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Neurosurgery. 2009 May;64(5 Suppl 2):301-15; discussion 315-7. doi: 10.1227/01.NEU.0000335178.15274.B4.

Microsurgical management of incompletely coiled and recurrent aneurysms: trends, techniques, and observations on coil extrusion.

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  • 1Department of Neurological Surgery, University of California, San Francisco, San Francisco, Californi 94143-0112, USA.



With the growing volume of aneurysms treated with endovascular methods and the unavoidable risks of incomplete coiling or recurrence, the volume of coiled aneurysms requiring surgical management is growing. We present a consecutive surgical experience with previously coiled aneurysms to examine clinical trends, the phenomenon of coil extrusion, microsurgical techniques, and morphological features affecting clippability.


During a 10-year period, 43 patients underwent surgical management of an incompletely coiled or recurrent aneurysm (Gurian group B). Most patients (88%) presented initially with subarachnoid hemorrhage, most commonly (28%) located in the anterior communicating artery, and 42% of aneurysms were large or giant sized.


Twenty-one patients had incompletely coiled aneurysms and 22 patients had recurrent aneurysms, with a mean time to recurrence of 28 months. Coil extrusion was observed in 1 of the incompletely coiled (5%) and 12 of the recurrent aneurysms (55%). Overall, 33 aneurysms were clipped directly, 7 unclippable aneurysms were bypassed, and 3 were wrapped. Three patients died (surgical mortality, 7%), 1 patient (2%) experienced permanent neurological morbidity, and the remaining 39 patients (91%) had good outcomes (mean follow-up, 4.3 years).


This study demonstrated a sharp increase in the incidence of coiled aneurysms requiring surgery, reflecting the increasing numbers of patients opting for endovascular therapy initially. Coil extrusion occurs more often than expected, is often misdiagnosed on angiography as simply compaction, and seems to be a time-dependent process not seen acutely. Direct clipping is the preferred microsurgical treatment of coiled aneurysms and may be predicted by the relationship between coil width and compaction height (C/H < 2.5, or a wedge angle < 90 degrees). We recommend a bypass strategy for unclippable coiled aneurysms because it can be executed methodically; has predictable ischemia times; and is associated with more favorable results than thrombectomy, coil extraction, and clip reconstruction.

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