Unilateral Moyamoya Disease

Abstract

The Research Committee on Spontaneous Occlusion of the Circle of Willis of the Ministry of Health and Welfare, Japan, defines typical moyamoya disease as specific angiographic findings of diffuse stenotic or occlusive lesions of the bilateral carotid fork and unique collateral vessels at the base of the brain. However, there are some atypical cases of moyamoya disease that show unilateral lesions on angiography and a normal terminal portion of contralateral internal carotid artery or proximal middle cerebral artery. These patients are categorized as having ‘ unilateral’ moyamoya disease. Kelly et al. reported that patients with angiographically unilateral lesions comprised up to 18% of patients with moyamoya disease who were treated surgically [1]. Recently, however, asymptomatic moyamoya diseases detected by MRI have been increasing, so that the real incidence is thought to be higher than expected. Also, until now, the natural history of unilateral moyamoya disease has been unclear, and whether it is an early form of moyamoya disease remains controversial.