Microneurosurgical management of internal carotid artery bifurcation aneurysms

Endovascular treatment of intracranial internal carotid artery bifurcation region aneurysms

Intracranial internal carotid artery (ICA) bifurcation region aneurysms are uncommon. When treatment is necessary for ICA, endovascular treatment (EVT) can be a useful option. Due to the complexity of these aneurysms and the variability of EVT techniques, EVT for ICA bifurcation aneurysms is challenging. Currently, it is necessary to perform a review to explore this issue further. In this review, the following issues were discussed: the anatomy of the ICA bifurcation region; the classification, natural history and EVT status of ICA bifurcation region aneurysms; the technique used for identifying ICA bifurcation region aneurysms; and the prognosis and complications of EVT for ICA bifurcation region aneurysms. According to the review and our experience, traditional coiling is currently the preferred therapy for ICA bifurcation region aneurysms. In addition, in select cases, new devices, such as flow diverters and Woven EndoBridge devices, can also be used to treat ICA bifurcation region aneurysms. Generally, EVT is an alternative treatment option for ICA bifurcation region aneurysms.

Fluid-structure interaction simulation of tissue degradation and its effects on intra-aneurysm hemodynamics

Tissue degradation plays a crucial role in vascular diseases such as atherosclerosis and aneurysms. Computational modeling of vascular hemodynamics incorporating both arterial wall mechanics and tissue degradation has been a challenging task. In this study, we propose a novel finite element method-based approach to model the microscopic degradation of arterial walls and its interaction with blood flow. The model is applied to study the combined effects of pulsatile flow and tissue degradation on the deformation and intra-aneurysm hemodynamics. Our computational analysis reveals that tissue degradation leads to a weakening of the aneurysmal wall, which manifests itself in a larger deformation and a smaller von Mises stress. Moreover, simulation results for different heart rates, blood pressures and aneurysm geometries indicate consistently that, upon tissue degradation, wall shear stress increases near the flow-impingement region and decreases away from it. These findings are discussed in the context of recent reports regarding the role of both high and low wall shear stress for the progression and rupture of aneurysms.

Flow-Diversion Treatment for Unruptured ICA Bifurcation Aneurysms with Unfavorable Morphology for Coiling

BACKGROUND AND PURPOSE

Few reports described flow diversion for ICA bifurcation aneurysms. Our aim was to provide further insight into flow diversion for ICA bifurcation aneurysms difficult to treat with other strategies.

MATERIALS AND METHODS

Consecutive patients receiving flow diverters for unruptured ICA bifurcation aneurysms were collected. Aneurysm occlusion (O'Kelly-Marotta grading scale) and clinical outcomes were evaluated.

RESULTS

Twenty saccular ICA bifurcation aneurysms were treated with the Pipeline Embolization Device deployed from the M1 to the ICA, covering the aneurysm and the A1 segment. All patients presented with an angiographic visualized contralateral flow from the anterior communicating artery. Mean aneurysm size was 6.5 (SD, 3.2) mm (range, 4.5-20 mm). All lesions had an unfavorable dome-to-neck ratio (mean/median, 1.6/1.6; range, 0.8-2.8; interquartile range = 0.5) or aspect ratio for coiling (mean/median = 1.5/1.55; range, 0.8-2.5; interquartile range = 0.6). One was a very large aneurysm (20 mm). Nineteen medium-sized lesions were completely occluded during the angiographic follow-up (13 months). No cases of aneurysm rupture or retreatment were reported. No adverse events were described. Aneurysm occlusion was associated with the asymptomatic flow modification of the covered A1 that was occluded and contralaterally filled among 10 patients (50%), narrowed among 9 patients (45%), and unchanged in 1 subject (5%). There was no difference in the mean initial diameter of the occluded (2.1 [SD 0.4] mm; range, 1.6-3 mm) and narrowed (2 [SD, 0.2] mm; range, 1.7-2.6 mm) A1 segments.

CONCLUSIONS

Medium-sized unruptured ICA bifurcation aneurysms with unfavorable morphology for coiling can be treated with M1 ICA flow diversion. Aneurysm occlusion is associated with flow modifications of the covered A1 that seems safe in the presence of a favorable collateral anatomy through the anterior communicating artery complex.

