vertebral artery dissecting aneurysms ( vadas ) frequently occur in the extradural portion of the vertebral artery ( va ) and commonly present with headache , neck pain or neurological deficits caused by ischemia.3)9 ) those aneurysms are an unusual but significant cause of non - traumatic subarachnoid hemorrhage ( sah ) , representing 3% of all intracranial aneurysm.5)6)13 ) because the risk of re - rupture is high in cases presenting with sah , urgent treatment is needed.2)7)9 ) however the treatment options for vadas are limited because of their angio - architecture . total occlusion of the parent artery has become a broadly established approach for treating vadas , but also it brings a probable risk of ischemic results in the posterior circulation territories when the va is abruptly occluded , mostly in patients who have a hypoplastic contralateral va.1)5)12 ) in this study , we report our experience with endovascular treatment of 15 patients presented with sah who had symptomatic vadas and establish a safe endovascular therapeutic strategy regard to the angio - architecture of vadas . this is a retrospective study of 22 consecutive patients with vadas presenting variable clinical features . fifteen patients among them showed specific symptoms in regard to sah and they were treated with endovascular strategies . a total of 7 males and 8 females were included in the study group , with ages ranging from 36 to 68 years ( mean age , 48.6 years ) . hunt hess scale was used to evaluate the patients at admission , and modified rankin score ( mrs ) was used to evaluate patients not only at admission ( initial mrs ) but also at 3 months after procedure ( post - procedure mrs ) . however , there were 2 patients who were expired or transferred out , so that the last mrs of those patients were included . diagnosis were confirmed using digital subtraction angiography ( dsa ) and magnetic resonance image ( mri ) , if one or both of the following qualifications were encountered : 1 ) the dissecting aneurysm was related to angio - architectures defined below and 2 ) mri confirmed a false lumen relating the parent artery and excluded luminal stenosis or fusiform transformation due to atherosclerosis . the main angio - architecture in this study were divided into the following 4 groups : " pearl and string sign " ( corresponding to a fusiform dilation associated with proximal or distal narrowing ; 9 dissections ) , " string sign " ( corresponding to an isolated irregular narrowing ; 1 dissection ) , " fusiform dilation " ( 3 dissections ) , and " saccular aneurysm " ( made by dissection with wide neck portion ; 2 dissections ) . the first was the dominancy of the va , and the second was the relation between the posterior inferior cerebellar artery ( pica ) and the dissecting aneurysm . of the 15 vadas , 5 cases were at the dominant va , and 7 cases were at the non - dominant va . the rest 3 cases showed co - dominant va . in the relation with the pica , 12 cases were distal to the pica and 3 cases were proximal to the pica . if the vada is located at the dominant va or proximal to the pica , additional balloon test occlusion ( bto ) was performed before selecting the treatment option . in considering those angio - architectures and results of bto , treatment technics were divided into the following 3 technics : va coil trapping , stent assisted coil embolization , and stent insertion alone . the summary of clinical characteristics of patients include initial mrs , angio - architectures , and results of bto are presented in table 1 . this is a retrospective study of 22 consecutive patients with vadas presenting variable clinical features . fifteen patients among them showed specific symptoms in regard to sah and they were treated with endovascular strategies . a total of 7 males and 8 females were included in the study group , with ages ranging from 36 to 68 years ( mean age , 48.6 years ) . hunt hess scale was used to evaluate the patients at admission , and modified rankin score ( mrs ) was used to evaluate patients not only at admission ( initial mrs ) but also at 3 months after procedure ( post - procedure mrs ) . however , there were 2 patients who were expired or transferred out , so that the last mrs of those patients were included . diagnosis were confirmed using digital subtraction angiography ( dsa ) and magnetic resonance image ( mri ) , if one or both of the following qualifications were encountered : 1 ) the dissecting aneurysm was related to angio - architectures defined below and 2 ) mri confirmed a false lumen relating the parent artery and excluded luminal stenosis or fusiform transformation due to atherosclerosis . the main angio - architecture in this study were divided into the following 4 groups : " pearl and string sign " ( corresponding to a fusiform dilation associated with proximal or distal narrowing ; 9 dissections ) , " string sign " ( corresponding to an isolated irregular narrowing ; 1 dissection ) , " fusiform dilation " ( 3 dissections ) , and " saccular aneurysm " ( made by dissection with wide neck portion ; 2 dissections ) . the first was the dominancy of the va , and the second was the relation between the posterior inferior cerebellar artery ( pica ) and the dissecting aneurysm . of the 15 vadas , 5 cases were at the dominant va , and 7 cases were at the non - dominant va . the rest 3 cases showed co - dominant va . in the relation with the pica , 12 cases were distal to the pica and 3 cases were proximal to the pica . if the vada is located at the dominant va or proximal to the pica , additional balloon test occlusion ( bto ) was performed before selecting the treatment option . in considering those angio - architectures and results of bto , treatment technics were divided into the following 3 technics : va coil trapping , stent assisted coil embolization , and stent insertion alone . the summary of clinical characteristics of patients include initial mrs , angio - architectures , and results of bto are presented in table 1 . in the 3 different treatment technics , 12 patients ( 80% ) were treated with va coil trapping ( fig . 1 ) , 2 patients ( 13% ) with stent assisted coil embolization ( fig . 2 ) , and 1 ( 6% ) patient with stent insertion alone ( fig . 