Endovascular treatment of intracranial aneurysms.

The article by Cekirge et al in this issue of the AJNR (1) is another chapter in the growing use and recognition of coils as an endovascular method to treat cerebral aneurysms. In this paper, the authors report their experience with the use of the interlocking detachable coil (IDC) as an alternative to the recognized and increasingly used Guglielmi detachable coil (GDC). Having used the IDC successfully in five cases, they report their results and discuss the IDC in comparison with other detachable coils. The question we raise is, why should we be looking for an alternative coil device, since we have gathered (in multicenter studies of over 6000 patients) good experience using the GDC? If a new device is needed, will “just another coil” be the answer? We think, with many others, that the GDC is the most appropriate actual and available coil to treat a great variety of cerebral aneurysms safely through an endovascular approach. Switching to a new device, or even testing an alternative device, should not be done if its safety is not comparable to or a significant improvement over the GDC. If less favorable results are produced, such a trial could discredit endovascular treatment of aneurysms, which has greatly improved since the introduction of the GDC in 1991 (2). The reasons to look for an alternative coil device may be variable; the following comment does not claim to be exhaustive. The different factors are not treated in the order of importance, but in the order of the problems currently faced in the use of coils by neuroradiologists. Indication.—The average berry aneurysm is treatable with commercially available GDC devices; only if the endovascular access is difficult (eg, very tortuous) or the site of aneurysm implantation difficult to reconstruct (eg, large overall neck size in relation to the size of the parent artery, vessels originating from the aneurysm pouch, fusiform involvement of a whole arterial segment) are there insurmountable obstacles to successful treatment with the GDC (3). Most of these situations will require not only an improved coil design but a completely different way of treatment, perhaps involving additional devices, such as stents (4, 5) or liquid polymers (6). GDC devices can be used for other, less delicate situations, such as venous occlusions for the treatment of dural arteriovenous fistulas (7), where many coils might be required to obtain occlusive packing of a dural sinus. In addition to the need to fill a potentially larger space than an aneurysmal cavity, because of the presence of an arteriovenous shunt, the fast venous flow might require stronger or more complex coils to withhold the imposed pressure and flow conditions. However, coil systems constructed to treat such conditions still have to be flexible enough to negotiate the path to intracranial compartments. Availability and Price.—GDC devices have not been available worldwide to all clinicians hoping to deal with cerebral aneurysms. This certainly has been a good reason to look for an alternative device and this was the case also with many Japanese colleagues using the IDC (mechanically detachable or interlocking detachable coil). Another, potentially more important, reason to look for alternative devices may be price. This varies from country to country and, considering an average need of 3.6 to 4.5 GDCs for complete endovascular treatment of an aneurysm, may cause the procedure to exceed the price of a competitive surgical procedure. Choice of Material and Implant Characteristics.—Platinum was chosen as the material for GDC and IDC, and tungsten for mechanical de-