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Year : 2007  |  Volume : 55  |  Issue : 2  |  Page : 148--150

Spontaneous extrusion of guglielmi detachable coils from anterior communicating artery aneurysm

Kishor A Choudhari1, Peter A Flynn2, Steven C McKinstry2,  
1 Department of Neurosurgery, Regional Neurosciences Unit, Royal Victoria Hospital, Belfast BT12 6BA, United Kingdom
2 Department of Neuroradiology, Regional Neurosciences Unit, Royal Victoria Hospital, Belfast BT12 6BA, United Kingdom

Correspondence Address:
Kishor A Choudhari
Department of Neurosurgery, Regional Neurosciences Unit, Royal Victoria Hospital, Belfast BT12 6BA
United Kingdom


Recurrence of coiled aneurysm usually due to coil compaction is a known phenomenon. Extent of recurrence and its relation to re-bleeding is not known. The authors report a case of spontaneous asymptomatic extrusion of guglielmi detachable coils from the dome of a previously ruptured anterior communicating artery aneurysm two years after the initial endovascular obliteration. The initial aneurysm had a suitable neck-aspect ratio for endovascular obliteration with uncomplicated coiling procedure. Extreme degree of coil compaction with subsequent expulsion of the coils from the dome due to water-hammer effect of blood flow is thought to be the main pathogenic mechanism of this rare but worrying complication. Surgical management includes clipping at the neck ensuring complete obliteration of the aneurysm. Postoperative angiogram to confirm its satisfactory obliteration is advised.

How to cite this article:
Choudhari KA, Flynn PA, McKinstry SC. Spontaneous extrusion of guglielmi detachable coils from anterior communicating artery aneurysm.Neurol India 2007;55:148-150

How to cite this URL:
Choudhari KA, Flynn PA, McKinstry SC. Spontaneous extrusion of guglielmi detachable coils from anterior communicating artery aneurysm. Neurol India [serial online] 2007 [cited 2021 Jun 13 ];55:148-150
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Full Text


Endovascular embolization of ruptured aneurysms is the increasingly preferred modality of treatment for ruptured aneurysms in the United Kingdom and Ireland. The procedure is not, however, free from risks[1] and recurrence of the aneurysm is well known. In the acute stages, the most untoward events are protrusion of the coils into the parent vessel lumen and distal embolization with thromoembolic consequences. Spontaneous extrusion of the coils in the subarchnoid space through the dome of the aneurysm within two years of coiling is rare, unreported, but nevertheless an important complication.

 Case Report

A 33-year-old woman presented with Grade I subarachnoid hemorrhage (SAH). A small aneurysm in the region of the anterior communicating artery (AComA) was diagnosed by an angiogram [Figure 1]. This was 4 mm in its maximum diameter with 1.5 mm neck. With its suitable neck-aspect ratio it was deemed to be suitable for endovascular obliteration. The aneurysm was subsequently coiled using a 4 mm diameter GDC 10 3-D coil [Figure 2]. She made an uneventful recovery, but one-year digital subtraction angiography (DSA) showed some compaction of coils with a small neck-remnant. Further magnetic resonance angiogram (MRA) after 18 months and a DSA two years later confirmed continued aneurysmal recurrence almost to the same size (4 mm) as was prior to coiling. The neck of the recurrent aneurysm was ill-defined compared to the precoiling angiogram with coils pushed up to the dome [Figure 3]. The recurrent aneurysm, considering the patient's young age and early recurrence, was considered by the multidisciplinary neurovascular team to be more suitable for clipping than coiling. At surgery through pterional craniotomy, the aneurysm had re-grown to precoiling size and was free of coils [Figure 4]. Extruded coil loops were found to be lying freely in the subarchnoid space between the two distal anterior cerebral arteries (A2). Base of the coil mass was in contiguity with the aneurysm. There was also new de novo satellite aneurysm just adjacent to the previous site. Both aneurysms were clipped uneventfully [Figure 4]. As a routine, the aneurysmal sac was opened and inspected. No thrombus was found inside the sac or adjacent to the coils. Presence of a thrombus prior to or during coiling may, in theory, have had a role to play in the subsequent recanalization and expulsion of the coils. This would have been detected only by a MRI scan after subarchnoid hemorrhage. Unfortunately, we do not routinely perform MRI scans after subarchnoid hemorrhage. A CT scan, CT angiogram and a DSA, if required, is performed prior to coiling. Aneurysmal wall was not sent for histological examination. Postoperative angiogram was satisfactory and the patient made complete neurological recovery.