Anterior perforated substance region aneurysms: review of a series treated with microsurgical technique

Aneurysms arising from the distal carotid, proximal A1, and proximal M1 that project posteriorly and superiorly toward the anterior perforated substance (APS) are rare. Their open surgical treatment is particularly difficult due to poorly visualized origin of the aneurysm and the abundance of surrounding perforators. We sought to analyze the anatomical and clinical characteristics of APS aneurysms and discuss surgical nuances that can optimize visualization, complete neck clip obliteration, and preservation of adjacent perforators. Thirty-two patients with 36 APS aneurysms were surgically treated between November 2000 and September 2017. Patients were prospectively enrolled in a cerebral aneurysm database and their clinical, imaging, and surgical records were retrospectively reviewed. Twenty-seven aneurysms originated from the distal ICA, 7 from the proximal A1, and 2 from the proximal M1; 15 patients presented with subarachnoid hemorrhage. Careful intraoperative dissection revealed 4 aneurysms originating at the takeoff of a perforator; another 25 had at least 1 adherent perforator. All aneurysms were clipped except for one that was trapped. Postoperatively, 3 patients had radiographic infarctions in perforator territory with only 1 developing delayed clinical hemiparesis. Good outcome (modified Rankin Scale, 0-2) was achieved in 28 patients (88%). APS aneurysms present a challenging subset of aneurysms due to their complex anatomical relationship with surrounding perforators. These should be identified on preoperative imaging based on location and projection. Successful microsurgical clipping relies on optimization of the surgical view, meticulous clip reconstruction, preservation of all perforators, and electrophysiological monitoring to minimize ischemic complication.

Aneurysms of the communicating segment of the internal carotid artery with posterior communicating artery agenesis are associated with perforator infarction after embolization

BACKGROUND

While anatomic features associated with the risk of posterior communicating artery (PcoA) occlusion after embolization of aneurysms of the PcoA segment of the internal carotid artery (ICA) are well known, the link between perforator origin and perforator infarction has only been reported following neurosurgical clipping. The aim of this study was to determine the origin of anterior thalamic perforators and correlate it with risk of perforator infarction after embolization of PcoA segment aneurysms.

METHODS

One-hundred-and-ninety consecutive patients treated for PcoA segment aneurysms between 2017 and 2019 were included. PcoA and anterior thalamic perforator origin anatomy was assessed with computed tomography (CT) angiography, digital subtracted angiography, and high-resolution three-dimensional rotational cone-beam CT angiography (CBCT-A) by two independent interventional neuroradiologists. The presence of perforator infarction after embolization was ascertained from the patient's notes and follow-up imaging.

RESULTS

CBCT-A was superior in demonstrating the origin of perforators (P<0.001). The prevalence of perforator origin was estimated at 86% (95% CI 81%-92%) for PcoA, 8% (95% CI 4%-13%) for aneurysm wall, and 5% (95% CI 2%-9%) for ICA. The aneurysm wall origin was exclusively associated with PcoA agenesis, as well as higher risk of perforator infarction after aneurysm coiling compared with other variants (OR=14, 95% CI 2-88, P=0.006).

CONCLUSIONS

Our study suggests that anterior thalamic perforators may arise from aneurysm wall when there is no PcoA. Anatomic association between PcoA agenesis and perforator arising from ICA could underlie such findings, and careful consideration is essential before aneurysm repair to anticipate the risk of thalamic infarction in such cases.

Trapping, dome puncture, and direct suction decompression in conjunction with assistant superficial temporal artery- middle cerebral artery bypass to clip giant internal carotid artery bifurcation aneurysm

Background:

Very large and giant aneurysms (≥20 mm) of the internal carotid artery (ICA) bifurcation (ICAbif) are definitely rare, and optimal treatment is not established. Endovascular treatments are reported as suboptimal due to difficulties of complete occlusion and tendencies to recanalization. Therefore, direct surgery remains an effective strategy if the clipping can be performed safely and reliably, although very difficult.

Case Description:

Two cases of ICAbif aneurysms (>20 mm) were treated. Prior assistant superficial temporal artery (STA)-middle cerebral artery (MCA) bypass was performed to avoid ischemic complications during prolonged temporary occlusion of the arteries in both cases. In Case 1 (22-mm aneurysm), the dome was inadvertently torn in applying the clip because trapping had resulted in insufficient decompression. Therefore, in Case 2 (28-mm aneurysm), almost complete trapping of the aneurysm and subsequent dome puncture was performed, and the aneurysm was totally deflated by suction from the incision. This complete aneurysm decompression allowed safe dissection and successful clipping.

