Parasellar Meningiomas

Intradural anatomy and mobilization techniques of oculomotor, trochlear and abducens nerve after microsurgical dissection: a cadaveric study

BACKGROUND

This study investigates the mobilization of cranial nerves in the upper clival region to improve surgical approaches. Cadaveric specimens (n = 20) were dissected to examine the oculomotor, trochlear, and abducens nerves. Dissection techniques focused on the nerves' intradural course and their relationship to surrounding structures.

METHODS

Pre-dissection revealed the nerves' entry points into the clival dura and their proximity to each other. Measurements were taken to quantify these distances. Following intradural dissection, measurements were again obtained to assess the degree of nerve mobilization.

RESULTS

Dissection showed that the abducens nerve takes three folds during its course: at the dural foramen, towards the posterior cavernous sinus, and lastly within the cavernous sinus. The trochlear nerve enters the dura and makes two bends before entering the cavernous sinus. The oculomotor nerve enters the cavernous sinus directly and runs parallel to the trochlear nerve. Importantly, intradural dissection increased the space between the abducens nerves (by 4.21 mm) and between the oculomotor and trochlear nerves (by 3.09 mm on average). This indicates that nerve mobilization can create wider surgical corridors for approaching lesions in the upper clivus region.

CONCLUSIONS

This study provides a detailed anatomical analysis of the oculomotor, trochlear, and abducens nerves in the upper clivus. The cadaveric dissections and measurements demonstrate the feasibility of mobilizing these nerves to achieve wider surgical corridors. This information can be valuable for surgeons planning endoscopic or microscopic approaches to lesions in the upper clivus region.

Peptide radionuclide radiation therapy with Lutathera in multirecurrent nonanaplastic meningiomas: antitumoral activity study by growth rate analysis

PURPOSE

Several retrospective studies and meta-analyses of Peptide Radionuclide Radiation Therapy in meningiomas suggest six-month progression-free survival improvement for WHO grade 1 and 2 meningiomas. In the present study, we aimed to evaluate the impact of such treatment on three-dimensional volume growth rate (3DVGR) in nonanaplastic meningiomas.

METHODS

The authors performed a retrospective study including eight patients treated with Lutathera®. Millimetric 3D T1-weighted with gadolinium enhancement magnetic resonance imaging sequences were requested for volume measurement. Then, tumor growth rate was classified following a previously described 3DVGR classification (Graillon et al.).

RESULTS

Patients harbored seven WHO grade 2 meningiomas and one aggressive WHO grade 1. All patients, except one, underwent four treatment cycles. 3DVGR significantly decreased at 3, 6, and 12 months after treatment initiation analyzing each lesion separately. Mean and median 3DVGR from all patients were respectively at 29.5% and 44.5%/6 months before treatment initiation, then at 16.5% and 25%/6 months at three months post-treatment initiation, 9.5% and 4.5%/6 months after 6 months, as well as 9.5% and 10.5%/6 months after 12 months. At 3, 6, and 12 months after treatment initiation, 4/8, 6/7, and 5/6 patients were class 2 (stabilization or severe 3DVGR slowdown), respectively. No patient was class 1 at 6 and 12 months, suggesting a lack of drug response.

CONCLUSION

In nonanaplastic meningiomas, Lutathera®'s antitumoral activity appeared delayed and more likely observed at six months, while no major response was observed under treatment. Moreover, its antitumoral activity persisted for 12-18 months following treatment initiation.

