uias , particularly those that are asymptomatic , have a low risk of aneurysmal subarachnoid hemorrhage ( sah ) . therefore , the decision to manage elderly patients with asymptomatic uias requires a rigorous assessment of the risks of various treatment options and knowledge of the natural course of the disease process . however , the development of endovascular devices and increased experience has significantly reduced the procedure related risks of endovascular therapy of intracranial aneurysms . to our knowledge , the published series on endovascular therapy of uias in elderly patients is relatively small.15 therefore , precise risk evaluations of endovascular therapy of asymptomatic uias in elderly patients have not yet been established . the purpose of this study was to report the treatment results of endosaccular coil embolization of asymptomatic uias in elderly patients and to elucidate the procedural feasibility , risks , and clinical outcomes . from april 2001 through march 2013 , 1011 patients with 1087 asymptomatic uias underwent endosaccular coil embolization at the juntendo university hospital and affiliated hospitals . patients with symptomatic uias , dissecting or fusiform aneurysms , aneurysms treated with parent artery sacrifice , aneurysms associated with brain arteriovenous malformations , and mycotic aneurysms were excluded . pre and post treatment clinical conditions were assessed according to the modified rankin scale ( mrs).6 asymptomatic uias associated with ruptured aneurysms were included if patients underwent curative treatment of ruptured aneurysms and could be assessed ( mrs < 1 ) at least 3  months after the onset of sah without the influence of the sah and/or the treatment of the ruptured aneurysm . for comparative purposes , patients were divided into two groups : group a included patients aged 6574 years and group b patients aged 75 years or older . the principal investigator ( ho ) , with the opinions of the coauthors , assessed the procedure related complications , immediate / followed - up clinical outcomes , and anatomical outcomes according to the patients medical records , outpatient charts , and surgical records . procedure related complications were defined as neurologic deterioration , abnormal neuroimaging findings , and any treatment related undesirable events . morbidity and mortality were defined as a deterioration of > 0 on the mrs and any deaths related to the treatments . unfortunately , we could not collect or analyze data of asymptomatic uias surgically or conservatively treated during the study period for various reasons . the degree of aneurysm occlusion with catheter angiography was defined using the criteria previously described by roy et al.7 if there was no contrast filling of the dome , body , or neck of the aneurysm , it was defined as complete occlusion ( co ) . if the contrast medium entered part of the neck but did not fill the body and/or dome of the aneurysm , it was defined as residual neck ( rn ) . if the contrast medium entered the body and/or dome of the aneurysm , it was defined as residual aneurysm ( ra ) . failure of endosaccular coil embolization was defined as impossible to place the coil or navigate the microcatheter into the aneurysm because of technical difficulties . our radiological follow - up protocol was mr angiography at 6  months and catheter angiography at 1 and 2  years after the procedure . if aneurysm occlusion was stable at the 2 year follow - up or at the 1 year follow - up ( after 2012 ) , the patient underwent mr angiography every year after that . mr angiography could replace catheter angiography if the patient 's condition was determined to be unsuitable or if the patient refused repeated catheter angiography . we defined the change in aneurysm occlusion as : unchanged , the area of aneurysm filling was stable ; minor recurrence , an increased area of aneurysm filling without necessitating retreatment ; major recurrence , an increased area of aneurysm filling ideally necessitating retreatment ; and improved , a decreased area of aneurysm filling . systemic heparinization was initiated in all patients to maintain an activated clotting time of 250300  s throughout the procedure and was stopped at the end of the procedure for most patients . patients were given aspirin 100  mg as an antiplatelet medication a few hours before the procedure which was continued daily for 12  months after the procedure to prevent thromboembolic events due to thrombus formation at the neck of the coiled aneurysms . if a stent assisted technique was scheduled , dual antiplatelet therapy with aspirin 100  mg plus clopidogrel 75  mg was given at least 5  days before the procedure and was continued for at least 6  months . in most patients , one or two working projections providing the best views of the aneurysm neck / body and microcatheter approach routes were decided on the basis of images generated by three - dimensionally reconstructed rotational dsa . if that was not available , two - dimensional dsa in multiple projections was performed to obtain optimal working projections . after the procedure , angiograms in the frontal , lateral , and working projections were acquired to assess the degree of aneurysm occlusion and to rule out angiographically detectable thromboembolic events . a simple technique of using a single microcatheter was done if a satisfactory aneurysm occlusion was expected . adjunctive techniques ( balloon assisted , double catheter , or