Neurovascular Cases

What’s the diagnosis?

There are tandem right-sided posterior circulation lesions; severe stenosis of the right vertebral artery origin and an acute basilar artery occlusion. The right vertebral artery is much larger than the contralateral left vertebral artery and is therefore the dominant vertebral artery.

CT angiogram head and neck, axial slices, demonstrates thrombus at the basilar apex with basilar artery occlusion. The diminutive left vertebral artery is smaller than the large, dominant right vertebral artery.

CT angiogram head and neck, coronal reformats, demonstrates significant calcification and stenosis at the right vertebral artery origin. Again, there is concern for basilar artery occlusion.

On this right subclavian artery injection there is severe right vertebral artery ostial stenosis. Notice that the flow of contrast into the right vertebral artery is stagnant and does not wash out quickly. This is because of the occlusion in the basilar artery itself, which blocks meaningful anterograde flow through the vertebrobasilar junction.

Differential Diagnosis

  1. Given the severe atherosclerotic disease at the right vertebral artery ostium, vessel-to-vessel thromboembolism → acute vertebrobasilar occlusion is the most likely diagnosis.

Background

  • In general , atherosclerotic disease of the vertebrobasilar system causes significant morbidity and mortality and requires aggressive medical management, typically antiplatelet agents.
  • Patients who present with an acute blockage of an intracranial vessel (in the head) and also an extracranial vessel (in the neck) at the same time are classified as having “tandem” lesions.
  • Most tandem lesions are in the anterior circulation, such as a simultaneous blockage of the middle cerebral artery in the head and also of the ipsilateral internal carotid artery in the neck.
  • Tandem lesions of the posterior circulation, such as severe vertebral artery ostial disease with acute vertebrobasilar occlusion is rare, and a cerebrovascular emergency.
  • It is important to recognize whether or not one vertebral artery is much larger than the other. A tiny, diminutive vertebral artery is not typically a successful route for performing a basilar artery thrombectomy.

What's your treatment plan?

  • It is useful to study the patient's non-invasive imaging before deciding on an endovascular access route. In the case of a dominant right vertebral artery lesion, a right transradial approach may be more direct and simple than a transfemoral approach.
  • It is currently a matter of debate whether to treat the extracranial neck lesion before the intracranial lesion, or vice versa. Proponents of treating the neck lesion first argue that it is useful to secure a stable pathway through the neck to the brain first, so that you can approach the intracranial lesion under more controlled circumstances. Proponents of treating the intracranial lesion first argue that opening up flow to the brain tissue is the most time-sensitive priority and should be completed first.
  • Atherosclerotic disease at a vessel ostium can be treated with balloon angioplasty alone or by angioplasty and stenting. If a metallic stent is going to be placed, then the patient does need to be loaded with antiplatelet medications even during the procedure to prevent acute in-stent thrombosis.

In this case, a right transradial approach was used because this approach was felt to provide the simplest route to the target vessel, the dominant right vertebral artery. Balloon angioplasty of the right vertebral artery ostium was performed to make space for a thrombectomy aspiration catheter to reach the basilar artery. Aspiration thrombectomy was performed to achieve reperfusion of the basilar artery occlusion. Finally, the extracranial vertebral artery ostium was stented using a balloon-mounted stent.

A stiff balloon is tracked over the guide wire and across the right vertebral artery ostium. It is partially inflated (not shown here) and its body is used to help track the catheter over both the balloon and the guide wire into the right vertebral artery.

When significant ostial stenosis prohibits the ability to pass a system of catheters through a vessel origin, it can be useful to use a balloon angioplasty to dilitate the ostium and allow passage into that vessel. In this case, a 3 mm by 20 mm balloon was used to create enough space for a large thrombus aspiration catheter to be advanced into the right vertebral artery.

Stentriever-assisted manual aspiration thrombectomy of the basilar apex clot was performed and this first, post-thrombectomy injection demonstrates complete filling of the basilar artery and the bilateral posterior cerebral arteries, superior cerebellar arteries, and posterior inferior cerebellar arteries.

A balloon-mounted stent is deployed across the stenosed origin of the right vertebral artery. Accurate placement of the stent is critical because it is possible that during stent deployment the stent can advance too distal or retract too proximal, missing the area of stenosis altogether. Note how in this case, the balloon inflates on either book-end of the point of maximal stenosis, and then inflates at the mid point as well. Once adequate angioplasty has been performed, the balloon is deflated revealing the stent in excellent position.

Right subclavian artery fluoroscopy, AP view, demonstrates the vertebral artery ostium stent in excellent position. There is good, brisk flow through the stent and no significant residual stenosis.

Right subclavian artery injection, AP view, demonstrates brisk anterograde flow through the right vertebral artery and a widely patent basilar artery.