Innovative treatments for meningiomas

Multi-recurrent high-grade meningiomas remain an unmet medical need in neuro-oncology when iterative surgeries and radiation therapy sessions fail to control tumor growth. Nevertheless, the last 10years have been marked by multiple advances in the comprehension of meningioma tumorigenesis via the discovery of new driver mutations, the identification of activated intracellular signaling pathways, and DNA methylation analyses, providing multiple potential therapeutic targets. Today, Anti-VEGF and mTOR inhibitors are the most used and probably the most active drugs in aggressive meningiomas. Peptide radioactive radiation therapy aims to target SSTR2A receptors, which are strongly expressed in meningiomas, but have an insufficient effect in most aggressive meningiomas, requiring the development of new techniques to increase the dose applied to the tumor. Based on the multiple potential intracellular targets, multiple targeted therapy clinical trials targeting Pi3K-Akt-mTOR and MAP kinase pathways as well as cell cycle and particularly, cyclin D4-6 are ongoing. Recently discovered driver mutations, SMO, Akt, and PI3KCA, offer new targets but are mostly observed in benign meningiomas, limiting their clinical relevance mainly to rare aggressive skull base meningiomas. Therefore, NF2 mutation remains the most frequent mutation and main challenging target in high-grade meningioma. Recently, inhibitors of focal adhesion kinase (FAK), which is involved in tumor cell adhesion, were tested in a phase 2 clinical trial with interesting but insufficient activity. The Hippo pathway was demonstrated to interact with NF2/Merlin and could be a promising target in NF2-mutated meningiomas with ongoing multiple preclinical studies and a phase 1 clinical trial. Recent advances in immune landscape comprehension led to the proposal of the use of immunotherapy in meningiomas. Except in rare cases of MSH2/6 mutation or high tumor mass burden, the activity of PD-1 inhibitors remains limited; however, its combination with various radiation therapy modalities is particularly promising. On the whole, therapeutic management of high-grade meningiomas is still challenging even with multiple promising therapeutic targets and innovations.

The spatial-temporal reactive changes of compressed optic nerve in a clinically relevant rabbit model of persistent compressive optic nerve axonopathy

The optic nerve (ON) can get compressed in different diseases. However, the pathological and functional changes occurring in the compressed ON over time under constant compression are still unclear. In the present study, we implanted an artificial tube around the optic nerve of a rabbit to primarily create a clinically relevant persistent compressive optic nerve axonopathy (PCOA). Due to the protuberance on the inner ring of the tube, steady and persistent compressions were maintained. In this model, we investigated the thickness of ganglion cell complex (GCC), retinal ganglion cell (RGC) density, axon density of optic nerve, flash visual evoked potential (FVEP), and anterograde axonal transport at various times in four different groups viz. the no comp, 1/2 comp, 3/4 comp, and crush groups. The GCC thickness, RGC density, and axon density of ON were hierarchically and significantly decreased in 1/2 comp, 3/4 comp, and crush groups. Compared to no comp eyes, the P2 amplitude ratio of FVEP was significantly decreased in 3/4 comp but not in 1/2 comp eyes. Only a portion of the optic nerve lost the ability of anterograde axonal transport in the 1/2 comp group. However, it was evident at 2-wpo and more prominent at 4-wpo in 3/4 comp eyes. This study reveals that the compression only induces the homolateral ON axons impairment and the proportion of the affected axons maintains the same for mild compression for at least three months. Furthermore, an underlying threshold effect highlights that mild compression does not require urgent surgery, while the severe compression warrants immediate surgical intervention.

A radiomics-based study for differentiating parasellar cavernous hemangiomas from meningiomas

To investigate the value of the radiomic models for differentiating parasellar cavernous hemangiomas from meningiomas and to compare the classification performance with different MR sequences and classifiers. A total of 96 patients with parasellar tumors (40 cavernous hemangiomas and 56 meningiomas) were enrolled in this retrospective multiple-center study. Univariate and multivariate analyses were performed to identify the clinical factors and semantic features of MRI scans. Radiomics features were extracted from five MRI sequences using radiomics software. Three feature selection methods and six classifiers were evaluated in the training cohort to construct favorable radiomic machine-learning classifiers. The performance of different classifiers was evaluated using the AUC and compared to neuroradiologists. The detection rates of T1WI, T2WI, and CE-T1WI for parasellar cavernous hemangiomas and meningiomas were approximately 100%. In contrast, the ADC maps had the detection rate of 18/22 and 19/25, respectively, (AUC, 0.881) with 2.25 cm as the critical value diameter. Radiomics models with the SVM and KNN classifiers based on T2WI and ADC maps had favorable predictive performances (AUC > 0.90 and F-score value > 0.80). These models outperformed MRI model (AUC 0.805) and neuroradiologists (AUC, 0.756 and 0.545, respectively). Radiomic models based on T2WI and ADC and combined with SVM and KNN classifiers have the potential to be a viable method for differentiating parasellar hemangiomas from meningiomas. T2WI is more universally applicable than ADC values due to its higher detection rate for parasellar tumors.

Does Endoscopic Transnasal Optic Nerve Decompression Followed by Radiosurgery Improve Outcomes in the Treatment of Parasellar Meningiomas?

