Contralateral Approach to Bilateral Middle Cerebral Artery Aneurysms: Comparative Study, Angiographic Analysis, and Surgical Results

Comparative efficacy and safety of therapeutic strategies for mirror aneurysms: A systematic review and meta-analysis

Mirror aneurysms are rare and pose therapeutic challenges, with both endovascular and microsurgical options available. Single-stage and two-stage procedures are employed, but the optimal strategy remains unclear. This systematic review and meta-analysis evaluate the efficacy and safety of different therapeutic strategies for managing mirror aneurysms. The study adhered to PRISMA guidelines and comprehensively analyzed data from multiple databases, including Pubmed, Scopus, Embase, Web of Science, and the Cochrane Library, up to 30th September 2024. Statistical analysis utilized the Comprehensive Meta-analysis (CMA) software version 3.0. This systematic review encompasses 42 studies, with 11 studies undergoing meta-analysis. The meta-analysis included 629 participants. Both microsurgical clipping and endovascular interventions achieved high rates of complete occlusion (RROC 1) (ES = 0.896; 95% CI: 0.840 to 0.931; P < 0.001) with low to moderate heterogeneity (I2 = 46.46%). Favorable neurological outcomes (mRS ≤ 2) were significantly achieved among all patients (ES = 0.924; 95% CI: 0.891 to 0.948; P < 0.001) with low heterogeneity (I2 = 15.52%). Subgroup analysis revealed that microsurgical clipping demonstrated superior occlusion rates and more consistent neurological outcomes compared to endovascular treatment. Also, complications were reported in seven studies (n = 492) and included cerebral infarction, hydrocephalus, and vasospasm. As well, mortality and recurrence were rare. Both microsurgical clipping and endovascular interventions are effective and safe for treating mirror aneurysms, with clipping showing superior occlusion rates and consistent outcomes. Single-stage procedures and unilateral craniotomy are associated with better neurological outcomes when feasible.

Contralateral interoptic approach to paraclinoid aneurysms: a patient-selection algorithm based on anatomical investigation and clinical validation

OBJECTIVE

Aneurysms that arise on the medial surface of the paraclinoid segment of the internal carotid artery (ICA) are surgically challenging. The contralateral interoptic trajectory, which uses the space between the optic nerves, can partially expose the medial surface of the paraclinoid ICA. In this study, the authors quantitatively measure the area of the medial ICA accessible through the interoptic triangle and propose a potential patient-selection algorithm that is based on preoperative measurements on angiographic imaging.

METHODS

The contralateral interoptic trajectory was studied on 10 sides of 5 cadaveric heads, through which the medial paraclinoid ICA was identified. The falciform ligament medial to the contralateral optic canal was incised, the contralateral optic nerve was gently elevated, and the medial surface of the paraclinoid ICA was inspected via different viewing angles to obtain maximal exposure. The accessible area on the carotid artery was outlined. The distance from the distal dural ring (DDR) to the proximal and distal borders of this accessible area was measured. The superior and inferior borders were measured using the clockface method relative to a vertical line on the coronal plane. To validate these parameters, preoperative measurements and intraoperative findings were reviewed in 8 clinical cases.

RESULTS

In the sagittal plane, the mean (SD) distances from the DDR to the proximal and distal ends of the accessible area on the paraclinoid ICA were 2.5 (1.52) mm and 8.4 (2.32) mm, respectively. In the coronal plane, the mean (SD) angles of the superior and inferior ends of the accessible area relative to a vertical line were 21.7° (14.84°) and 130.9° (12.75°), respectively. Six (75%) of 8 clinical cases were consistent with the proposed patient-selection algorithm.

CONCLUSIONS

The contralateral interoptic approach is a feasible route to access aneurysms that arise from the medial paraclinoid ICA. An aneurysm can be safely clipped via the contralateral interoptic trajectory if 1) both proximal and distal borders of the aneurysm neck are 2.5-8.4 mm distal to the DDR, and 2) at least one border of the aneurysm neck on the coronal clockface is 21.7°-130.9° medial to the vertical line.