Conclusion:

Trapping, deliberate aneurysm dome puncture, and suction decompression from the incision in conjunction with assistant STA-MCA bypass can achieve complete aneurysm deflation, and these techniques enable safe dissection of the aneurysm and direct clipping of the aneurysm neck. Direct clipping with this technique for very large and giant ICAbif aneurysms may be the optimal treatment choice with the acceptable outcome if endovascular treatment remains suboptimal.

Potential Risks and Limited Indications of the Supraorbital Keyhole Approach for Clipping Internal Carotid Artery Aneurysms

Background

Internal carotid artery (ICA) aneurysm may be a good target for supraorbital keyhole clipping. We discuss the surgical indications and risks of keyhole clipping for ICA aneurysms based on long-term clinical and radiologic results.

Methods

This was a retrospective analysis of 51 patients (aged 35–75 years, mean 62 years) with ICA aneurysms (mean 5.8 ± 1.8 mm) who underwent clipping via the supraorbital keyhole approach between 2005 and 2017. Neurologic and cognitive functions were examined by several methods, including the modified Rankin Scale and Mini-Mental Status Examination. The state of clipping was assessed 1 year and then every few years after the operation.

Results

Complete clipping was confirmed in 45 patients (88.2%), dog-ear remnants behind the clip persisted in 4 patients, and wrapping was performed in 2 patients. Mean duration of postoperative hospitalization was 3.4 ± 6.9 days. The mean clinical follow-up period was 6.6 ± 3.2 years. The overall mortality was 0, and overall morbidity (modified Rankin Scale score ≥2 or Mini-Mental Status Examination <24) was 3.9%. Completely clipped aneurysms did not show any recurrence during the mean follow-up period of 6.3 ± 3.1 years, but the 2 (3.9%) aneurysms with neck remnants showed regrowth.

Conclusions

The risk of neck remnant behind the clip blade is a drawback of supraorbital keyhole clipping. The surgical indication requires preoperative simulation and careful checking of the clip blade state is essential.

Characteristics of Peri-Internal Carotid Artery Bifurcation Aneurysms According to a New Anatomic Classification: How to Overcome Difficulties in the Microsurgical Treatment of Posteroinferiorly Projecting Carotid-A1 Junctional Aneurysms

OBJECTIVE

Based on our clinical experience, posteroinferiorly projecting carotid-A1 junctional aneurysms are often difficult to treat microsurgically. Our objective was to classify peri-internal carotid artery (ICA) bifurcation aneurysms according to their location and analyze their characteristics.

METHODS

From January 2008 to October 2017, microsurgical or endovascular treatment of 6777 aneurysms were performed at our hospital. We identified 199 peri-ICA bifurcation aneurysms (2.94%) classified into true ICA bifurcation aneurysm, carotid-A1 junctional aneurysm, and carotid-M1 junctional aneurysm according to the anatomic location. Medical records including patient characteristics, aneurysm location, surgical method, any neurologic deficits, clinical outcomes, medical history, and radiologic findings were retrospectively reviewed. The anatomic position of the aneurysm was defined from the virtual surgical, anteroposterior, and lateral views, and the degree of agreement was calculated.

RESULTS

There were 103 true ICA bifurcation aneurysms, 92 carotid-A1 junctional aneurysms, and 4 carotid-M1 junctional aneurysms. Carotid-A1 junctional aneurysms tended to be smaller, elongated, and more often posteroinferiorly projecting than true ICA bifurcation aneurysms. Posteroinferiorly projecting carotid-A1 junctional aneurysms tended to require complex aneurysm surgery. The virtual surgical view had an almost perfect degree of agreement with the actual surgical view.

CONCLUSIONS

The characteristics of carotid-A1 junctional aneurysms and true ICA bifurcation aneurysms differ. In particular, carotid-A1 junctional aneurysms tend to have a posteroinferior projection and that causes difficulty in surgical treatment. We recommend the virtual surgical view for preoperative planning. Furthermore, an adequate Sylvian fissure opening and a strategic approach using appropriate devices to inspect blind spots should be considered for a successful treatment outcome.

Flow diversion covering the M1 origin as a last resort

Introduction

Internal carotid artery termination (ICAT) and proximal A1 aneurysms can be challenging for open surgical clipping or endovascular coiling. Treatment with flow diversion covering the middle cerebral artery (MCA), an end vessel supplying a terminal circulation, has not been reported.

