What are the approaches for endovascular management of wide neck aneurysms?

Endovascular Management of Wide Neck Aneurysms

For wide neck aneurysms, stent-assisted coiling and balloon remodeling techniques are the primary endovascular approaches, as they provide better aneurysm occlusion rates while maintaining parent vessel patency compared to conventional coiling alone. 1

Definition and Challenges

• Wide neck aneurysms are typically defined as those with a neck diameter >4mm or a dome-to-neck ratio <2:1, making them technically challenging for standard endovascular coiling 1
• These aneurysms pose a higher risk of coil herniation into the parent vessel and have higher rates of incomplete occlusion and recurrence compared to narrow-necked aneurysms 1

Assessment and Planning

• Accurate assessment of aneurysm morphology requires optimal orthogonal arteriographic projections or rotational angiography with 3D reconstructions 1
• The relationship between parent artery diameter and aneurysm neck size is a critical factor in determining the need for adjunctive techniques 1
• Complete aneurysm obliteration should be the goal of treatment whenever possible to reduce rebleeding risk 1

Endovascular Techniques for Wide Neck Aneurysms

1. Stent-Assisted Coiling (SAC)

• SAC involves deploying a self-expandable stent across the aneurysm neck to create a scaffold that prevents coil herniation into the parent vessel 1, 2
• Immediate complete occlusion rates range from 19.3-98.1%, with an average of 46.3%, improving to 71.9% at follow-up 2
• Complications include:
  • Intraprocedural thrombosis (4.6%) 2
  • Post-procedural thromboembolic events (4.3%) 2
  • Delayed in-stent stenosis (5.3%) 2
• Requires dual antiplatelet therapy, which increases hemorrhagic risk, particularly in patients with subarachnoid hemorrhage 1

2. Y-Stent Technique for Bifurcation Aneurysms

• Particularly useful for wide-neck bifurcation aneurysms (common in anterior communicating and middle cerebral arteries) 3
• Involves deploying two stents in a Y-configuration to reconstruct the bifurcation and support coil placement 3
• Recent data shows high efficacy with complete or near-complete occlusion in 97.6-100% of cases at follow-up 3
• Major stroke complications occur in approximately 2.5% of cases 3

3. Balloon Remodeling Technique

• Temporary balloon inflation across the aneurysm neck during coil deployment, followed by balloon deflation and removal after coiling 1
• Avoids the need for long-term antiplatelet therapy required with stents 1
• Particularly useful for wide-neck aneurysms where parent vessel preservation is critical 1

4. Stent-Jack Technique

• Specialized technique for aneurysms with dome-to-neck ratio <1.5 4
• Involves deploying the first coil within the aneurysm before stent deployment, then deploying the stent to "jack" or constrain the coil within the aneurysm sac 4
• Helps achieve better initial coil positioning in extremely wide-necked aneurysms 4

5. Flow-Diverting Stents

• Low-porosity stents designed to redirect flow away from the aneurysm while providing a scaffold for endothelial growth 1
• Conceptually beneficial for dissecting aneurysms where vessel sacrifice is not an option 1
• May represent a better option for many saccular aneurysms, though more research is needed in the setting of subarachnoid hemorrhage 1

Follow-Up Considerations

• Aneurysm recurrence is not uncommon after endovascular coiling and may occur even in aneurysms that appear completely occluded initially 1
• Long-term angiographic monitoring is mandatory after endovascular treatment 1
• Follow-up imaging at 6 months and then annually is recommended, as approximately 50% of recurrences may be missed by a single 6-month follow-up 1

Decision-Making Algorithm

1. Assess aneurysm morphology (neck size, dome-to-neck ratio, parent vessel relationship)
2. For narrow neck aneurysms (neck ≤4mm, dome-to-neck ratio ≥2): Consider standard coiling 1
3. For wide neck aneurysms (neck >4mm, dome-to-neck ratio <2):
   • If at bifurcation: Consider Y-stent technique 3
   • If dome-to-neck ratio <1.5: Consider stent-jack technique 4
   • If patient can tolerate antiplatelet therapy: Consider stent-assisted coiling 2
   • If antiplatelet therapy contraindicated: Consider balloon remodeling 1
4. For giant or fusiform aneurysms: Consider flow-diverting stents 1

Pitfalls and Caveats

• Dual antiplatelet therapy required for stent placement increases hemorrhagic risk, especially in the setting of subarachnoid hemorrhage 1
• Complete aneurysm occlusion is less likely in larger aneurysms with wide necks, and additional embolizations are often required during follow-up 1
• The risk of recanalization is higher with endovascular treatment (2.9%) compared to surgical clipping (0.9%) 1
• Endovascular treatment of wide-neck aneurysms requires specialized expertise and should involve multidisciplinary decision-making between experienced cerebrovascular surgeons and endovascular specialists 1