Surgical Clipping of Complex Basilar Apex Aneurysms: A Strategy for Successful Outcome Using the Pretemporal Transzygomatic Transcavernous Approach

Transcavernous Approach in Vascular Neurosurgery

The cavernous sinus is no more considered no man's land. It is a very well organized anatomic entity that can safely be navigated. It is both a route and a destination. Unlocking the cavernous sinus provides a highway that can be used to reach different vascular and tumor locations that were deemed very risky to handle.

Pretemporal Transcavernous Approach for Resection of Non-meningeal Tumors of the Cavernous Sinus: Single Center Experience

Objectives

To study the outcomes of the pretemporal transcavernous approach in the treatment of non-meningeal tumors involving cavernous sinus and to investigate the surgical strategy for these lesions.

Methods

We conducted a retrospective study of 45 patients with non-meningeal tumors involving cavernous sinus. All 45 patients received microsurgical resection via the pretemporal transcavernous approach from April 2012 to January 2019 by the same neurosurgeon. We analyzed clinical manifestations, image data, perioperative complications, surgical outcomes, functional outcomes, and follow-up data of these patients.

Results

Gross total resection was achieved in 38 cases (84.4%) of the 45 patients. Preoperatively, a total of 64 individual cranial nerves were affected. Postoperatively, 92.2% of 64 impaired cranial nerves completely or partially restored function, 7.8% had worsened function compared with their preoperative statuses, and 5 new cranial nerve deficits (CNV) were observed in five patients during the last follow-up. Seven patients presented transient new cranial nerve deficits (5 CNIII and 2 CNVI), three cases suffered transient worsen cranial nerve deficits (3 CNIII and 1 CNVII). There were no cases of intracranial hematoma, intracranial infection, cerebrospinal fluid leaks, and death. The progression of residual tumor was observed in two patients (1 chordoma and 1 pituitary adenoma).

Conclusions

Non-meningeal tumors involving cavernous sinus can be safely and radically removed with less morbidity and mortality. Pretemporal transcavernous approach is an ideal approach to the cavernous sinus and can be tailored individually.

Posterior Circulation Aneurysms

Posterior circulation aneurysms have a higher tendency to rupture and become symptomatic in comparison to anterior circulation aneurysms. Current treatment modalities for aneurysms in these locations vary widely including microsurgical clipping, trapping with bypass, wrapping, and various endovascular methods such as coiling, balloon or stent-assisted coiling, flow diversion, and vessel sacrifice, among others.Overall, surgical versus endovascular treatment of posterior circulation aneurysms continue to be a controversial topic in cerebrovascular neurosurgery. At our center, multi-disciplinary assessments including surgeons capable of both endovascular and microsurgical treatments of these aneurysms are employed to guide the treatment strategies. As advancements in both fields are made, this will continue to be a topic for debate. Anatomy and individual patient's characteristics will dictate the correct approach and therefore proficiency in the microsurgical techniques required to treat these aneurysms will continue to be both relevant and important.

Case Report: Internal Carotid Artery Thrombosis: A Rare Complication After Fibrin Glue Injection for Cavernous Sinus Hemostasis

Background: Fibrin glue injection within the cavernous sinus (CS) is a demonstrably safe and simple technique to control venous bleeding with a low complication rate. However, this technique does have inherent risks. We illustrate 2 cases of internal carotid artery (ICA) thrombosis after fibrin glue injection in the CS for hemostasis.

Methods: After encountering this complication recently, we conducted a retrospective review of the surgical database of 2 senior neurosurgeons who specialize in cerebrovascular and skull base surgery to identify patients with any complications associated with the use of fibrin glue injection for hemostasis. Approval was given by respective institutional review boards, and patient consent was obtained.

Results: Of more than 10,000 microsurgery procedures performed by 2 senior neurosurgeons with a combined experience of 40 years, including procedures for aneurysms and skull base tumors, 2 cases were identified involving ICA thrombosis after fibrin glue injection in the CS for hemostasis. Both cases involved severe ischemic complications as a result of the ICA thrombosis. In this article, we present their clinical presentation, characteristics, management, and outcomes.

Conclusion: Direct injection of fibrin glue into the CS for hemostasis can effectively control venous bleeding and facilitate complex dissections. However, it can be associated with ICA thrombosis, with subsequent serious ischemia and poor prognosis. Although this complication appears to be rare, increased awareness of this problem should temper the routine use of fibrin glue in anterior clinoidectomy and transcavernous approaches.

