Surgical management of petroclival meningiomas: factors determining the choice of approach

Texture Analysis of Fibrous Meningioma Using Label-Free Multiphoton Microscopy

Fibrous meningiomas, a common type of brain tumor, present surgical challenges due to their variable hardness, which is crucial for complete resection and patient prognosis. This study explores the use of label-free multiphoton microscopy (MPM) for the objective assessment of the texture of fibrous meningiomas. Fresh tumor samples from 20 patients were analyzed using both multichannel and lambda mode MPM, with quantitative image analysis algorithms determining collagen content and multi-peak spectral fitting providing additional optical collagen metrics. The study compared medium and hard fibrous meningiomas, utilizing receiver operating characteristic analysis to evaluate predictive performance. Microstructural features were clearly visualized, enabling accurate diagnosis. Collagen-related parameters significantly differentiated between moderate and hard tumors (p < 0.05). High predictive values were observed for collagen content, collagen-to-NADH-free ratio, and collagen-to-FAD ratio (AUC = 0.748-0.839). A multivariate logistic model combining these biomarkers significantly improved diagnostic accuracy (AUC = 0.907). The findings suggest that MPM, with its ability to visualize and quantify microstructures such as collagen and cells without the need for staining, holds strong potential for rapid, objective, and accurate assessment of tumor texture during neurosurgery. The integration of MPM with multiphoton endoscopy paves the way for potential in vivo applications in the future.

Combined presigmoid approach: A literature review

Background

The presigmoid approach represents the standard route to reach the petrous area anterior to the sigmoid sinus. Several lateral skull base approaches have been integrated into this approach for the purpose of widening the window, leading to variable combined approaches and variable terminology. Herein, the authors conducted a systematic review of the literature to simplify understanding of the potential combination of different approaches and their complications.

Methods

PubMed, EMBASE and Web of Science databases were searched on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to include studies describing modifications of the presigmoid approach.

Results

We included 27 studies comprising 545 patients. Five combination types applied to the presigmoid approach were identified: Anterior petrosal (Kawase's) approach (Type-1), Supra-tentorial approach (Type-2), Infratemporal fossa approach (Type-3), retrosigmoid approach (Type-4), and Far-lateral suboccipital approach (Type-5). Type-1 combined approach was the commonest type (n = 204, 37.5%), followed by type-2 (n = 197, 36%), type-4 (n = 54, 9.9%), type-5 (n = 51, 9.4%), and type-3 (n = 39, 7.2%). Meningioma was the typical target lesion in all types except type 3, where it is solely used for paraganglioma. The petroclival region was the prevalent access location in all the types of combined presigmoid approaches (type-1, 92%; type-2, 95%; type-3, 100%; type-4, 59%; and type-5, 64%). The intraoperative lateral patient position was dominantly utilized in type-1, type-3, and type-5 approaches (65%, 100%, and 100%, respectively), while park-bench was the most common position in type-2 (36%) and type-4 (100%) approaches. Overall, all types exhibited good outcomes in the form of gross total resection of the lesion and the absence of surgical complications in the follow-up.

Conclusion

Presigmoid approaches are becoming increasingly complex with the application and integration of the lateral skull base approaches, resulting in broadening the surgical field and easy access to the targeted lesions. The importance of designing a comprehensive nomenclature of the combined presigmoid approaches may add distinctive contributions to the growing knowledge of neurosurgery.

Tumor Embolization via the Meningohypophyseal and Inferolateral Trunk in Patients with Skull Base Tumors Using the Distal Balloon Protection Technique

BACKGROUND AND PURPOSE

Tumor embolization through the meningohypophyseal trunk and inferolateral trunk is known to be effective in skull base tumors; however, microcatheter cannulation into these arteries is difficult, and the number of cases that can be safely embolized is limited. In this study, we present a novel embolization procedure for the meningohypophyseal trunk and inferolateral trunk using the distal balloon protection technique and detail its clinical efficacy and complication risks. We developed this procedure to allow safe embolization in patients who cannot be adequately cannulated with microcatheters into these arteries.

MATERIALS AND METHODS

Patients who underwent meningohypophyseal trunk or inferolateral trunk embolization using the distal balloon protection technique for skull base tumors at our institution between 2010 and 2023 were included. In this procedure, the ICA was temporarily occluded with a balloon at the ophthalmic artery bifurcation, the microcatheter was guided to the meningohypophyseal trunk or inferolateral trunk vicinity, and embolic particles were injected into the arteries. The balloon was deflated after the embolic particles that had refluxed into the ICA were aspirated.

RESULTS

A total of 25 meningohypophyseal trunks and inferolateral trunks were embolized during 21 operations. Of these 25 arteries, only 9 (36.0%) were successfully cannulated with microcatheters. Nevertheless, effective embolization was achieved in all cases. Permanent complications occurred in only 1 case (4.8%) in which the central retinal artery was occluded during inferolateral trunk embolization, resulting in a visual field defect. No permanent complications resulting from the embolic cerebral infarction were observed. Of 16 cases that underwent MR imaging within a week after embolization, however, 11 (68.8%) demonstrated embolic cerebral infarctions.

CONCLUSIONS

In patients with skull base tumors with meningohypophyseal trunk or inferolateral trunk feeders that cannot be catheterized directly, embolization using the distal balloon protection technique for tumor supply can be considered as a salvage technique.

Staged Resection of Difficult-to-Treat Intracranial Meningiomas: A Systematic Review of the Indications, Surgical Approaches, and Postoperative Outcomes

Introduction  Meningiomas-the most common extra-axial tumors-are benign, slow-growing dural-based lesions that can involve multiple cranial fossae and can progress insidiously for years until coming to clinical attention secondary to compression of adjacent neurovascular structures. For complex, multicompartmental lesions, multistaged surgeries have been increasingly shown to enhance maximal safe resection while minimizing adverse sequela. Here, we systematically review the extant literature to highlight the merits of staged resection. Methods  PubMed, Scopus, and Web of Science databases were queried to identify articles reporting resections of intracranial meningiomas using a multistaged approach, and articles were screened for possible inclusion in a systematic process performed by two authors. Results  Of 118 identified studies, 36 describing 169 patients (mean age 42.6 ± 21.3 years) met inclusion/exclusion criteria. Petroclival lesions comprised 57% of cases, with the most common indications for a multistaged approach being large size, close approximation of critical neurovascular structures, minimization of brain retraction, identification and ligation of deep vessels feeding the tumor, and resection of residual tumor found on postoperative imaging. Most second-stage surgeries occurred within 3 months of the index surgery. Few complications were reported and multistaged resections appeared to be well tolerated overall. Conclusions  Current literature suggests multistaged approaches for meningioma resection are well-tolerated. However, there is insufficient comparative evidence to draw definitive conclusions about its advantages over an unstaged approach. There are similarly insufficient data to generate an evidence-based decision-making framework for when a staged approach should be employed. This highlights the need for collaborative efforts among skull base surgeons to establish an evidentiary to support the use of staged approaches and to outline those indications that merit such an approach.

Mandibular Fossa Approach to Petroclival and Anterior Pontine Lesions

Objective  To describe the anatomy related to a novel approach to the petroclival region through the mandibular fossa for the treatment of petroclival and anterior pontine lesions. Design  Five dry skulls were examined for surgical approach. Three adult cadaveric heads underwent bilateral dissection. One cadaveric head was evaluated with computed tomography after dissection. Setting  This study was performed in an academic medical center. Participants  Neurosurgical anatomy researchers performed this study using dry skulls and cadaveric heads. Main Outcome Measurements  This was a proof-of-concept anatomical study. Results  The mandibular fossa approach uses a vertical preauricular incision above the facial nerve branches. Removal of the temporomandibular joint exposes the mandibular fossa. The anterior boundary is the mandibular nerve at the foramen ovale, and the posterior boundary is the jugular foramen. The chorda tympani, eustachian tube, and tensor tympani muscle are sectioned. The carotid artery is transposed out of the petrous canal, and a petrosectomy is performed from Meckel's cave to the foramen magnum and anterior occipital condyle. Dural opening exposes the anterior pons, vertebrobasilar junction, bilateral vertebral arteries, and the ipsilateral anterior and posterior inferior cerebellar arteries. At completion, the temporomandibular joint is reconstructed with a prosthetic joint utilizing a second incision along the mandible. Conclusions  The mandibular fossa approach is a new trajectory to the petroclival region and the anterior pons. It combines the more anterior angle of endoscopic approaches along with the enhanced control of open approaches. Further study is necessary before this approach is used clinically.