stent assisted ) were used for aneurysms with an unfavorable angioarchitecture . the appropriate sizes and shapes of the coils were selected according to the target aneurysm . as is our standard procedure , we inserted the coils within the aneurysm from the wall to the center as densely as possible or until another coil could no longer be inserted , without compromising the parent artery lumen , even after complete angiographic obliteration was achieved . the biologically modified coils ( matrix 2 ; striker , california , usa ) were used in 81 selected aneurysms treated after august 2008 . in most of the procedures we used a braided microcatheter ( excelsior sl 10 ; striker ) with the tip manually steam shaped . navigation of the microcatheter into the aneurysm was performed with the assistance of a 0.012 inch microguidewire ( gt wire ; terumo , tokyo , japan ) . we usually used an over the wire balloon catheter ( eg , hyperform or hyperglide ; ev3 , irvine , california , usa ) and a closed cell stent ( enterprise vascular reconstruction device ; codman , raynham , massachusetts , usa ) to perform the balloon assisted and stent assisted techniques , respectively . a total of 375 elderly patients with 400 asymptomatic uias were included in this study . table  1 shows the characteristics of the patients and the sizes of the aneurysms . characteristics of the patients and aneurysms mean age was 71.04.7  years , with a female predominance ( 73.3% ) . group a included 292 patients with 315 aneurysms and group b included 83 patients with 85 aneurysms . there were no statistically significant differences in gender / comorbidities between the groups , but group b had a high rate of aneurysms detected during examination of aneurysmal sah ( p=0.042 ) . there were no significant differences in aneurysm size , neck width , or dome to neck ratio between the groups . frequent locations were the anterior communicating artery , posterior communicating artery , and siphon of the internal carotid artery in the anterior circulation , and the basilar artery bifurcation in the posterior circulation . aca , anterior cerebral artery ; achoa , anterior choroidal artery ; acoma , anterior communicating artery ; ba , basilar artery ; ica , internal carotid artery ; mca , middle cerebral artery ; pca , posterior cerebral artery ; pcoma , posterior communicating artery ; pica , posterior inferior cerebral artery ; sca , superior cerebral artery ; va , vertebral artery . table  3 shows the embolization techniques used . endovascular procedures were completed in 391 aneurysms ( 97.8% ) and failed in nine ( 2.2% ) . the techniques used were simple in 37.0% , balloon assisted in 44.3% , double catheter in 9.0% , and stent assisted in 7.5% . the reasons for the technical failures in nine aneurysms from nine patients were : unfavorable dome to neck ratio in four patients , wide neck in three patients , difficulty in preserving the branch originating from the aneurysm neck in one patient , and difficulty in navigating the microcatheter into the aneurysm due to the tortuosity of the cervical and intracranial vessels in one patient . although there was no statistically significant difference , eight of the technical failures were in group a. two of the nine patients who had a technical failure underwent surgical clipping of the aneurysm . embolization techniques used table  4 shows the immediate and follow - up anatomical outcomes of 391 aneurysms which were technically completed . follow - up anatomical outcomes were assessed by catheter angiography or mr angiography > 179  days after treatment . immediate anatomical outcomes showed co in 53.7% , residual neck in 18.9% , and residual aneurysm in 27.4% . there was no significant difference in the immediate anatomical outcomes between the groups but there was a trend to a the high rate of co in group a and of residual aneurysm in group b. a total of 291 patients with 314 aneurysms underwent anatomical follow - up . the overall mean anatomical follow - up period was 36.328.1  months ( range 6  months to 10  years ) . the mean anatomical follow - ups with catheter angiography and with mr angiography were 20.917.0  months and 31.626.7  months , respectively . anatomical follow - ups showed unchanged in 55.7% , improved in 22.6% , minor recurrence in 11.5% , and major recurrence in 10.2% . there was no significant difference in anatomical follow - up outcomes between the groups but there was a trend to a high rate of improvement and a low rate of recurrence in group b. group a had a significantly higher rate of anatomical follow - up compared with group b ( 82.2% vs 61.4% ; p<0.01 ) . there was a significant difference in anatomical follow - up modality between the groups ( p<0.05 ) . catheter angiography was more frequently used in group a than in group b ( 78.8% vs 54.9% ) . immediate and follow - up anatomical outcomes co , complete occlusion ; ra , residual aneurysm ; rn , residual neck . fifteen patients had ischemic complications : ischemic findings on mr or ct images in nine , angiographically thromboembolic findings during the procedure in three , and coil loop herniation with thrombus formation within the parent artery in three . ten patients had hemorrhagic complications : intraprocedural aneurysmal rupture in six , post treatment aneurysmal rupture in two ( on the day of the procedure and 9.1  years after the procedure ) , guidewire induced branch perforation in one , and intracranial hemorrhage most likely