Anatomic feasibility of endoscopic endonasal intracranial aneurysm clipping: a systematic review of anatomical studies

Clinical studies have suggested the endoscopic endonasal approach (EEA) for aneurysm clipping as a feasible way to treat select intracranial aneurysms. Among neurosurgery, there is not a consensus on the utility of EEA aneurysm clipping. This review aims to define the anatomic feasibility of EEA for aneurysm clipping. Two databases (PubMed, Cochrane) were searched for anatomical studies assessing EEA for intracranial aneurysm clipping. Literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Quantitative anatomical studies were included. Eleven studies met inclusion criteria. Vascular exposure and clip placement on vessels of interest were possible, although only one study assessed these parameters with physical aneurysm models. Anterior circulation vessels, although accessible in over 90% of specimens, had low successful clipping rates in a small and large aneurysm models. Small and large model posterior circulation aneurysms were more readily clipped. Proximal and distal controls were readily attainable in posterior circulation aneurysms, but not anterior. This current literature review highlights the relevance of anatomical studies in assessing the feasibility of the EEA for clipping intracranial aneurysms. As such, anterior circulation aneurysms are poor candidates for EEA given difficulties in clip placement and obtaining proximal control and distal control in small and large aneurysms. While our results suggest that clipping of posterior circulation aneurysms is feasible from a technical stand of view, further clinical experience is required to assess its feasibility in terms of safety and efficacy, balancing the indications with endovascular treatment options.

Temporary Clipping of the Intracavernous Internal Carotid Artery: A Novel Technique for Proximal Control

BACKGROUND

Securing proximal control in complex paraclinoid aneurysm surgery through traditional techniques may be challenging and risky in certain situations. Advancements of anatomical knowledge of the cavernous sinus (CS) and hemostasis have made it more accessible as a surgical option.

OBJECTIVE

To describe the technique of temporary clipping of the horizontal segment of the intracavernous internal carotid artery (IC-ICA) in preparation for permanent clipping of complex paraclinoid aneurysms.

METHODS

Through an extradural pretemporal approach, the lateral wall of the CS is exposed. The dura between the trochlear nerve and V1 is opened, and access is made to the horizontal segment of the IC-ICA. After circumferential dissection, the temporary clip can be introduced to the artery, and the extradural clinoidectomy can be continued under secured proximal control.

RESULTS

Seven patients with complex paraclinoid aneurysms were treated between May 2013 and May 2016 by the senior author. Temporary clipping of the IC-ICA was performed in all cases. Average time to achieve proximal control was 22.6 min (22.6 ± 13.8). One patient developed transient oculomotor palsy postoperatively. There were no other complications.

CONCLUSION

When the exposed clinoidal segment of the internal carotid artery does not offer sufficient proximal space for temporary clipping, the extradural approach can be extended to the horizontal portion of the IC-ICA. In our experience, this technique is a quick, reliable, and safe alternative to the classical modalities of temporary occlusion.

Safety and effectiveness of endoscopic endonasal intracranial aneurysm clipping: a systematic review

Once considered far-fetched, endoscopic endonasal clipping (EEC) has been reported as a feasible alternative route for treating intracranial aneurysms located in the midline. Appropriately, debates regarding EEC applicability have arisen amongst the neurosurgical community. We aim to define the safety, effectiveness, and current state-of-art in the use of EEC for intracranial aneurysms. Two databases (PubMed, Cochrane) were queried for intracranial aneurysms that underwent EEC between inception and 2019. Literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Data regarding clinical presentation, radiological imaging, and outcome were extracted and analyzed from selected publications. Nine studies with 27 patients (8 males, 19 females), harboring 35 aneurysms (9 ruptured, 26 nonruptured), met the predetermined inclusion criteria. Patient age range is from 34 to 70 (median = 50) years old. Four aneurysms were considered not suitable for EEC during the procedure, and two aneurysms required additional treatment, leading to an overall treatment success (obliteration) rate of 86%. Complications occurred in 7 patients (26%), including CSF leakage in 5 patients (18%) and ischemic complications in 4 (15%). Among the cases reported, complications occurred more frequently in posterior circulation aneurysms in comparison with anterior circulation aneurysms (62.5 vs 10.5%). Ischemic complications occurred in 4 out of 8 posterior circulation aneurysms. Although feasible, EEC is associated with a significant risk of complications, with rates identified that are significantly higher than established open clipping or endovascular management. The current data suggest that transcranial clipping and endovascular occlusion are still the primary indication for treating intracranial aneurysms.

Tailoring the surgical corridor to the basilar apex in the pretemporal transcavernous approach: morphometric analyses of different neurovascular mobilization maneuvers

BACKGROUND

The pretemporal transcavernous approach (PTA) provides optimal exposure and access to the basilar artery (BA); however, the PTA can be invasive when vital neurovascular structures are mobilized. The goal of this study was to evaluate mobilization strategies to tailor approaches to the BA.

METHODS

After an orbitozygomatic craniotomy, 10 sides of 5 cadaveric heads were used to assess the surgical access to the BA via the opticocarotid triangle (OCT), carotid-oculomotor triangle (COT), and oculomotor-tentorial triangle (OTT). Measurements were obtained, and morphometric analyses were performed for natural neurovascular positions and after each stepwise expansion maneuver. An imaginary line connecting the midpoints of the limbus sphenoidale and dorsum sellae was used as a reference to normalize the measurements of BA exposure and to facilitate the clinical applicability of this technique.