Meningioma consistency assessment based on the fusion of deep learning features and radiomics features

PURPOSE

This study aims to combine deep learning features with radiomics features for the computer-assisted preoperative assessment of meningioma consistency.

METHODS

202 patients with surgery and pathological diagnosis of meningiomas at our institution between December 2016 and December 2018 were retrospectively included in the study. The T2-fluid attenuated inversion recovery (T2-Flair) images were evaluated to classify meningioma as soft or hard by professional neurosurgeons based on Zada's consistency grading system. All the patients were split randomly into a training cohort (n = 162) and a testing cohort (n = 40). A convolutional neural network (CNN) model was proposed to extract deep learning features. These deep learning features were combined with radiomics features. After multiple feature selections, selected features were used to construct classification models using four classifiers. AUC was used to evaluate the performance of each classifier. A signature was further constructed by using the least absolute shrinkage and selection operator (LASSO). A nomogram based on the signature was created for predicting meningioma consistency.

RESULTS

The logistic regression classifier constructed using 17 radiomics features and 9 deep learning features provided the best performance with a precision of 0.855, a recall of 0.854, an F1-score of 0.852 and an AUC of 0.943 (95 % CI, 0.873-1.000) in the testing cohort. The C-index of the nomogram was 0.822 (95 % CI, 0.758-0.885) in the training cohort and 0.943 (95 % CI, 0.873-1.000) in the testing cohort with good calibration. Decision curve analysis further confirmed the clinical usefulness of the nomogram for predicting meningioma consistency.

CONCLUSIONS

The proposed method for assessing meningioma consistency based on the fusion of deep learning features and radiomics features is potentially clinically valuable. It can be used to assist physicians in the preoperative determination of tumor consistency.

Comparison of the Retrosigmoid Suprameatal and Anterior Subtemporal Transpetrosal Approaches After Full Exposure of the Internal Acoustic Meatus

BACKGROUND AND OBJECTIVES

Surgical approaches to the ventral brainstem and petroclival regions are complex, and standard retrosigmoid and subtemporal approaches are often inadequate. Retrosigmoid suprameatal tubercle (RSMTA) and anterior subtemporal transpetrosal (ASTA) approaches may provide extended surgical exposure with less brain retraction. The objective of this study was to evaluate advantages and disadvantages of RSMTA vs ASTA, and illustrate the surgical corridors and 3-dimensional microsurgical anatomy of the related structures.

METHODS

Four silicone-injected adult cadaver heads (8 sides) were dissected to evaluate the accessibility of lesions located at the petrous apex, ventral brainstem, and pontomedullary region using ASTA and RSTMA.

RESULTS

Both ASTA and RSMTA provide access from the petrous apex to the ventral lower pons and pontomedullary junction. A greater extent of safely resected bone was found in ASTA vs RSMTA. ASTA provides a larger surgical view to the ventrolateral midpons, peritrigeminal region, superior neurovascular complex, pontomesencephalic junction, and posterior cavernous sinus. Meanwhile, through cranial nerve V mobilization, RSMTA provides a larger surgical view to the lower half part of the pons, ventrolateral part of the pontomedullary junction, and middle and lower neurovascular structures.

CONCLUSION

The choice of surgical approach is determined by considering the area where the lesion originates, lesion size, the anatomic structures to which it extends, and evaluation of the area that can be surgically exposed. Our study highlights the differences between these approaches and important surgical anatomic considerations.

Postoperative Complications and Neurological Deficits After Petroclival Region Meningioma Resection: A Case Series

BACKGROUND

Surgical management of meningiomas involving the petroclival junction remains a challenge because of nearby critical neurovascular structures.

OBJECTIVE

To describe surgical approach selection, outcomes, and factors associated with postoperative complications and neurological deficits in a series of patients undergoing resection of petroclival region meningiomas.

METHODS

Retrospective review of patients undergoing symptomatic petroclival region meningioma resection was performed. Logistic regression was performed to identify variables associated with postoperative complications and new neurological deficits.

RESULTS

Sixty-five patients underwent 54 one-stage and 11 two-stage resections with median follow-up of 51 months. Most tumors were World Health Organization grade 1 (90.8%), and the median volume was 23.9 cm 3 . Posterior petrosectomy and anterior petrosectomy were performed in 67.1% and 6.6% of operations, respectively. The gross or near total resection rate was 15.4%, and 8 patients (12.3%) progressed on follow-up. The surgical complication rate was 26.2% with no perioperative mortalities. Postoperatively, 45.8% of patients had new, persistent neurological deficits, with cranial nerves VII palsy being most common. On multivariate analysis, higher body mass index (odds ratio [OR]: 1.1, P = .04) was associated with risk of surgical complications. Longer operative time (OR: 1.4, P = .004) and staged procedures (OR: 4.9, P = .04) were associated with risk of new neurological deficit on follow-up, likely reflecting more challenging tumors. Comparing early vs later career surgeries performed by the senior author, rates of severe complications and neurological deficits decreased 23.1% and 22.3%, respectively.

CONCLUSION

Petroclival region meningiomas remain surgically challenging, but improved outcomes are seen with surgeon experience. These data help inform patients on perioperative morbidity risk and provide a guide for surgical approach selection.

Combined petrosal approach: a systematic review and meta-analysis of surgical complications

Transpetrosal approaches are known to be associated with a significant risk of complications, including CSF leak, facial palsy, hearing impairment, venous injury, and/or temporal lobe injury. We aimed to evaluate the morbidity of the standard combined petrosal approach (CPA), defined as a combination of the posterior (retrolabyrinthine) and the anterior petrosal approach. We performed a systematic review and meta-analysis of articles reporting on clinical series of patients operated on for petroclival meningiomas through CPA. Studies that used the terminology "combined petrosal approach" without matching the aforementioned definition were excluded as well as clinical series that included less than 5 patients. A total of 8 studies were included involving 160 patients. The pooled complication rates were 3% (95% CI, 0.5-5.6) for CSF leak, 8.6% (95% CI, 4.1-13.2%) for facial palsy, 8.2% (95% CI, 3.9-12.6%) for hearing impairment, 2.8% (95% CI, 0.9-6.5%) for venous complications, and finally 4.8% (95%, 1.2-8.4%) for temporal lobe injury. Contrary to the general belief, CPA is associated with an acceptable rate of complications, especially when compared to alternative approaches to the petroclival area. In view of the major advantages like shorter trajectory, multiple angles of surgical attack, and early tumor devascularization, CPA remains an important tool in the armamentarium of the skull base surgeon.

Correlation of Surgical Outcomes of Petroclival Meningiomas with Clinicoradiologic Parameters and Molecular and Chromosomal Alterations

OBJECTIVE

To identify clinical, radiologic, intraoperative, histopathologic, and molecular factors that might affect the surgical outcome of petroclival meningiomas.

METHODS

Medical records of 53 cases of petroclival meningiomas operated from 2003 to 2021 were reviewed for clinicoradiologic and molecular factors that were correlated with extent of resection.