Multiples of multiple: Case series of mirror aneurysms and review of literature

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Incidentally detected unruptured mirror intracranial aneurysms are on the rise due to advanced imaging modalities.

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Further studies are required to elucidate theories of development, inheritance pattern and the need for screening of 1st-degree relatives with twin aneurysms.

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Treatment strategy for mirror aneurysms should be customised based on the location, size, morphology and clinical manifestations of each patient.

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Randomised control trials that compare [single/multistage] clipping and coiling of mirror aneurysms are necessary to decide the best intervention strategy.

Introduction

Mirror aneurysms are a rare subtype of multiple aneurysms, located in identical or adjacent arterial segment bilaterally. We report a case series of 3 such patients amongst whom one of them had 3 sets of mirror aneurysms and the other patient had 2 sets of mirror aneurysm on the same arterial segment which has not been reported till date.

Methods

A retrospective analysis of 3 patients with incidentally detected multiple mirror aneurysms, who were treated with microsurgical clipping and coiling, was conducted. A systematic search was performed using the PUBMED database and relevant articles were reviewed with particular attention to incidence, associated conditions, risk factors and management strategies. Written informed consent was obtained from all of the patients for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request. This research work has been reported in line with the PROCESS criteria (Agha et al., 2018).

Results

All the 3 patients were females with incidentally detected multiple mirror aneurysms. All the 3 patients were known Hypertensives. All the aneurysms were successfully clipped by a multistage, bilateral craniotomy except the one in the cavernous ICA, for which an endovascular procedure is planned. All of them had an uneventful postoperative course with the CT angiogram showing obliteration of all the clipped aneurysms except the one in the cavernous ICA.

Conclusions

Multiple mirror aneurysms represent a rare occurrence of a diverse pathology. Both these described types of cases have not been reported so far in the literature. The treatment strategy for mirror aneurysms should be determined individually based on the location, size, and morphology of the aneurysms, as well as, on the clinical manifestations of each patient.

Safety and Efficacy of Bilateral Flow Diversion for Treatment of Anterior Circulation Cerebral Aneurysms

BACKGROUND

Nearly 20% of individuals with an aneurysm will have multiple aneurysms-these individuals are at increased risk of subarachnoid hemorrhage. Treatment of bilateral aneurysms with flow diverters (FDs), or Pipeline embolization device, has not yet been established as an effective therapy. We evaluated the safety and efficacy of a 2-stage treatment of bilateral aneurysms with Pipeline embolization devices placed 6 months apart.

METHODS

We performed a retrospective review to analyze the clinical and angiographic outcomes of 16 individuals with bilateral aneurysms treated with 2-stage flow diversion at a tertiary referral center from January 2010 to July 2018.

RESULTS

Of the 16 patients with 33 aneurysms treated with bilateral flow diversion, 1 had 2 aneurysms treated with a single FD on the contralateral side. The aneurysms treated were ophthalmic, superior hypophyseal, posterior communicating, or cavernous segment aneurysms, with an average size of 6.5 mm. No major complications, such as in-stent stenosis, thromboembolic events, distal intraparenchymal hemorrhage, rerupture, stent migration, or neurological death, were recorded. All the patients had good functional outcomes. At the 24-month follow-up examination, 81% of aneurysms showed complete occlusion. No aneurysm required repeat treatment.

CONCLUSIONS

The results from the present study have demonstrated that 2-stage treatment of bilateral aneurysms with FDs is both safe and efficacious. The timing of contralateral FD stent placement is critical. We found that 6 months allows for adequate neurological recovery and stent endothelialization.

Intracranial Mirror Aneurysm: Epidemiology, Rupture Risk, New Imaging, Controversies, and Treatment Strategies

There are some controversies about the surgical treatment strategy of mirror aneurysms. Whether to choose 1-stage or 2-stage surgery, bilateral or unilateral craniotomy, or surgical or interventional treatment are the main points in dispute. In this review, the different surgery strategies faced by patients are discussed. Different surgical methods are adopted based on the patient's individual state and the location and size of the aneurysm. A new imaging method is introduced using 3D Slicer, which clearly recognizes the relationship among aneurysm, brain tissue, skull, and nerve. The 3D Slicer can help surgeons undertake adequate preoperative preparation. In addition, we also introduce some ruptured factors (e.g., age, gender, hypertension, morphologic, and hemodynamic) concerning mirror aneurysm. Systematic discussion of the controversies and methods in surgical treatment of mirror aneurysms may provide new perspectives in future research for the prevention and treatment of mirror aneurysms.