Methods

A prospective, Institutional Review Board-approved database was analysed for patients with pipeline embolisation device (PED) placement from the anterior cerebral artery (ACA) to the ICA during cerebral aneurysm treatment.

Results

Nine cases were identified, including five proximal A1, three posterior communicating artery and one ICAT aneurysm locations. Average aneurysm size was 8.3 mm (range 3-17), with 67% saccular and 78% right-sided. Primary indication for treatment was significant dome irregularity (44%), recurrence or enlargement (33%), underlying collagen vascular disorder (11%) and traumatic pseudoaneurysm (11%). Preservation of the ipsilateral ACA (with PED placed in A1) was performed when the anterior communicating artery (67%) or contralateral A1 (33%) were absent on angiography. Adjunctive coiling was done in four cases (44%). There was one major stroke leading to mortality (11%) and one minor stroke (11%). Clinical follow-up was 27 months on average. Follow-up digital subtraction angiography (average interval 15 months) showed complete aneurysm obliteration (88%) or dome occlusion with entry remnant (12%). The jailed MCA showed minimal or mild delay (primarily anterograde flow) in 75% of cases and significant delay (reliance primarily on ACA and external carotid artery collaterals) in 25%.

Conclusions

Covering the MCA with a flow diverting stent should be reserved for select rare cases. Strict attention to blood pressure augmentation during the periprocedural period is necessary to minimise potential ischaemic compromise.

Pipeline embolization device treatment of internal carotid artery terminus aneurysms

Background

The pipeline embolization device (PED) is approved for the treatment of large aneurysms of the proximal internal carotid artery (ICA). Its off-label application in treating aneurysms located specifically at the ICA terminus (ICA-T) has not been studied.

Methods

We conducted a retrospective chart review of patients from 2011 to 7 treated with PEDs. Out of 365 patients, 10 patients with ICA-T aneurysms were included. Patient demographics, procedural information, follow-up imaging, and clinical assessments were recorded.

Results

Mean age was 46.9 years (± 8.8), and 6 (60%) patients were women. The mean maximum diameter of the aneurysms treated was 14.7 mm (± 10.7) and the mean neck diameter was 9.3 mm (± 6.6). Reasons for presentation included six incidental findings, one acute subarachnoid hemorrhage (SAH), and three patients with prior SAH. Kamran–Byrne Occlusion Scale scores for the treated aneurysms were as follows: three class IV (complete obliteration), four class III (<50% filling in both height and width for fusiform aneurysms or residual neck for saccular aneurysms), one class II fusiform aneurysm, 1 class 0 saccular aneurysm (residual aneurysm body), and one not classified due to pipeline thrombosis. Two clinically asymptomatic complications were noted: one patient who had a small distal cortical SAH post PED and one patient whose stent was found to be thrombosed on follow-up angiogram. All patients were seen in follow-up, and no patients were found to have worsening of their pre-procedure modified Rankin Scale score.

Conclusion

The PED has potential for treating ICA-T aneurysms not amenable to conventional treatment strategies. Further studies are warranted to confirm the long term outcomes.

Internal Carotid Artery Bifurcation Aneurysms: Microsurgical Strategies and Operative Nuances for Different Aneurysmal Directions

BACKGROUND

Internal carotid artery bifurcation aneurysms (ICAbifAs), comprising approximately 5% of intracranial aneurysms, are characterized clinically by their tendency to occur at a younger age and surgically by the technical difficulties posed by their domes being adherent to the frontal lobe, their location at the apex of the sylvian fissure, and their relation to myriad perforator complexes.

OBJECTIVE

To review the nuances of technique and operative strategy specific to aneurysmal direction in the light of our experience with ICAbifAs.

METHODS

ICAbifAs managed at our institute from January 2001 to July 2016 were analyzed. Detailed analysis of clinical data, pre- and postoperative radiology, operative notes and videos, and clinical outcome was done.

RESULTS

Fifty-one patients with ICAbifAs were treated in the study period out of which 40 patients underwent microsurgical clipping. The median age was 48 yr (range 14-68 yr). Nearly 95% of the patients presented in a good clinical grade (World Federation of Neurological Surgeons grade 1 and 2). At 6-mo follow-up, 36 patients (90%) had good clinical outcome (Glasgow Outcome Scale 4 and 5). According to their direction, ICAbifAs were grouped as anteriorly directed (10 cases), superiorly directed (23 cases), and posteriorly directed (7 cases). Operative techniques and nuances utilized depend on aneurysmal direction and are presented here.