RESULTS

Modified Dolenc-Kawase anterior transpetrous rhomboid (44, 83.0%) was the most commonly used approach, followed by retrosigmoid (2, 3.8%) and combined (7, 13.2%) approaches. Hypointense tumors on T2-weighted magnetic resonance imaging (odds ratio [OR] 5.85; 95% confidence interval [CI] 1.70-20.41) and presence of brainstem edema (OR 4.53; 95% CI 1.36-15.12) were found to be significant factors increasing the likelihood of subtotal resection (STR; P = 0.004 and P = 0.011, respectively). In the presence of both tumor T2 hypointensity and brainstem edema, there was a significant increase in the likelihood of STR (P = 0.001; OR 25; 95% CI 3.52-177.48). Of the 16 cases for which molecular analysis was performed, no specimen was found to have pTERT, AKT-1 E17K, and SMO L412F and W535L mutations. All (100%) the patients harboring H3K27me3 loss and/or hemizygous CDKN2A deletion had cavernous sinus extension compared with 62.5% of patients without H3K27me3 loss and 72.7% with hemizygous CDKN2A retention. Similarly, hemizygous CDKN2A deletion and H3K27me3 loss were associated with an increase in the rate of brainstem edema from 27.3% to 60% and 25% to 50%, respectively.

CONCLUSIONS

T2 hypointense tumor and brainstem edema on preoperative imaging are significant predictors of STR. H3K27me3 loss and hemizygous CDKN2A deletion may be associated with cavernous sinus extension, suggesting their role in tumor spread.

The feasibility of three port endonasal, transorbital, and sublabial approach to the petroclival region: neurosurgical audit and multiportal anatomic quantitative investigation

PURPOSE

The petroclival region represents the "Achille's heel" for the neurosurgeons. Many ventral endoscopic routes to this region, mainly performed as isolated, have been described. The aim of the present study is to verify the feasibility of a modular, combined, multiportal approach to the petroclival region to overcome the limits of a single approach, in terms of exposure and working areas, brain retraction and manipulation of neurovascular structures.

METHODS

Four cadaver heads (8 sides) underwent endoscopic endonasal transclival, transorbital superior eyelid and contralateral sublabial transmaxillary-Caldwell-Luc approaches, to the petroclival region. CT scans were obtained before and after each approach to rigorously separate the contribution of each osteotomy and subsequentially to build a comprehensive 3D model of the progressively enlarged working area after each step.

RESULTS

The addition of the contralateral transmaxillary and transorbital corridors to the extended endoscopic endonasal transclival in a combined multiportal approach provides complementary paramedian trajectories to overcome the natural barrier represented by the parasellar and paraclival segments of the internal carotid artery, resulting in significantly greater area of exposure than a pure endonasal midline route (8,77 cm² and 11,14 cm² vs 4,68 cm² and 5,83cm², extradural and intradural, respectively).

CONCLUSION

The use of different endoscopic "head-on" trajectories can be combined in a wider multiportal extended approach to improve the ventral route to the most inaccessible petroclival regions. Finally, by combining these approaches and reiterating the importance of multiportal strategy, we quantitatively demonstrate the possibility to reach "far away" paramedian petroclival targets while preserving the neurovascular structures.

Skull Base Meningiomas

Skull base meningiomas are among the most challenging meningiomas to treat clinically due to their deep location, involvement or encasement of adjacent essential neurovascular structures (such as key arteries, cranial nerves, veins, and venous sinuses), and their often-large size prior to diagnosis. Although multimodal treatment strategies continue to evolve with advances in stereotactic and fractionated radiotherapy, surgical resection remains the mainstay of treatment for these tumors. Resection of these tumors however is challenging from a technical standpoint, and requires expertise in several skull-base surgical approaches that rely on adequate bony removal, minimization of brain retraction, and respect for nearby neurovascular structures. These skull base meningiomas originate from a variety of different structures including, but are not limited to: the clinoid processes, tuberculum sellae, dorsum sellae, sphenoid wing, petrous/petroclival area, falcotentorial region, cerebellopontine angle, and foramen magnum. In this chapter, we will cover the common anatomical areas in the skull base from which these tumors arise, and the specific or optimal surgical approaches and other treatment modalities for meningiomas in these such locations.

Surgical Strategy in Modification of the Transpetrosal Approach to Avoid Postoperative Venous Complications: A Report of 74 Consecutive Cases

BACKGROUND

The transpetrosal approach is a complex skull base procedure with a high risk of complications, particularly caused by injury of the venous system. It is in part related to variability of blood outflow pathways and their distinctive patterns in each individual patient.

OBJECTIVE

To evaluate outcomes and complications after skull base surgery with use of the petrosal approach modifications, which selection was based on the detailed preoperative assessment of venous drainage patterns.

METHODS

Overall, 74 patients, who underwent surgery via the transpetrosal approach at our institution between 2000 and 2017, were included in this study. In all cases, the venous drainage pattern was assessed preoperatively and categorized according to the predominant blood outflow pathway into four types as previously suggested by Hacker: (1) sphenoparietal sinus (SpPrt), (2) sphenobasal vein (SpB), (3) sphenopetrosal sinus (SpPS), and (4) cortical. The blood outflow through the bridging petrosal vein and the vein of Labbé was also taken into consideration. In patients with SpPrt- and a cortical-type venous drainage, the transpetrosal approach was used in a standard way. In patients with SpB-type venous drainage, limited extradural anterior petrosectomy was combined with intradural anterior petrosectomy after dural opening, superior petrosal sinus transection, tentorial cutting, Meckel's cave opening, and trigeminal nerve mobilization. In patients with SpPS-type venous drainage, after standard petrosectomy, dural opening, and tentorial cutting, SpPS ligation was done followed by 2-week interval before staged definitive tumor resection.

RESULTS

Gross total, near-total, and subtotal resection of the lesion (meningioma, 48 cases; retrochiasmatic craniopharyngioma, 11 cases; brain stem cavernoma, 7 cases; other tumors, 8 cases) was achieved in 30 (40.5%), 24 (32.4%), and 20 (27.0%) patients, respectively. Postoperative complications that were possibly related to venous compromise were noted in 18 patients (24.3%), but neither one was major. Of these 18 patients, 9 were symptomatic, but all symptoms-aphasia (4 cases), seizures (2 cases), and confusion (3 cases)-fully resolved after conservative treatment. Overall, 13 patients, including 4 symptomatic, had signal changes on T2-weighted brain MRI, which were permanent only in 3 cases (all asymptomatic).

CONCLUSION

Our suggested surgical strategy can be applied to any type of the venous drainage pattern. Preoperative evaluation and intraoperative preservation of the blood outflow pathways are crucial means for safe and effective application of the transpetrosal approach.

Mortality and morbidity in surgically treated patients with petroclival meningiomas: a systematic review and meta-analysis of case series

BACKGROUND

Reports on petroclival meningioma (PCM) surgical mortality and morbidity often deviate from established standards; as such, a comprehensive summary is lacking.

METHODS

Eligibility/sources. Peer-reviewed case series of at least 10 PCM patients identified from PubMed, Web of Science, Ovid, or Google Scholar. Outcomes. Primary: mortality, tumor recurrence, any cranial nerve deficit (CND); other: individual CNDs, other complications. Data synthesis. Random-effects meta-analysis/meta-regression [effects: surgical approach (supratentorial, S; infratentorial, I; combined, (C), average age and follow-up, sample size, and percent of patients with gross-total resection (GTR)] of logit-transformed proportions.

RESULTS

Data. 73 case-series/3553 patients. Mortality. Adjusted predicted mortalities of 2.4%, 2.5%, and 1.2% (50-month follow-up) for the S, I, and C approaches, respectively, with the upper limits of the 95% credibility intervals at 3.3%, 3.7%, and 3.6%, respectively. Recurrence. Adjusted predicted recurrences of 5.5%, 11.1%, and 12.0% (50-month follow-up and 57% GTR) for the S, I, and C approaches, respectively; recurrence was positively associated with follow-up period and negatively associated with having received GTR. At all covariates at median values but at GTR 90% predictions: 3.1% (95%CI 3.1-9.8), 6.3% (3.8-10.4), and 6.9% (3.4-13.2) with the S, I, and C; prediction credibility intervals 1-4% and 22.4%. Any CND. Adjusted predicted probabilities of 37.2%, 23.4%, and 29.5% (at median covariate values) for the S, I, and C approaches, respectively; prediction credibility intervals ranged from <10% to 78%. Other outcomes. The most common individual CNDs were nVII (14.4%), nV (11.5%), and nIII (10.2%); other common complications included motor deficit (10.8%), infection (9.8%), and CSF leak (7.5%).

