Suzuki staging
The staging system for moyamoya disease first described by Suzuki and Takaku in their seminal 1969 article 1) is still in use today. Formally, the staging refers to findings on conventional angiography, although there are efforts to apply similar systems to MR angiography 2).
Suzuki stage appears to correlate with collateralization in children, but not in adults 3).
The vast majority of patients will progress through some or all of the Suzuki stages, although progression may occur at different rates 4), and appears to occur more rapidly in children than in adolescents or adults 5)
The Suzuki stages are as follows:
stage I “narrowing of the carotid fork” * narrowed ICA bifurcation
stage II “initiation of the moyamoya” dilated ACA, MCA and narrowed ICA bifurcation with moyamoya change
stage III “intensification of the moyamoya” further increase in moyamoya change of the ICA bifurcation and narrowed ACA and MCA
stage IV “minimization of the moyamoya” moyamoya change reducing with occlusive changes in ICA and tenuous ACA and MCA
stage V “reduction of the moyamoya” further decrease in moyamoya change with occlusion of ICA, ACA and MCA
stage VI “disappearance of the moyamoya” ICA essentially disappeared with supply of brain from ECA
* the description in inverted commas (quotation marks) is that of Suzuki in the original paper.