Efficacy and outcomes of facial nerve-sparing treatment approach to cerebellopontine angle meningiomas

Minimally invasive approach for skull base meningiomas

INTRODUCTION

Skull base meningiomas constitute a complex group of skull base tumors. The endoscopic endonasal approaches (EEA) and endoscopic Keyhole have a minimally invasive philosophy with high effectiveness, safety, and a significant decrease in postoperative morbidity in these tumors.

OBJECTIVE

To describe the results of the use of minimally invasive approaches to skull base meningiomas.

METHOD

A descriptive, retrospective study was carried out in 140 patients at the "Hermanos Ameijeiras" Hospital who underwent surgery for cranial base meningiomas using minimally invasive approaches to the cranial base. The degree of tumor resection, tumor recurrence, reinterventions, and complications were evaluated.

RESULTS

ESA were used in 72.8% of the study, while endoscopic Keyholes were used in 26.4% and combined approaches in 0.7%. In relation to total tumor resection, 91.9% was generally achieved. Overall tumor recurrence and reinterventions were less than 8.5% and 4%, respectively. Complications in ESA were: cerebrospinal fluid (CSF) fistula (2.1%), diabetes insipidus, hydrocephalus, cerebral infarction, surgical site hematoma, worsening of cranial nerves I-IV (1.4%) respectively. While in the Keyhole type approaches: seizures (2.9%), hydrocephalus (1.4%), CSF fistula (1.4%), worsening of Nerves IX-XII (0.7%).

CONCLUSIONS

The following study reaffirms that minimally invasive approaches for skull base meningiomas constitute advanced surgical techniques for these tumors, associated with a low rate of postoperative complications.

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.

The otologic approach in the management of posterior petrous surface meningiomas

PURPOSE

Report our experience in the management of posterior petrous surface meningiomas (PPSMs), and identify features that affect hearing, facial nerve (FN) function, and control of the disease.

METHODS

Retrospective case series of 131 patients surgically managed for PPSMs. FN status, hearing and tumour radicality were assessed and compared between patients with tumours of different locations (Desgeorges classification) and internal auditory canal involvement (IAC).

RESULTS

At the time of surgery 74.8% of patients had a hearing loss. Hearing was mostly unserviceable in tumors attached to the meatus. Pure tone audiometry did not correlate to IAC extension, while speech discrimination scores were statistically worse when the tumor occupied the IAC (unpaired t test, p = 0.0152). Similarly, extrameatal tumors undergoing removal by otic preserving techniques maintained postoperative hearing, whereas hearing worsened significantly in tumors involving the IAC (paired t test, p = 0.048). The FN was affected preoperatively in 11.4% of cases. Postoperative FN palsy was significantly correlated to the IAC involvement (Fisher's exact test, p = 0.0013), while it was not correlated to tumor size. According to the Desgeorges classification, a postoperative FN palsy complicated the majority of anteriorly extending tumors and, two-fifths of meatus centred tumors. 75% of posterior located tumors had a postoperative FN grade I HB.

CONCLUSIONS

Since the involvement of the IAC by the tumor affects both hearing and FN function, the IAC is of primary importance in PPSMs and should be studied and addressed as much as the tumor location in the CPA.

Skull Base Meningiomas in Patients with Neurofibromatosis Type 2: An International Multicenter Study Evaluating Stereotactic Radiosurgery

Objective  Meningiomas are the second most common tumors in neurofibromatosis type 2 (NF-2). Microsurgery is challenging in NF-2 patients presenting with skull base meningiomas due to the intrinsic risks and need for multiple interventions over time. We analyzed treatment outcomes and complications after primary Gamma Knife radiosurgery (GKRS) to delineate its role in the management of these tumors. Methods  An international multicenter retrospective study approved by the International Radiosurgery Research Foundation was performed. NF-2 patients with at least one growing and/or symptomatic skull base meningioma and 6-month follow-up after primary GKRS were included. Clinical and radiosurgical parameters were recorded for analysis. Results  In total, 22 NF-2 patients with 54 skull base meningiomas receiving GKRS as primary treatment met inclusion criteria. Median age at GKRS was 38 years (10-79 years). Most lesions were located in the posterior fossa (55.6%). Actuarial progression free survival (PFS) rates were 98.1% at 2 years and 90.0% at 5 and 10 years. The median follow-up time after initial GKRS was 5.0 years (0.6-25.5 years). Tumor volume at GKRS was a predictor of tumor control. Lesions >5.5 cc presented higher chances to progress after radiosurgery ( p  = 0.043). Three patients (13.64%) developed adverse radiation effects. No malignant transformation or death due to meningioma or radiosurgery was reported. Conclusions  GKRS is effective and safe in the management of skull base meningiomas in NF-2 patients. Tumor volume deserve greater relevance during clinical decision-making regarding the most appropriate time to treat. GKRS offers a minimally invasive approach of particular interest in this specific group of patients.

