Contralateral Approach to Internal Carotid Artery Ophthalmic Segment Aneurysms: Angiographic Analysis and Surgical Results for 30 Patients

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 Clipping of Multiple Intracranial Aneurysms

The reported incidence of multiple intracranial aneurysms (MIA) is approximately 7-35% of all intracranial aneurysms. The primary goal in the management of MIAs is to secure the ruptured aneurysm and to treat as many of the remaining lesions as possible without affecting the outcome of the patient. In recent era endovascular treatment is the preferred treatment of multiple bilateral intracranial aneurysms if all aneurysms are amenable to addressed in single stage. But most often all aneurysms were not possible to addressed due to complexity of different aneurysms, technical limitation and infrastructure. In such scenarios options left were two stage sequential craniotomy on either sides and clipping of bilateral aneurysms or unilateral craniotomy and clipping of bilateral MIA. Bilateral two stage surgery or two stage endovascular treatment caries risk of bleeding from one of the untreated aneurysms, morbidity due to two stage and increase the cost of treatment. In properly selected cases of unilateral craniotomy and clipping of bilateral MIA secure the all aneurysm in one stage and decreased morbidity and cost of treatment. When patient selection done meticulously, clipping of MIA including contralateral side aneurysms is feasible and safe.

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.

The extradural minipterional approach for the treatment of paraclinoid aneurysms: a cadaver stepwise dissection and clinical case series

Minipterional (MPT) craniotomy has recently been added to the neurosurgical armamentarium as a less invasive alternative to the pterional craniotomy for the treatment of parasellar lesions. However, its clinical applicability in the treatment of certain complex aneurysms, such as those arising in the paraclinoid region, remains unclear. To illustrate the microsurgical anatomy of a modified extradural MPT approach, which combines a classic MPT craniotomy with an extradural anterior clinoidectomy, and to demonstrate its clinical applicability in the treatment of complex paraclinoid aneurysms. A stepwise extradural MPT approach is illustrated in a cadaver study. Clinical outcome data from a series of 19 patients with 20 paraclinoid aneurysms treated surgically using the extradural MPT approach between 2016 and 2018 were retrospectively collected. In 95% of the cases, complete aneurysm occlusion was achieved. No aneurysm recurrences were seen during follow-up with a median length of 21 months. The outcome, according to the modified Rankin Scale, was 0 points in 12 patients (63%), 1 point in 6 patients (32%), and 2 points in 1 patient (5%). Four out of 6 patients (67%) with initial visual symptoms showed improvement following treatment, whereas in two (11%), vision became worse. The extradural MPT approach ensures a sufficiently large exposure of the paraclinoid region that is comparable with conventional approaches with the advantage of being minimally invasive. Our case series demonstrates the feasibility of this approach for the treatment of complex paraclinoid aneurysms.

Interoptic, Trans-lamina Terminalis, Opticocarotid Triangle, and Caroticosylvian Windows From Mini-Supraorbital, Frontomedial, and Pterional Perspectives: A Comparative Cadaver Study With Artificial Lesions

Introduction: The mini-supraorbital (MSO) and pterional (PT) approaches have been compared in a number of studies focusing on the treatment of aneurysms, craniopharyngiomas, and meningiomas. The goal of this study was to analyze the surgical exposure to different artificial lesions through interoptic (IO), trans-lamina terminalis (TLT), opticocarotid triangle (OCT), and caroticosylvian (CS) windows from the MSO, frontomedial (FM), and PT perspectives. Methods: The MSO, PT, and FM approaches were performed sequentially in two fixed cadaver heads. Three colored spheres were placed around the optic chiasm: (1) between the optic nerves; (2) between the optic nerve and the internal carotid artery; and (3) between the internal carotid artery and the oculomotor nerve. The surgical exposures to these structures by using the IO, TLT, OCT, and CS windows were compared. Results: (1) IO window: from the MSO and PT approaches, the total surgical exposure mainly allows visualization of contralateral lesions. The FM approach was superior for exploration of both sides of the area between the optic nerves. (2) TLT pathway: the MSO and PT approaches mainly expose the contralateral third ventricle wall. (3) OCT window: the PT approach allows exposure of a larger part of the sphere between the optic nerve and the internal carotid artery than the MSO approach. (4) CS window: the PT approach allows a better exposure of lateral structures such as the oculomotor nerve and of the medial prepontine area in comparison to the MSO approach. Conclusion: Simulation of the surgical situation with artificial lesions is a good model for comparing surgical perspectives and for analyzing feasibility of lesion exposure and resection.