CONCLUSION

This is the first systematic review on PCM surgical mortality, recurrence, and morbidity. Outcomes differ between surgical approaches and reporting quality varies greatly.

The Bigger the Better? Analysis of Surgical Complications and Outcome of the Retrosigmoid Approach in 449 Oncological Cases

Introduction

Exposure of the posterior skull base and the cerebellopontine angle is challenging due to important neurovascular structures. The retrosigmoid approach (RSA) has become the standard method used in surgery. We report our experiences with RSAs regarding technical obstacles, complications, and approach-related outcomes.

Materials and Methods

We performed a retrospective chart review at a tertiary neurosurgical center between January 2007 and September 2020. We included all patients undergoing surgery for oncologic lesions through RSAs, concentrating on surgical technique, postoperative outcome, and complications.

Results

A total of 449 RSAs were included. The median age at the time of surgery was 58 years; 168 (37.4%) were male and 281 (62.6%) were female. The median approach surface was 7.8 cm². The median tumor volume was 5.9 cm³. The median Clavien–Dindo grade was 2, the total complication rate was 28.7%, and gross total resection (GTR) was 78.8%. Findings revealed that tumor volume had no significant impact on postoperative complications in general (p = 0.086) but had a significant impact on postoperative hemorrhage (p = 0.037) and hydrocephalus (p = 0.019). Tumor volume was significant for several preoperative symptoms (p < 0.001). The extent of the approach had no significant impact on complications in general (p = 0.120) but was significant regarding postoperative cerebrospinal fluid (CSF) leaks (p = 0.008). Craniotomy size was not significant regarding GTR (p = 0.178); GTR rate just missed significant correlation with tumor volume (p = 0.056). However, in the case of vestibular schwannomas, the size of craniotomy was important for GTR (p = 0.041).

Conclusion

Tumor volume has an important impact on preoperative symptoms as well as on postoperative complications. Although the extent of the craniotomy barely missed significance regarding GTR, a correlation can be assumed. Thus, the extent of craniotomy should be taken into presurgical consideration, especially in the case of postoperative CSF leaks. Regarding vestibular schwannomas, craniotomy size plays an important role in achieving satisfactory oncological outcomes. Different approaches should be selected where necessary regarding superior resection rates.

The mini-combined transpetrosal approach: an anatomical study and comparison with the combined transpetrosal approach

BACKGROUND

The combined transpetrosal approach (CTPA) is a versatile technique suitable for challenging skull base pathologies. Despite the advantages provided by a wide surgical exposure, the soft tissue trauma, complex and time-consuming bony work, and cosmetic issues make it far from patient expectations. In this study, the authors describe a less invasive modification of the CTPA, the mini-combined transpetrosal approach (mini-CTPA), and perform a quantitative comparison between these two approaches.

METHODS

Five human specimens were used for this study. CTPA was performed on one side and mini-CTPA on the opposite side. The surgical freedom, petroclival and brainstem area of exposure, and maneuverability for 6 anatomical targets, provided by the CTPA and mini-CTPA, were calculated and statistically compared. The bony volumes corresponding to each anterior petrosectomy were also measured and compared. Three clinical cases with an operative video are also reported to illustrate the effectiveness of the approach.

RESULTS

The question-mark skin incision done along the muscle attachments permits an optimal cosmetic result. Even though the limited incision, the smaller craniotomy, and the less extensive bone drilling of mini-CTPA provide a smaller area of surgical freedom, the areas of exposure of petroclival region and brainstem were not statistically different between the two approaches. The antero-posterior maneuverability for the oculomotor foramen (OF), Meckel's cave (MC) and the REZ of trigeminal nerve, and the supero-inferior maneuverability for OF, MC, Dorello's canal, and REZ of CN VII are significantly reduced by the smaller opening. The bony volume of anterior petrosectomy resulted similar among the approaches.

CONCLUSIONS

The mini-CTPA is an interesting alternative to the CTPA, providing comparable surgical exposure both for petroclival region and for brainstem. Although the lesser soft tissue dissection and bony opening decrease the surgical maneuverability, the mini-CTPA may reduce surgical time, potential approach-related morbidities, and improve cosmetic and functional outcomes for the patients.

Endoscopic-assisted combined transcrusal anterior petrosal approach for resection of large petroclival meningioma: operative video and nuances of technique

In this illustrative video, the authors demonstrate an endoscopic-assisted combined transcrusal anterior petrosal approach for resection of a large petroclival meningioma with significant brainstem compression involving Meckel’s cave. This unique petrosal variant provides increased petroclival exposure that can potentially preserve hearing by combining a transcrusal labyrinthectomy with anterior petrosectomy (Kawase’s approach). The advantages include multidirectional angles of attack to the brainstem and petroclival region without cerebellar retraction. Endoscopic assistance allows expanded visualization into deep surgical corridors. The surgery was performed in a two-stage fashion, and a near-total resection was achieved with cranial nerve and hearing preservation. The operative nuances are demonstrated.

The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21257

Microsurgical resection of a large petroclival meningioma via translabyrinthine approach combined with middle fossa craniotomy

Petroclival meningiomas arise from the upper two-thirds of the clivus at the petroclival junction and are reached via various approaches. As petroclival meningiomas expand, they displace the brainstem and basilar artery toward the contralateral side. Because of their proximity to critical structures and deep skull base location, surgical treatment is challenging. Although several approaches have been introduced, their rationales vary. Herein, the authors demonstrate microsurgical resection of a large petroclival meningioma via a translabyrinthine approach combined with middle fossa craniotomy. For each approach, the pros and cons should be carefully evaluated based on the patient’s presentation and lesion characteristics.

The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21253

Anterior petrosal (Kawase) approach to petroclival meningioma: 2-dimensional operative video

Petroclival meningiomas are challenging lesions that can be treated with several surgical approaches. The authors present a 66-year-old woman with a 1.6-cm left petroclival meningioma that was initially observed and then radiated after it grew 8 years later. Despite radiation, the tumor continued to grow to 4 cm; therefore, the patient was referred to the authors’ institution. A left anterior petrosal (Kawase) approach was performed. Postoperatively, the patient had transient cranial nerve IV and VI palsy that improved. The case presentation, surgical anatomy, operative technique, postoperative course, and different surgical approaches are reviewed. The patient gave verbal consent for participating in the surgical video.

The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21259

The combined TL-RS approach: Advantages and disadvantages of working 360 degrees around the sigmoid sinus

Abstract Objective: To highlight the advantages and disadvantages of the combined translabyrinthine (TL) and classic retrosigmoid (RS) approach. Design: Retrospective chart review. Setting: National Tertiary Referral Center for skull base pathology. Participants: Twenty-two patients with very large cerebellopontine angle tumors were resected using the combined TL-RS approach. Main outcome measures: Preoperative patient characteristics, including age, sex, and hearing loss. Tumor characteristics, pathology, and size. Intraoperative outcome: Tumor removal. Postoperative outcomes included facial nerve function, residual tumor growth, and neurological deficits. Results: Thirteen patients had schwannoma, eight had meningioma, and one had both. The mean age was 47 years, mean tumor size was 39 × 32 × 35 mm (anterior-posterior, medial-lateral, craniocaudal), and mean follow-up period was 80 months. Tumor control was achieved in 13 patients (59%), and nine (41%) had residual tumor growth that required additional treatment. Seventeen patients (77%) had postoperative HouseBrackmann (HB) facial nerve function grade 12, one had HB grade 3, one HB V, and three HB VI. Conclusion: Combining TL and RS approach may be helpful in safely removing large meningiomas and schwannomas in selected cases. This valuable technique should be considered when sufficient exposure cannot be achieved with the TL or RS approach alone.

