The natural history of this disorder is not well known. The long term outlook for patients with treated<unk>  seems to be good when direct bypass is used. Although symptoms may seem to improve almost immediately after the in-direct EDAS, EMS, and multiple burr holes surgeries, it will take probably 6 to 12 months before new vessels can develop to give a sufficient blood supply. With the direct STA-MCA surgery, increased blood supply is immediate. Once a major stroke or bleeding takes place, even with treatment, the patient may be left with permanent loss of function so it is very important to treat this condition promptly.
Moyamoya disease
Vein of Galen aneurysmal malformations
Cerebral amyloid angiopathy
Cerebral arteriovenous malformation
Meningism
Giant cell arteritis
Hypertensive leukoencephalopathy
Chiari malformation