Nation Wide Study on Moyamoya Disease, Unilateral Moyamoya Disease and Quasi-moyamoya Disease

Moyamoya disease (MMD) is characterized by progressive occlusion of the internal carotid artery or its terminal branches, associated with formation of extensive collateral vessels (moyamoya vessels) at the base of the brain. Whether unilateral moyamoya disease, confirmed by typical angiographic evidence of moyamoya disease unilaterally and normal or equivocal findings contralaterally, is an early form of definite (bilateral) moyamoya disease remains controversial. Inherited or acquired disorders and conditions may present in conjunction with moyamoya disease. This condition is known as quasi-moyamoya disease (quasi-MMD). We attempted to determine the incidence and total patient number of moyamoya disease, unilateral MMD and quasi-MMD, who were treated during 2005 in Japan. Questionnaires were sent to 2,998 departments, which are listed in resident training programs of neurosurgery, neurology and pediatrics. Totally, 1,183 departments replied, and the response rate was 39.5%. The number of annual first-visit patients of MMD, unilateral MMD and quasi-MMD is 571, 118, and 53, respectively. Thus, the number of annual revisit patients of MMD, unilateral MMD and quasi-MMD is 2,064, 214, and 117 respectively. It is estimated that 6,670.9 MMD patient exists in Japan. The incidence rate of MMD, unilateral MMD and quasi-MMD is 1.13, 0.23 and 0.11/100,000, respectively, and the prevalence is 5.22, 0.66 and 0.34/100,000, respectively. This nationwide study revealed the present epidemic status of MMD, unilateral MMD and quasi-MMD.