Tailored Skull Base Approach to Management of Intracranial Aneurysms

Surgical management of intracranial aneurysms (IAs) remains one of the most challenging and dynamic tasks for neurosurgeons. The rivalry between modern time microsurgery and progress in endovascular intervention has provided a great arena for advancement and lead to redefine training concept and referral pattern. Both approaches has its own merits, risks and complications and the best outcome is achieved by case individualization and complimentary multidisciplinary approach.The recent innovation in microscopic and endoscopic tailored skull base approaches, intraoperative 3D and ICG video-angiography, design of high quality aneurysm clips, and refinement of cerebral bypass techniques enhance IAs neurosurgical management and their clinical outcome. The command of tailored skull base approaches should be part of the training curriculum of young generation of neurosurgeons to compliment the emerging treatment options of endovascular intervention.

Combined Presigmoid-Subtemporal Approach in a Semi-Sitting Position for Petroclival Meningiomas: A Technical Report

The removal of petroclival meningiomas (PMs) is considered a neurosurgical challenge due to the critical mobilization of key neurovascular structures. Limited knowledge about the benefits of operating on patients with PMs using the combined presigmoid-subtemporal approach (CPSA) in a semi-sitting position has precluded its generalizability. We report on ten patients with PMs operated in a semi-sitting position using CPSA. We remark that before the surgical approach was accomplished in our group of patients, the CPSA via semi-sitting position was conducted and standardized in six adult cadaveric heads. The neuroanatomic dissections made in cadavers allowed us to confidently use CPSA in our set of patients. There were no comorbidities, perioperative complications, or deaths associated with the surgical procedure. CPSA via a semi-sitting position can be considered a safe approach to remove PMs.

Modified Transpetrosal-Transtentorial Approach for Resection of Large and Giant Petroclival Meningioma: Technical Nuance and Surgical Experiences

BACKGROUND

 Meningiomas arising from the petroclival area remain a challenge for neurosurgeons. Various approaches have been proposed to achieve maximum resection with minimal morbidity and mortality. Also, some articles correlated preservation of adjacent veins with less neurologic deficits.

OBJECTIVE

 To describe the experiences in using a new technique to achieve maximal resection of petroclival meningiomas and preserving the superior petrosal veins (SPVs) and the superior petrosal sinus (SPS).

METHODS

 A retrospective analysis of 26 patients harboring a true petroclival meningioma with a diameter ≥25 mm and undergoing surgery with the modified transpetrosal-transtentorial approach (MTTA) was performed.

RESULTS

 Fifty-four percent of 22 patients complained of severe headache at presentation. There was also complaint of cranial nerve (CN) deficit, with CN VII deficit being the most common (present in 42% of patients). The average tumor size (measured as maximum diameter) was 45.2 mm, and most of the tumors compressed the brainstem. Total resection was achieved in 12 patients (46.2%), whereas the others were excised subtotally (54.8%). Most of the patients had WHO grade I (96.1%) meningioma; only one had a grade II (3.8%) meningioma. In addition, clinical improvement and persistence of symptoms were observed in 17 (65.4%) and 8 (30.7%) patients, respectively, and postoperative permanent CN injury was observed in 3 (11.5%) patients.

CONCLUSION

 Using the MTTA, maximal resection with preservation of the CNs and neurovascular SPV-SPS complex can be achieved. Therefore, further studies and improvements of the technique are required to increase the total resection rate without neglecting the complications that may develop postoperatively.

Combined Microscopic-Endoscopic Transmastoid Resection of a Petrous Meningioma: 2-Dimensional Operative Video

Petrous meningiomas are defined as tumors with a basal dural attachment on the posterior surface of the petrous bone.1 Their insertion can be anterior to the meatus (petrous apex meningiomas), or posterior to the meatus, with associated hyperostotic bony invasion either pre- or retro-meatal.2 These meningiomas are amenable to curative surgical removal and have better surgical outcomes than more medially located true petroclival meningiomas that originate medial to the fifth nerve.2-4 They, however, remain challenging because of their close relationship to critical neurovascular structures in the cerebellopontine angle.5 The posterior petrous meningiomas might reach a significant size with compression of the cerebellum, the brainstem, and involvement of the cranial nerves, and extend posteriorly to the transverse sigmoid sinus.2,6  Transmastoid approach with skeletonization and lateral reflection of the transverse sigmoid sinus provides a superb exposure without cerebellar retraction.6,7 The ease and complete resection of the tumor and invaded bone can be facilitated by combined microscopic-endoscopic techniques. We demonstrate these principles through the resection of a petrosal meningioma in a 56-yr-patient who presented with headaches, nystagmus, and mild cerebellar signs. The patient consented to the procedure.  Image at 1:36 reprinted with permission from Al-Mefty O, Operative Atlas of Meningiomas. Vol 1, ©LWW, 1998.

Minimal anterior and posterior combined transpetrosal approach for large petroclival meningiomas

OBJECTIVE

Petroclival meningiomas (PCMs) remain difficult to remove, and radical tumor resection continues to pose a relatively high risk of neurological morbidity in patients with these lesions because of the proximity of the tumor to neurovascular structures. The anterior and posterior combined (APC) transpetrosal approach allows resection of a large petroclival lesion with minimal retraction of the temporal lobe. However, this approach is thought to be complex and time-consuming. The authors simplified this approach by minimizing the petrosectomy and used this method for large PCMs. This retrospective study describes the surgical technique and surgical outcomes of large PCMs.

METHODS

Between 2014 and 2019, 23 patients (19 women and 4 men) with benign (WHO grade I) PCMs were treated using the minimal APC (MAPC) transpetrosal approach. The mean age at surgery was 54.0 years (range 37-74 years). The mean tumor diameter was 40.3 mm (range 30-74 mm). The surgical technique consisted of a temporo-suboccipital craniotomy and minimal drilling of the petrous ridge. After opening Meckel's cave and removing the lesion at the prepontine cistern, drilling of the petrous apex with superior mobilization of the trigeminal nerve was performed through the subdural space for further tumor resection around the petrous apex. Finally, the tumor was removed as much as possible.

RESULTS

The mean preoperative and postoperative tumor volumes were 26.8 and 1.3 cm3, respectively. The mean extent of resection was 95.4% (range 62%-100%). Postoperative impairments included facial numbness in 7 patients, trochlear nerve palsy in 3 patients, mild oculomotor nerve palsy in 2 patients, and transient abducens nerve palsy in 1 patient. Preoperative Karnofsky Performance Status was improved in 13 patients, remained stable in 9 patients, and deteriorated in 1 patient.

CONCLUSIONS

The MAPC transpetrosal approach provides sufficiently wide exposure of petroclival lesions. Maximal resection via the MAPC transpetrosal approach is a suitable surgical option for the treatment of large PCMs.

The Minimally Invasive Posterolateral Transcavernous-Transtentorial Approach. Technical Nuances, Proof of Feasibility, and Surgical Outcomes Throughout a Case Series of Sphenopetroclival Meningiomas

OBJECTIVE

Sphenopetroclival (SPC) meningiomas are considered among the most complex skull-base neoplasms to approach surgically. We aim to determine whether some SPC meningiomas can be safely and effectively treated using a modified minimally invasive pterional posterolateral transcavernous-transtentorial approach (MIPLATTA).

METHODS

Fourteen patients harboring SPC meningiomas were surgically treated through a MIPLATTA. MIPLATTA includes a minipterional craniotomy, anterior extradural clinoidectomy, peeling of the temporal fossa, decompression of cranial nerves (CNs) in the cavernous sinus, and sectioning of the tentorium to reach the upper part of the posterior fossa.

RESULTS

Gross total resection was achieved in 11 of 14 patients (78%), whereas near-total resection was accomplished in the other 3 patients (22%), each of whom underwent a further complementary retrosigmoid approach for gross total tumor resection. There were no deaths, and 13 of 14 patients were independent at 6 months follow-up (modified Rankin Scale score ≤2). One patient had pontine infarction after the procedure and experienced moderate disability at follow-up (modified Rankin Scale score 3). All patients had some degree of CN impairment. Of 38 cranial neuropathies, 15 (39%) improved, 20 (53%) remained stable, and 3 (8%) worsened postoperatively. Four new CN deficits were observed postoperatively in 3 patients (fourth CN, 2 patients; third CN, 1; fifth CN, 1).

