Abstract W P118: Constriction of Outer Diameter in the Involved Arteries in Moyamoya Disease - Proposal of Novel Diagnosis Criteria

Abstract

Background and Purpose: Moyamoya disease is an uncommon cerebrovascular disease that is characterized by progressive occlusion of terminal portion of the internal carotid artery and its main branches within the circle of Willis. However, it is often difficult to distinguish non-moyamoya disease from moyamoya disease in a certain subgroup of adult patients on conventional modalities such as cerebral angiography. Therefore, this study was aimed to determine the outer diameter of the involved arteries in moyamoya disease, using 3-dimensional (3D) constructive interference in steady state (CISS). Patients and Methods: This prospective study included 65 patients with moyamoya disease. There were 25 males and 40 females. There were 13 children and 52 adults. As the control, 8 patients with middle cerebral artery (MCA) stenosis and 17 healthy subjects were also included. Using 3D-CISS, the outer diameters of the internal carotid artery (C1), middle cerebral artery (M1), anterior cerebral artery (A1), and basilar artery (BA) were quantified in all patients. The involved carotid fork was directly observed during surgical revascularization in 3 adult patients with moyamoya disease. Results: In patients with moyamoya disease, the outer diameters of C1, M1, and A1 segments were significantly smaller in the involved side than those in the non-involved side (P<0.01). As the disease stage progressed, the C1 and M1 segments decreased in outer diameter (P<0.05). The outer diameters of C1 and M1 segments were also significantly smaller in moyamoya disease than those in MCA stenosis and those in healthy subjects (P<0.01). There was no significant difference in the outer diameter of BA among moyamoya disease, MCA stenosis, and healthy subjects. Direct observations of the carotid fork revealed a marked decrease in the outer diameter, supporting the findings on 3D-CISS. Conclusion: These findings strongly suggest that the involved arteries themselves are constricted in moyamoya disease. Their constriction may be pathognomonic in moyamoya disease, which would provide essential information to distinguish moyamoya disease from non-moyamoya disease. Diagnosis guideline should be renewed in future, based on the information on the outer diameter of the involved arteries.