Moyamoya disease


A progressive occlusive disease of the cerebral vasculature with particular involvement of the circle of Willis and the arteries that feed it.

Angiographic changes of vascular collateral networks that develop adjacent to stenotic vessels.

Stenotic occlusive blood vessels usually bilateral.

Characterized by intimal thickening in the walls of the terminal portions of the internal carotid vessels bilaterally.

Consists of nonarteriosclerotic narrowing of the distal internal carotid arteries in the proximal branches.

Proliferating intima may contain lipid deposits, with thinning of the media.

The anterior, middle, and posterior cerebral arteries that emanate from the circle of Willis may show varying degrees of stenosis or occlusion.

On angiogram these changes appear like “puff of smoke“

When these vascular abnormalities occur, typically with Down syndrome, neurofibromatosis type I, and sickle cell disease, they are classified as Moyamoya syndrome.

When the process occurs in isolation diagnosis is Moyamoya disease.

Because of decreased blood flow collateral blood vessels form.

Can occur following brain radiation, or with renal artery stenosis or hyperthyroidism.

Numerous small vascular channels can be seen around the circle of Willis.

Occurs more frequently in Asians than Caucasians, but have been documented in all races.

Etiology unknown.

Familial 10% of the time, suggesting familial relationship and autosomal dominance with reduce penetrance.

Patients usually present with ischemic strokes .

Some individuals present with hemorrhagic stroke, headaches, or other neurological changes.

Diagnostic confirmation occurs with MRI or angiography.

May be associated with autoimmune disease-up to 22% disease.

Type I diabetes, thyroiditis and hyperthyroidism are more prevalent.

CSF abnormal in 80-90% of cases, usually with an increase in leukocytes and increase total protein.

Needs to be differentiated from CNS vasculitis, as vasculitis usual treatment is steroids or immunosuppressive agents and moyamoya is not treated with such drugs. .

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