Intermediate risk | - Narrowing proximal to the circle of Willis*
- Stenosis of the proximal ICA if there is normal collateral flow in ACA and PCA
| - Referral to neurologist.
- Repeat imaging when sedation no longer needed or sooner for new signs or symptoms.
- May be at increased risk later in life if additional risk factors arise (atherosclerosis or traumatic injury).
- Avoid contact sports and sports with extreme neck positions.
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High risk | - >25% narrowing of principal cerebral vessels
- In association with an incomplete circle of Willis
- Tandem stenosis that causes a risk of diminished cerebral perfusion
- Signs of chronic or silent
- Ischemia
- Existing infarction
- Border zone ischemic changes
- Presence of lenticulostriate collateral dilation
- Pial collaterals
| - Referral to neurology.
- Repeat imaging at 6 months and 1 year. Then to be determined based on symptoms and progression.
- Avoid contact sports and sports with extreme neck positions.
- Aspirin 4 to 5 mg/kg/day up to 81 mg per day.
- If progressive moyamoya, refer to tertiary care center with experienced neurologist and neurosurgeon.
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