CONCLUSION

An appropriate surgical strategy based on the direction of ICAbifAs as per the preoperative radiology, meticulous dissection of aneurysmal wall from adjacent perforators, and clip application with the aim of remodeling the ICA bifurcation are integral to achieving a good outcome.

The Clinical Importance of Perforator Preservation in Intracranial Aneurysm Surgery: An Overview with a Review of the Literature

Clipping for intracranial aneurysms is done to achieve complete occlusion of the aneurysm without a remnant sac. Despite modern advancements of neurosurgical techniques, morbidity related to the clipping of intracranial aneurysms still exists. Clip occlusion of a parent artery or small hidden perforators commonly leads to permanent neurological deficits, and is a serious and unwanted complication. Thus, preserving blood flow in the branches and perforators of a parent artery is very important for successful surgery without postoperative morbidity and mortality. The aim of this review article is to discuss the consequences of perforator injury and how to avoid this phenomenon in aneurysm surgeries using intraoperative monitoring devices.

Unruptured internal carotid artery bifurcation aneurysms: general features and overall results after modern treatment

BACKGROUND

Internal carotid artery bifurcation aneurysms (ICAbifAs) present unique challenges to endovascular and surgical operators, and little is known about their natural history. We reviewed our institution's experience with ICAbifAs studying outcomes of surgical and endovascular management and natural history.

METHODS

Consecutive patients with unruptured ICAbifAs evaluated and/or treated over an 8-year interval were studied. Baseline demographics, neurovascular risk factors, aneurysm location and size, clinical presentation, treatment recommendations, and outcomes were prospectively collected and retrospectively analyzed. Continuous variables were compared with Student's t test and categorical variables with Chi-square tests.

RESULTS

Fifty-nine patients with 61 unruptured ICAbifAs were included. Seven aneurysms were treated surgically (11.5 %), 22 underwent endovascular treatment (36 %), and 32 were managed conservatively (52.5 %). In the surgical group, short- and long-term complete aneurysm occlusion rates were 100 % with no cases of perioperative or long-term permanent morbidity or treatment-related mortality. In the endovascular group, two patients (11.7 %) with giant aneurysms had perioperative thromboembolic events with transient morbidity. There was one case of aneurysm rupture at follow-up in a giant aneurysm treated with partial coil embolization. Complete/near-complete occlusion rates were 63 %. There was one case of aneurysm rupture after 114 aneurysm-years of follow-up in the conservative management group (0.89 %/year), but no ruptures were observed in small aneurysms selected for conservative management.

CONCLUSIONS

Unruptured small ICAbifAs have a benign natural history. In patients selected for treatment, excellent results can be achieved in the vast majority of patients with judicious use of endovascular and surgical therapy.

Surgical flow modification of the anterior cerebral artery-anterior communicating artery complex in the management of giant aneurysms of internal carotid artery bifurcation: An alternative for a difficult clip reconstruction

BACKGROUND

Internal carotid artery bifurcation (ICAb) aneurysms account for about 2-15% of all intracranial aneurysms. In giant and complex cases, treatment may be difficult and dangerous, once some aneurysms have wide neck and anterior cerebral artery (ACA) and middle cerebral artery (MCA) may arise from the aneurysm itself. Clip reconstruction may be difficult in such cases. Whenever possible, the occlusion of ACA transform the bifurcation in a single artery reconstruction (ICA to MCA), much easier than a bifurcation reconstruction.

METHODS

In patients with giant and complex ICAb aneurysms, we propose routine preoperative angiography with anatomical evaluation of anterior communicating artery (ACoA) patency during cervical common carotid compression with concomitant contralateral carotid artery injection. This allowed visualization of the expected reversal of flow in the A1 segment-ACoA complex. When test is positive, we can perform ipsilateral ACA (A1 segment) clip occlusion and flow modification of the ACA-ACoA complex transforming a three vessel (ICA, ACA, and MCA) reconstruction into a two vessel (ICA and MCA) reconstruction.

RESULTS

Two patients were treated, with 100% of occlusion and good outcome.

CONCLUSIONS

Surgical treatment of giant and complex ICAb may be achieved with acceptable morbidity.

Endovascular and surgical treatment of internal carotid bifurcation aneurysms: comparison of results, outcome, and mid-term follow-up

BACKGROUND

Aneurysms of the internal carotid artery (ICA) bifurcation are rare, and no studies have compared patient outcomes after endovascular vs surgical treatment.

