Current state of study on moyamoya disease in Japan

Moyamoya disease is a unique cerebrovascular disease with much higher incidence in Japanese and Asians than in Caucasians. The Research Committee on Spontaneous Occlusion of the Circle of Willis (Moyamoya disease) of the Ministry of Health and Welfare, Japan, has studied the pathogenesis, epidemiology, clinical investigations, and treatment of the disease since 1977. The current status of the study of moyamoya disease in Japan is presented.

There were 821 registered cases of moyamoya disease in Japan up to 1994. The study group also obtained statistical data from a questionnaire sent to hospitals dealing with the disease. [The data collected were analyzed.]

The estimated number of patients in Japan through 1994 was 3800. Characteristic epidemiologic data were: female dominance (male to female ratio = 1:1.7); highest rate of onset in the age group below 10 years, with a second mild peak from 30-40 years; and rate of familial cases around 10%, including identical twins. The most recent development is diagnosis by MRI and MRA-it is now possible to obtain a diagnosis without conventional angiography. The study of the cerebral perfusion and metabolism by positron emission tomography (PET) or SPECT is becoming more important in understanding the state of illness and in deciding the indications for surgery. Treatment of moyamoya disease can be either medical or surgical. The latter consists of either direct bypass surgery (STA-MCA anastomosis) or indirect bypass procedures, including EDAS, EMS, EMAS, and omental transplantation. At present, although not statistically significant, the surgically-treated groups seem to have better results than the medically-treated groups.

The clinical features of moyamoya disease are becoming more elucidated. However, further studies are necessary including the pathogenesis, which is still not known.