Contralateral Approach Based on a Preoperative 3-Dimensional Virtual Osteotomy Technique for Anterior Circulation Aneurysms

OBJECTIVE

Our objective was to review 15 consecutive patients with anterior circulation aneurysms managed through a contralateral approach. Individualized surgical simulation using three-dimensional (3D) imaging was adopted to enable safe performance of clipping surgery.

METHODS

Five patients had multiple intracranial aneurysms, and 10 patients had a single aneurysm on the contralateral side of the craniotomy. Preoperatively, the unique architecture of aneurysms was fully understood in their 3-dimensionality reconstructed by Mimics software. The location of the cranial bone window and the patient's head position was individually optimized using a preoperative simulation system.

RESULTS

In this cohort, 17 contralateral aneurysms showed no wall calcifications. Projections of the aneurysms were superomedial (3/17, 17.6%), medial (8/17, 47.1%), posterior (3/17, 17.6%), and superior (3/17, 17.6%). The visual similarity between the simulating scene and the operative view was excellent in 100% of the cases. Four patients were treated with a contralateral pterional approach, and the remaining 11 patients were treated with a contralateral supraorbital keyhole approach. All of them were well-clipped, except 1 blister-like aneurysm being wrapped. All 15 patients had good outcomes (mRS ≤ 3) after a mean 13 months follow-up. There were no recurrences after surgical treatment.

CONCLUSIONS

The contralateral approach for the selected anterior circulation aneurysms is feasible in experienced hands with acceptable morbidity. This approach should be the choice only under judicious case-to-case planning based on a preoperative 3D virtual osteotomy technique.

Contralateral Approach to Middle Cerebral Artery Aneurysms: An Anatomical-Clinical Analysis to Improve Patient Selection

BACKGROUND

A contralateral approach to aneurysm clipping in cases of bilateral middle cerebral artery (MCA) aneurysms reduces surgical time and cost. However, there is a lack of evidence for objective patient selection. In this study, we assessed the change in surgical freedom along the contralateral MCA to provide objective evidence for patient selection.

METHODS

Sixteen cadaveric specimens were studied. Through a pterional approach, the surgical freedom was calculated moving distally along the contralateral MCA in 5-mm increments. In addition, in a series of 19 MCA aneurysms clipped contralaterally by the senior author, the average length of the MCA from its origin to the aneurysm neck was measured on angiography.

RESULTS

In these patients treated via a contralateral approach, the average length of the MCA segment from its origin to the aneurysm neck was 12.4 mm. Starting at the MCA origin, surgical freedom decreased significantly between all adjacent target points except at 5-10 mm from the MCA origin.

CONCLUSIONS

After the proximal 5 mm, there is no significant decrease in surgical maneuverability within the proximal 10 mm of MCA when approached contralaterally. When compared to the average length of the MCA from its origin to the aneurysm neck in the clinical series, it can be concluded that the first 10 mm (average, 12.4 mm) of the contralateral MCA may be considered a surgical comfort zone for a contralateral approach. This criterion may be useful for patient selection for a contralateral approach in cases of multiple bilateral intracranial aneurysms.

Monolateral Pterional Keyhole Approaches to Bilateral Cerebral Aneurysms: Anatomy and Clinical Application

OBJECTIVE

To study the anatomy and clinical application of monolateral pterional keyhole approaches for treating bilateral cerebral aneurysms.

METHODS

Twelve formalin-fixed cadaveric heads underwent right pterional keyhole approaches for management of simulative contralateral aneurysms. The length of the contralateral middle cerebral artery (MCA), distal internal carotid artery (DICA), anterior cerebral artery, and ophthalmic segment of the internal carotid artery (OICA) was recorded. The operability of contralateral aneurysms was assessed using a modified numeric grading system. A total of 16 patients (12 patients with ruptured aneurysms) with bilateral cerebral aneurysms undergoing contralateral pterional keyhole approaches were included.