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.

Facial pain and sensory outcomes following resection of tumors compressing the trigeminal nerve

OBJECTIVE

Tumors compressing the trigeminal nerve can cause facial pain, numbness, or paresthesias. Limited data exist describing how these symptoms change after resection and what factors predict symptom improvement. The objective of this study was to report trigeminal pain and sensory outcomes after tumor resection and identify factors predicting postoperative symptom improvement.

METHODS

This retrospective study included patients with tumors causing facial pain, numbness, or paresthesias who underwent resection. Trigeminal schwannomas were excluded. Logistic regression, recursive partitioning, and time-to-event analyses were used to report outcomes and identify variables associated with facial sensory outcomes.

RESULTS

Eighty-six patients met inclusion criteria, and the median follow-up was 3.1 years; 63 patients (73%) had meningiomas and 23 (27%) had vestibular schwannomas (VSs). Meningioma patients presented with pain, numbness, and paresthesias in 56%, 76%, and 25% of cases, respectively, compared with 9%, 91%, and 39%, respectively, for patients with VS. Most meningioma patients had symptoms for less than 1 year (60%), whereas the majority of VS patients had symptoms for 1-5 years (59%). The median meningioma and VS diameters were 3.0 and 3.4 cm, respectively. For patients with meningiomas, gross-total resection (GTR) was achieved in 27% of patients, near-total resection (NTR) in 29%, and subtotal resection (STR) in 44%. For patients with VS, GTR was achieved in 9%, NTR in 30%, and STR in 61%. Pain improved immediately after tumor resection in 81% of patients and in 92% of patients by 6 weeks. Paresthesias improved immediately in 80% of patients, increasing to 84% by 6 weeks. Numbness improved more slowly, with 52% of patients improving immediately, increasing to 79% by 2 years. Pain recurred in 22% of patients with meningiomas and 0% of patients with VSs. After resection, the Barrow Neurological Institute (BNI) facial pain intensity score improved in 73% of patients. The tumor diameter significantly predicted improvement in BNI score (OR 0.47/cm larger, 95% CI 0.22-0.99; p = 0.047). Complete decompression of the trigeminal nerve was associated with qualitative improvement in pain (p = 0.037) and decreased pain recurrence (OR 0.08, 95% CI 0.01-0.67; p = 0.024).

CONCLUSIONS

Most patients with facial sensory symptoms caused by meningiomas or VSs experienced improvement after resection. Surgery led to immediate and sustained improvement in pain and paresthesias, whereas numbness was slower to improve. Patients with smaller tumors and complete decompression of the trigeminal nerve were more likely to experience improvement in facial pain.

Clinical Studies and Pre-clinical Animal Models on Facial Nerve Preservation, Reconstruction, and Regeneration Following Cerebellopontine Angle Tumor Surgery-A Systematic Review and Future Perspectives

Background and purpose: Tumorous lesions developing in the cerebellopontine angle (CPA) get into close contact with the 1st (cisternal) and 2nd (meatal) intra-arachnoidal portion of the facial nerve (FN). When surgical damage occurs, commonly known reconstruction strategies are often associated with poor functional recovery. This article aims to provide a systematic overview for translational research by establishing the current evidence on available clinical studies and experimental models reporting on intracranial FN injury.

Methods: A systematic literature search of several databases (PubMed, EMBASE, Medline) was performed prior to July 2020. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Included clinical studies were reviewed and categorized according to the pathology and surgical resection strategy, and experimental studies according to the animal. For anatomical study purposes, perfusion-fixed adult New Zealand white rabbits were used for radiological high-resolution imaging and anatomical dissection of the CPA and periotic skull base.

Results: One hundred forty four out of 166 included publications were clinical studies reporting on FN outcomes after CPA-tumor surgery in 19,136 patients. During CPA-tumor surgery, the specific vulnerability of the intracranial FN to stretching and compression more likely leads to neurapraxia or axonotmesis than neurotmesis. Severe FN palsy was reported in 7 to 15 % after vestibular schwannoma surgery, and 6% following the resection of CPA-meningioma. Twenty-two papers reported on experimental studies, out of which only 6 specifically used intracranial FN injury in a rodent (n = 4) or non-rodent model (n = 2). Rats and rabbits offer a feasible model for manipulation of the FN in the CPA, the latter was further confirmed in our study covering the radiological and anatomical analysis of perfusion fixed periotic bones.

