Basilar Artery Bifurcation Aneurysm Research Articles

Acutely ruptured basilar artery bifurcation aneurysm, treated with simultaneous Cascade and Comaneci temporary-assisted coiling

Temporary stent-assisted coiling is an eligible approach for the treatment of acutely ruptured complex cerebral aneurysms. Improved material properties and industrial advances in braiding technology have led to the introduction...

Therapeutic strategy and effect of different approaches for microsurgical treatment of basilar artery bifurcation aneurysms

Objective To investigate the strategy and effect of microsurgical treatment of basilar artery bifurcation aneurysms with different surgical approaches. Methods We retrospectively reviewed the clinical data of 43 patients with basilar artery bifurcation aneurysms who underwent microsurgical clipping at Department of Neurosurgery, the Second Xiangya Hospital, Central South University from April 2011 to April 2018. Of all 43 cases, 32 cases had ruptured basilar aneurysms and 11 cases had unruptured basilar aneurysms. According to the different morphological and anatomical locations of aneurysms, 17 cases underwent infraorbital approach, 26 cases underwent transsyvian approach (including the transorbirozygomatic approach, the 'half-half’ approach which combined the subtemporal approach with pterion approach and the simple pterion approach) to conduct microsurgical clipping. Intraoperative monitoring was performed using the combination of multiple technologies. Clinical and imaging follow-up was conducted over 6 months post surgery. Results Of all 43 cases with basilar artery bifurcation aneurysms, 38 cases were completely clipped, 4 cases were partially clipped, and 1 case was wrapped. There were 2 cases (4.7%) of hemiplegia after operation, 1 case (2.3%) of coma, 14 cases (32.6%) of oculomotor nerve palsy and no death during perioperative period. Thirty-seven patients (86.4%) were followed up for 25.0±10.1 months (range: 6 months to 4 years). Among them, 35 patients underwent radiographic review without aneurysm residual and 1 patient with partial clipping was treated with second-stage interventional embolization. In 1 case with wrapped aneurysm, the significantly enlargement of aneurysm was not observed in the follow-up image. Of 14 cases with oculomotor nerve palsy after operations, 11 were followed up and 8 of them improved significantly afterwards. Glasgow′s outcome scale(GOS) showed that grade V was reported in 34, grade IV in 1 case, grade III in 1 case, grade II in 0 and grade I in 1 case who died from severe pulmonary infection at 42 days post operation. Conclusions The superior treatment of the basilar artery bifurcation aneurysm could be achieved through subtemporal and transsyvian approach. Preoperative evaluation of anatomical and morphological characteristics of aneurysm seems important for the choice of surgical approach. The application of various assistive techniques during surgery is an important part of ensuring the safety of surgery. Key words: Intracranial aneurysm; Basilar artery; Microsurgery; Treatment outcome

Association of Basilar Bifurcation Aneurysms With Age, Sex, and Bifurcation Geometry.

Basilar artery (BA) bifurcation aneurysms are common, but the correlation between BA bifurcation morphology and aneurysm formation remains to be established. Our purpose was to determine the association of BA bifurcation aneurysms with patient age, sex, bifurcation angle, and branch diameter. Three-dimensional angiographic data of 195 patients were used, including 59 patients with BA bifurcation aneurysms and 136 control subjects. The angles formed between left and right posterior cerebral arteries (φ1) and between posterior cerebral artery and BA (the smaller angle defined as φ2 and the larger one as φ3), arterial diameters, and BA bifurcation aneurysm geometric characters were examined. Women of 40 to 70 years of age are more vulnerable to BA bifurcation aneurysm formation than men. The φ1 bifurcation angle significantly increased (P<0.0001), whereas both φ2 and φ3 angles significantly decreased (P<0.0001 and P=0.09, respectively) with increase of patients' age. Statistically significant (P<0.0001 and P=0.0002, respectively) positive correlations were observed between BA bifurcation branch diameter and aneurysm size. The φ1 angle was significantly (P<0.0001) wider in patients harboring BA bifurcation aneurysms than the control, whereas φ2 and φ3 angles in aneurysm group were significantly smaller than those in the control group (P<0.0001). The BA bifurcation aneurysms were mostly deviated toward the smaller φ2 angle side between φ2 and φ3 angles and deviated toward the smaller-diameter daughter posterior cerebral artery branch. BA bifurcation aneurysms are significantly associated with patients' age, female sex, wider bifurcation angles, and smaller vascular diameter at the BA bifurcation.

