The evolution of neurointervention has revolutionized the treatment of intracranial aneurysms. Today, specialists are equipped with a growing arsenal of endovascular tools—from bare platinum coils to high-density flow diverters and intricate stent-assisted systems.

But with choice comes complexity. Particularly in complex aneurysms—those with wide necks, irregular shapes, fusiform morphology, or difficult locations—device selection becomes a critical determinant of both procedural success and long-term durability.

So how do we choose the right device for the right aneurysm, in the right patient, at the right time?

What Defines a “Complex” Aneurysm?

While definitions vary, complex aneurysms typically involve one or more of the following:

• Wide necks (>4 mm or dome-to-neck ratio <2)
• Bifurcation or branch involvement
• Irregular or multilobulated morphology
• Large (>10 mm) or giant (>25 mm) aneurysms
• Fusiform or dissecting types
• Location in distal or tortuous anatomy
• Recurrent aneurysms after prior coiling or clipping

Each of these factors directly impacts device choice, access strategy, and long-term follow-up.

Device Options and Their Strategic Use

Let’s explore the most commonly employed endovascular approaches:

1. Simple Coiling

Best for:

• Narrow-necked aneurysms
• Small saccular aneurysms (<7 mm)
• Distal or technically challenging locations

Advantages:

• Minimally invasive
• Quick procedure
• Low device cost

Limitations:

• Poor long-term durability in wide-necked or large aneurysms
• High recurrence in certain morphologies
• Limited efficacy in fusiform/dissecting aneurysms

Clinical tip: Coil compaction and recanalization remain risks, particularly in younger patients and high-flow locations.

2. Stent-Assisted Coiling (SAC)

Best for:

• Wide-necked aneurysms at bifurcations or side branches
• Those requiring neck bridging to retain coils
• Recurrent aneurysms after failed coiling

Advantages:

• Provides scaffold to prevent coil prolapse
• Maintains patency of adjacent vessels
• Durable occlusion in anatomically favorable cases

Limitations:

• Dual antiplatelet therapy required
• Technically more demanding (crossing neck, jailed vs trans-cell techniques)
• Delayed endothelialization in some cases

Clinical tip: Closed-cell stents offer better coil containment; open-cell stents allow greater conformability in tortuous anatomy.

3. Flow Diversion

Best for:

• Large, giant, fusiform, or dissecting aneurysms
• Internal carotid artery (ICA) locations (cavernous to paraophthalmic)
• Failed prior coiling/clipping
• Uncoilable aneurysms with unfavorable neck-to-dome ratio

Advantages:

• Promotes intra-aneurysmal thrombosis by redirecting flow
• Treats parent vessel pathology (dissection, ectasia)
• May lead to progressive remodeling over months

Limitations:

• Not ideal for bifurcation aneurysms
• Requires dual antiplatelet therapy
• Delayed rupture risk in large/giant aneurysms
• Not yet widely accepted for posterior circulation use (except select cases)

Clinical tip: Always confirm vessel diameter and landing zones; ensure platelet function testing is optimized to reduce thromboembolic complications.

Choosing the Right Strategy: A Decision Framework

Patient factors such as age, platelet function, compliance with dual antiplatelet therapy, and comorbidities must always be part of the equation.

Adjuncts and Evolving Tools

• Balloon-Assisted Coiling (BAC): Temporarily supports coil placement across wide necks, useful when stent use is contraindicated.
• Intrasaccular devices (e.g., WEB, Contour): Offer neck-bridging from within the aneurysm, increasingly used in bifurcation locations without need for long-term antiplatelets.
• Dual-layer stents and next-gen flow diverters: Designed for complex curvature and branch integration, currently under investigation in various trials.

Final Thought: Tailoring Tools to Anatomy

In complex aneurysm care, no single device is universally ideal.
Success lies in understanding aneurysm morphology, vascular geometry, hemodynamics, and the limitations of each tool in our hands.

Device selection is a strategic decision—not just about what can be deployed, but what will achieve the most complete, safe, and durable occlusion in that individual patient.

Because in the world of neurointervention, the difference between filling an aneurysm and fixing it — is the strategy behind the stent.

Coming Soon on TriVasc Academy
Device comparison charts, annotated case videos, and interactive 3D models for planning coil, stent, and flow diverter strategies.