OBJECTIVE

To report the safety, efficacy, and follow-up outcome of these 2 treatment options for patients with ICA bifurcation aneurysms.

METHODS

Patient and aneurysm characteristics, treatment results, and follow-up outcomes (at 30 months) were analyzed from patient records and review of imaging findings.

RESULTS

A total of 58 patients with ICA bifurcation aneurysms were treated. By interdisciplinary consensus, 30 aneurysms were assigned for coiling and 28 for clipping. Patients who underwent surgical clipping were younger and had larger aneurysms. More patients were assigned to coiling if their aneurysms originated only from the ICA bifurcation or projected superiorly. For the combined angiographic endpoint, complete and nearly complete occlusion (Raymond-Roy I + II), similar rates of 96% (coiling) or 100% (clipping) could be achieved. Raymond-Roy I occlusion occurred more often after clipping (79% vs 41% coiling). Follow-up of the endovascular group showed minor recanalization of the aneurysm neck (Raymond-Roy II) in 42%. One patient (4%) showed a major recanalization (Raymond-Roy III) and needed re-treatment. For incidental findings, no bleeding complications or new persistent neurological deficits occurred during follow-up.

CONCLUSION

Treatment of ICA bifurcation aneurysms after interdisciplinary assignment to clipping or coiling is effective and safe. Despite significantly more minor recanalizations after coiling, the re-treatment rate was very low, and no bleeding was observed during follow-up. Multivariate analysis revealed that origin only from the ICA bifurcation was an independent predictor of aneurysm recanalization after endovascular treatment.

Different ophthalmic artery origins: Embryology and clinical significance

This retrospective study gives a summary of ophthalmic artery (OA) variations to serve as guidelines for surgical interventionists and trainees. Pubmed and Medline searches were conducted. The OA usually arises intradurally (superomedial, anteromedial, or rarely superolateral) from the internal carotid artery (ICA). Rare extradural origin (primitive dorsal OA) (PDOA) remnant and extremely rare interdural origin (primitive ventral OA) (PVOA) remnant are of significance when sectioning the dural ring. Rarely, a persistent PDOA with ICA origin, or a PDOA remnant with inferolateral trunk origin, enters the orbit via the superior orbital fissure (SOF) for sole or partial orbital supply. Extremely rare, the PDOA and PVOA persist and form double OAs that arise from the ICA and run via the SOF and optic foramen. Occasionally, the OA arises from the middle meningeal artery (MMA), when both the PDOA and VDOA regress and enter the orbit via the SOF. Sole orbital supply via the external carotid artery (ECA), i.e. meningo-ophthalmic artery and/or MMA branches, or dual OAs (ECA and ICA origins) may occur. Other rare OA origins include anterior or posterior communicating artery; anterior or middle cerebral artery; basilar artery; posterior inferior cerebellar artery; and the carotid bifurcation. Primitive arteries (persistent or remnant), and/or abnormal anastomoses play pivotal roles in manifestations of OA variations. Of clinical importance are orbital collateral routes and dangerous extracranial-intracranial anastomoses. Awareness of OA origins and collateral routes is imperative for transarterial embolizations or infusion chemotherapy in the ECA territory to prevent visual complications.

Endovascular treatment of internal carotid artery bifurcation aneurysms: a single-center experience and a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Endovascular coiling of internal carotid artery bifurcation aneurysms can be challenging due to unfavorable morphologic features. With improvements in endovascular techniques, several series have detailed the results and complications of endovascular treatment of aneurysms at this location. We performed a systematic review and meta-analysis of published series on the endovascular treatment of ICA bifurcation aneurysms, including a tertiary referral center experience.

MATERIALS AND METHODS

We performed a comprehensive literature search for reports on contemporary endovascular treatment of ICA bifurcation aneurysms from 2000 to 2013, and we reviewed our experience. We extracted information regarding periprocedural complications, procedure-related morbidity and mortality, immediate angiographic outcome, long-term clinical and angiographic outcome, and retreatment rate. Event rates were pooled across studies by using random-effects meta-analysis.

