わが国における筋緊張性ジストロフィーの臨床症候と障害度—全国アンケート調査の解析から

CLINICAL SYMPTOMS AND DISABILITY OF MYOTONIC DYSTROPHY IN JAPAN

　抄録　筋緊張性ジストロフィーについて，わが国で初めての全国調査を実施した。その結果集計された670症例について，主要臨床症候の発現頻度および日常生活動作（ADL）障害度と性，発病年齢，罹病期間との関連を検討した。男女比は1.6：1であった。発病年齢は平均27歳，罹病期間は平均13年であり，いずれも男女ほとんど同じであった。ミオトニア，筋力低下，筋萎縮は，いずれも大部分の症例に認められ，白内障は過半数の症例に，知能低下は半数弱の症例にみられた。早期頭髪脱毛は，男の方に圧倒的に高い頻度でみられた。各症候は罹病期間が長くなるほど，概して発現頻度が高くなる傾向がみられた。9歳以下で発病した症例では，ミオトニアを欠くものが多く，白内障，早期頭髪脱毛の発現頻度は低いが，知能低下の頻度は高いという特徴がみられた。体幹，下肢の機能を反映するADLで，男より女の方が障害度が高かった。またすべてのADLにおいて，罹病期間が長い症例ほど障害度が高く，罹病期間が同じであれば，発病年齢の高い症例ほど障害度が高い傾向がみられた。

We performed the first nationwide survey of myotonic dystrophy (MyD) in Japan. This paper reports the result of analysis of clinical pictures and disability of 670 patients found in this survey. 413 cases (61.6%) were males and 257 (38.4 %) were females. Male/female ratio was approxi-mately 1.6. The age of onset was most often in the third or fourth decade. Mean age of onset was 27.7 years in the males and 26.8 years in the females. Eight percent of the cases presented their sympotoms before the age of 9years. These cases were considered to belong to congenital or infantile form of MyD. There were also a few patients who started noticing their sympotoms after the age of 60 years. Dura-tion of the illness at the time of examination was approximately 13 years in both sexes.

Myotonia was observed in 97.3% of the males and 98.1% of the females. Muscular weakness was seen in 99.0% of the males and 96.5% of the females. Atrophy was present in 93.5% of the males and 88.9% of the females. These data showed that almost all cases had these three major sympotoms related to the skeletal muscles. There were 16 cases which lacked myo-tonia, and most of them belonged to congenital or infantile form of MyD. Cataract was present in more than a half of the patients (54.4% in the males and 52.0% in the females). Mental retar-dation was observed in 42.4% of the males and 35.9% of the females. Frontal baldness was seen much more frequently in the males (74.6%) than in the females (22.7%). Generally, as the dura-tion of the illness was longer, these clinical symptoms were seen in higher frequency. Cases which started noticing their symptoms before the age of 9 years showed cataract and frontal baldness in lower frequency and mental retar-dation in higher frequency compared with adult-onset cases.

Comparing the degree of disability between both sexes, the females were significantly more disable than the males in the activities of daily living mainly using the trunk and lower extre-mities, such as standing up from a chair, walking and climbing up stairs. However, in the activities of daily living mainly using the upper extremities, such as dressing and undressing, wringing a towel and eating with chopsticks, there was no diffe-rence in the disability between both sexes. The disability tended to become more severe as the duration of the illness becomes longer. However, if the disability was compared between the two with the same duration of the illness, it tended to be more severe in the patient with a higher age of onset.