A Novel Staging System to Evaluate Cerebral Hypoperfusion in Patients With Moyamoya Disease.

Background and Purpose- The study goal was to evaluate cerebral perfusion in moyamoya patients with a novel staging system and investigate the association between differences of perfusion status and clinical outcomes in patients treated with revascularization. Methods- About 506 consecutive patients from 2009 to 2015 were enrolled. The perfusion status was evaluated by a staging system-the stage of preinfarction period based on the result of computed tomography perfusion. Hemisphere in different perfusion stage was compared between hemorrhagic patients (n=155) and ischemic patients (n=351). The modified Rankin Scale was applied to evaluate the prognosis of patients. Results- In the enrolled 506 patients: 229 hemispheres (22.6%) with normal perfusion, 72 hemispheres (7.1%) in stage I, 205 hemispheres (20.3%) in stage II, 308 hemispheres (30.4%) in stage III, and 198 hemispheres (19.6%) in stage IV. Significant difference was observed in stage distribution between hemorrhagic patients and ischemic patients ( P<0.01). The ratio of hemispheres with normal perfusion in hemorrhagic group is more than the ischemic group ( P<0.05; odds ratio, 1.440; 95% CI, 1.144-1.811). The ratio of hemispheres in stage III in ischemic group is more than the hemorrhagic group ( P<0.01; odds ratio, 0.618, 95% CI, 0.487-0.783). In the prognosis-related analysis, the stage I group has the highest improved ratio (73.9%) and the normal perfusion group has the lowest improved ratio (33.3%). The improved ratio has a decreasing tendency from stage I to stage IV. Conclusions- The novel preinfarction staging system is a valuable assessment tool to evaluate cerebral perfusion status in moyamoya patients and predict the efficacy of revascularization. Ischemic patients suffer more from hypoperfusion. Patients in stage I and stage II are more likely to obtain improvement after revascularization. This is a retrospective study.