50-year-old PMHx poorly-controlled diabetes mellitus and hypertension with episode of gait instability
What’s the diagnosis?
High-grade mirror (bilateral) internal carotid artery supraclinoidal segment stenosis with complete occlusion on the right side. Large bilateral posterior communicating arteries with robust posterior-to-anterior collateral circulation. It is possible that the patient’s gait instability was related to anterior circulation steal and consequent posterior circulation hypoperfusion.
Background
Diabetes and hypertension are independent risk factors for intracranial atherosclerosis.
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.
What's your treatment plan?
Conservative management options include blood pressure control, antiplatelet medications, and low-density lipoprotein control.
If there is high grade (70-99%) stenosis of a major intracranial artery, and the patient has recurrent ischemic symptoms, and the patient has failed conservative measures, it is reasonable to consider intracranial angioplasty and stenting.
It is important to keep in mind that in general, randomized clinical trials have not shown a mortality benefit for angioplasty and stenting or for extracranial-to-intracranial bypass in patients with intracranial atherosclerosis.
In this case because the patient’s symptoms completely resolved, conservative management including diabetes control, blood pressure control, antiplatelet medications and low-density lipoprotein control were administered.