After ISAT, most ruptured aneurysms in the region of the anterior communicating artery are primarily offered endovascular intervention. Thromboembolic episodes at the time of coiling and delayed coil compaction in the dome of the aneurysm are probably the two most common complications associated with GDC embolization.[2],[3] While the former are mostly self-limiting, the precise significance of coil compaction is not known. Most recent series, however, indicate that the actual re-bleeding rate subsequent to re-growth at the neck and/or coil compaction is small.[4] Perhaps, significant recurrences are diagnosed at the time of radiological follow-up and are treated in a timely fashion before re-rupture occurs.

The interventionalists are familiar with coil protrusion in the parent vessel lumen,[5] occasional distal migration of inadvertently detached coil and minor peri-procedural embolic events that often require short-term anticoagulation. While delayed coil compaction is frequent, complete extrusion of the coil mass out of the aneurysmal confines is rare. The likely mechanism seems to be progressive coil compaction into the dome. If the original aneurysm is thin-walled, the coil mass is gradually pushed through the dome by "water-hammer" effect of the blood flow. Although the exact incidence of neck re-growth resulting from coil compaction is quoted to be as high as 35% in some studies,[4] such extreme compaction leading to complete expulsion of the coils from the aneurysm lumen and subsequent re-bleeding is fortunately rare. This, however, poses a dilemma for the neurovascular team as to at what stage of recurrence should aneurysms be treated and which is the best modality of treatment. In our case, there was early and progressive recanalization of the aneurysm almost to the pretreatment size and the patient was young. All these factors swayed our decision towards early surgical intervention without waiting further, as the cumulative risk of re-bleed was thought to be significant.

Most of the coil loops had migrated outside the aneurysmal wall lying in the arachnoid space, the dome being flimsily sealed by the base of the coil mass. The aneurysm had not healed as one would have hoped after satisfactory coiling. At surgery, it appeared that the coil mass had simply migrated through the dome of the aneurysm due to the water-hammer effect of blood flow. There was minimal fibrous or thrombogenic reaction around the coils that were bathing freely in the CSF. Although subsequent rupture was imminent from these operative findings, the patient did not have sentinel headaches to suggest minor leaks. Dissection of the neck and clipping was as straightforward as that in unruptured aneurysms as the coils had moved distally making reasonable neck and body to facilitate satisfactory clipping. Formation of another small satellite aneurysm was unrelated to coil expulsion, but confirmed an ongoing biological process of active aneurysm formation that was not halted by seemingly satisfactory embolization of the primary aneurysm.

This case emphasizes the importance of careful long-term radiological follow-up of small coiled aneurysms.[3] We do not have a rigid protocol for follow-up of coiled aneurysms. Most cases, however, undergo an MRI/MRA after six months and a DSA after a year following initial coiling. Further radiological follow-up is decided by the results of these investigations on the individual merits of the case. Unfortunately, precise natural history of small neck-remnants and minor coil-compaction remains elusive. Asymptomatic spontaneous coil extrusion as seen in our patient may perhaps be more common than the literature suggests and is likely to be encountered more frequently in future as we continue to embrace the endovascular means of treatment for ruptured aneurysms. Surface modification technology allowing protein-coated platinum is promising to enhance adhesiveness and reduce distal coil migration.[6] From our experience and available literature data, we advocate early re-treatment of aneurysms with coil-extrusion.[7],[8] As this phenomenon seems uncommon and unpredictable, each case of minor coil compaction needs to be followed up and managed on its individual merits. Nevertheless, whether spontaneous extrusion of coil mass from the aneurysm is simply a progression in the natural history and whether it indeed increases the risk of subsequent re-bleed remains unclear at this stage.


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