Comprehensive Anatomic Assessment of Ipsilateral Pterional Versus Contralateral Subfrontal Approaches to the Internal Carotid Ophthalmic Segment: A Cadaveric Study and Three-Dimensional Simulation

OBJECTIVE

Medially pointing aneurysms of the ophthalmic segment of the internal carotid artery (oICA) represent a neurosurgical challenge. Conventional ipsilateral approaches require internal carotid artery and optic nerve (ON) mobilization as well as anterior clinoidectomy (AC), all associated with increased surgical risk. Contralateral approaches could provide a better exposure of the superomedial aspect of the oICA, ophthalmic artery, and superior hypophyseal artery, sparing AC and internal carotid artery or ON mobilization. However, the microsurgical anatomy of this approach has not been systematically studied. In the present work, we exhaustibly analyzed the anatomic and morphometric characteristics of contralateral approaches to the oICA and compared them with those from ipsilateral approaches.

METHODS

We assessed 36 ipsilateral and contralateral approaches to the oICAs in cadaveric specimens and live patients, using for the latter a three-dimensional virtual reality (VR) system.

RESULTS

Contralateral approaches spared sylvian fissure dissection and required only minimal frontal lobe retraction. The ipsilateral and contralateral oICA were found at a depth of 49.2 ± 1.8 mm (VR, 50.1 ± 2.92 mm) and 65.1 ± 1.5 mm (VR, 66.05 ± 3.364 mm) respectively. The exposure of the superomedial aspect of oICA was 7.25 ± 0.86 mm (VR: 6 ± 1 mm) contralaterally without ON mobilization and 2.44 ± 0.51 mm (VR, 2 ± 1 mm) ipsilaterally even after AC. Statistical analysis showed that, for nonprefixed chiasm, contralateral approaches achieved a significantly higher exposure of the ophthalmic artery, superior hypophyseal artery, and the superomedial aspect of the oICA with its perforating branches (all P < 0.01).

CONCLUSIONS

Contralateral approaches may enable successful exposure of the oICA and related vascular structures, reducing the need for AC or ON mobilization. Systematic clinical/surgical studies are needed to further determine the effectiveness and safety of the approach.

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.

A literature review concerning contralateral approaches to paraclinoid internal carotid artery aneurysms

Ipsilateral approaches remain the standard technique for clipping paraclinoid aneurysms. Surgeons must however be prepared to deal with bony and neural structures restricting accessibility. The application of a contralateral approach has been proposed claiming that some structures in the region can be better exposed from this side. Yet, only few case series have been published evaluating this approach, and there is a lack of systematic reviews assessing its specific advantages and disadvantages. We performed a structured literature search and identified 19 relevant publications summarizing 138 paraclinoid aneurysms operated via a contralateral approach. Patient's age ranged from 19 to 79 years. Aneurysm size mainly varied between 2 and 10 mm and only three articles reported larger aneurysms. Most aneurysms were located at the origin of the ophthalmic artery, followed by the superior hypophyseal artery and carotid cave. All aneurysm protruded from the medial aspect of the carotid artery. Interestingly, minimal or even no optic nerve mobilization was required during exposure from the contralateral side. Strategies to achieve proximal control of the carotid artery were balloon occlusion and clinoid segment or cervical carotid exposure. Successful aneurysm occlusion was achieved in 135 cases, while 3 ophthalmic aneurysms had to be wrapped only. Complications including visual deterioration, CSF fistula, wound infection, vasospasm, artery dissection, infarction, and anosmia occurred in a low percentage of cases. We conclude that a contralateral approach can be effective and should be considered for clipping carefully selected cases of unruptured aneurysms arising from medial aspects of the above listed vessels.

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.

Keyhole Approach for Clipping Intracranial Aneurysm: Comparison of Supraorbital and Pterional Keyhole Approach

OBJECTIVE

The aim of this research was to compare the functional outcome and safety between supraorbital keyhole approach (SKA) and pterional keyhole approach (PKA) for clipping intracranial aneurysms.

METHODS

This is a retrospective study involving 318 patients with a total of 365 aneurysms who underwent keyhole surgery, comprising 195 cases in SKA group and 123 cases in PKA group. The outcome measures include Glasgow Outcome Scale, complete clipping rate, adverse events incidence, operation view angle, working distance, and surgical incision condition.

