What’s the diagnosis?
On these left internal carotid artery injections, notice the advanced moyamoya vasculature about the terminus segment of the vessel. There is cross filling through the anterior communicating artery to the contralateral middle cerebral artery as well.
On these right internal carotid artery injections, notice the advanced moyamoya vasculature about the terminus segment of the vessel.
On this right external artery injection note the trans-osseous collaterals that have developed from the superficial temporal artery through the bony skull and into the right intracranial circulation.
On this left vertebral artery injection, note the extensive leptomeningeal collateral flow that has developed from the posterior cerebral artery to the anterior cerebral artery.
- Moyamoya disease is an odd, progressive disease of the intracranial circulation where the internal carotid arteries gradually occlude. To compensate, new collateral blood flow pathways form.
- Abnormal, small-caliber networks of “moyamoya” vessels, such as dilated lenticulostriate and choroidal arteries, form at the base of the brain. (Flow through these tiny vessels at the base of the brain are responsible for the angiographic puff of smoke appearance.)
- Collateral pathways route blood from the external carotid artery circulation to the intracranial circulation as well.
- Unlike moyamoya disease that presents in children with ischemic events, moyamoya that presents in older adults is commonly hemorrhagic. Chronic hemodynamic stress to the small-caliber moyamoya vessels → development of microaneurysms that may rupture. Hemorrhage about these vessels is typically located in the thalamus, basal ganglia, and ventricular system.