What is flow diversion therapy of intracranial aneurysms?

The endovascular treatment of intracranial aneurysms has rapidly evolved during the past 2 decades. However, our ability to achieve a durable and complete occlusion of aneurysms remains, in some cases, limited especially large and wide-necked or blister aneurysms.

During the past 3-4 years, a new generation of endovascular devices—the flow diverters—has been developed. These are essentially stents designed to reconstruct the parent artery and divert blood flow along the normal anatomical course of the vessel and away from the aneurysm neck. Complete aneurysm occlusion is not achieved at the time of the procedure.  There is slow progressive thrombosis and the stent provides a scaffolding over which endothelium grows to ultimately seal off the aneurysm.

What are the different stents used?

There are two stents specifically made for flow diversion: SILK and PIPELINE.

However, ENTERPRISE or SOLITAIRE stents which are usually used for stent assisted coiling of aneurysms can also be used and can be effective in certain situations.

Is the treatment established

The PIPELINE device is currently an investigational device in the United States, which is only available within the context of ongoing US Food and Drug Administration (FDA) clinical trials. 

It has received CE Mark approval in Europe on the basis of the Pipeline Embolization Device in the Intracranial Treatment of Aneurysms (PITA) study.

In addition, Dr. Pedro Lylyk in Argentina an Dr Saruhan Cekirge from Turkey have continued to treat patients under individual compassionate use provisions.

The Silk stent (Balt Extrusion, Montmorency, France) is a braided, self-expanding, high metal surface area coverage construct that also has CE Mark approval in Europe for the treatment of intracranial aneurysms. Other similar flow-diverting constructs are at earlier stages of development and are currently without published clinical data.

However, it is important to acknowledge that flow-diversion technology is at a very early stage, and in the Unites States, the PED remains an investigational device. As such, the available data do not provide a sufficient foundation on which to make firm recommendations regarding patient selection.

 The PIPELINE stent

See three case examples below and an animation of the PIPELINE stent being used.