RESULTS

Of a total of 356 aneurysms that were clipped and 9 trapped, no significant difference was observed in Glasgow Outcome Scale score, adverse events incidence, or complete clipping rate between the SKA and PKA groups. The distance from skin incision to anterior clinoid process was 5.87 ± 0.24 cm in SKA and 5.12 ± 0.27 cm in PKA. The operation view angle (from midline to the operating channel in sagittal plane) was 30°-40° in the SKA group and 60°-68° in the PKA group.

CONCLUSIONS

Our research demonstrates that both SKA and PKA are safe and effective for most anterior circulation aneurysms and parts of posterior circulation aneurysms. The SKA exposures aneurysm better on deep and sagittal directions and is more suitable for clipping aneurysms by the contralateral approach due to the short distance. The PKA has a good exposure on the neck of aneurysm with dorsal direction of parent artery and can be used to evacuate hematoma in the temporal lobe when clipping the aneurysm. Integrating multimodal 3-dimensional images could help neurosurgeon in selecting an appropriate and effective approach.

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.

[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.

Contralateral supraorbital keyhole approach to medial optic nerve lesions: an anatomoclinical study

OBJECTIVE The authors describe the supraorbital keyhole approach to the contralateral medial optic nerve and tract, both in a series of cadaveric dissections and in 2 patients. They also discuss the indications and contraindications for this procedure. METHODS In 3 cadaver heads, bilateral supraorbital keyhole minicraniotomies were performed to expose the ipsilateral and contralateral optic nerves. The extent of exposure of the medial optic nerve was assessed. In 2 patients, a contralateral supraorbital keyhole approach was used to remove pathology of the contralateral medial optic nerve and tract. RESULTS The supraorbital keyhole craniotomy provided better exposure of the contralateral superomedial nerve than it did of the same portion of the ipsilateral nerve. In both patients gross-total resections of the pathology was achieved. CONCLUSIONS The authors demonstrate the suitability of the contralateral supraorbital keyhole approach for lesions involving the superomedial optic nerve.

Clinical and Radiological Outcomes After Treatment of Unruptured Paraophthalmic Internal Carotid Artery Aneurysms: a Comparative and Pooled Analysis of Single-Center Experiences

OBJECTIVE

Unruptured paraophthalmic aneurysms present unique challenges, and the ideal management remains unknown.

METHODS

We performed a pooled analysis of single-center experiences to compare the risks and effectiveness involving patients with unruptured paraophthalmic aneurysms treated with clipping, coiling alone, stent-assisted coiling, and flow-diversion. The MEDLINE database was searched and thirty-three series (including our institutional experience) were included.

RESULTS

Clipping caused more intracranial hemorrhage (ICH) and neurologic complications (NCs) than coiling alone (ICH: odds ratio [OR] = 3.058, P = 0.013; NC: OR = 5.809, P < 0.001), stent-assisted coiling (ICH: P = 0.018; NC: OR = 7.367, P < 0.001), and flow-diversion (ICH: P = 0.006; NC: OR = 16.954, P < 0.001). Clipping also caused more unfavorable visual outcomes than both coiling alone (OR = 3.037, P = 0.001) and stent-assisted coiling (OR = 6.055, P = 0.005). Clipping resulted in a lower reoperation rate than coiling alone in large/giant aneurysm group, which approached statistical significance (OR = 0.133, P = 0.057). Clipping, stent-assisted coiling, and flow-diversion all showed higher occlusion rates compared with coiling alone (OR [clipping vs. coiling alone] = 2.852, P ≤ 0.001; OR [coiling alone vs. stent-assisted coiling] = 0.302, P = 0.003; OR [coiling alone vs. flow-diversion] = 0.400, P = 0.013). Flow-diversion showed comparative complication rate, clinical outcomes, and angiographic result compared with stent-assisted coiling. No significant differences were found among all 4 treatment modalities on mortality and poor outcome.

CONCLUSIONS

Endovascular therapies have benefits over surgical clipping in terms of fewer intracranial hemorrhage complications, fewer NCs, and lower unfavorable visual outcome rate. Flow diversion showed comparative safety and effectiveness to stent-assisted coiling, and they both achieved better radiologic results than coiling alone. Further validation by randomized cohort studies is still needed to provide robust evidence.