Which factor increases procedural thromboembolic events in patients with unruptured paraclinoid internal carotid artery aneurysm treated by coil embolization? Morio Nagahata, Rei Kondo*, Shinjiro Saito*, Atsuhito Takemura**, Toru Hatayama** Department of Radiology and Radiation Oncology, Hirosaki University Graduate School of Medicine, Japan * Department of Neurosurgery, Yamagata City Hospital SAISEIKAN, Japan **Department of Neurosurgery, Aomori City Hospital, Japan

Introduction paraclinoid internal carotid artery aneurysm Coil embolization is not always easy due to its anatomical location or shape of the aneurysm.

Simple technique? Combination with adjunctive technique? such as balloon / stent assistance Selection of the microcatheter How about the steam shaping of the catheter tip? Interventional neuroradiologists often worry about the appropriate coiling procedure

Does the maneuver of –exchanging microcatheter / coils –combined adjunctive technique (assist balloon) lead to more frequent ischemic complication? 60F, unruptured left ICA aneurysm diameter: 6mm coiling with balloon assistance silent infarction

Purpose To analyze the factors which increase the frequency of thromboembolic events during the coil embolization of the unruptured paraclinoid internal carotid artery aneurysms.

Materials and Methods December 2007 – April consecutive patients with unruptured paraclinoid internal carotid aneurysms –Treated with GDCs. –1 male, 13 females –Aged 40-71, mean 58.6 y.o. –Max. diameter of aneurysm: , mean 5.5mm –Simple coiling in 7 patients –Balloon assisted technique in 7 patients

All patients Received dual antiplatelet agents preoperatively. Systemic heparinization during the procedure. Posttreatment DWI was performed within 4 days. A neuroradiologist and a neurosurgeon evaluated the DWI.

Analysis Existence of the hyperintense lesion on postoperative DWI (within 4 days). –Patients’ age, sex. –Maximum diameter of the aneurismal dome. –Coil packing density. –Use of assistant balloon. –Exchange of microcatheter. –Withdrawal of undetached coil.

Results Neurologically symptomatic complications did not occur in our series. Silent procedure-related infarction was detected on postoperative DWI in 6 cases (35.7%). 49 F, left ICA aneurysm aneurysm diameter: 4.0mm balloon assistance (+) exchange of microcatheter (+) withdrawal of undetached coil (+) packing density: 29.5% silent infarcts (++)

n.s. n.s. n.s. n.s. Sex M/F Age (mean) y.o. max. diameter of aneurysm (mean) mm Coil packing density (VER) (mean) % ischemic complication + 0 / (58.8) (4.72) (26.3) ischemic complication - 1 / (65.5) (6.10) (29.7)

with balloon assistance without balloon assistance ischemic complication + 33 ischemic complication - 44 Assist balloon (HyperGlide) n.s.

Exchange of microcatheter + Exchange of microcatheter - ischemic complication + 33 ischemic complication - 17 Exchange of microcatheter during the procedure n.s.

Withdrawal of coil + Withdrawal of coil - ischemic complication + 60 ischemic complication - 35 Withdrawal of undetached coil during the procedure P=0.031

Silent infarcts found in 35.7% of our cases –66.7% cases in which we needed to withdraw the undetached coil during the procedure –versus 0% in patients without intraprocedural coil withdrawal. (P=0.03) Patient’s age, sex Aneurysm diameter Packing density Balloon-assisted technique Exchanging maneuver of microcatheter did not increase the frequency of silent infarcts.

Discussion Previous reports (cerebral aneurysms treated by coils) –Symptomatic thromboembolic complication: 1-31% –Silent infarcts observed on postoperative DWI: 20-61% –Perioperative antiplatelet management reduce the risk Our complication rate (IC paraclinoid aneurysm): 35.7% –Asymptomatic infarcts observed on DWI –Using dual antiplatelet agents. –May be acceptable rate!

Thromboembolic complication can occur more frequently –large or wide-neck aneurysms, –balloon-assisted technique Soeda M, et al. AJNR 24: , 2003 Risky maneuvers during the balloon-assisted coiling –microcatheter repositioning, –coil removal and repositioning Albayram S, et al. AJNR 25: , 2004

In the present study, Withdrawal of the unreleased coil the only factor increasing the rate of silent infarcts. Aneurismal size, Use of the assist balloon, Exchange of microcatheter during the procedure did not increase the frequency of silent infarcts.

It has not been known which maneuver during the procedure may be responsible for most thromboembolic events. We should make an appropriate selection of the coil to avoid the coil withdrawal which may lead to thromboembolic complication.

Conclusion Coil embolization of unruptured IC paraclinoid aneurysms Only the withdrawal of undetached coil from the aneurysm increased the frequency of the postoperative DWI abnormalities in our series. Appropriate coil selection, which may reduce the necessity of coil withdrawal, is important to perform safer embolization.