CONCLUSIONS

MIPLATTA is a useful and safe treatment alternative that allows resection of large SPC tumors with dominant invasion of cavernous sinus and middle fossa, preserves hearing and facial motor function, and provides good chances of recovery of visual and oculomotor deficits.

Petroclival Meningiomas: A Simple System That Could Help in Selecting the Approach

BACKGROUND

Petroclival meningiomas (PCM) represent a neurosurgical challenge due to their strategic location close to the brainstem.

OBJECTIVE

To assess the applicability of a retrosigmoid approach (RSA) by analyzing the degree of displacement of the middle cerebellar peduncle (MCP) elicited by PCM.

METHODS

Patients with PCM were prospectively included and divided into those whose imaging studies showed that the posterior end of the MCP was displaced by the tumor and were eligible for and underwent RSA (group A) and those who were not eligible for RSA and who underwent surgery via a posterior transpetrosal approach (group B). We compared tumor behavior, clinical characteristic of patients and surgical results.

RESULTS

Twenty patients with PCM were enrolled and allocated to group A (n = 15) or group B (n = 5). The clinical manifestations were more severe in group B; tumors in this group were larger and gross total removal was achieved in only 1 patient (20%). In comparison, in 12 cases on group A, tumors could be totally removed (80%) and all of these patients could recover their quality of life after surgery.

CONCLUSION

To our knowledge, this study is the first to consider displacement of the MCP when establishing a suitable surgical approach for PCM. Our results suggest that the RSA becomes increasingly suitable when peduncle displacement is greater. By using this method, it was also possible to identify two types of tumors: petroclivals (group A) and clivopetrosals (group B), that show some specific clinical and surgical differences.

Two-Stage Double Petrosal Approach for the Total Resection of Petroclival-Cavernous Meningioma: 2-Dimensional Operative Video

The utilization of skull base approaches has markedly facilitated the safe surgical removal of challenging petroclival meningiomas.1 The anterior petrosal approach has been utilized for tumors limited to the upper clivus, above the meatus, whereas the posterior petrosal approach has been the workhorse for the resection of larger tumors in the posterior fossa extending down the clivus.2 Giant cases with extension in the middle fossa, cavernous sinus, and ventral to the brain stem would benefit from a wider exposure than each of these approaches provide. This could be achieved by total petrosectomy. However, in patients with serviceable hearing anterior and posterior petrosals can be combined while preserving the hearing apparatus.2,3 This procedure is lengthy; hence, we tend to stage it in 2 subsequent days. The first stage is focused on the soft tissue and bone work including the mastoidectomy, sigmoid transverse sinus, and jugular bulb skeletonization, as well as anterior petrosectomy. The second stage is dedicated to tumor exposure through tentorial sectioning and microsurgical resection. We report the case of a 40-yr-old woman diagnosed with large left-sided petroclival meningioma with significant extension into the cavernous sinus and Meckel's cave. The patient had neurological deficits including cranial nerves, cerebellar dysfunction, and hydrocephalus, although her hearing was intact. Total tumor resection was achieved through the double petrosal approach in 2002. Extensive anatomic knowledge and thorough preoperative clinical and radiological evaluation, particularly the venous system, are key in the successful planning of this procedure. The patient consented for surgery and publication of their image.  Figures at 2:40 and 3:47, ©Ossama Al-Mefty, used with permission.

Total Petrosectomy for the Total Resection of Sphenopetroclival Meningioma: 2-Dimensional Operative Video

Sphenopetroclival meningioma is a most formidable meningioma. Many patients have few preoperative deficits and surgery has the potential of severe neurological complications. Surgical treatment is challenging due to brainstem compression, the involvement of multiple cranial nerves and cerebral vessels. Wide tumor exposure, multiple dissection axis, and short distance are paramount factors in the quest of achieving total removal of Simpson grade I, including the involved dura and bone. The posterior petrosal, transtentorial presigmoid approach offers a wide and shallow operative field.1-7 When the patient has hearing loss, extending the resection of the temporal bone provides unmatchable exposure facilitating safer and more complete tumor removal. This article demonstrates the removal of a sphenopetroclival meningioma through total petrosectomy with closing of the external auditory canal and preservation of the facial nerve in the Fallopian canal. A total resection of the tumor was achieved with long-term preservation of cranial nerve function. The surgical steps of total petrosectomy are shown, including the skin flap, combined middle and posterior fossa craniotomy, skeletonization of the sigmoid transverse sinus, radical mastoidectomy, dissection of the Fallopian canal, and drilling of the labyrinth, cochlea, and petrous apex for superb exposure.8 We demonstrate the intra-arachnoidal microsurgical dissection utilized for the radical resection of petroclival meningioma. This surgery performed in 1995 is a testament to the time-tested technique. The patient consented to the procedure and image use. Images at 1:33 and 3:57 © Ossama Al-Mefty, used with permission.

Dissection of the Petrosal Presigmoid-Retrolabyrinthine Approach for the Petroclival Region on a Cadaver: 2-Dimensional Operative Video

Skull base epidermoid tumors, meningiomas, and schwannomas can be accessed by different techniques depending on the location and size of the lesion. Small lesions located anterior to the internal acoustic meatus (IAM) can be accessed via the subtemporal approach, and lesions located posterior to the IAM can be approached via retrosigmoid craniotomy. However, expansive lesions that are located anterior to the IAM and extend posteriorly toward the lower clivus can be accessed via the petrosal approach. The petrosal approach (presigmoid-retrolabyrinthine) is centered on the petrous ridge of the temporal bone and is mainly performed for intradural lesions located at the clivus and petroclivus junction area. Patients with intact hearing can benefit from this technique, as the labyrinth is untouched and yet the middle and posterior fossa compartments are connected. Additionally, extension of the lesion from the suprasellar area/cavernous sinus to the foramen magnum can be dissected and removed. There are variations of the petrosal approach, such as translabyrinthine, transotic, and transchoclear, with which hearing cannot be preserved, and the "transcrusal" approach, wherein posterior and superior semicircular canals are sacrificed yet hearing preserved. The endolymphatic duct is usually transected and not reapproximated. Neurotology input is always helpful when dealing with inner ear structures. This complex approach demands exhaustive practice with temporal bone dissection in a cadaver laboratory. Although this approach can be extended anteriorly, combination with an anterior petrosal approach permits more rostral exposure. In this video, we demonstrate the stepwise dissection of the posterior petrosal approach only, showing procedure nuances in a cadaver.1-8Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Venous Anatomy Influence on the Approach Selection of a Petroclival Clear Cell Meningioma With Associated Multiple Spinal Meningiomas: 2-Dimensional Operative Video

Preoperative careful evaluation of the sigmoid transverse sinus and its tributary veins is paramount for the safe surgical planning of petroclival lesions.1,2 When the vein of Labbé is running within the tentorium, classic petrosal approach involving transection of the tentorium is modified to avoid the risk of postoperative morbid temporal lobe venous infarcts.1-3 Thus, the surgical plan should be tailored to the specific patient anatomy as demonstrated in the presented case during which a transmastoid approach was followed, in the same surgical setting, by a middle fossa approach to resect a large petroclival clear cell meningioma with extension into Meckel cave. These meningiomas are WHO grade II tumors with a propensity to local recurrence and cerebrospinal fluid seeding.4 SMARCE1 mutations define this subtype of meningioma, with frequent familial inheritance, and predispose patients to both skull base and spinal clear cell meningiomas.5,6 Maximal surgical resection is the best initial treatment option allowing to withhold or delay the use of radiation in tumors frequently encountered in young patients.7 In this report, we demonstrate the microsurgical techniques deployed to achieve maximal resection of a petroclival clear cell meningioma and associated lumbar and sacral spinal meningiomas in a 20-yr-old patient with a familial SMARCE1 mutation. The patient agreed to the surgical intervention and to the use of her image.