One burr-hole craniotomy: Subtemporal approach in helsinki neurosurgery.

Background:In this video-abstract, we present the Helsinki Neurosurgery one burr-hole craniotomy standard subtemporal approach to the floor of the middle fossa and the interpeduncular space. This procedure facilitates access to the multiple structures; the basilar artery bifurcation, the superior cerebellar artery, or the P1-P2 segments of the posterior cerebral artery, and lesions located around the posterior clinoid process/less than 10 mm above it. Even though the specific location and size of the lesion may vary, this approach accesses all mentioned structures with very minimal variation.Case Description:The patient with a basilar artery bifurcation aneurysm is placed in park bench position. A spinal drain is inserted to release 50–100 ml of cerebrospinal fluid. Next, the skin incision starts in front of the tragus above the earlobe, crossing the zygomatic line. Inferior retraction for the craniotomy is provided by hooks and hemostatic Raney clips placed at the superior border of the skin flap. The zygomatic line represents the anatomical landmark of the floor of the middle fossa. A burr-hole is made at the most cranial border of the bone flap. After the detachment of the dura with long flexible blunt dissectors, a craniotomy is performed to expose the dura of the inferior temporal lobe. A few drill holes are made for tacking-up sutures. The dural opening is then performed based on the zygomatic line. Cutting and opening of the tentorium runs posterior to the tentorial insertion of the fourth nerve.Conclusion:The described one burr-hole craniotomy offers a more efficient subtemporal approach.Videolink:http://surgicalneurologyint.com/videogallery/subtemporal-approach-unedited/

Surgical treatment of unruptured distal basilar artery aneurysm: durability and risk factors for neurological worsening.

Distal basilar artery aneurysms (DBAs) consist of basilar apex and basilar artery-superior cerebellar artery bifurcation (BA-SCA) aneurysms. The authors aimed to investigate clinical and radiological differences between two locations and to evaluate the 12-month surgical outcome in unruptured DBAs. Fifty-six consecutive patients who underwent surgical treatment (37 basilar apex and 19 BA-SCA aneurysms) between April 2012 and February 2016 were retrospectively evaluated. In patients with a preoperative modified Rankin Scale score (mRS) of more than 1, neurological worsening (NW) was defined as an increase in one or more mRS. In patients without symptoms, NW was defined as mRS ≥2. The mean age of the patient population was 64±9.6years, and 48 (86%) were female. Mean follow-up period was 2.6 ± 0.94years. An excellent (mRS 0 to 1) outcome was archived in 31 (55%), 45 (82%), and 48 (87%) patients at 30 days, 6 months, and 12 months, respectively. Clinical and radiological characteristics showed no differences between two locations. One early death (1.8%) and one severe morbidity (1.8%) due to rupture were observed. The postoperative annual rupture rate was 1.4% overall (145 patient-years). After adjustment for age and location, large or giant DBA was related to 30-day and 12-month NW [n=22 (39%) and n=6 (11%); p=0.009 and 0.002, respectively], aneurysm localization in the interpeduncular cistern (LIC) and perforator territory infarction were related to 30-day NW (p=0.002 and 0.002), and DBA that needed bypass surgery and previously treated recurrent DBA were related to NW at 12 months (p=0.017 and 0.001). Multivariate analysis showed that LIC was significantly related to perforator territory infarction (p=0.003). Clinical and radiological characteristics were not different between basilar apex and BA-SCA aneurysms; therefore, they should not be discussed separately. To avoid neurological worsening, results of surgical treatment for unruptured DBAs should be improved.