Conclusion: The particular anatomical and physiological features of the intracranial FN warrant a distinguishment of experimental models for intracranial FN injuries. New Zealand White rabbits might be a very cost-effective and valuable option to test new experimental approaches for intracranial FN regeneration. Flexible and bioactive biomaterials, commonly used in skull base surgery, endowed with trophic and topographical functions, should address the specific needs of intracranial FN injuries.

Small Cerebellopontine Angle Meningioma-Surgical Experience of 162 Patients and Literature Review

Objective

To retrospective analyze the clinical data of 162 patients with small cerebellopontine angle meningiomas. To compare with the nature of tumors, symptoms pre- and post-treatments, neurological deficit, and prognosis in literatures. To explore the surgical outcomes of small cerebellopontine angle meningiomas and summarize the surgical experience.

Methods

All of 162 patients with small cerebellopontine angle meningiomas underwent surgery between January 2010 and December 2019 in the neurosurgery department of the First Affiliated Hospital of Soochow University. This cohort of eight literatures reported about stereotactic radiotherapy of small cerebellopontine angle meningiomas between January 2010 and December 2019. All clinical data were obtained for analysis.

Results

Compared with stereotactic radiotherapy, surgical treatment for small cerebellopontine angle meningiomas lead to the better results in relieving symptoms and inhibiting tumor progression. Surgical treatment can obtain the exact pathological examination results to guide the further treatment.

Conclusions

Surgical treatment should be the first choice for small cerebellopontine angle meningiomas.

Surgery for posterior fossa meningioma: elevated postoperative cranial nerve morbidity discards aggressive tumor resection policy

Radical excision of meningioma is suggested to provide for the best tumor control rates. However, aggressive surgery for meningiomas located at the posterior cranial fossa may lead to elevated postoperative morbidity of adjacent cranial nerves which in turn worsens patients' postoperative quality of life. Therefore, we analyzed our institutional database with regard to new cranial nerve dysfunction as well as postoperative cerebrospinal fluid (CSF) leakage depending on the extent of tumor resection. Between 2009 and 2017, 89 patients were surgically treated for posterior fossa meningioma at the authors' institution. Postoperative new cranial nerve dysfunction as well as CSF leakage were stratified into Simpson grade I resections with excision of the adjacent dura as an aggressive resection regime versus Simpson grade II-IV tumor removal. Simpson grade I resections revealed a significantly higher percentage of new cranial nerve dysfunction immediately after surgery (39%) compared with Simpson grade II (11%, p = 0.01) and Simpson grade II-IV resections (14%, p = 0.02). These observed differences were also present for the 12-month follow-up (27% Simpson grade I, 3% Simpson grade II (p = 0.004), 7% Simpson grades II-IV (p = 0.01)). Postoperative CSF leakage was present in 21% of Simpson grade I and 3% of Simpson grade II resections (p = 0.04). Retreatment rates did not significantly differ between these two groups (6% versus 8% (p = 1.0)). Elevated levels of postoperative new cranial nerve deficits as well as CSF leakage following radical tumor removal strongly suggest a less aggressive resection policy to constitute the surgical modality of choice for posterior cranial fossa meningiomas.

Petrous face meningiomas

Cerebellopontine angle (CPA) meningiomas arise from the petrous face of the temporal bone, which forms the lateral boundary of the CPA. They can be categorized into anterior, middle, and posterior, based on their attachment in relation to the internal acoustic meatus. Each of them presents with their own characteristic clinical syndromes. Because of their close proximity to neurovascular structures, they pose a challenge during surgery. Microsurgery remains the primary treatment modality for large and symptomatic meningiomas. The retrosigmoid approach provides an ideal access for most of the tumors in this location. Radiosurgery is the primary modality of adjuvant therapy for residual, recurrent, and small lesions. Fully fractionated external beam radiotherapy can be used for larger, broader-based residual/recurrent tumors. Management of these complex lesions should include patient preferences and a team approach, including a skull base neurosurgeon, neurotologist, and radiation oncologist.

