Moyamoya
Background
- A cerebrovascular disease characterized by progressive stenosis/occlusion of the arteries around the Circle of Willis.
- The narrowing or blockage stimulates angiogenesis to provide collateral circulation to the brain.
- On angiography, these small blood vessels give off a "puff of smoke" appearance (also known as "MoyaMoya" in Japanese).
- The disease is found more commonly in Asian countries and was first descried in Japanese literature in 1957.
- There is mounting evidence there is a genetic cause of the disease.
Clinical Features
- The developed collateral circulation is prone to bleeding, aneurysm, thrombosis exhibiting: focal neurological deficits, TIA, epilepsy, and bowl/bladder incontinence.
- Children predominately exhibit ischemic strokes.
- Approximately 2/3rd of children exhibit Electroencephalography (EEG) abnormalities: high voltage slow waves that occur during hyperventilation.
- Can be associated with atherosclerosis, meningitis, vasculitis, autoimmune diseases, hematological conditions, brain tumors, and chromosomal abnormalities
Differential Diagnosis
- Hemorrhagic stroke/Ischemic stroke
- Giant cell arteritis/Vasculitis
- Cranial trauma
- Basilar Artery Thrombosis
- Blood Dyscrasias
- Cavernous Sinus Syndrome
- Cerebral Aneurysms
- Dissection Syndromes
- Carotid atherosclerosis
- Fibromusclar Dysplasia
- Craniopharyngioma
Evaluation
- Head CT and/or brain MRI are important studies to visualize infarctions and brain hemorrhages.
- CT can show dilation of the sulci accompanies by focal ventricular enlargement.
- MRI has higher sensitivity for detecting ischemic regions.
- Magnetic Resonance Angiographic studies can demonstrate occlusions within the circle of Willis and better visualize the collateral vasculature. It is preferred over CTA in most institutions.
Management
- Symptomatic treatment: decrease elevated intracranial pressure, improve cerebral blood flow, control active seizures, pain control , supplemental O2
- Avoid hypotension, hypervolemia, hypernatremia, hypocarbia
- Ventricular drainage if there is hemorrhage
- Minimize crying/hyperventilation a decreased PaCO2 can worsen ischemia by vasoconstriction
- Antithrombotic and thrombolytic surgery has not been systematically analyzed for Moyamoya disease
Disposition
- Admit