English

This study investigates the change of endothelial cell morphology and function at the rabbit basilar bifurcations in response to sustained high blood flow after bilateral common carotid artery ligation. Fifteen adult female New Zealand white rabbits were divided into experimental and sham control groups. The experimental group was subjected to bilateral common carotid artery ligation to increase the compensatory basilar artery flow. Basilar artery flow was monitored by transcranial Doppler after surgery. The endothelial cells at the arterial bifurcations were studied morphologically by electron microscopy and immunohistochemistry using β-catenin antibodies. Basilar artery flow increased significantly following common carotid artery ligation. Early-stage basilar artery bifurcation aneurysms were present in all rabbits at three months after ligation. The endothelial cells changed from a fusiform to column shape at the basilar artery bifurcation. Gaps between endothelial cells of the experimental group appeared wider in the electron microscopic photographs compared with those of the control group. The expression of endothelial β-catenin at the arterial bifurcations also decreased. This study is the first to present endothelial cell changes of basilar artery bifurcation in response to sustained high blood flow in rabbits. Endothelial cell impairment possibly initiates aneurysm formation.

Stent-assisted coiling strategies for the treatment of wide-necked basilar artery bifurcation aneurysms

Stent-assisted coiling is now the preferred treatment option for wide-necked basilar artery bifurcation aneurysms (BABA). However, the optimal choice of specific treatment strategies is still not well documented. In this paper, based on the “two-neck” theory of BABA, we classified the stent-assisted coiling treatment of BABA into three types: unilateral stent-assisted coiling, unilateral stent plus contralateral microcatheter or microwire-assisted coiling, and bilateral stent-assisted coiling. We assessed the feasibility and effectiveness of different stent-assisted coiling strategies for the treatment of BABA. Twenty-three BABA patients treated with stent-assisted coiling between May 2003 and September 2012 were included. Of the 23 aneurysms, 16 were treated with unilateral stent-assisted coiling, two were treated with unilateral stent and microcatheter or microwire-assisted coiling, and five were treated with bilateral stent-assisted coiling. All 23 BABA were successfully embolized, with a technical success rate of 100%. According to the Raymond classification, the immediate procedural outcome was grade I in nine patients, grade II (neck residue) in four patients and grade III (body filling) in 10 patients. The rate of procedure-related complications was 4.3% (1/23), where intra-operative hemorrhage occurred during coiling due to rupture of the aneurysm. Of the 23 patients, 16 (69.6%) had angiographic follow-up. The mean follow-up duration was 13.5months (range 1–46months). Angiographic follow-up showed complete occlusion in 10 patients (62.5%), improvement in two patients (12.5%), stability in three patients (18.7%), and recanalization in one patient (6.25%). The various stent-assisted coiling strategies available at present are feasible and effective for the treatment of wide-necked BABA.

P-001 Outcome of the patients with ruptured basilar artery bifurcation aneurysm who underwent endovascular approach in acute phase—a single center experience

BackgroundDue to the presence of a high morbidity and mortality associated with surgical clipping, most of patients with basilar artery bifurcation (BA) aneurysm are offered endovascular therapy. Objective of our...

Abstract 22: Outcome Of Patients With Basilar Artery Bifurcation Aneurysm Who Underwent With Endovascular Approach

Background: Due to a high surgical risk, endovascular repair of the basilar artery (BA) aneurysm is considered the primary option for most of the cases. However, procedure related complications, clinical outcome and rate of recurrence in BA bifurcation aneurysms are not specifically addressed. Objectives: is to describe the incidence of endovascular procedure related complications, recurrence of aneurysm and long-term clinical outcome of BA aneurysm. Methods: Consecutive patients who underwent endovascular repair of BA bifurcation aneurysm were enrolled from 2007 to 2010. Patient’s demographics including the Hunt &amp; Hess (H&amp;H) grade, Fished scale, and size of aneurysm were collected. Complications including aneurysm rupture, intracranial hemorrhage or thromboembolic event were recorded. Additionally, 90-days outcome measurement was obtained using Glasgow Outcome Scale (GOS). Results: 36 patients with a mean age of 50 plus-minus 14 years required 48 successful procedures to treat 36 BA bifurcation aneurysms. Ruptured aneurysm was present in 20 cases (H&amp;H I in 6, II in 4, III in 4 and IV in 6). 30 patients (83%) had wide neck aneurysm, 25 (69%) of which required stent in order to secure the aneurysm. There was no intraoperative rupture of aneurysm or thromboembolic event. However, one patient developed diplopia with visual incoordination on day one and other developed diplopia due to a small pontine stroke while stopping clopidogrel on post operative day 30 of stent-assisted repair. Both patients recovered completely with no disability. Ten patients (28%) had recurrence of aneurysm and required subsequent procedure. In recurrent aneurysms, repeat procedures had no negative impact on the clinical outcome. One patient died (GOS 1) who initially presented with H&amp;H IV and never recovered. Good outcome was observed in 32 (89%) patients (GOS 5 in 31, GOS 4 in 1) including all unruptured cases and 3 of 5 ruptured BA aneurysm patients who presented with H&amp;H of IV. Poor outcome was observed in 3 (8%) patients (GOS 3 in 3, 2 of which presented with H&amp;H IV). Conclusion: Endovascular repair of the BA bifurcation aneurysms are associated with good clinical outcome despite requirement of multiple procedures to complete the treatment. However, the recurrence of aneurysm is very high. Therefore, a very close angiographic follow-up is necessary.