Introduction: The clinical management of parasellar meningiomas (PM) is challenging due to their intimate association with critical neurovascular structures. Consensus regarding the recommended treatment protocol is lacking. This study will evaluate patients’ visual outcomes following endoscopic transnasal optic nerve decompression (ETOND) and will investigate the possibility of reducing the rate of complications associated with stereotactic radiosurgery (SRS). Methods: Retrospective analysis was conducted on all patients who underwent ETOND for PM between 2013 and 2020. The study comprised 12 patients (7 women and 5 men aged 36–75 years; mean, 55.2 years; median, 57.6 years) in which 14 optic nerve decompression procedures were carried out. Patients were followed up for 6 to 86 months (mean, 29.3 months; median, 25 months). There were five cases of spheno-orbital meningioma, four cases of cavernous sinus meningioma, and one case each of petro-clival meningioma, optic nerve sheath meningioma, and planum sphenoidale/tuberculum sellae meningioma. Visual outcome was evaluated and any postoperative complications noted. Results: Improvements in visual acuity were noted in 10 of 14 eyes (71.4%) 3 to 6 months postoperation. Visual acuity remained stable in the remaining four eyes. No deterioration of visual acuity was noted during the follow-up period. In total, 9 of the 12 patients underwent SRS. No tumor growth was determined, while reduction in tumor volume was noted in five patients following SRS. No complications associated with SRS or the surgical procedure were noted. Conclusions: ETOND appears to be a promising technique for increasing rates of improved visual function, while reducing the risk of post SRS-related complications. In combination with subsequent SRS, it is an ideal treatment modality in the management of parasellar meningiomas. Confirmation of our findings would require a larger, prospective multicenter study.

Midline Skull Base Meningiomas: Transcranial and Endonasal Perspectives

Simple Summary

Skull base meningiomas have always represented a challenge for neurosurgeons. Despite their histological nature, they may be associated with unfavorable outcomes due to their deep-seated location and the surrounding neurovascular structures. Over time, several corridors have been proposed, each one carrying its own pros and cons. During the last decades, the endoscopic endonasal route has been asserted among the classic routes for a growing number of midline and paramedian lesions. Therefore, the aim of our paper is to present a comprehensive review of the indications and techniques for the management of skull base meningiomas, emphasizing the ambivalent and complementary role of the low and high routes.

Abstract

Skull base meningiomas have always represented a challenge for neurosurgeons. Despite their histological nature, they may be associated with unfavorable outcomes due to their deep-seated location and the surrounding neurovascular structures. The state of the art of skull base meningiomas accounts for both transcranial, or high, and endonasal, or low, routes. A comprehensive review of the pertinent literature was performed to address the surgical strategies and outcomes of skull base meningioma patients treated through a transcranial approach, an endoscopic endonasal approach (EEA), or both. Three databases (PubMed, Ovid Medline, and Ovid Embase) have been searched. The review of the literature provided 328 papers reporting the surgical, oncological, and clinical results of different approaches for the treatment of skull base meningiomas. The most suitable surgical corridors for olfactory groove, tuberculum sellae, clival and petroclival and cavernous sinus meningiomas have been analyzed. The EEA was proven to be associated with a lower extent of resection rates and better clinical outcomes compared with transcranial corridors, offering the possibility of achieving the so-called maximal safe resection.

Management of cavernous sinus meningiomas: Consensus statement on behalf of the EANS skull base section

Introduction

The evolution of cavernous sinus meningiomas (CSMs) might be unpredictable and the efficacy of their treatments is challenging due to their indolent evolution, variations and fluctuations of symptoms, heterogeneity of classifications and lack of randomized controlled trials. Here, a dedicated task force provides a consensus statement on the overall management of CSMs.

Research question

To determine the best overall management of CSMs, depending on their clinical presentation, size, and evolution as well as patient characteristics.

Material and methods

Using the PRISMA 2020 guidelines, we included literature from January 2000 to December 2020. A total of 400 abstracts and 77 titles were kept for full-paper screening.

Results

The task force formulated 8 recommendations (Level C evidence). CSMs should be managed by a highly specialized multidisciplinary team. The initial evaluation of patients includes clinical, ophthalmological, endocrinological and radiological assessment. Treatment of CSM should involve experienced skull-base neurosurgeons or neuro-radiosurgeons, radiation oncologists, radiologists, ophthalmologists, and endocrinologists.

