Moya Moya disease is a condition in which part of the brain’s arteries (the anterior circulation), start to disappear. In an attempt to get more blood, the brain makes small fragile arteries to compensate for the lsos of blood flow. On an angiogram these blood vessels look like “Puff of Smoke’, thereby the name Moya Moya, which in Japaneese means “Puff of Smoke”. It is more commmon in patients with asian heritage. Suzuki has classified this disease in 6 stages. Stage 1 has mild stenosis of distal ICA, as well as MCA and ICA, while in stage 6, diatal ICA as well as MCA and ICA are gone and there is extensive growth of small vessel both fron small bracnhes of ICA and ECA. It affects the pediatric population as well as adult. It usually leads to stroke. Risk of ischemic stroke is higher than hemorrhagic. The annual risk of ischemic stroke is about 14% and the annual risk of hemorrhagic stroke (Bleeding) is 4%. The posterior circultion of the brain is not affected in Moya Moya.
Treatment consists of Cerebral Revascularisation through a procedure that is called By-pass.
There are 2 types of By-pass: Direct By-pass when a vessel is connect to another vessel, and Indirect By-pass in which the brain is stimulated to make its own vessels.
If Moya Moya is not advacned and there are some good caliber vessels left, patient’s own vessel providing blood to the skin (STA) can be connected to patient’s brain vessels (MCA). This procedure is called STA-MCA-By-Pass. This method brings immediate blood flow to the bain
If Moya Moya is advacned and there is no good caliber artery left for direct by-pass then indirect by-pass can be performed. It takes 6 months before brain develops a new circulation thorugh indirect by-pass. There are 2 types of Indirect By-Pass
EDAS (Encephalo Duro AngioS ynangiosis)
Here a skin vessel (STA) is dissected and brought and put on the brain surface. Over time this blood vessel stimulates blood vessel evelopment on the brain surface. It usualy takes 6 months.
EDAMS (Encephalo Duro Angio Myo Synangiosis)
Here, a head muscle (Temporalis Muscle) is put on the brain surface. The surface of the muscle will make connections with the brain and over 6 months the brain will develop many small blood vessel connections that provide the brain with blood.
Moya Moya Disease can be distinguished from Moya Moya Syndrome. In Moya Moya Syndrome, the disease does not follow the typical pattern of Moya Moya Disease such as, some arteries are affected and some not but the treatment is the same.