E-013 Comparison of initial results following dual aneurysm embolization with the new penumbra coil 400 and 10-size coils in a single patient treated by the same operator

PurposeThe recently available Penumbra Coil 400 has 400% the volume per unit length of a 10-size coil due to its 0.020″ primary diameter, double that of conventional 10-coils. The Penumbra...

Risk of Aneurysm Rupture at Intracranial Arterial Bifurcations

Background: Aneurysms on the posterior circulation, most commonly located at the basilar top, have a higher risk of rupture than aneurysms on the anterior circulation. If hemodynamic shear stress, which has its maximum impact at the distal carina of bifurcations, explains the higher rupture rate of basilar top aneurysms, aneurysms at the top of the carotid artery should have similar rupture rates given their geometrical similarities. Aim: Our purpose was to compare rupture risks of carotid and basilar artery bifurcation aneurysms. Methods: We included studies from Medline and Embase searches and compared proportions of ruptured and unruptured aneurysms at the basilar and carotid bifurcation with the assumption that carotid aneurysms are twice as prevalent based on the presence of 2 carotid and 1 basilar artery bifurcation on the circle of Willis. Results: Of all unruptured aneurysms, 8.3% were located on the basilar and 6.0% on the carotid bifurcation; 8.0% of all ruptured aneurysms were located on the basilar and 4.3% on the carotid bifurcation. Subsequently the ratios of carotid versus basilar aneurysms were 0.72 for unruptured and 0.55 for ruptured aneurysms, instead of the expected 2.0. Conclusions: Aneurysms are less frequently located on the carotid than on the basilar artery bifurcation. The proportion of ruptured carotid aneurysms is smaller than that of unruptured carotid aneurysms, suggesting a lower rupture risk for aneurysms at the carotid artery bifurcation. The anatomical geometry of the bifurcations and concomitant hemodynamic stress are considered an unlikely explanation for the higher risk of posterior circulation aneurysms.

Nuances and technique of the pretemporal transcavernous approach to treat low-lying basilar artery aneurysms

Basilar artery bifurcation aneurysms (BAAs) constitute a major surgical challenge, due to the depth of the target anatomy and narrowness of field, the close relationship with thalamoperforating arteries, and difficulty in obtaining proximal control. Moreover, to treat these aneurysms may be especially technically demanding when situated in a low-lying basilar apex configuration. The most used approaches to treat BAA are the subtemporal approach and the pterional approach. The advantages and disadvantages of these techniques are very well known. Variations of these approaches were created attempting to overcome the limitations imposed by the limited deep operative area. They have not been able to improve the working space in the depths of the interpeduncular and prepontine cisterns. The transcavernous approach was devised as a means of enlarging the area of exposure around the interpeduncular and prepontine cisterns. It involves the removal of the anterior clinoid process, cutting distal and proximal dural rings, opening the cavernous sinus, and drilling varied extension of dorsum sellae and clivus. The senior author (EdO) has used a pretemporal approach to deal with BAAs. The authors have added a transcavernous approach in a pretemporal perspective to treat low-lying, complex, or giant basilar artery aneurysms. In this paper, the authors detail its anatomical principles and technical nuances and present the clinical experience with using this technique.

