What’s the diagnosis?
- Diabetes and hypertension are independent risk factors for intracranial atherosclerosis.
- Advanced intracranial atherosclerosis → stenosis → ↓ cerebral blood flow.
- Arteriography helps to quantify the degree of stenosis and to assess collateral blood flow.
- A mid-cervical internal carotid artery tapering is a radiological sign referred to as a “flame” shape.
- The flame shape is classically taught to be associated with extracranial internal carotid artery dissections, which commonly occur at the skull base. It is the stagnation of anterograde flow caused by the dissection that causes the flame shape and not the dissection flap itself.
- The flame shape is a flow related phenomenon. It is caused by a stagnant column of unopacified blood located proximal to the occlusion site that impedes migration of contrast into the actually patent extracranial internal carotid artery segment. Due to laminar flow, which is maximal centrally, the flow that does push farthest is in the middle, creating the appearance of a tapered flame.
- In this case, flow actually does pass through the right internal carotid artery to the ophthalmic artery, but the supraclinoid segment is occluded.