Encephaloduroarteriosynangiosis (EDAS) is a surgical procedure performed most commonly in children with moyamoya disease or less commonly in individuals with intracranial atherosclerotic disease (ICAD) as a form of indirect revascularization to bypass the occlusive terminal internal carotid and/or circle of Willis vessels .
It involves applying superficial temporal artery branches, or sometimes middle cerebral artery branches, after careful dissection, directly onto the pial surface of the brain. Revascularization occurs as a result of angiogenesis driven by local hypoperfusion and ischemia .
Encephaloduroarteriomyosynangiosis (EDAMS) differs from EDAS in so far as parts of the temporalis muscle are also included surrounding the superficial temporal artery and applied to the brain. In contrast, encephalomyosynangiosis (EMS) only entails laying vascularized temporalis muscle onto the brain .
In EMS, EDAS and EDAMs, and unlike superficial temporal artery to middle cerebral artery (STA-MCA) bypass, no direct anastomosis is created.