Discussion and conclusion

Radiosurgery is preferred as first-line treatment in small, enclosed, pauci-symptomatic lesions/in elderly patients, while large CSMs not amenable to resection or WHO grade II-III are candidates for radiotherapy. Microsurgery is an option in aggressive/rapidly progressing lesions in young patients presenting with oculomotor/visual/endocrinological impairment. Whenever surgery is offered, open cranial approaches are the current standard. There is limited experience reported about endoscopic endonasal approach for CSMs and the main indication is decompression of the cavernous sinus to improve symptoms. Whenever surgery is indicated, the current trend is to offer decompression followed by radiosurgery.

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A thorough evaluation of cavernous sinus meningiomas by a multidisciplinary team is mandatory.

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Microsurgery should be considered for aggressive lesions in young patients.

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Extended endoscopic approaches can be effective when combined with radiotherapy.

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Stereotaxic radiotherapy and stereotaxic radiosurgery offer excellent tumour control in small/asymptomatic lesions .

Individualized Cerebral Artery Protection Strategies for the Surgical Treatment of Parasellar Meningiomas on the Basis of Preoperative Imaging

Objective

Parasellar meningiomas (PMs) represent a cohort of skull base tumors that are localized in the parasellar region. PMs tend to compress, encase, or even invade the cerebral arteries and their perforating branches. The surgical resection of PMs without damaging neurovascular structures is challenging. This study aimed to analyze functional outcomes in a series of patients who underwent surgery with individualized cerebral artery protection strategies based on preoperative imaging.

Methods

A retrospective review was performed on a single surgeon’s experience of the microsurgical removal of PMs in 163 patients between January 2012 and March 2020. Individualized approaches with a bidirectional dissection strategy were used. Cerebral artery invasion classification, neurological outcomes, MRC Scale for muscle strength, and Karnofsky performance scale were used to assess tumor vascular invasion, functional outcome, and patient quality-of-life outcomes, respectively.

Results

Total resection (Simpson grade I or II) was achieved in 114 patients (69.9%) in our study. A total of 44.7% of patients had improved vision at consecutive follow-ups, 51.1% were stable, and 3.8% deteriorated. Improvements in cranial nerves III, IV, and VI were observed in 41.1%, 36.2%, and 44.8% of patients, respectively. The mean follow-up time was (38.8 ± 27.9) months, and the KPS at the last follow-up was 89.6 ± 8.5. Recurrence was observed in eight patients (13.8%) with cavernous sinus meningiomas, and the recurrence rates in anterior clinoid meningiomas and medial sphenoid wing meningiomas were 3.8% and 2.8%, respectively.

Conclusions

Preoperative imaging is important in the selection of surgical approaches. Maximum tumor resection and cerebral artery protection can be achieved concurrently by utilizing the bidirectional dissection technique. Individualized cerebral artery protection strategies provide great utility in improving a patient’s quality of life.

STA-MCA Bypass in Carotid Stenosis after Radiosurgery for Cavernous Sinus Meningioma

BACKGROUND

Cavernous sinus meningiomas (CSM) are mostly non-surgical tumors. Stereotactic radiosurgery (SRS) or radiotherapy (SRT) allow tumor control and improvement of pre-existing cranial nerve (CN) deficits. We report the case of a patient with radiation-induced internal carotid artery (ICA) stenosis. We complete the picture with a review of the literature of vascular and non-vascular complications following the treatment of CSMs with SRS or SRT.

METHODS

After a case description, a systematic literature review is presented, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2015 guidelines.

RESULTS

115 abstracts were screened and 70 titles were retained for full-paper screening. A total of 58 articles did not meet the inclusion criteria. There were 12 articles included in our review, with a follow-up ranging from 33 to 120 months. Two cases of post-SRT ischemic stroke and one case of asymptomatic ICA stenosis were described. Non-vascular complications were reported in all articles.

CONCLUSION

SRS and SRT carry fewer complications than open surgery, with similar rates of tumor control. Our case shows the importance of a follow-up of irradiated CSMs not only by a radio-oncologist, but also by a neurosurgeon, illustrating the importance of multidisciplinary management of CSMs.