Embolization of Intracranial Aneurysms with Hydrogel-Coated Coils versus Inert Platinum Coils

Gaba RC, Ansari SA, Roy SS, Marden FA, Viana M, Malisch TW.
Stroke 2006;37:1443–50

Background: Background of this study is the still existing recanalization rate in coil-embolized intracranial aneurysms which is higher compared to clipping.

Methods: The authors describe a consecutive series of 45 pa-tients with 50 intracranial aneurysms treated solely or dominantly with hydrogel-coated coils. They retrospectively compared this group with an own historical matched group of aneurysms treated with bare platinum coils. In a meticulous manner, differences were analyzed (coil length and costs, length of hospital stay, angiographic results, complications). Focus was on volumetric percentage aneurysm occlusion, initial and long-term angiographic results.

Results: The authors found a three times higher theoretical volume percentage aneurysm occlusion and a reduction in recurrent rate, which was significant in small aneurysms.

Comment

Background of this study is the still existing recanalization rate in coil-embolized intracranial aneurysms which is higher compared to clipping. The presumed advantage of hydrogel-coated coils is a higher packing density inside the aneurysm leading to a better long-term result. The coils are covered with a hydrophilic polymer that expands in contact with blood. This study demonstrates that this coil technology is obviously safe to use and capable of reducing recurrent aneurysm rate.

A drawback of this study is that aneurysm treatment was not randomized and aneurysm should be matched by size, location, ruptured and nonruptured as well as configuration and neck size since all those parameters influence recurrence rate. Matching is extremely difficult and requires a great cohort. The authors did match the aneurysms for volume and shape only and did not tell the ranges. The next problem is volume measurement: there is no exact method of doing it properly. Measurement variations of even < 1 mm would lead to a dramatical change in volume, especially in small- and medium-sized aneurysms.

Therefore, these parameters should be regarded with caution. A randomized trial, which is ongoing (HELPS study) will help to define the effectiveness and eventual superiority of the hydrogel technology versus use of bare coils.

(submitted October 25, 2006)

I. Wanke, Essen