RESULTS

The contralateral A1 segment of the anterior cerebral artery, proximal A2 segment, M1 segment of the MCA, DICA, and OICA was exposed via pterional keyhole approaches. An additional 2 mm of the OICA was exposed after incision of the falciform dural fold was completed. Contralateral aneurysms of the M1 segment (posterior), M2 segment, MCA bifurcation (inferior), A2 segment (lateral), DICA (posterior and lateral), and OICA (superior, inferior, and lateral) could not be fully exposed to perform simulated surgical clipping (operability rate <75%). A total of 36 aneurysms underwent adequate surgical clipping via unilateral pterional keyhole approaches, whereas 1 aneurysm of the A3 segment did not.

CONCLUSIONS

Contralateral aneurysms of the M1 segment (anterior, superior, and inferior), MCA bifurcation (superior and lateral), A1 segment, A2 segment (anterior, posterior, and medial), internal carotid artery bifurcation, DICA (anterior and medial), and OICA (medial) were fully exposed from different angles and surgical maneuvers were performed via pterional keyhole approaches, including in patients presenting with subarachnoid hemorrhage.

Comparison of Unilateral and Bilateral Craniotomy for the Treatment of Bilateral Middle Cerebral Artery Aneurysms: Anatomic and Clinical Parameters and Surgical Outcomes

OBJECTIVE

To compare 2 craniotomy approaches (unilateral and bilateral) in terms of anatomic and clinical parameters and surgical outcomes.

METHODS

Between January 2011 and December 2014, 19 patients with bilateral unruptured middle cerebral artery (MCA) aneurysm were treated with unilateral craniotomy (group 1), and 10 patients were treated with bilateral mini-craniotomy (group 2). We compared demographic data, characteristics of aneurysms, radiologic and clinical parameters, postoperative complications, and surgical outcomes between the 2 groups.

RESULTS

No statistically significant differences in aneurysm characteristics were found between the 2 groups. Radiologic parameters did not have any influence on surgical outcomes or the incidence of postoperative complications. Group 1 had a higher incidence of olfactory dysfunction (11 of 19; 58%) and residual neck at the contralateral aneurysm (10 of 19; 53%), whereas no patients in group 2 had olfactory dysfunction or residual neck at the contralateral aneurysm. All patients in group 2 had good surgical outcomes (modified Rankin scale score 0). The length of hospital stay was similar in the 2 groups.

CONCLUSIONS

Bilateral mini-craniotomy for the treatment of bilateral MCA aneurysms was associated with better surgical outcomes and fewer complications. Bilateral mini-craniotomy does not require as much retraction of the frontal lobe to apply a clip completely at the contralateral aneurysm. Therefore, it represents a safe and effective therapeutic option for unruptured bilateral MCA aneurysms.

Microneurosurgical Management of Posterior Communicating Artery Aneurysm: A Contemporary Series from Helsinki

OBJECTIVE

The objectives of this study were to analyze microsurgical techniques and to determine correlations between microsurgical techniques and the radiographic findings in the microneurosurgical treatment of posterior communicating artery aneurysms (PCoAAs).

METHODS

We retrospectively analyzed radiographic findings and videos of surgeries in 64 patients with PCoAAs who underwent microsurgical clipping by the senior author from August 2010 to 2014.

RESULTS

From 64 aneurysms, 30 (47%) had acute subarachnoid hemorrhage (SAH) that necessitated lamina terminalis fenestration (odds ratio [OR], 67.67; P < 0.001) and Liliequist membrane fenestration (OR, 19.62; P < 0.001). The low-lying aneurysms significantly necessitated the coagulation of the dura covering the anterior clinoid process (ACP) (OR, 7.43; P = 0.003) or anterior clinoidectomy (OR, 91.0; P < 0.001). We preferred straight clips in 45 (83%) of 54 posterolateral projecting aneurysms (OR, 45.0; P < 0.001), but preferred curved clips for posteromedial projecting aneurysms (OR, 6.39; P = 0.008). The mean operative time from the brain retraction to the final clipping was 17 minutes and 43 seconds. Postoperative computed tomography angiography revealed complete occlusion of 60 (94%) aneurysms. Three (4.6%) patients with acute SAH suffered postoperative lacunar infarction.