Meningiomas: skull base versus non-skull base

To identify differences between skull base meningiomas (SBM) and non-skull base meningiomas (NSBM). All adult patients (18.0-69.9 years) operated for intracranial meningiomas between 1990 and 2010 at our institution were investigated. Al-Mefty's definition was used to dichotomize tumors into SBM and NSBM. Overall, 1148 consecutive patients were identified. Median age at surgery was 54.2 years [18.1-69.9]. Median follow-up was 7.4 years [0.0-20.9]. There were 562 patients (49%) with SBM and 586 (51%) with NSBM. The two groups were similar with respect to patient age, follow-up time, and number of patients. Overall female-to-male ratio was 2.6:1, but 3.2:1 in SBM and 2.2:1 in NSBM (p < 0.005). With respect to presenting symptoms, SBMs had more often neurological deficits (risk ratio (RR) 1.4; p < 0.0001) and less often seizures (RR 0.4; p < 0.0001). Gross total resections were less frequent in SBM than NSBM (62 vs 84%) (RR 1.3; p < 0.0001). SBMs had a lower risk of WHO grades II and III histology (4.5 vs 9.5%) (RR 0.5; p < 0.001). Worsening of neurological function was more frequent in SBM (21 vs 121%) (RR 1.8; p < 0.001). Retreatment-free survival at 5, 10, and 15 years, respectively, was 80, 70, and 62% for SBM versus 90, 82, and 74% for NSBM (p < 0.0001). Overall survival at 5, 10, and 15 years, respectively, was 93, 85, and 78% for SBM and 96, 91, and 79% for NSBM (p = 0.14). Patients with SBMs had more new-onset neurological deficits and significantly shorter retreatment-free survivals, but this did not adversely affect the overall survival.

Petrous Face Meningiomas: Classification, Clinical Syndromes, and Surgical Outcomes

BACKGROUND

Petrous face meningiomas (PFMs) are challenging tumors because of their proximity to the cranial nerves, brainstem, and critical vasculature. The objective of this study is to present surgical outcomes and support an anatomic classification for PFM based on clinical presentation.

METHODS

A retrospective chart review was performed, and 51 PFMs were identified. Tumors were classified by location along the petrous face into anterior, middle, and posterior. Presentation and outcomes were analyzed with logistic regression.

RESULTS

The median follow-up was 31.6 months. Tumors were World Health Organization grade I (n = 50), with 1 World Health Organization grade II tumor. Location was anterior (22%), middle (14%), posterior (53%), and overlapping (12%). Median tumor diameter was 3.0 cm (range, 0.8-6.2 cm). Anterior location was associated with facial pain/numbness on presentation (P < 0.0001), middle location with hearing loss/vestibular dysfunction (P = 0.0035), and posterior with hydrocephalus (P = 0.0190), headache (P = 0.0039), and vertigo (P = 0.0265). Extent of resection was gross total (63%), near total (14%), and subtotal (25%). The observed radiographic recurrence rate was 15%. Mean progression-free survival after diagnosis was 9.1 years with 2-year, 5-year, and 10-year progression-free survival of 91.8%, 78.6%, and 62.9%, respectively. The complication rate was 27%. Age, location, and approach were not associated with complications.

CONCLUSIONS

PFMs present with distinct clinical syndromes based on their location along the petrous face: anterior with trigeminal symptoms, middle with auditory/vestibular symptoms, and posterior with symptoms of mass effect/hydrocephalous. Surgical resection is associated with excellent long-term survival and a low rate of recurrence, which can be managed with radiotherapy.

Early-Career Surgical Practice for Cerebellopontine Angle Tumors in the Era of Radiosurgery

We analyzed the outcomes of patients with large cerebellopontine angle (CPA) tumors treated by a skull-base team in which two surgeons (one neurosurgeon and one otological surgeon) were in the beginning of their careers (<40 years old). Data of patients operated on between April 2012 and March 2016 were reviewed. All factors related to surgical training were considered. Thirty-one patients had vestibular schwannomas, while 26 had meningiomas. Mean tumor diameter was 30.6 mm (range, 23-49 mm) for schwannomas and 35 mm (range, 22-51 mm) for meningiomas. Satisfactory postoperative facial nerve function (House-Brackmann's grade I or II) was achieved in 20 (64.5%) schwannoma patients and 21 (80.7%) meningioma patients. Gross total and near-total resections (residual tumor < 5 mm) were achieved in 21 (67.7%) and 9 (29%) schwannoma patients, respectively. Gross total resection (Simpson's grade II) was achieved in 18 (69.2%) meningioma patients. In both groups, the retrosigmoid approach was the most common approach. Regarding surgical training of the two younger surgeons, during the residency period, they attended high-volume centers for CPA tumors. Application of microsurgical techniques was systematically applied from the beginning of their personal series in every intracranial pathology case. During the first 2 years of the series, they were supervised by more experienced surgeons and followed a stepwise sharing of increasingly difficult surgical phases; by comparing results of this period with the last 2 years of the series, where they acquired a complete autonomy, no relevant difference was detected. Our results suggest that young surgeons may achieve good results even at the beginning of their careers, if specific conditions related to training and mentorship are met.