Adult moyamoya disease in the asymptomatic Japanese population.

Moyamoya disease (MMD) is a spontaneous occlusive disease of the Willis circle. This study evaluated the presence of the radiological hallmarks of adult MMD on a "brain check-up" (BC) using MRI and MR angiography, in Japan. BC was offered to 11,402 healthy subjects (7570 men and 3832 women) between January 1997 and November 2003.