocular symptoms and shows that many of these patients have AChR antibodies. By contrast, patients presenting in later age appear to be very uncommon in comparison with recent studies in Caucasian populations.