Regional differences in incidence and patient characteristics of moyamoya disease: a systematic review.

BACKGROUND AND
PURPOSE: Moyamoya disease (MMD) is a rare cause of stroke, initially described in Japan. In other countries, incidences and presenting symptoms may differ from those in Japan. The literature on regional differences in incidence and patient characteristics of MMD was systematically reviewed.
METHODS: Medline, EMBASE and CINAHL were searched for population based studies on MMD published between January 1969 and January 2011. From studies that met predefined inclusion criteria, information was extracted on incidence and patient characteristics. Incidences with corresponding 95% CIs if possible were calculated and descriptive statistics for patient characteristics were used.
RESULTS: 8 studies were included: three from Japan, one each from Taiwan and China and three from the USA. Incidences per 100 000 patient years ranged in Japan from 0.35 to 0.94 (95% CI 0.69 to 1.19), in the USA from 0.05 (-0.04 to 0.12) in Iowa to 0.17 (-0.06 to 0.40) in Hawaii and were 0.41 (0.28 to 0.54) in Nanjing, China and 0.02 (0.003 to 0.04) in Taiwan. Female to male ratio ranged from 1.1 (0.9 to 1.5) in Nanjing to 2.8 (1.2 to 6.1) in Iowa. Proportions with intracerebral haemorrhage as the initial presentation were 56% in China, 52% in Taiwan, 29% in Hawaii, 21% in Japan and 10% in Iowa. Patients with childhood onset presented most often with ischaemia (>75%) in all regions.
CONCLUSIONS: MMD incidence was higher in Japan and China than in Taiwan and North America and presenting symptoms showed regional differences, which are thus far unexplained. Population based data on MMD in Europe are lacking.