Differences in surgical outcome between petroclival meningioma and anterior petrous meningioma

BACKGROUND

Petroclival meningiomas (PC MNGs) and anterior petrous meningiomas (AP MNGs) have similar locations. However, these are different tumors clearly divided by the trigeminal nerve. There has never been a study on the comparison of the surgical outcomes of these two meningiomas. In this study, we compared and analyzed the surgical outcome of PC MNGs and AP MNGs.

METHODS

The charts of 85 patients diagnosed with PC MNGs of AP MNGs who underwent surgical treatment were retrospectively reviewed. And we analyzed the characteristics of 49 PC MNGs (57.6%) and compared them with those of 36 AP MNGs.

RESULTS

Preoperative brainstem edema was observed in 11 patients (22.4%) of the PC MNG group and 1 patient (2.8%) of the AP MNG group (p = 0.024). Total tumor removal was achieved in 21 patients (58.3%) of the AP MNG group, but only 17 patients (34.7%) of the PC MNG group were able to completely (p = 0.047). In addition, sixth cranial nerve palsy occurred in 17 patients (34.7%) of the PC MNG group and 4 patients (11.1%) of the AP MNG group (p = 0.025).

CONCLUSIONS

In this study, we found that PC MNGs has a worse surgical outcome than AP MNGs, because PC MNGs were difficult to completely remove and were more likely to damage abducens nerve.

Importance of Sufficient Petrosectomy in an Anterior Petrosal Approach: Relightening of the Kawase Pyramid

BACKGROUND

In 1985, Kawase published an anterior petrosal approach to expose the posterior cranial fossa and to minimize retraction of the temporal lobe. However, some neurosurgeons still have difficulty with removing tumors through an anterior petrosal approach because a complete understanding of the Kawase pyramid has not been achieved. We hypothesized that if anterior petrosectomy were performed with three-dimensional understanding of the Kawase pyramid, it would have a positive effect on extent of tumor resection.

METHODS

We performed a retrospective study of patients who underwent surgical treatment for meningioma through an anterior petrosal approach. Patients were divided into total resection and subtotal resection groups, and statistical differences between the groups were analyzed. To identify factors predictive of complete tumor removal, univariable and multivariable logistic regression analyses were performed.

RESULTS

Width and height of the drilled internal auditory canal of the total resection group were significantly larger than those of the subtotal resection group (P = 0.001, P = 0.033). The operative angle of the total resection group was significantly larger than that of the subtotal resection group (P < 0.001). Regression analyses showed only drilled internal auditory canal width to be predictive of complete tumor removal, increasing the likelihood of complete tumor removal by 2.778-fold with an increase in drilled internal auditory canal width by 1 mm (P = 0.023).

CONCLUSIONS

Insufficient petrosectomy during an anterior petrosal approach adversely affects the extent of tumor resection. Furthering three-dimensional understanding of the Kawase pyramid could aid in complete tumor resection and better outcomes without causing damage to the surrounding organs.

Petroclival Meningioma: Management Strategy and Results in 21st Century

Background

Petroclival meningioma (PCM) is considered among the most difficult tumors to be treated by microneurosurgery because of its location and its relation to critical structures. The authors report on the outcome in a series of patients with PCM treated in the new millennium with a tailored approach of gross total excision or subtotal removal and adjuvant Gamma Knife Radiosurgery (GKR) depending on the particular case.

Methods

Between 2001 and 2017, 72 consecutive PCMs were operated in a single center by the senior surgeon. Clinical presentation, operative approaches, intraoperative findings, complications, and imaging findings were retrospectively analyzed. Postoperative outcome, adjuvant Gamma knife, and follow-up findings were reviewed.

Results

The average age was 47.95 years, and female-to-male ratio was 52:20. Cavernous sinus extension was present in 21 patients. The mean duration of follow-up was 66.65 months. Gross-total resection, near-total resection (NTR), and subtotal resection (STR) resection was achieved in 30, 24, and 18 (42.8%, 34.28%, and 25%) patients, respectively, with recurrences of 10%, 33%, and 50%, respectively. Twenty-two patients (18 STR and 4 NTR) had received postoperative GKR. Only four patients had recurrences following GKR. New cranial nerve deficits were more common in patients in whom a total resection was performed. There was no mortality.

Conclusions

Gross total excision had the best recurrence free rate though with a higher morbidity. Upfront GKR is advisable in patients with residual tumor, if the preoperative temporal course had a rapid symptomatology, to reduce recurrence. Wait and watch for a small intracavernous residue and radiosurgery on growth is also a valid option as long as follow-up is not suspect. A flexible approach of individualizing the treatment protocol for a given patient goes a long way toward optimal outcome.

Tentorial Peeling: Surgical Extradural Navigation to Protect the Temporal Lobe in the Focused Combined Transpetrosal Approach

BACKGROUND

Transpetrosal approaches have been used for treatment of tumors in the petroclival region for many years. Injury to the temporal lobe, however, has been a potential drawback of the techniques described to date.

OBJECTIVE

To describe modifications of the transpetrosal surgical technique, which allows extradural manipulation of the temporal lobe during the focused combined transpetrosal approach. This extra layer of protection avoids mechanical brain retraction, direct trauma to the temporal lobe and disruption of the local venous structures.

METHODS

The present manuscript describes an innovative technical nuance based on the combination of the focused combined transpetrosal approach, the peeling of the dural layers of the tentorium, and the reverse peeling of the middle fossa dura mater. Ample illustrative material is provided and illustrative cases are presented.

CONCLUSION

Peeling of the dural layers of the tentorium is a promising modification of the transpetrosal approach to increase the safety of the temporal lobe manipulation.

Petroclival meningiomas: the risk of post-operative cranial nerve deficits among different surgical approaches-a systematic review and meta-analysis

BACKGROUND

The surgical resection of petroclival meningiomas (PCMs) remains a challenge. Both the relationship with neurovascular structures and the deep location of the tumor can affect the extent of resection and the rate of post-operative morbidity.

METHODS

The authors performed a systematic review and meta-analysis of the literature examining the rate of new cranial nerve (CN) deficits after resection of PCM. A systematic search of two databases was performed for studies published between 1990 and 2018. Random-effect meta-analysis was used to pool the rate of post-operative CN deficits, mortality rate, and rate of radical resection.

RESULTS

We included twelve studies and 334 patients harboring PCM. The overall rate of complete resection was 68% (95% CI 57.9-78.2%; p < 0.01; I² = 83%). The rate of early and late post-operative CN deficits was the following: 3.8 and 2.7% (III CN), 6.6 and 3% (IV), 7.3 and 5.5% (V CN), 8 and 3.6% (VI CN), 8.9 and 8.9%% (VIII), and 4 and 2.7% (IX-XI CNs) (I² = 0%, and p < 0.01 for all analyses). The risk of post-operative deficit of the IV CN was higher among the petrosal group (7.6%; I² = 0% vs 2.1%; I² = 0%), whereas the impairment of VII CN function was higher among retrosigmoid group (16.6%; I² = 64.6% vs 11.4%; I² = 52.8%), but it was transient in the majority of cases.

CONCLUSIONS

This systematic review and meta-analysis provides a detailed overview of post-operative CN deficits ensuing surgical resection of PCMs. These findings should be acknowledged when counseling patients with PCMs regarding the more appropriate approach for their tumor.