Ｃｏｉｌ ｅｍｂｏｌｉｚａｔｉｏｎとｂａｓｉｌａｒ ａｒｔｅｒｙ ｏｃｃｌｕｓｉｏｎの併用にて治療したクリッピング術後１２年で症状が出現した再発血栓性脳底動脈先端部動脈瘤の１例

Partially thrombosed basilar artery bifurcation aneurysms that are not amenable to clip application are among the most challenging lesions. We report a case with a partially thrombosed basilar artery bifurcation aneurysm successfully treated by parent artery occlusion combined with endovascular embolization. The patient, who had undergone neck clipping 12 years before, presented with conscious disturbance, tetraparesis, dysphagia, dyarthria, and diplopia. Neuroimaging examinations such as CT scan, MRI and angiography revealed that a partially thrombosed basilar artery aneurysm compressed the brain stem severely. We performed rough packing of the aneurysm by GDC. After coil embolization, we surgically obliterated the basilar artery at the proximal portion of superior cerebellar artery. An MRI study demonstrated reduction of the mass volume of aneurysm and an angiography study did not show regrowth of the aneurysm over a 5-year follow-up period. The patient’s neurological deficits caused by the compression of the brain stem disappeared. We consider that basilar artery occlusion combined with coil embolization is a valid procedure for partially thrombosed basilar artery aneurysms.

Investigation of new flow modifying endovascular image-guided interventional (EIGI) techniques in patient-specific aneurysm phantoms (PSAPs) using optical imaging.

Effective minimally invasive treatment of cerebral bifurcation aneurysms is challenging due to the complex and remote vessel morphology. An evaluation of endovascular treatment in a phantom involving image-guided deployment of new asymmetric stents consisting of polyurethane patches placed to modify blood flow into the aneurysm is reported. The 3D lumen-geometry of a patient-specific basilar-artery bifurcation aneurysm was derived from a segmented computed-tomography dataset. This was used in a stereolithographic rapid-prototyping process to generate a mold which was then used to create any number of exact wax models. These models in turn were used in a lost-wax technique to create transparent elastomer patient-specific aneurysm phantoms (PSAP) for evaluating the effectiveness of asymmetric-stent deployment for flow modification. Flow was studied by recording real-time digitized video images of optical dye in the PSAP and its feeding vessel. For two asymmetric stent placements: through the basilar into the right-posterior communicating artery (RPCA) and through the basilar into the left-posterior communicating artery (LPCA), the greatest deviation of flow streamlines away from the aneurysm occurred for the RPCA stent deployment. Flow was also substantially affected by variations of inflow angle into the basilar artery, resulting in alternations in washout times as derived from time-density curves. Evaluation of flow in the PSAPs with real-time optical imaging can be used to determine new EIGI effectiveness and to validate computational-fluid-dynamic calculations for EIGI-treatment planning.

Angiographic and clinical results in 316 coil-treated basilar artery bifurcation aneurysms

The aim of this study was to analyze the effect of the endovascular treatment of basilar artery (BA) bifurcation aneurysms and to compare the results with those published by other neuroendovascular teams. The authors performed a retrospective analysis of 316 aneurysms of the BA bifurcation that had been treated using endovascular coil occlusion between November 6, 1992, and February 12, 2005. After the initial embolization procedure, a 90 to 100% occlusion rate was achieved in 86% of the aneurysms. No complication was evident in 80% of the lesions, although periprocedural aneurysm rupture (3.2%) and thromboembolic events (12.3%) were the most frequent complications. Clinical outcome according to the Glasgow Outcome Scale (GOS) was a score of 5 or 4 in 77%, 3 in 11%, 2 in 5%, and 1 in 7% of patients. Initial follow-up angiography studies were obtained in 56% of patients at a mean of 19 months posttreatment and demonstrated a 90 to 100% occlusion rate in 70%. No recurrence was seen on 65% of the aneurysms. Coil compaction was evident on 24% of the follow-up angiograms. A second treatment was performed on 48 aneurysms (15%) a mean of 27 months after the first therapeutic session and resulted in 90 to 100% occlusion in 83% of the lesions. Complications were encountered in 19% of the aneurysms. Rupture did not occur during any of the procedures. Clinical outcome was rated as GOS Score 5 or 4 in 83% of the patients and Grade 3 in 17%. During a cumulative clinical follow up of 821 years in 237 patients, 182 patients (81%) were independent (GOS Score 5 or 4), 33 (14%) were dependent (GOS Score 3), eight (3%) were in a vegetative state, and two (1%) had died. Clinical outcome was significantly worse after previous aneurysm rupture and following procedural complications. These results are within the range of published data for coil treatment of BA tip aneurysms and confirm both the safety and efficacy of this endovascular treatment method.