RESULTS

Including our series of 37 patients, 6 studies with 158 patients were analyzed. Approximately 60% of the aneurysms presented as unruptured; 88.0% (95% CI, 68.0%-96.0%) of aneurysms showed complete or near-complete occlusion at immediate postoperative angiography compared with 82.0% (95% CI, 73.0%-88.0%) at last follow-up. The procedure-related morbidity and mortality were 3.0% (95% CI, 1.0%-7.0%) and 3.0% (95% CI, 1.0%-8.0%), respectively. The retreatment rate was 14.0% (95% CI, 8.0%-25.0%). Good neurologic outcome was achieved in 93.0% (95% CI, 86.0%-97.0%) of patients.

CONCLUSIONS

Endovascular treatment of ICA bifurcation aneurysms is feasible and effective and is associated with high immediate angiographic occlusion rates. However, retreatment rates and procedure-related morbidity and mortality are non-negligible.

Anatomical configuration of the Sylvian fissure and its influence on outcome after pterional approach for microsurgical aneurysm clipping

Background:

The sylvian fissure (SF) is the anatomical pathway used in a pterional approach, which leads to most aneurysms. There are four different anatomical variants of the SF described. In the present retrospective study the four different categories of the SF were studied in order to evaluate any correlation of these variants to surgical outcome.

Methods:

Patients treated for intracranial aneurysms by a pterional transsylvian approach during 2003-2012 (N = 237) were included in the study. The SF category was determined by analysis of preoperative computed tomography (CT) scanning. Patients were grouped into unruptured intracranial aneurysms (UIA) and ruptured intracranial aneurysms with subarachnoid hemorrhage (SAH) according to the Hunt and Hess grades. Brain edema, vasospasms, ischemic lesion rate, and outcome were evaluated for possible correlation with SF anatomical variants.

Results:

Postsurgically brain edema formation correlated significantly with more complex anatomical variants of the SF in patients with UIAs and in patients with Hunt and Hess 1 and 2. Ischemia rate, vasospasms, or clinical outcome was not negatively affected though.

Conclusion:

The classification of the SF as proposed by Yasargil is more than a pure anatomical observation. In this retrospective study, we show that the anatomical variants of the SF can be associated to postoperative complications like formation of brain edema or ischemic lesions Preoperative knowledge of the SF anatomy and possibly consecutive adapted extend of the surgical approach can decrease procedure-related morbidity.

Perforator and secondary branch origin in relation to the neck of saccular, cerebral bifurcation aneurysms

OBJECTIVE

Perforator and secondary branch origin in relation to the neck of cerebral, saccular bifurcation aneurysms were analyzed. These two features were considered important for treatment.

METHODS

From a series of microsurgically clipped saccular cerebral aneurysms, 142 bifurcation aneurysms had detailed imaging studies and operative records that could be analyzed.

RESULTS

The incidence of perforator origin from the aneurysm neck was as follows: basilar, 1/15 (7%); internal carotid artery bifurcation, 4/23 (17%); main stem of the middle cerebral artery/secondary branch of the middle cerebral artery, 6/52 (12%); anterior communicating artery region, 5/46 (11%); and distal bifurcation vessels, 0/6 (0%). Aneurysms arising from the anterior communicating artery between the anterior cerebral arteries had a high incidence of perforator origin from the aneurysm neck. The location of secondary branch origin from the aneurysm neck varied depending on the aneurysm group.

CONCLUSION

Perforator origin from the aneurysm neck was infrequent. A subgroup of anterior communicating artery region aneurysms had a high incidence of perforator origin from the aneurysm neck. Although protection of these neck perforators will be difficult, their identification may be even more challenging. Secondary branch origin from the aneurysm neck varied depending on the aneurysm group. Advanced endovascular techniques are needed to obliterate aneurysms in which the secondary branch(es) arise from the aneurysm neck. If this is not possible, craniotomy and clip ligation will be required if complete aneurysm obliteration is the goal.

Lateral supraorbital approach vs pterional approach: an anatomic qualitative and quantitative evaluation

BACKGROUND

Several minimally invasive modifications of the standard pterional approach have been proposed recently. The lateral supraorbital approach is one of these modifications.

OBJECTIVE

To provide a qualitative and quantitative anatomic comparison of the surgical exposure and the operability afforded by the standard pterional approach and the lateral supraorbital approach.

METHODS

Eight pterional approaches and 8 lateral supraorbital approaches were used in 8 fresh human cadaver heads. One qualitative and 2 quantitative tools were used to assess the surgical exposure.