due to the dual antiplatelet therapy in one . the remaining six patients had other complications : carotid artery dissection during guiding catheter insertion in two , renal artery injury during femoral sheath insertion in two , transient cortical blindness due to the contrast medium in one , and transient oculomotor nerve palsy due to the coil mass in one . there was no significant difference in the risk of procedure related complications between the two groups . a total of 366 patients with 391 aneurysms technically completed showed a mean clinical follow - up of 39.131.2  months ( range 37  days to 11.5  years ) after treatment . among these , 363 patients ( 99.2% ) had a favorable clinical outcome ( mrs < 1 ) at 30  days after treatment . the causes of clinical worsening were acute in - stent thrombus formation leading to cerebral infarction , thromboembolic event leading to brainstem infraction , and post treatment aneurysmal rupture in one patient each . one patient suffered from cerebral infarction due to an in - stent thrombus formation 2  months after treatment ; this patient had stopped taking dual antiplatelet drugs 1  week before the event . the other patient suffered from sah 9.1  years after treatment ; the patient refused retreatment of the aneurysm during the follow - up period . the overall latest clinical follow - up outcomes showed an mrs score of 0 in 362 patients , mrs score of 1 in one , mrs score of 3 in one , mrs score of 4 in one , and mrs score of 5 in one . therefore , the permanent morbidity and mortality rates of the patients technically completed were 1.1% and 0% , respectively . retreatments were performed in 16 patients ( 4.3% ) with 16 aneurysms : once in 14 patients , and twice and three times in one patient each . only one middle cerebral artery aneurysm was surgically treated because of the technical difficulty of repeat endosaccular coil embolization . the duration between the initial treatment and retreatment ranged from 7.1 to 109.5  months ( mean 35.030.9  months ) . there was no morbidity or mortality related to the retreatment . among the nine patients for whom the procedure technically failed , two patients underwent surgical clipping without any adverse events , and the remaining seven patients were conservatively treated with no aneurysmal sah during the mean clinical follow - up period of 45.132.9  months . the elderly population has been growing every year and comprised about 20% of the japanese population in 2013 . the increase in radiological examinations and the development of less invasive neuroimaging techniques has resulted in more frequent incidental detection of asymptomatic uias in elderly patients . reported permanent morbidity and mortality rates range from 9.5% to 36% and from 4.8 to 23% , respectively.813 prevention of aneurysm rupture has been considered as an effective treatment but the natural course and treatment related risks of uias in elderly patients have not been clarified . recently , endovascular treatment of ruptured intracranial aneurysms has made remarkable progress and has been accepted as an alternative to surgical clipping with favorable clinical outcomes and low morbidity / mortality rates.1417 in general , aggressive treatment of uias in elderly patients is not recommended because of their relatively short life expectancy and potential risks related to aging associated comorbidities . however , excessive psychological stress from the fear of aneurysm rupture can seriously affect a patient s physical and mental well being . because all decisions on preventive treatment should be based on risk versus benefit rules , knowledge of the risks of endosaccular coil embolization for asymptomatic uias in elderly patients can help both physicians and patients in determining the management strategy . some authors found that patient age was a significant risk factor for aneurysmal sah.12 
 1822 morita et al23 reported on the nationwide study of the natural course of uias in the japanese population . in their report in contrast , they found that older patients tended to have larger aneurysms than younger patients . aneurysms 7  mm were found in 18.0% of patients younger than 50  years of age , in 21.4% of patients aged 5059  years , in 24.7% of patients aged 6069  years , in 32.6% of patients aged 7079  years , and in 39.7% of patients aged 80  years ( p<0.001 ) . small aneurysms in elderly patients have a lower risk of rupture as well as those in non - elderly patients . there have been several reports on the outcomes of endovascularly treated elderly patients with uias . barker et al24 reported a comparison between the results of endovascular and surgical treatment of patients with uias . they found a better discharge disposition of patients treated with endovascular compared with surgical treatment in patients older than 65  years of age . cai et al25 reported 91% excellent outcome ( mrs 01 ) in their single center experience of 22 endovascularly treated elderly patients with uias . gonzalez et al4 reported 91% good outcome ( mrs 2 ) in 97 elderly patients with endovascularly treated uias . in a systemic review and meta - analysis of endovascular treatment of intracranial aneurysms in elderly patients ( 65  years ) by sturiale et al,26 the rate of good clinical outcome at 1  year was 93% , and the mortality rate at 612  months was 10% overall in patients with uias . in our series , the rates of mrs < 2 at 30  days , and the latest follow - ups , were 