What are the Different Types of Intracranial Stents?
**Author:** Standard Technology
**Date:** 2026-02-22T00:00:00Z
Introduction
Intracranial stents represent a significant advancement in the neurovascular field, offering crucial support in the treatment of various cerebrovascular diseases, particularly intracranial aneurysms and stenosis. The evolution of these devices has been driven by the need for more effective and safer interventions, moving from early adaptations of coronary stents to highly specialized neurovascular devices. This academic blog post will delve into the different types of intracranial stents, outlining their design principles, mechanisms of action, clinical applications, and the historical context of their development. It is important to note that this article provides general information for educational purposes and should not be considered medical advice.
The Development of Intracranial Stents: A Historical Overview
The journey of intracranial stents began with the adaptation of percutaneous transluminal angioplasty for intracranial stenosis over three decades ago. The invention of Guglielmi detachable coils in the 1990s further propelled the need for stent-assisted procedures. Since then, roughly four generations of intracranial stent designs have emerged: balloon expandable stents, self-expandable open-cell stents, self-expandable closed-cell stents, and flow-diverting stents. Beyond these, conventional Bare Metal Stents (BMS) and intracranial covered stents are also part of the evolving landscape [Zhao et al., n.d.].
Types of Intracranial Stents
1. Balloon Expandable Stents (BES)
**First Generation Intracranial Stents**
In the nascent stages of intracranial stent development, balloon expandable coronary stents were repurposed for intracranial transluminal angioplasties. These stents were primarily used to crush plaques and dilate vessel lumens. While they offered a solution for vessel patency, their use was associated with high risks, including distal thromboembolism and perforator occlusion due to plaque fragmentation. The first reported use of BES in stent-assisted coil embolization for intracranial aneurysms was in 1997. However, subsequent clinical applications revealed significant challenges, such as a high deployment failure rate (15%), high procedural hemorrhage rate (7%), and a notable delayed in-stent stenosis rate (4%), leading to considerable neurological morbidity and mortality [Zhao et al., n.d.].
2. Self-Expandable Open Cell Stents (OCS)
**Second Generation Intracranial Stents**
Self-expandable open-cell stents marked a significant improvement, designed specifically for intracranial applications. These stents are characterized by their open-cell design, which offers flexibility and conformability to tortuous intracranial vasculature.
- **Neuroform Stent:** Approved by the FDA in 2002, the Neuroform stent was one of the first devices specifically designed for intracranial use. Made of a nickel-titanium alloy, it features 6-8 linked radiolucent cells. Early studies indicated a deployment failure rate of 7%, stent migration in approximately 2% of cases, and permanent neurological morbidity and mortality rates of 4% and 2% respectively. Subsequent generations, like Neuroform 2 and 3, introduced enhancements such as hydrophilic braided micro-catheters and additional connectors to improve navigability, reduce deployment failure, and increase radial force [Zhao et al., n.d.].
- **Wingspan Stent:** The Wingspan stent, made of nitinol, received FDA approval in 2005. It is another prominent OCS. Clinical trials, such as the SAMMPRIS trial, documented successful deployment in 98% of cases with no stent migration. However, the trial also highlighted a 4% mortality or ipsilateral stroke rate within 30 days. While initial results suggested no superiority over aggressive medical treatment for intracranial arteriosclerosis due to high peri-procedural complication rates, subsequent studies with stricter inclusion criteria have shown improved outcomes [Zhao et al., n.d.].
3. Self-Expandable Close Cell Stents (CCS)
**Third Generation Intracranial Stents**
Closed-cell stents represent the third generation, offering enhanced structural support and radial force due to their tightly woven or linked cell designs. This design provides greater scaffolding but can sometimes compromise flexibility.
- **Enterprise Stent:** Approved by the FDA in 2007, the Enterprise stent is a nitinol-based closed-cell stent. Its design provides stronger supporting strength and radial force, along with the unique ability to be recaptured and repositioned up to 70% after deployment. This feature offers a significant advantage in device delivery. However, its closed-cell design can lead to increased stiffness and reduced plasticity, potentially affecting its interface with highly curved vessels. Cases of vascular perforation and stent entanglement have been reported. Despite these challenges, the Enterprise stent boasts a low deployment failure rate (1%), delayed in-stent stenosis rate (3%), and peri-procedural hemorrhage rate (2%) [Zhao et al., n.d.].