RESULTS

Qualitatively, the lateral supraorbital approach has the advantages of reduced trauma to the temporalis muscle and exposure that is comparable to that provided by the standard pterional approach to the sellar and suprasellar regions. This approach offers limited exposure of the interpeduncular fossa compared with the pterional one. Quantitatively, the pterional approach provides a greater surgical volume than the lateral supraorbital approach (32.90 mL vs 23.60 mL with P < .05). Also, the pterional approach provides a greater associated surgical operability than the lateral supraorbital approach (exposure score of 66 and 53, respectively). However, the lateral supraorbital approach offers an equivalent access to the anterior communicating artery complex, optic nerve, optic chiasm, and sellar area (the exposure scores were 19 for both approaches).

CONCLUSION

From an anatomic point of view, both approaches provide similar exposure to the sellar, suprasellar, and anterior communicating artery areas. The pterional approach provides better exposure of the retrosellar area. The ability to operate in the retrosellar area, as judged by our model, was higher with the pterional than with the lateral supraorbital approach.

Endovascular therapy of internal carotid artery bifurcation aneurysms

BACKGROUND

Internal carotid artery (ICA) bifurcation aneurysms are uncommon. Therefore, there have been only a few endovascular series on ICA bifurcation aneurysms published to date. The purpose of this study is to report the safety and efficacy of endovascular therapy for ICA bifurcation aneurysms.

METHODS

There were 25 ICA bifurcation aneurysms (unruptured n=23, ruptured n=2) in 25 patients in this study. There were 14 women, with a mean age of 60.9±10.1 years. All patients underwent endosaccular coil embolization.

RESULTS

Aneurysm size and neck size ranged from 2.5 to 10.0 mm (mean 5.4±1.5) and from 1.5 to 4.0 mm (mean 2.7±0.8), respectively. Regarding the clinical outcomes of the 23 patients with unruptured aneurysms, 22 patients had no change in their preprocedural modified Rankin Scale (mRS) score. The other patient died of ventilator associated aspiration pneumonia. Two patients with ruptured aneurysms each had scores of mRS 0. Overall morbidity and death rates were 0% and 4%, respectively. 15 aneurysms were treated with a simple technique. The 10 remaining aneurysms required adjunctive techniques: balloon assisted (n=9) and double catheter (n=1). The immediate anatomical outcomes were complete occlusion (n=19 (76.0%)), residual neck (n=4 (16.0%)) and residual aneurysm (n=2 (8.0%)). The overall follow-up of anatomical outcomes were unchanged (n=14 (63.7%)), improved (n=5 (22.7%)) and recurrence (n=3 (13.6%)). No patient suffered from aneurysmal subarachnoid hemorrhage after endovascular therapy. Thromboembolic events without clinical modification occurred in two patients.

CONCLUSIONS

Endovascular therapy of ICA bifurcation aneurysms is safe and effective, with a low risk of recanalization and re-treatment.

Lateral Supraorbital Approach Applied to Anterior Clinoidal Meningiomas: Experience With 73 Consecutive Patients

BACKGROUND:

Anterior clinoidal meningiomas (ACMs) are a subgroup of meningiomas accounting for less than 10% of supratentorial meningiomas.

OBJECTIVE:

To assess the reliability and safeness of the lateral supraorbital approach (LSO) to remove ACMs.

METHODS:

Between September 1997 and October 2009, a total of 73 ACM patients were operated on at the Department of Neurosurgery, Helsinki University Central Hospital, by the senior author (J.H.). We retrospectively analyzed the clinical data, radiological findings, surgical treatment, histology, and outcome of patients, and discuss the operative technique.

RESULTS:

Seventy-three patients were operated on by applying the LSO approach. Apparently complete removal was achieved in 57 patients (78%). Anterior clinoidectomy was performed in 21 cases. Preexisting visual deficit improved in 11 of 39 patients and worsened in 4; 3 had de novo visual deficit. At 3 months after discharge, 60 (82%) patients had a good recovery, 9 (12%) patients were moderately disabled, 1 presented with severe disability, and 3 (4%) patients died of surgery-related causes. Sixteen (22%) patients had residual tumors, 6 of which required reoperation. During the median follow-up of 36 months (range, 3–146), tumor recurred in 3 patients: 2 were followed-up and 1 was reoperated on.

CONCLUSION:

ACMs can be removed via the LSO approach with relatively low morbidity and mortality. Anterior clinoidectomy is required only in selected cases, and we prefer the intradural approach during the LSO approach. High-power coagulation should be avoided in proximity of the optic nerve.