Microscopic and Endoscopic Skull Base Approaches Hands-On Cadaver Course at 30: Historical Vignette

Laboratory-based cadaveric training is essential for the development and refinement of neurosurgical technical skills in the operating room and has become an integral training component around the world. Postresidency fellowship-the first pillar of skull base surgery training-includes both hands-on clinical care and surgery supervised by an experienced skull base surgeon. Time is spent in a skull base laboratory practicing approaches and developing anatomic mastery. The second pillar includes formal skull-base courses-institutional dissection laboratories provide continuous anatomic and surgical education while complementary annual or semiannual cadaver courses gather recognized experts to share their knowledge and experience in an essential 2- to 3-day setting. In this paper, we present the history of the longest running annual skull-base cadaver microsurgical course, which was started by Dr. Ossama Al-Mefty: Annual Surgical Approaches to the Skull Base Course. At the Microscopic and Endoscopic Hands-on Cadaver Workshop, held in St. Louis, Missouri, we celebrated its 30th anniversary in April 2019. We also present the impact this course has had on neurosurgery and skull base surgery and on the professional and scientific developments of its participants in particular.

Petroclival meningiomas: long-term outcomes of multimodal treatments and management strategies based on 30 years of experience at a single institution

OBJECTIVE

A thorough investigation of the long-term outcomes and chronological changes of multimodal treatments for petroclival meningiomas is required to establish optimal management strategies. The authors retrospectively reviewed the long-term clinical outcomes of patients with petroclival meningioma according to various treatments, including various surgical approaches, and they suggest treatment strategies based on 30 years of experience at a single institution.

METHODS

Ninety-two patients with petroclival meningiomas were treated surgically at the authors' institution from 1986 to 2015. Patient demographics, overall survival, local tumor control rates, and functional outcomes according to multimodal treatments, as well as chronological change in management strategies, were evaluated. The mean clinical and radiological follow-up periods were 121 months (range 1-368 months) and 105 months (range 1-348 months), respectively.

RESULTS

A posterior transpetrosal approach was most frequently selected and was followed in 44 patients (48%); a simple retrosigmoid approach, undertaken in 30 patients, was the second most common. The initial extent of resection and following adjuvant treatment modality were classified into 3 subgroups: gross-total resection (GTR) only in 13 patients; non-GTR treatment followed by adjuvant radiosurgery or radiation therapy (non-GTR+RS/RT) in 56 patients; and non-GTR without adjuvant treatment (non-GTR only) in 23 patients. The overall progression-free survival rate was 85.8% at 5 years and 81.2% at 10 years. Progression or recurrence rates according to each subgroup were 7.7%, 12.5%, and 30.4%, respectively.

CONCLUSIONS

The authors' preferred multimodal treatment strategy, that of planned incomplete resection and subsequent adjuvant radiosurgery, is a feasible option for the management of patients with large petroclival meningiomas, considering both local tumor control and postoperative quality of life.

Natural history of intracranial meningiomas

We know that the extent of resection is the greatest predictor of long-term survival. However, the potential tradeoff for gross total resection in difficult locations is diminished quality of life. Benign subtotally resected or small incidentally discovered meningiomas may be followed clinically especially in the elderly. In addition, radiosurgery plays a role in the treatment of meningiomas as a primary treatment modality, or as a salvage therapy. Decisions regarding management should be made with an understanding of the natural history and rate of growth. In this chapter we review the known meningioma epidemiology as well as the growth patterns of meningiomas based upon location.

Petroclival meningiomas and the petrosal approach

As with other meningiomas, the goal of petroclival meningioma treatment should be curative total removal by achieving a Simpson I resection of the tumor, dura, and bone. Petroclival meningiomas particularly pose a great technical challenge because of their deep location and intimate relation with vital neurovascular structures. They require adequate exposure and trajectory to achieve total removal while minimizing the manipulation and risk to critical neurovascular structures, such as the vertebrobasilar system, the brainstem, and the cranial nerves. Here, we describe the indications and technical nuances of the posterior and combined posterior-anterior petrosal approaches for petroclival meningiomas.

Association between the Symptomatic Appearance of Dural Arteriovenous Fistula and Trigeminal Ganglion Radiofrequency Thermocoagulation

Fluoroscopy-guided radiofrequency thermocoagulation of the trigeminal ganglion is an alternative treatment for symptomatic trigeminal neuralgia. The most common complications of the procedure are circumscribed to sensitivity alterations. We report a case of an 83-year-old female patient with a history of petroclival meningioma resection, radiotherapy at the level of the petrous apex, and radiofrequency thermocoagulation for trigeminal neuralgia who developed a symptomatic dural arteriovenous fistula as an early complication, which required selective embolization. Dural arteriovenous fistula as an immediate complication of percutaneous thermocoagulation of the trigeminal ganglion has not been previously reported.

The historical perspective in approaches to the spheno-petro-clival meningiomas

The current literature regarding surgical treatment for tumors in the sphenopetroclival (SPC) region is merely scarce. Through a comprehensive literature review, we investigated the indications, outcomes, and complications of different surgical approaches to the SPC meningiomas. Given its complicated relationship between these slow-progression tumors and some critical neurovascular structures in the SPC region, surgical treatment of these tumors faces the challenge of achieving a maximal grade of resection, while preserving patient functionality. The development of new surgical techniques and approaches in recent years have permitted the advancement in the treatment of these tumors, with acceptable rates of morbidity and mortality. The choice of a surgical approach as a treatment for the lesion depends mainly on the type of tumor extension, surgeon's preferences, and the displacement of neurovascular structures. Rather than focusing on one single strategy of treatment, the skull-base surgeon should tailor the approach based on the origin and features of the lesion; as well as the peculiarities of the surgical anatomy. This strategy aims to decrease morbidity and to optimize tumor resection and patient quality of life.

Surgery of the lateral skull base: a 50-year endeavour

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

Intradural Combined Transpetrosal Approach for Primary Pontine Hemorrhage

OBJECTIVE

The standard combined transpetrosal approach (CTPA) is fundamentally an epidural approach that has been quite successfully practiced for many decades. However, it has some disadvantages, such as cosmetic problems, difficulties with custom-tailored petrosectomy, and cerebrospinal fluid leakage, as it is a complicated epidural procedure. We describe here a case of primary pontine hemorrhage via intradural CTPA (iCTPA), which is a modified technique of CTPA and includes intradural anterior petrosectomy and partial posterior petrosectomy without mastoidectomy and skeletonization of the sigmoid sinus.

METHODS

A 63-year-old woman with primary pontine hemorrhage underwent surgery via iCTPA to improve postoperative functional outcomes. After the temporal craniotomy without mastoidectomy and skeletonization of the sigmoid sinus, Kawase's triangle and Trautmann's triangle were identified from the intradural space. Resection of Kawase's triangle and partial resection of Trautmann's triangle were performed to approach the frontotemporal surface of the pons. The hematoma was irrigated and totally removed after corticotomy on the pons.

RESULTS

The postoperative symptoms of the patient improved within 2 weeks without surgical complication.

CONCLUSIONS

The intradural approach allows for custom-tailored petrosectomy and is more straightforward than the epidural route, although it can injure the vein of Labbé. Moreover, it can also reduce cosmetic problems and cerebrospinal fluid leakage. iCTPA could provide enough working space for the frontolateral surface of pontine and petroclival lesions without the need for mastoidectomy and skeletonization of the sigmoid sinus.

Combined petrosal approach

PURPOSE OF REVIEW

The combined petrosal approach to the lateral skull base merges a retrolabyrinthine-presigmoid posterior fossa craniotomy with an adjacent middle fossa craniotomy, which are rendered continuous by division of the tentorium. This is a hearing-preserving approach that affords wide access to the lateral aspect of the clivus, the prepontine space, and the cerebellopontine angle.

RECENT FINDINGS

This article details the historical development of the combined petrosal approach alongside a description. In particular, the critically relevant anatomy is reviewed, including the course of the vein of Labbé, with a view toward avoiding the known complications associated with this approach. Outcomes for application of this approach as applied for various lesions are also reviewed as portrayed by the current literature.

SUMMARY

The combined petrosal approach affords wide access to the lateral skull base in the middle and posterior fossa. The approach and the lesions addressed by this approach involve delicate and sensitive anatomy. We review the evolution of this approach and highlight advancements that have allowed the combined petrosal approach to be a safe addition to the surgeon's armamentarium.