3 ) . there were no procedure - related complications such as extravasation of dye , distal embolic events , or coil migration . in regard to the angio - architecture , 11 of 15 patients ( 73% ) showed the lesion was located at the non - dominant side or co - dominant side of the va and 9 lesions among them were located distal to the pica . va coil trapping was performed for those 9 cases , the angiographic result showed complete occlusion . for the rest of 2 patients whose lesion was located proximal to the pica , bto was followed and the flow of contralateral va was filling enough to the ipsilateral pica territory during the test , so that they also treated with va coil trapping and the angiographic result showed complete occlusion . the rest 4 patients ( 27% ) showed the lesion was at the dominant va and additional bto was followed . the result of 3 patients was negative and treatment options were divided as their angio - architectures ; va coil trapping for the lesion with " pearl and string sign " ( 1 patient ) , and stent - assisted coil embolization for the lesion with " saccular aneurysm " ( 2 patients ) . the result of bto for the rest of 1 patient was positive and the patient showed " fusiform dilation " in the dsa , stent insertion alone technic was followed and angiographic result was incomplete . thirteen patients ( 86.7% ) showed good clinical results in regard to post - procedure mrs . four patients ( 26.7% ) were evaluated as 0 point and the other 9 patients ( 60% ) were 1 point . the other 2 patients ( 13% ) were evaluated as 2 and 6 points respectively , the patient who expired 1 week after the endovascular treatment showed stuporous mentality at admission ; hunt hess scale = 4 , and initial mrs = 5 points . vada is a rare disease and the annual occurrence rate has been stated to be 1/100,000 cases in the usa11 ) . ruptured vada patients presented with severe sah usually show disastrous neurological results and a high occurrence rate of rebleeding.4)7)8 ) mizutani et al . retrospectively analyzed 42 patients with re - bleeding triggered by the ruptured vada and discovered that 40.5% of re - bleeding occurred within 24 hours and that 57.1% occurred one week following the initial hemorrhage,7 ) so that after the diagnosis is confirmed , the treatment for ruptured vada should be performed as soon as possible to prevent re - bleeding . all patients in our study were presented with sah and initially evaluated by hunt hess scale , 2 patients among them are score 3 and 4 respectively , and rest of 13 patients are score 1 or 2 . all the 15 patients were treated within 24 hours at the diagnosis , but the 2 patients with high hunt hess scale showed poor prognosis after the treatment . they were evaluated as 3 and 5 points for each of them at initial mrs , 2 and 6 points respectively at post - procedure mrs . endovascular treatments such as va coil trapping , coil embolization of the aneurysmal sac with or without stent insertion , and stent insertion alone become the treatment of choice because vadas do not have a real neck and conventional clipping does not manage the aneurysm successfully.10 ) the angio - architecture of the vertebrobasilar system is the most important factor to select proper method of the endovascular treatments . we selected stent - assisted coil embolization in " saccular aneurysm " cases because the lesion could be well - localized , and we could preserve the flow of parent artery with making complete occlusion of the lesion . however coil embolization alone technic was impossible because of the aneurysmal sac had wide neck and the coil frame was unstable , so additional stent insertion was inevitable to prevent loosening of the coils . we selected va coil trapping as a first treatment of choice for the rest " pearl and string sign " , " string sign " and " fusiform dilation " cases , because they could not be localized and we had to make complete occlusion both the lesion and the parent artery . in those cases , if the vada was located at the non - dominant side or co - dominant side of the va and distal to the pica , we selected va coil trapping as a treatment option without performing bto . however , if the lesion was located at the dominant side of va or proximal to the pica , bto should be performed before selecting the treatment option . if the result of bto was negative , va coil trapping could be still the first treatment of choice . six patients were performed bto in our study and 5 patients of them showed negative results . va coil trapping or stent - assisted coil embolization were performed as their angio - architecture . the other 1 patient showed positive result , and the angio - architecture of the patient was " fusiform dilation " . we could apply limited treatment methods including a stent insertion alone technic or a flow diverter , so stent insertion alone technic was applied in our study as an alternative treatment option because of the lesion should not be occluded . the angiographic result was incomplete , but the clinical result of the patient was tolerable . the limitations of our study are the small number of patients , the lack of comparative data for patients managed with surgical treatments , and the lack of long - term follow - up data . especially , there was no mandatory short or long - term follow - up image studies after endovascular treatments , we could only estimate post - procedure mrs of patients . in the future , a randomized , multicenter trial with long - term follow up studies will be necessary to evaluate the safety and clinical efficacy of endovascular treatments for vadas . endovascular treatments are safe and effective procedures for treating symptomatic vadas , and the patients managed with endovascular treatments showed favorable clinical outcomes . to reduce the risk of the complication of endovascular treatments , it is important to analyze angio - architectures of the lesion in dsa and select proper procedure among the endovascular treatments .
objectivevertebral artery dissecting aneurysms ( vadas ) are rare and many debates are present about treatment options . 
 we review types and efficacy of our endovascular treatments and establish a safe endovascular therapeutic strategy regard to the angio - architecture of vadas.materials and methodsbetween july 2008 and october 2015 , we treated 22 patients with symptomatic vadas . 
 fifteen patients presented with subarachnoid hemorrhage from the ruptured vadas , digital subtraction angiography and magnetic resonance image confirmed the diagnosis and endovascular treatments were followed as their angio-architecture.resultsclinical results were good in 13 patients ( 86.7% ) , and there were no technical problems during endovascular procedures . 
 the other 2 patients with poor prognosis showed severe neurological deficits at the initial evaluation . among the three different endovascular treatments 
 , there were no radiologic cure in one patient with stent insertion alone , but the patient had no significant clinical symptoms either.conclusionendovascular treatments are safe and effective treatment option for managing vadas and can be the first treatment of choice for most patients . to select proper endovascular treatment according to the angio - architecture of vadas can reduce the risk of the treatment .