RESULTS

In the OCT, the exposed BA segment ranged from - 1 ± 3.9 to + 6 ± 2.0 mm in length in its natural position. In the COT, the accessible BA segment ranged from - 4 ± 2.3 to - 2 ± 3.0 mm in length in its natural position. Via the OTT, the accessible BA segment ranged from - 7 ± 2.6 to - 5 ± 2.8 mm in length in its natural position. In the OCT, COT, and OTT, a posterior clinoidectomy extended the exposure down to - 6 ± 2.7, - 8 ± 2.5, and - 9 ± 2.9 mm, respectively.

CONCLUSIONS

This study quantitatively evaluated the need for the expansion maneuvers in the PTA to reach BA aneurysms according to the patient's anatomical characteristics.

Resection of an Isolated Pituitary Stalk Epidermoid Cyst Through a Pretemporal Approach: Case Report and Review of the Literature

BACKGROUND

Intracranial epidermoid cysts are congenital epidermal inclusion cysts derived from ectodermal origin with desquamated skin. The majority of these cysts occur in the cerebellopontine angle cistern. Epidermoid cyst of the pituitary stalk, however, is a rare location. To date, only 4 previous cases have been reported.

CASE DESCRIPTION

A 63-year-old male presented to our clinic with migraine headaches, dizziness, increased thirst, increased urinary frequency, and impotence. Magnetic resonance imaging of the brain demonstrated a rim-enhancing cystic mass with diffusion restriction on diffusion-weighted imaging located within the pituitary stalk. The patient underwent a pretemporal approach with gross total resection of the cyst. The patient's postoperative course was uneventful with no new deficits and/or endocrinopathies.

CONCLUSION

Epidermoid cyst of the pituitary stalk is an unusual and rare presentation. Four other cases treated via endoscopic approaches have been previously reported in the neurosurgical literature. To our knowledge this is the first case description of an infundibular epidermoid cyst pressing with isolated diabetes insipidus surgically treated via a transcranial pretemporal approach with gross total resection. The patient had a smooth and uneventful postoperative course with persistent diabetes insipidus.

The anterior incisural width as a preoperative indicator for intradural space evaluation: An anatomical investigation

Background:

The opticocarotid triangle (OCT) and the carotico-oculomotor triangle (COT) are two anatomical triangles used in accessing the interpeduncular region. Our objective is to evaluate if the anterior incisural width (AIW) is an indicator to predict the intraoperative exposure through both triangles.

Methods:

Twenty sides of 10 cadaveric heads were dissected and analyzed. The heads were divided into the following: Group A – narrow anterior incisura and Group B – wide anterior incisura – using 26.6 mm as a cutoff distance of the AIW. Subsequently, the area of the COT and the OCT in the transsylvian approach was measured, along with the maximum widths through the two trajectories in modified superior transcavernous approach.

Results:

The COT in the wide group was shown to have a significantly larger area compared with the COT in the narrow group (38.4 ± 12.64 vs. 58.3 ± 15.72 mm, P < 0.01). No difference between the two groups was reported in terms of the area of the OCT (50.9 ± 19.22 mm vs. 63.5 ± 15.53 mm, P = 0.20), the maximum width of the OCT (6.6 ± 1.89 vs. 6.5 ± 1.38 mm, P = 1.00), or the maximum width of the COT (11.7 ± 2.06 vs. 12.2 ± 2.32 mm, P = 0.50). Clinical cases were included.

Conclusion:

An AIW <26.6 mm is an unfavorable factor related to a limited COT area in a transsylvian approach for pathologies at the interpeduncular fossa. Preoperative identification and measurement of a narrow AIW can suggest the need to add a transcavernous approach.

Anterior Clinoid Metastasis as First Presentation of a Signet Ring Cell Carcinoma: An Intriguing Diagnosis

Background  We report an extremely unusual case of anterior clinoid process (ACP) metastasis as the first presentation of a signet ring cell carcinoma.

Case Description  A 54-year-old female patient presented with right-sided visual disturbances due to optic nerve compression from a computed tomography (CT)-identified right anterior clinoid bone lesion. Contrast-enhanced magnetic resonance imaging showed an extra-axial, well-bordered enhancing mass extending from the right ACP toward the inner lumen of the optic canal. Pterional approach was adopted to remove the lesion and decompress the optic canal. Histological examination demonstrated a metastasis from a signet ring cell carcinoma. Postoperative CT showed near-total resection of the tumor and decompression of the optic canal. Visual defect remained unchanged.

Conclusion  Metastasis should be considered in the differential diagnosis of the ACP lesions. The early suspicion and identification of this extremely rare pathological entity can be helpful for the prompt management of patients, especially in the absence of any other signs of oncological diseases.