Endovascular therapy versus surgical clipping for basilar artery bifurcation aneurysm: retrospective analysis of 117 cases.

The purpose of this study was to retrospectively evaluate and compare the feasibility, indication and limitations of two treatment options, clipping and coil embolization, for basilar artery (BA) bifurcation aneurysms. During the last 13 years, 117 patients with 117 BA bifurcation aneurysms were treated exclusively with direct surgery until February 1997, and with either direct surgery or coil embolization therapy since March 1997. Of them, 76 (65%) aneurysms were treated with direct clipping and 41 (35%) were treated with Guglielmi detachable coils (GDCs) embolization. The 76 surgically clipped aneurysms were analyzed on the basis of the pre-operative angiograms as to whether coil embolization would be feasible or not if each case had been attempted. The 41 embolized aneurysms, on the other hand, were analyzed as to whether clipping surgery would be feasible or not if it had been attempted. In the total 117 aneurysms, complete coil obliteration was judged to be possible and simple in 61 (52%) aneurysms, possible with complex techniques (difficult) in 29 (25%) and impossible in 27 (23%). Whereas, complete obliteration with direct clipping was judged to be simple in 66 (57%) aneurysms, difficult in 38 (32%) and impossible in the remaining 13 (11%). Linear correlation as to the technical difficulty was found in 61 (52%) aneurysms, but 14 (12%) had marked discrepancy between the two methods. Of the 76 patients treated with clipping surgery, 17 (22%) were left with some post-operative neurological deficits, and in six out of the 17 aneurysms, embolization might have been simple. There were complications in two patients; one procedure-related and the other with late re-bleeding due to aneurysmal re-growth, in the embolization, group. Endovascular therapy is an effective alternative for treating BA bifurcation aneurysms, although a quarter of the cases cannot be obliterated completely. It is important to select a suitable treatment option in each case depending on the patient's condition and the angiographical features of each aneurysm as well as the characteristics of the two methods.

未破裂脳底動脈先端部動脈りゅうの治療 ５０例の検討

We retrospectively analyzed the results of our 16 years of experience in the treatment of unruptured upper basilar artery aneurysms by surgery or coil embolization. This analysis involved 32 basilar tip aneurysms and 18 basilar superior cerebellar artery bifurcation aneurysms in 19 men and 31 women who ranged in age from 26 to 75 years (mean 57.0 years). Thirty-three aneurysms (66%) were small, 13 (26%) were large, and 4 (8%) were giant. Surgery were performed by 4 selected neurosurgeons and coil embolization was performed by 2 selected endovascular interventionalists. Treatment consisted of aneurysm neck clipping in 24, aneurysm coating in 5, and coil embolization in 21 patients. Surgery was mainly performed by the transsylvian approach. Immediate anatomic outcomes demonstrated complete or near-complete occlusion in 16 aneurysms (76.2%). Five aneurysms (23.8%) could not be embolized because of anatomic difficulties. In small aneurysms, 24 of the 26 (91.3%) patients treated with surgery remained neurologically intact or unchanged from their initial clinical status. Procedure-related morbidity and mortality were 7.7% and 0%, respectively. In small aneurysms, 8 of the 9 (88.9%) patients treated with coil embolization remained neurologically intact or unchanged from their initial clinical status. Procedure-related morbidity and mortality were 11.1% and 0%, respectively. In large aneurysms, the postoperative courses were uneventful in all 3 (100%) patients treated with surgery. There was no procedure-related morbidity or mortality. Eight of the 10 (80%) patients with large aneurysms treated with surgery remained neurologically intact or unchanged from their initial clinical status. Procedure-related morbidity and mortality were 10% and 10%, respectively. There were 3 poor results (75%) in patients with giant aneurysms, including 1 death caused by premature rupture. One severe disability patient treated with coil embolization died of rebleeding. Four of the 21 patients treated with coil embolization required additional coils because of coil compaction. Operative results of surgically accessible small aneurysms were satisfactory when patients were treated by selected surgeons. Therapeutic results of coil embolization for small and medium-sized aneurysms were also satisfactory. Aneurysmal neck clipping is superior to coil embolization in therapeutic radicality. Poor results cannot justify the therapeutic indication in every case with asymptomatic unruptured giant BA aneurysms.