99.7% and 99.2% , respectively , comparable with previous reports . with increasing experience and the development of devices , the procedural risks of endovascular therapy of intracranial aneurysms have been decreasing . hwang et al2 reported the results of endovascular therapy of 96 elderly patients ( > 70  years ) with 122 uias . khosla et al1 reported on the results of endovascular therapy of 108 elderly patients ( > 65  years ) with 122 uias . overall major complications and major complications with neurologic deficits occurred in 17% and 8.2% , respectively . stiefel et al5 reported the results of endovascular therapy of 77 elderly patients ( 70  years ) with 99 uias . permanent morbidity and mortality rates were 1% and 3% , respectively . in the systemic review and meta - analysis by sturiale et al,26 transient neurological deficits and the morbidity rate at 30  days was 1.6% , and there was no mortality . important drawbacks of endosaccular coil embolization are the high risks of incomplete occlusion and recanalization which , leading to aneurysmal rupture and procedural failure , were comparable with surgical clipping . in the systemic review and meta - analysis by sturiale et al,26 immediate and followed - up ( > 12  months ) complete / near occlusion rates immediate and followed - up ( > 6  months ) complete / residual neck rates were 71% and 80.6% , respectively . increasing physician experience , device development , and appropriate aneurysm selection warrant the satisfactory immediate anatomical results and reduced the rate of procedural failure . sturiale et al26 also found that the risk of rupture after treatment , with a mixture of ruptured and unruptured aneurysms , was 2.0% . in our series , two coiled aneurysms ( 0.5% ) therefore , endosaccular coil embolization proved to be an effective method of protecting asymptomatic uias from rupture . patients treated with endosaccular coil embolization of intracranial aneurysms should undergo long term radiological follow - up for detecting aneurysm recurrence and regrowth.27 although catheter angiography is currently the standard modality , patients in group b underwent catheter angiography less often than those in group a because catheter angiography is more invasive compared with mr angiography for elderly patients . this study indicated that elderly patients with asymptomatic uias are potential candidates for endosaccular coil embolization , and old age itself should not be considered a contraindication . however , neurointerventionalists should choose patients carefully , and should perform the procedure anticipating a very low risk and a favorable clinical outcome . because this study included retrospective data acquisition , and the authors assessed the anatomical / clinical outcomes and procedure related complications , the results could be biased . the patients in our series were not representative of the whole population of elderly patients with asymptomatic uias because untreated or surgically treated patients were not included in this study . there may have been case selection of patients who had favorable anatomical characteristics of uias for endovascular procedures , good neurological status , and good daily activity . therefore , decisions regarding treatment indications may have had an inclusion bias . we could not collect or analyze data of asymptomatic uias of elderly patients surgically or conservatively treated during the study period for various reasons . further systematic prospective studies with a more rigorous technical and follow - up strategy are warranted to help physicians when determining an appropriate decision in the management of asymptomatic uias in elderly patients .
background and purposewe report the results of endosaccular coil embolization of asymptomatic unruptured intracranial aneurysms ( uias ) in elderly patients ( 65  years).materialsthere were 375 elderly patients with 400 asymptomatic uias . 
 patients were divided into two groups : group a included patients aged 6574 years and group b patients aged 75 
 years.resultsendovascular procedures were completed in 97.8% of patients . 
 immediate anatomical outcomes showed complete occlusion in 53.7% , residual neck in 18.9% , and residual aneurysm in 27.4% . 
 anatomical follow - ups ( mean 36.328.1  months ) were unchanged in 55.7% , improved in 22.6% , minor recurrence in 11.5% , and major recurrence in 10.2% . 
 procedure related complications occurred in 31 patients ( 8.3% ) . 
 15 patients had ischemic and 10 hemorrhagic complications . 
 retreatments were performed in 16 patients ( 4.3% ) . among 
 366 patients technically completed , 363 ( 99.2% ) showed a favorable clinical outcome ( modified rankin scale ( mrs ) score < 1 ) at 30  days . 
 the remaining three patients showed a worsening of mrs > 0 at 30  days . 
 the latest clinical follow - up outcomes showed : mrs score 0 in 362 patients ; mrs score 1 in one ; mrs score 3 in one ; mrs score 4 in one ; and mrs score 5 in one patient . 
 permanent morbidity and mortality rates were 1.1% and 0% , respectively . 
 there were no statistically significant differences in gender , comorbidities , aneurysm size , neck width , dome - to - neck ratio , immediate anatomical outcomes , anatomical follow - up outcomes , or procedure related complications between the groups.conclusionsendosaccular coil embolization is safe and feasible for elderly patients with asymptomatic uias . 
 old age itself should not be a contraindication .