Anterior temporal approach for clipping of ruptured basilar tip aneurysms: Surgical techniques and treatment outcomes

BACKGROUND

Basilar tip (BT) aneurysms are challenging to treat with microsurgical clipping, especially in subarachnoid hemorrhage cases. The anterior temporal approach is one of the surgical approaches for the treatment of aneurysms in this area. The majority of the previous reports on this approach have described unruptured cases. For the ruptured cases assessed in our study, the authors describe the surgical technique, patient characteristics, and surgical outcomes following the use of this technique.

METHODS

Fourteen patients with ruptured BT aneurysms who received aneurysm clipping with an anterior temporal approach between December 2015 and August 2019 were retrospectively evaluated. The surgical techniques are described, an illustrative case is shown.

RESULTS

The average patient age was 62.2 years (range: 46-78) for ten women and four men. Nine patients (64.3%) were classified as having a poor grade (World Federation of Neurosurgical Societies Grades 4 and 5) at the first presentation. All of the cases demonstrated complete aneurysm obliteration. Good outcomes (mRS 0 to 2) at 6 months were achieved in 58.3% of the patients and in 77.8% of the patients who had a good Glasgow Coma Score after resuscitation before surgery. Postoperative transient oculomotor nerve palsy and thalamic infarctions were detected in six patients (42.9%) and two patients (14.3%), respectively.

CONCLUSION

With appropriate case selection, the anterior temporal approach was effective and safe for the clipping of ruptured BT aneurysms.

Surgical Approaches to Basilar Apex Aneurysms: An Illustrative Review

Surgical management of basilar apex aneurysms remains one of the most challenging areas in neurovascular surgery. Technical demands of treating these aneurysms have inspired several generations of neurosurgeons to push the limitations of technical achievement. Advances in neuroanesthesia, cerebral protection paradigms, and critical care management have enhanced surgical outcomes of these lesions. Several approaches have been described to reach these lesions from anterolateral or lateral corridors. Each surgical approach has its own advantages and limitations and should be chosen for each patient according to the aneurysm's position, projection, parent arteries, and perforators. In this review, we will discuss pros and cons of the common approaches to these aneurysms with description of the important steps of each surgical procedure.

Anterior Clinoid Metastasis Removed Extradurally: First Case Report

Background  We report a case of isolated metastasis on the anterior clinoid process (ACP) mimicking meningioma.

Clinical Presentation  A 58-year-old male presented with headaches, right-sided visual disturbances, and blurred and double vision. The cause of double vision was partial weakness of the right III nerve, resulting from compression of the nerve by “hypertrophied” tumor-involved right anterior clinoid. Medical history revealed two primary malignant tumors—male breast cancer and prostate cancer (diagnosed 6 and 18 months prior, respectively). The patient was treated with chemotherapy and showed no signs of active disease, recurrence, or metastasis. Postcontrast head magnetic resonance imaging (MRI) showed extra-axial well-bordered enhancing mass measuring 1.6 × 1.1 × 1 × 1 cm (anteroposterior, transverse, and craniocaudal dimensions) on the ACP, resembling a clinoidal meningioma. Extradural clinoidectomy with tumor resection was performed via right orbitozygomatic pretemporal skull base approach. Visual symptoms improved. Follow-up MRI showed no signs of tumor residual or recurrence.

Conclusion  This is the first case report of a metastasis of any kind on ACP. Metastasis should be included as a part of the differential diagnosis of lesions of the anterior clinoid. Extradural clinoidectomy is a safe and effective method in the treatment of these tumors.

Should we still consider clips for basilar apex aneurysms? A critical appraisal of the literature

Background:

Basilar apex aneurysms constitute 5–8% of all intracranial aneurysms, and their treatment remains challenging for both microsurgical and endovascular approaches. The perceived drawback of the microsurgical approach is its invasiveness leading to increased surgical morbidity. However, many high-volume centers have shown excellent clinical results with better occlusion rates compared to endovascular treatment. With endovascular therapy taking a larger role in the management of cerebral aneurysms, the future role of microsurgery for basilar apex aneurysm treatment is unclear.

Methods:

We performed a literature search to review the microsurgical and endovascular outcomes for basilar apex aneurysms.

Results:

Many studies have examined the efficacy of microsurgical and endovascular treatment for intracranial aneurysms, including large randomized trials such as ISAT and BRAT, prospective observational series such as ISUIA, and many single-center retrospective reviews. The recruitment number for posterior circulation aneurysms, specifically for basilar apex aneurysms, was limited in most prospective trials, thus failing to offer clear guidance on basilar apex aneurysm treatment. Recent single-center series report good clinical outcomes between 57–92% for surgical series and 73–96% in endovascular series. The durability of aneurysm occlusion remains superior in surgical cases. The techniques and devices in endovascular treatment have improved treatment aneurysm occlusion rates but more follow-up is needed to confirm long-term durability.

Conclusions:

Both microsurgical and endovascular approaches should be complementing each other to treat basilar apex aneurysms. Although endovascular therapy has taken a larger role in the treatment of basilar apex aneurysms, many indications still exist for the use of microsurgery. Advancements in microsurgical techniques and good case selection will allow for acceptably low morbidity after surgical treatment while maintaining its superior durability.