Surgical management of unruptured basilar artery bifurcation aneurysms

The basilar artery (BA) bifurcation is the most common site for aneurysms arising from the posterior circulation. Their inhospitable location, nested within the narrow confines of the interpeduncular fossa anterior to the brainstem, coupled with the rich network of adjacent critical thalamoperforating arteries irrigating the midbrain and thalamus, pose difficult anatomical obstacles for the surgeon. The age old adage that the only cure for intracranial aneurysms remains exclusion from circulation before rupture still holds true. Although management of unruptured aneurysms in general is still controversial, unruptured aneurysms of the BA bifurcation can be treated surgically with acceptable rates of morbidity. The clinician must gather and weigh all clinical, pathological, and radiological data when formulating recommendations for the individual patient. In the present report the authors describe their current technique for the surgical management of unruptured BA bifurcation aneurysms; this represents the culmination of the senior author's (N.K.) experience in the management of both ruptured and unruptured BA bifurcation aneurysms. A modified, right-sided subtemporal transtentorial approach has been adopted in all cases of isolated unruptured BA bifurcation aneurysms. Technical nuances are described.

Intentional body clipping of wide-necked basilar artery bifurcation aneurysms

Neck clipping or coil embolization cannot always achieve complete neck obstruction in wide-necked basilar artery (BA) bifurcation aneurysms. Clipping of the aneurysm body, leaving a small aneurysm rest, is one clipping method used for this kind of aneurysm to maintain the patency of the posterior cerebral arteries and perforating vessels. However, the long-term efficacy of intentional body clipping has not been well investigated. The authors reviewed their experience with intentional body clipping of wide-necked BA bifurcation aneurysms to determine suitable clipping techniques and the long-term efficacy of the procedure. Complete neck occlusion was abandoned and body clipping intentionally performed in 17 patients with BA bifurcation aneurysms; wrapping of the aneurysm rest was made in seven cases. There were 10 ruptured aneurysms (58.8%), and the size of the aneurysm was larger than 10 mm in 11 patients (64.7%). The width between the clip blades and the base of the aneurysm neck was 1 mm in 11 cases, 2 mm in four, and 3 mm in two. Favorable outcome (Glasgow Outcome Scale [GOS] Score 4 or 5) was obtained in 13 cases (76.5%) and unfavorable outcome (GOS Scores 1-3) in four cases (23.5%). Major causes of unfavorable outcome included injury to perforating arteries and major vessel occlusion following surgical manipulation, in addition to the primary damage caused by subarachnoid hemorrhage. Subarachnoid hemorrhage did not occur during a mean follow-up period of 7.4+/-5.6 years (range 0.7-18.1 years) after treatment. Intentional body clipping of wide-necked BA aneurysms proved to be effective to prevent subarachnoid hemorrhage, although injury to perforating arteries remains problematic. The choice of complete neck clipping or body clipping should be established early during the microsurgical procedure to reduce the risk of injury to perforating vessels.

Long-term outcome of 17 cases of large-giant posterior fossa aneurysm

Long-term outcome of 17 patients who harbored a large or giant aneurysm of posterior fossa was summarized. The anatomical distribution of aneurysms included eight cases of basilar artery (BA) bifurcation aneurysms, three cases of BA trunk aneurysms, and six cases of vertebral artery (VA) aneurysms. Eight patients received surgical or endovascular treatment for their lesion. The clinical outcome was good recovery in six, moderate disability in one, and vegetative state in one case, respectively. The other nine patients were followed conservatively. Four of them had fatal aneurysmal rupture, and another two patients suffered from aggravation of pre-existing symptoms related to their aneurysm. Only three patients remain intact. Comparison of the radiographic parameters between those who bled and those who did not bleed revealed that those with subsequent rupture had significantly higher rate of aneurysmal thrombus and had a trend for larger diameter of the aneurysm. Although more aggressive and multidisciplinary measure should be taken to these patients to improve their long-term outcome, our results showed the limitation of treatment for these patients in the present era at the same time. The patients with broad neck BA bifurcation aneurysm in which efferent vessels were incorporated into aneurysmal dome, and those with fusiform, giant BA trunk aneurysm with thrombus were the least amenable to treatment in our series.