CONCLUSIONS

For ruptured aneurysms, lamina terminalis and Liliequist membrane fenestration are useful for additional cerebrospinal fluid drainage. For low-lying aneurysms, coagulation of the dura covering the ACP or tailored anterior clinoidectomy might be necessary for exposing the proximal aneurysm neck. Type of clips depends on the direction of projection. The microsurgical clipping of the PCoAAs can achieve good immediate complete occlusion rate with low postoperative stroke rate.

Coexistence of intracranial epidermoid tumor and multiple cerebral aneurysms: A case report and literature review

RATIONALE

There were a few case reports concerning epidermoid tumor coexisted with multiple cerebral aneurysms. Here, we present one case of coexistence of intracranial epidermoid tumor and multiple cerebral aneurysms and performed a literature review.

PATIENT CONCERNS

A 42 years old male patient was admitted to our institution with complaints of headache and dizziness.

INTERVENTIONS

The radiological examinations showed a hypointense lesion in the right parasellar and petrous apex region and an ipsilateral saccular aneurysm originated from the M2-M3 junction of the right middle cerebral artery (MCA) and a saccular aneurysm of the clinoid segment of right internal carotid artery (ICA).

INTERVENTIONS

The patients underwent a right frontotemporal approach for removal of the epidermoid tumor and clipping of the MCA aneurysm in one stage. The aneurysm located at the clinoid segment of ICA was invisible and untreated during operation.

OUTCOMES

No postoperative complications were found in the patient. The patient's follow up after 5 years of surgical treatment was uneventful, and the untreated aneurysm remains stable.

LESSONS

The coexistence of intracranial epidermoid tumor and cerebral aneurysm is a rare event. The secondly inflammation in cerebral arterial wall may be responsible for the aneurysm formation. Surgical treatment of the intracranial epidermoid tumor and cerebral aneurysm repair may be an optimal scheme in one stage.

[Surgical treatment of «Mirror» aneurysms of the internal carotid artery]

BACKGROUND

A relatively high occurrence of "mirror" aneurysms of the anterior cerebral circulation in neurosurgical practice necessitates generalization of experience of using different surgical approaches. The choice of treatment is usually associated with the number of surgical stages.

MATERIAL AND METHODS

Forty nine patients (19 males and 30 females) with mirror aneurysms of the anterior circulation underwent one- and two-step surgery at the Novosibirsk Federal Center of Neurosurgery in 2013-2015. The total number of bilateral aneurysms was 51 couples (102 aneurysms). The patients' age ranged from 19 to 66 years (mean age, 47.1±11.6 years). Most of the patients (47) underwent elective surgery; 2 patients were operated on in acute subarachnoid hemorrhage.

RESULTS

Sixty nine microsurgical operations and 19 endovasal interventions were performed during the main step. Microsurgery alone was used in 34 cases; endovascular surgery alone was performed in 6 cases; a combination of the techniques was used in 9 cases. Ten patients underwent one-step surgery, and 39 patients underwent two-step surgery. The radicalness of surgery amounted to 94.1% for the microsurgical technique and 83.3% for the endovasal technique. The excellent and good functional outcome (modified Rankin scale, 0-2) was achieved in 46 (93.9%) patients, and the poor outcome (mRs, 3-5) was observed in 3 (6.1%) patients.

CONCLUSION

Generalization of the results indicates that one-stage surgery is more preferable in the treatment of mirror cerebral aneurysms. However, the two-stage approach remains important and, in the case of certain anatomical peculiarities, is the only possible treatment. A combination of microsurgical and endovascular techniques improves clinical outcomes in treatment of mirror aneurysms of the anterior part of the cerebral arterial circle.