Morphometric Study of the Anterior Thalamoperforating Arteries

Objective

To evaluate the morphometry of the anterior thalamoperforating arteries (ATPA).

Methods

A microanatomical study was performed in 79 specimens from 42 formalin-fixed adult cadaver brains. The origins of the ATPAs were divided into anterior, middle, and posterior segments according to the crowding pattern. The morphometry of the ATPAs, including the premammillary artery (PMA), were examined under a surgical microscope.

Results

The anterior and middle segments of the ATPAs arose at mean intervals of 1.75±1.62 mm and 5.86±2.05 mm from the internal carotid artery (ICA), and the interval between these segments was a mean of 3.17±1.64 mm. The posterior segment arose at a mean interval of 2.43±1.46 mm from the posterior cerebral artery (PCA), and the interval between the middle and posterior segments was a mean of 3.45±1.39 mm. The mean numbers of perforators were 2.66±1.19, 3.03±1.84, and 1.67±0.98 in the anterior, middle, and posterior segments, respectively. The PMA originated from the middle segment in 66% of cases. A perforator-free zone was located >2 mm from the ICA in 30.4% and >2 mm from the PCA in 67.1% of cases.

Conclusion

Most perforators arose from the anterior and middle segments, within the anterior two-thirds of the posterior communicating artery (PCoA). The safest perforator-free zone was located closest to the PCA. These anatomical findings may be helpful to verify safety when treating lesions around the PCoA and in the interpeduncular fossa.

Extradural temporopolar approach for parahypothalamic hypothalamic hamartoma and use of posterior communicating artery as resection margin pointer

BACKGROUND

Hypothalamic hamartomas (HH) are malformations originating from the hypothalamus and are associated with seizures, hormonal and behavioral abnormalities.

METHOD

Most patients, especially those with a typical syndrome characterized by gelastic seizures, precocious puberty, cognitive decline, and behavior problems, are diagnosed in childhood. Pedunculated and parahypothalamic types of hamartomas are attached to the floor by a narrow or wide peduncle in the absence of distortion of the overlying hypothalamus. This location is most commonly associated with a clinical presentation of precocious puberty, and surgical removal has proved curative in small case series. Enthusiastic resection of hypothalamic lesions are known to produce severe hypothalamic disturbance while under resection might mean inadequate response to surgery.

CONCLUSIONS

In this article, the authors describe the use of extradural temporopolar approach to hypothalamic hamartoma as an improvisation to improve access with reduced morbidity and describe a surgical nuance of using posterior communicating artery to determine a safe but maximal resection margin.

Successful surgical optic nerve decompression in a patient with hypertrophic pachymeningitis due to granulomatous polyangiitis

A 57-year-old woman presented with subacute vision loss of first the left, and later the right eye. She was diagnosed with granulomatous polyangiitis with hypertrophic pachymeningitis and optic nerve compression. Her visual acuity could not be permanently restored with immune suppressants alone, so a surgical decompression of the right optic nerve, via a modified cranio-orbitozygomatic pretemporal approach, was performed. Her right eye regained 20/20 vision and has remained stable during 8 months of follow-up.

Lateral transzygomatic middle fossa approach and its extensions: surgical technique and 3D anatomy

BACKGROUND

Various approaches to lesions involving the middle fossa and cavernous sinus (CS), with and without posterior fossa extension have been described. In the present study, we describe the surgical technique for the extradural lateral tranzygomatic middle fossa approach and its extensions, highlight relevant 3D anatomy.

METHODS

Simulations of the lateral transzygomatic middle fossa approach and its extensions were performed in four silicon-injected formalin fixed cadaveric heads. The step-by-step description and relevant anatomy was documented with 3D photographs.

RESULT

The lateral transzygomatic middle fossa approach is particularly useful for lesions involving the middle fossa with and without CS invasion, extending to the posterior fossa and involving the clinoidal region. This approach incorporates direct lateral positioning of patient, frontotemporal craniotomy with zygomatic arch osteotomy, extradural elevation of the temporal lobe, and delamination of the outer layer of the lateral CS wall. Extradural drilling of the sphenoid wing and anterior clinoid process allows entry into the CS through the superior wall and exposure of the clinoidal segment of the ICA. Posteriorly, drilling the petrous apex allows exposure of the ventral brainstem from trigeminal to facial nerve and can be extended to the interpeduncular fossa by division of the superior petrosal sinus.

CONCLUSION

The present study illustrates 3D anatomical relationships of the lateral transzygomatic middle fossa approach with its extensions. This approach allows wide access to different topographic areas (clinoidal region and clinoidal ICA, the entire CS, and the posterior fossa from the interpeduncular fossa to the facial nerve) via a lateral trajectory. Precise knowledge of technique and anatomy is necessary to properly execute this approach.

