[Clinical evaluation of myasthenia gravis in elderly patients]

In Japan, elderly patients who develop myasthenia gravis (MG) are increasing in number. However, there are few clinical reports concerning this issue. We evaluated the clinical manifestations, inducing or exacerbating factors, complications, treatments and prognosis of systemic MG in 11 patients older than 60 years of age. Bulbar symptoms were more frequent in these patients compared with younger MG patients, and 6 out of 11 cases (54.5%) were mistakenly diagnosed as cerebrovascular disorders. Among inducing or exacerbating factors of MG were psychological problems inherently involved with the aged, physical factors, and inappropriate termination or rejection of medication. Increase in the level of anti-Ach-R antibodies was recognized in 10 out of 11 cases (90.9%). A high percentage of the patients had thymoma (36.4%) and thyroid diseases (45.5%): 3 with Hashimoto's thyroiditis (27.3%), 1 with thyroid ophthalmopathy associated with hyperthyroidism, and 1 with simple goiter. Others were accompanied by ischemic heart disease, prostatic hypertrophy or stomach cancer. We treated these patients with corticosteroids, immunoglobulin, radiation for thymoma, or thymectomy in addition to administration of anticholinesterase agents. Prognostically, we found that duration of illness before death was shorter in those with onset later than 70 years of age. Seven out of 11 (63.6%) patients died of either aspiration pneumonia (4 cases), complications of thymectomy, congestive pulmonary edema or stomach cancer. There were no deaths associated with myasthenic crisis.