[Prognosis for myotonic dystrophy].

Although the genetic basis of myotonic dystrophy (MD) has recently been clarified, data on prognosis and causes of death are few. To assess the relation between the age of onset and the degree to which activities of daily living (ADL) were affected, we studied statistically 586 patients with MD, who were registered in the database in hospitals of Japan in 1985. Many of the young onset patients had a long duration of illness, and many of the long-term patients showed the more severely affected ADL. When we adjusted the duration of illness, using the Mantel extension method, many patients whose age of onset was older had poorer ADL than the younger onset ones. To clarify the causes of death in MD, we collected data on 72 patients who succumbed to it from answers to questionnaires sent to all councilors of the Japanese Society of Neurology and the Japanese Society of Child Neurology in 1994. Before their deaths, among 32 MD cases unable to sit up, 16 (50%) died from respiratory involvement (respiratory failure and pneumonia), 8 (25%) from dysphagia (i.e., aspiration pneumonia and choking) and 2 (6%) from cardiac involvement. Moreover, among 25 cases that could sit up, 9 cases (36%) died from dysphagia, 4 (15%) from respiratory involvement and 2 (8%) from cardiac involvement. Dysphagia and cardiac involvement are often the causes of death in the early stage. To avoid these complications, management of swallowing and careful cardiac control is essential in patients with MD.