Extradural anterior clinoidectomy: Technical nuances from a learner's perspective

Background:

Extradural removal of the anterior clinoid process (ACP) is a crucial step in the proper surgical exposure of various pathologies in and around the central skull base. Since the pioneering description by Dolenc, the technique of extradural clinoidectomy has undergone several refinements in the light of improved understanding of microsurgical anatomy and maturation of neurosurgical techniques. Mastery of the surgical nuances involved in performing this surgical exercise will allow the young neurosurgeon to execute this step without undue reluctance and trepidation.

Objective:

This paper is an attempt to describe in detail, from a learner's viewpoint, the sequence of maneuvers involved in extradural removal of the ACP.

Materials and Methods:

The standard pterional approach and extradural anterior clinoidectomy was performed on four sides of two formalin fixed and latex injected cadaver heads. Important steps were photographed through the surgical microscope.

Conclusion:

An accurate understanding of the microsurgical anatomy of this region and the surgical nuances relevant to extradural clinoidectomy helps simplify the complexity of this surgical step.

Combined extradural subtemporal and anterior transpetrosal approach to tumors located in the interpeduncular fossa and the upper clivus

BACKGROUND

Central skull base lesions in the interpeduncular fossa and the upper clival regions can be challenging to access because of their location anterior to the brainstem. We have modified the anterior transpetrosal approach by combination with the extradural subtemporal route to increase the surgical corridor.

METHODS

Thirty-seven patients underwent surgical treatment via the anterior transpetrosal approach from 2002 to 2012. The combined surgical approach was primarily applied when the tumors arose from the upper clival portion and extended to the interpeduncular fossa. The combined approach was used in seven of these patients, comprising four patients with petroclival meningiomas, one patient with sphenoclival meningiomas, one patient with trigeminal schwannoma, and one patient with an epidermoid cyst extending from the interpeduncular fossa to the prepontine cistern.

RESULTS

The combined approach permitted excellent visualization of the interpeduncular fossa in addition to the upper clivus and the lateral aspect of the brain stem. Mobilization of the temporal lobe by the entire epidural dissection of the lateral wall of the cavernous sinus facilitates access via the subtemporal route. The transient symptom of the temporal lobe in the dominant site may be the only drawback for this combined approach, although it may disappear immediately after the surgery.

CONCLUSION

The present approach combines Dolenc's approach and Kawase's approach, providing a wide exposure to lesions of the interpeduncular fossa and the clivus.

Microsurgical management of basilar artery apex aneurysms: a single surgeon's experience from Louisiana State University, Shreveport

OBJECTIVE

Basilar artery apex aneurysms continue to generate technical challenges and management controversy. Endovascular intervention is becoming the mainstay in the management of these formidable aneurysms, but it has limitations, especially with large/giant or wide neck basilar apex aneurysms. There is paucity of data in the available literature pertaining to the successful management of large/giant, wide neck, and calcified/thrombosed basilar apex aneurysms. We present our experience with consecutively operated complex basilar apex aneurysms so as to present the role of microneurosurgery as a viable management option for these aneurysms.

METHODS

Ours is a retrospective analysis of case-records for operated cases of basilar artery aneurysms spanning 18 years. Basilar apex aneurysms >10 cm, calcified or thrombosed, neck ≥4 mm posterior direction, and retro/subsellar were considered as complex anatomy aneurysms. Basilar apex aneurysms with favorable anatomy were included in the study as a reference group for statistical analysis. Patient demographics, complex features of aneurysms, clinical grade, and outcomes were analyzed.

RESULTS

A total of 33 (53.2%) patients had complex anatomy: large (>10 mm) in eight (24.2%); giant aneurysms (>25 mm) in seven (21.2%); wide-neck in 22 (66.7%); and calcified/thrombosed morphology in five (15.1%). The mean age was 48.5 years, and 22 (66.67%) were women. All aneurysms were clipped by the use of various skull base approaches. A total of 71.9% of patients harboring complex aneurysm had good outcomes. If only unruptured and good grade complex aneurysms also are considered, then 86.9% (n = 20) patients had good outcomes. Statistically there was no significant difference in the outcomes of complex and noncomplex aneurysm.

CONCLUSIONS

Although concerning, the management of large/giant, wide neck, and calcified/thrombosed aneurysms with microneurosurgery is still a competitive alternative to endovascular therapy. After careful selection of appropriate skull base approaches based on the complexity of the basilar apex aneurysm, microneurosurgery can achieve acceptable results.

Accessing the basilar artery apex: is the temporopolar transcavernous route an anatomically advantageous alternative?