- **LEO Stent:** The LEO Stent, also made of nitinol with a small closed-cell structure, offers even greater radial force and elasticity. It can be re-sheathed and repositioned up to 90% of deployment. While its hemodynamic properties were innovative, it has been associated with a high thromboembolic incidence due to interrupted blood flow to perforators. Clinical trials reported a 5% deployment failure rate, 2% stent migration, and a 14% post-procedure thromboembolic event rate, leading to 4% morbidity and 3% mortality. Despite its poor clinical outcomes, its hemodynamic qualities influenced the development of flow-diverting stents [Zhao et al., n.d.].
- **Solitaire Stent:** The Solitaire stent, a fully retrievable nitinol stent with a honeycomb pattern, offers exceptional flexibility and elasticity, facilitating easier delivery and deployment. While not approved for stent-assisted coiling in North America, it is widely used for mechanical thrombectomy. It has demonstrated no deployment failure, stent migration, or in-stent stenosis in treating acute intracranial artery occlusion. However, it showed a 6% peri-procedural hemorrhage rate and a mortality rate of 17.4-22.2% [Zhao et al., n.d.].
4. Flow Diverting Stents (FDS)
**Fourth Generation Intracranial Stents**
Flow-diverting stents represent a paradigm shift in the treatment of complex intracranial aneurysms, particularly large or giant aneurysms that are not amenable to traditional coiling or clipping. These devices work by altering hemodynamics within the parent artery, promoting thrombosis and occlusion of the aneurysm while preserving blood flow to perforating arteries.
- **Silk Flow Diverter (SFD):** The Silk Flow Diverter is a closed-cell stent composed of braided nitinol strands and platinum microfilaments. It is retrievable up to 90% of deployment and is flexible, though with a relatively lower radial force. Its design reduces wall shear stress and decreases blood flow into the aneurysm, inducing hemostasis and thrombosis. However, its lower radial force has contributed to a higher rate of stent migration. Clinical outcomes reported a 3% deployment failure rate, less than 1% stent migration, 7% embolic events, 3% hemorrhage events, 10% in-stent stenosis, and 6% neurological morbidity and 4% mortality. A notable complication associated with SFD, and FDS in general, is Delayed Aneurysm Rupture (DAR) [Zhao et al., n.d.].
- **Pipeline Embolization Device (PED):** The Pipeline Embolization Device, approved by the FDA in 2011, is a closed-cell FDS made of woven cobalt and platinum microfilaments. Its tight woven mesh structure provides greater radial force than SFD and significantly reduces blood flow into the aneurysm. PED has shown fewer complications compared to SFD in clinical practice [Zhao et al., n.d.].
Conclusion
The landscape of intracranial stents has evolved dramatically, offering increasingly sophisticated solutions for neurovascular pathologies. From the early balloon-expandable stents to the advanced flow-diverting devices, each generation has brought improvements in design, material, and clinical efficacy. While challenges such as in-stent stenosis, thromboembolic events, and hemorrhagic complications persist, ongoing research and technological advancements continue to refine these devices, aiming for safer and more effective patient outcomes. The continuous development of biocompatible materials, endothelial progenitor cell capture techniques, and nanotechnology holds promise for the future of intracranial stent design, further enhancing their role in neurovascular intervention.
References
[1] Zhao, J., Kalaskar, D., Farhatnia, Y., Bai, X., Bulter, P. E., & Seifalian, A. M. (n.d.). *Intracranial Stents Past, Present and the Future Trend: Stents Made with Nano-particle or Nanocomposite Biomaterials*. UCL Discovery. Retrieved from https://discovery.ucl.ac.uk/id/eprint/1425462/1/Zhao_Intracranial_stents_past_present_new%20copy_AAM.pdf