In this study, the investigators aim to evaluate the indirect revascularization outcomes of a new combination therapy of multiple burrhole procedure with promotion of arteriogenesis by intravenous (IV) erythropoietin (EPO) pretreatment on Moyamoya patients with acute neurological presentation, and outline the clinical and vascular factors associated with revascularization through the burrholes.

This is a investigator led, single-center, single arm, interventional trial in prospective Moyamoya disease (MMD) and Moyamoya syndrome (MMS) registry. MMD or MMS patients with acute neurological presentation such as ischemic stroke or transient ischemic attack are eligible.

After inclusion, initial evaluation including transfemoral angiography is performed. A 3 day pre-procedure IV erythropoietin (120000 international units[IU] #3) is given for promotion of arteriogenesis, than multiple burrhole procedure is performed. Arteriogenesis is evaluated by 6 month transfemoral angiography.

Inclusion Criteria:

• Age ≥16 years
• Acute neurological presentation with recurrent transient ischemic attacks (TIA) or cerebral infarction within 30 days of symptom onset
• Angiographic findings compatible with the diagnostic criteria for MMD or MMS (unilateral findings, bilateral distal internal carotid artery involvement without Moyamoya vessels, or presence of other causative factors)
• Significant decrease in basal perfusion and reservoir capacity on brain perfusion CT or Brain single photon emission computed tomography with acetazolamide (Diamox®) challenge (D-SPECT)

Exclusion Criteria:

• Definite presence of transdural collateral flow on cerebral angiography.
• Sufficient perfusion status via Willisian, leptomeningeal, or other collateral systems, as evaluated by multimodal imaging methods.
• > 30 days after symptom onset