The restricted operative field, difficulty of obtaining proximal vascular control, and close relationship to important anatomic structures limit approaches to basilar apex aneurysms. We used a cadaveric model to compare three surgical transcavernous routes to the basilar apex in the neutral configuration. Five cadaveric heads were dissected and analyzed. Working areas and length of exposure provided by the transcavernous (TC) approach via pterional, orbitozygomatic, and temporopolar (TP) routes were measured along with assessment of anatomic variation for the basilar apex region. In the pterional TC and orbitozygomatic TC approaches, the mean length of exposure of the basilar artery measured 6.9 and 7.2 mm, respectively (p = NS). The mean length of exposure in a TP TC approach increased to 9.3 mm (p < 0.05). Compared with the pterional and orbitozygomatic approaches, the TP TC approach provided a larger peribasilar area of exposure ipsilaterally and contralaterally (p < 0.05). The multiplanar working area related to the TP TC approach was 77.7 and 69.5% wider than for the pterional TC and orbitozygomatic TC, respectively. For a basilar apex in the neutral position, the TP TC approach may be advantageous, providing a wider working area for the basilar apex region, improving maneuverability for clip application, fine visualization of perforators, and better proximal control.

[Transzygomatic pterional approach. Part 2: Surgical experience in the management of skull base pathology]

OBJECTIVES

To present our experience with the transzygomatic pterional approach in the treatment of neurosurgical pathology of the base of the skull located in the middle cranial fossa and surrounding areas.

METHOD

A retrospective study of pathological findings, surgical outcomes and complications in a series of 31 cases operated on between 2009 and 2011 using a transzygomatic pterional approach.

RESULTS

The lesions involved the sphenoid wing (25.9%), several regions due to invasive growth pattern (19.5%), the temporal lobe (16.1%) and cavernous sinus (12.9%). The others were located in the floor of the middle fossa, Meckel's cave, incisural space, cisterns and infratemporal region. The pathological nature of the lesions was: benign meningioma (42%), temporal lobe tumour (19.5%), vascular disease (12.9%), inflammatory lesions (6.4%), atypical meningioma (6.4%), epidermoid cyst (6.4%), neurinoma (3.2%) and poorly differentiated infratemporal carcinoma (3.2%). The approach was usually combined extra-intradural (58.1%) and, less frequently, just extradural (16.1%) or intradural (25.8%). Approach-related complications were minor: haematomas in the wound not requiring treatment (67.8%), superior transient facial paresis (9.7%), transient temporomandibular joint dysfunction (12.9%) and atrophy of the temporal muscle (16.2%). There were no hardware-related complications or cosmetic issues related to the osteotomy and posterior osteosynthesis of the zygomatic arch.

CONCLUSIONS

The pterional approach combined with osteotomy of the zygomatic arch allows mobilising the temporalis muscle away from the temporal fossa, consequently exposing its entire surface to complete the temporal craniotomy up to the middle fossa; it helps to access and treat pathology in this region or it can be used as a corridor to approach surrounding areas.

[Transzygomatic pterional approach. Part 1: anatomical study]

OBJECTIVE

Cadaveric study of the anatomical structures of the temporal region, as well as the technical aspects of the transzygomatic pterional approach.

MATERIAL AND METHODS

Six human formalin-fixed heads, whose arterial circulatory system was injected with red-dyed silicone, were studied (12 temporal regions). Dissections were performed using standard microsurgical techniques and instruments.

RESULTS

We confirm the existence of a double superficial and deep layer within the superficial temporal fascia, which makes possible to perform the zygomatic arch osteotomy without damaging the temporal muscle and the branches of the superficial temporal artery and the facial nerve. The shape and location of the osteotomies to preserve the témporo-mandibular joint and ligaments and to provide correct reconstruction of the bone flap are described. We compare the exposure of intracranial structures obtained by this approach with those obtained by the conventional pterional approach and the orbitozygomatic approach.

CONCLUSIONS

The transzygomatic pterional approach provides wide exposure of the temporal lobe for trans-sylvian, pre-temporal and/or subtemporal approaches in selected cases of neurosurgical pathology. A detailed anatomical knowledge of the temporal region is necessary to achieve the best surgical, functional and cosmetic results.

MRI-validation of SEP monitoring for ischemic events during microsurgical clipping of intracranial aneurysms

OBJECTIVE

During surgical clipping of intracranial aneurysms, reduction in SEP amplitude is thought to indicate cortical ischemia and subsequent neurological deficits. Since the sensitivity of SEP is questioned, we investigated SEP with respect to post-operative ischemia.

METHODS

In 36 patients with 51 intracranial aneurysms, clinical evaluation and diffusion-weighted MRI (DWI) was performed before and within 24h after surgery. During surgery, time of temporary occlusion was recorded. MRI images were reviewed for signs of ischemia.

RESULTS

For 43 clip applications (84%), we observed neither pathologic SEP events nor ischemia in MRI. In two cases where reduction lasted >10 min after clip release, SEP events correlated with ischemia in the MRI. Only one of the ischemic patients was symptomatic and developed a transient hemiparesis.

CONCLUSIONS

While pathologic SEP events correlated with visible ischemia in MRI only in two cases with late SEP recovery, ischemia in MRI may have been transient or may not have reached detection threshold in the other cases, in agreement with the absence of permanent neurological deficits.

SIGNIFICANCE

In complex aneurysm cases, where prolonged temporary occlusion is expected, SEP should be used to detect ischemia at a reversible stage to improve the safety of aneurysm clipping.

