An epidemiological survey of moyamoya disease, unilateral moyamoya disease and quasi-moyamoya disease in Japan

Objectives: Moyamoya disease (MMD) is a unique occlusive disease of the bilateral internal carotid arteries in which, compensation for occlusion results in an enrichment of collateral arteries at the base of the brain. However, the epidemiology of unilateral MMD (typical angiographic evidence of MMD unilaterally with equivocal contralateral findings), and quasi-MMD (MMD present with inherited or acquired disorders) is poorly known. Here, a nationwide epidemiological survey was conducted to estimate the total numbers of patients, the annual incidence rates and prevalences of MMD, unilateral MMD and quasi-MMD in Japan.

Patients and methods: The neurosurgery, neurology and pediatrics departments that were listed in Japanese resident training programs were recruited to participate in this survey. Questionnaires were directly mailed to 2998 departments in February 2006.

Results: A total of 1183 departments replied to the questionnaire (39.5% response rate). It was estimated that there were 6670.9 MMD patients, 840.5 unilateral MMD patients and 430.4 quasi-MMD patients in Japan. The annual incidence rates of MMD, unilateral MMD and quasi-MMD are 1.13, 0.23 and 0.11/100,000, respectively, and the prevalences are 5.22, 0.66 and 0.34/100,000, respectively. These patients were mainly treated by neurosurgeons. An estimated total of 929.1 surgical interventions are performed in Japan annually.

Conclusion: This nationwide study reports the current epidemiologic status of MMD, unilateral MMD and quasi-MMD in Japan.