Endovascular coil embolization of very small intracranial aneurysms

Introduction Endovascular coil embolization of very small (maximum dome diameter .3 mm) aneurysms is controversial because of a high risk for procedural rupture and technical difficulty. We report clinical and angiographic results of coil embolization of these aneurysms. Methods From August 2005 through July 2009, 43 very small aneurysms (23 ruptured, 20 unruptured) in 38 patients (12 males, 26 females; mean age, 53 years) were embolized with detachable coils. Of those 38 patients, 24 (63%) presented with subarachnoid hemorrhage (SAH) from a very small aneurysm (n=23) or another aneurysm (n=1). We assessed initial angiographic results, procedural complications, and clinical condition with initial Hunt and Hess grade (HH) and Glasgow outcome scale (GOS) at discharge. Follow-up results were evaluated with conventional angiography and/or magnetic resonance angiography (MRA). Results Initial aneurysmal occlusion was total in 16 (37%), subtotal in 22 (51%), and partial in five (12%) aneurysms. There were five incidents of thrombosis (12%) and one procedural rupture (2%), but there was no definite adverse effect on clinical outcome. Of 24 patients with SAH, ten patients (42%) were in poor condition (HH 3 or 4) at admission. Seventeen of 24 patients (71%) had good or excellent outcome (GOS .4) at discharge. A 6-month or more follow-up angiography and/or MRA was available in 33 (11 total and 20 subtotal and 2 partial in initial occlusion) aneurysms (77%) in 28 patients and revealed stable occlusion in 20 aneurysms (61%), progressive total occlusion in 10 (30%), minor recanalization in 2 (6%), and major recanalization in 1 (3%). Conclusions Coil embolization of very small aneurysms may be technically feasible with favorable clinical/angiographic outcomes and relatively low recanalization rate during 6 months or more follow-up period.