Analysis of clinical and radiological outcomes in microsurgical and endovascular treatment of basilar apex aneurysms

OBJECTIVE

We aimed to analyze clinical and radiological outcomes retrospectively in patients with basilar apex aneurysms treated by coiling or clipping.

METHODS

Outcomes of basilar bifurcation aneurysms were assessed retrospectively in 77 consecutive patients (61 women, 16 men), ranging in age from 25 to 79 years (mean, 53.7 years) from 1999 to 2007.

RESULTS

Forty-nine patients out of 77 patients (63.6%) presented with subarachnoid hemorrhages of the 49 patients treated with coiling, 27 (55.1%) showed complete occlusion of the aneurysm sac. Of these, 13 patients (26.5%) developed coil compaction on angiographic or MRI follow-up, with recoiling required in 9 patients (18.4%). Procedural complications of coiling were acute infarction in nine patients and the bleeding of the aneurysms in six patients. The remaining 28 patients underwent microsurgery: twenty-six of these (92.9%) with microsurgery followed up with conventional angiography. Complete occlusion of the aneurysm sac was achieved in 19 patients (73.1%). Operation-related complications of microsurgery were thalamoperforating artery injuries in three patients, retraction venous injury in two, postoperative epidural hemorrhage (EDH) in one, and transient partial or complete occulomotor palsy in 14 patients. Glasgow Outcome Scores (GOS) were 4 or 5 in 21 of 28 (75%) patients treated with microsurgery at discharge, and at 6 month follow-up, 20 of 28 (70.9%) maintained the same GOS. In comparison, GOS of four or 5 was observed in 36 of 49 (73.5%) patients treated with coiling at discharge and at 6 month follow-up, 33 of 49 patients (67.3%) maintained the GOS from discharge.

CONCLUSION

Basilar top aneurysms were still challenging lesions based on our series. Endovascular or microsurgery endowed with its inborn risks and procedural complications for the treatment of basilar apex aneurysms individually. Microsurgery provided better outcome in some specific basilar apex aneurysms. For reaching the most favorable outcome, endovascular modality as well as microsurgery was inevitably considered for each specific basilar apex aneurysm.

Intraoperative transaneurysmal coil-assisted clip occlusion of a complex anterior communicating artery aneurysm

✓The combination of surgical and endovascular treatment for complex intracranial aneurysms has previously been used in a staged fashion. To perfect the clipping process of a complex anterior communicating artery aneurysm and to avoid a second staged procedure, the authors used a method of direct intraoperative transaneurysmal coil-assisted clip occlusion of the aneurysm.

To the authors' knowledge this is the first time direct intraoperative transaneurysmal coil-assisted clip occlusion has been reported. It should be kept in mind as one of the options to help in complete obliteration of complex intracranial aneurysms.

Transcavernous approach to diseases of the anterior upper third of the posterior fossa

Object

The region in the upper anterior third of the posterior fossa is a surgically hidden, narrow corridor between the petroclival surface anteriorly and the surface of the brainstem posteriorly. Although several approaches have been described to help surgeons reach this region, few of them enable practitioners to reach the different corners of the area and provide as wide a view as the one achieved using the transcavernous route.

Methods

A transcavernous approach was used in 91 cases (50 complex upper basilar artery [BA] aneurysms, 30 upper petroclival junction meningiomas, five trigeminal nerve schwannomas, three upper clival chordomas, and three anterior pontine lesions) involving the anterior upper third of the posterior fossa. The approach uses the pretemporal route with exposure of the lateral wall of the cavernous sinus. It entails removal of the anterior clinoid process. The posterior clinoid process is also removed when necessary. The approach leads to the upper basilar region. It is widened inferiorly to expose the anterior aspect by removal of the posterior clinoid process and the petroclival osseous and dural elements. Its lateral extension exposes the region of the Meckel cave and it can be widened by removal of the petrous apex.

Seventy patients experienced new transient mild cranial neuropathies, 67 of whom recovered fully. Surgically related ischemic morbidities occurred in three patients with BA aneurysms (one small medial thalamic infarct, ataxia due to superior cerebellar artery ischemia, and distal middle cerebral artery embolus in a patient with atrial fibrillation in whom anticoagulation therapy was stopped). All the neuropathies in patients with BA aneurysms were oculomotor and recovery was the rule in all of them. Three new permanent cranial neuropathies occurred in the patients with meningiomas. In seven patients with preoperative neuropathy, two had partial improvement. Five patients with atypical meningiomas were treated with postoperative radiation therapy. Progression occurred later in four patients who were treated with gamma knife surgery. There were no surgery-related deaths. More than 1 year of follow-up data were available in 85 patients, and 94% of those patients were in an active and functional state (Glasgow Outcome Scale scores of 4 and 5).

Conclusions

The safety achieved with the transcavernous route allows surgeons to achieve wide exposures to lesions involving the anterior upper third of the posterior fossa. It is an approach that should be mastered by every neurosurgeon dealing with cranial lesions.