Management of growing vestibular schwannomas

Comparative Transcriptomic Analysis of Archival Human Vestibular Schwannoma Tissue from Patients with and without Tinnitus

Vestibular schwannoma (VS) is an intracranial tumor that commonly presents with tinnitus and hearing loss. To uncover the molecular mechanisms underlying VS-associated tinnitus, we applied next-generation sequencing (Illumina HiSeq) to formalin-fixed paraffin-embedded archival VS samples from nine patients with tinnitus (VS-Tin) and seven patients without tinnitus (VS-NoTin). Bioinformatic analysis was used to detect differentially expressed genes (DEG; i.e., ≥two-fold change [FC]) while correcting for multiple comparisons. Using RNA-seq analysis, VS-Tin had significantly lower expression of GFAP (logFC = −3.04), APLNR (logFC = −2.95), PREX2 (logFC = −1.44), and PLVAP (logFC = −1.04; all p < 0.01) vs. VS-NoTin. These trends were validated by using real-time RT-qPCR. At the protein level, immunohistochemistry revealed a trend for less PREX2 and apelin expression and greater expression of NLRP3 inflammasome and CD68-positive macrophages in VS-Tin than in VS-NoTin, suggesting the activation of inflammatory processes in VS-Tin. Functional enrichment analysis revealed that the top three protein categories—glycoproteins, signal peptides, and secreted proteins—were significantly enriched in VS-Tin in comparison with VS-NoTin. In a gene set enrichment analysis, the top pathway was allograft rejection, an inflammatory pathway that includes the MMP9, CXCL9, IL16, PF4, ITK, and ACVR2A genes. Future studies are needed to examine the importance of these candidates and of inflammation in VS-associated tinnitus.

Management of Vestibular Schwannoma with Normal Hearing

INTRODUCTION

This work aimed to study the management of vestibular schwannoma (VS) patients with normal hearing (NH).

METHODS

A retrospective study was undertaken in a Quaternary referral center for skull base pathologies. Among 4,000 VS patients 162 met our strict audiological criteria for NH. These patients were divided into 2 management groups, wait and scan (W&S) (45/162, 25%) and operated patients (123/162, 75%), and 6 patients were included in both groups.

RESULTS

Our management strategy achieved the goals for treatment of VS. First goal, all tumors were completely removed except for 2 intentional residuals. Second goal, facial nerve (FN) function preservation (House Brackmann I, II, and III) was 95.9%. Third goal, possible hearing preservation (HP) attempts occurred in (50/122) (40.9%) with an HP rate in 44% of the patients. Additionally, there were only 2 cases of postoperative complications with no CSF leakage. The prospect of HP in NH patients did not differ with respect to tumor size. However, patients with normal preoperative ABR seemed to have better chances of HP and good FN function and vice versa. HP rate was superior for the MCFA as opposed to the RS + RLA. W&S group demonstrated hearing stability in 88.9% of the patients and FN function stability of HB I in 100% of the patients.

CONCLUSIONS

Surgical resection is a reasonable and definitive management option for VS with NH. Nevertheless, choosing to manage cases with observation remains an appropriate management option for NH patients. ABR might be considered as an adjuvant tool indicating better prognosis for HP.

Defining clinically significant tumor size in vestibular schwannoma to inform timing of microsurgery during wait-and-scan management: moving beyond minimum detectable growth

OBJECTIVE

Detection of vestibular schwannoma (VS) growth during observation leads to definitive treatment at most centers globally. Although ≥ 2 mm represents an established benchmark of tumor growth on serial MRI studies, 2 mm of linear tumor growth is unlikely to significantly alter microsurgical outcomes. The objective of the current work was to ascertain where the magnitude of change in clinical outcome is the greatest based on size.

METHODS

A single-institution retrospective review of a consecutive series of patients with sporadic VS who underwent microsurgical resection between January 2000 and May 2020 was performed. Preoperative tumor size cutpoints were defined in 1-mm increments and used to identify optimal size thresholds for three primary outcomes: 1) the ability to achieve gross-total resection (GTR); 2) maintenance of normal House-Brackmann (HB) grade I facial nerve function; and 3) preservation of serviceable hearing (American Academy of Otolaryngology-Head and Neck Surgery class A/B). Optimal size thresholds were obtained by maximizing c-indices from logistic regression models.

RESULTS

Of 603 patients meeting inclusion criteria, 502 (83%) had tumors with cerebellopontine angle (CPA) extension. CPA tumor size was significantly associated with achieving GTR, postoperative HB grade I facial nerve function, and maintenance of serviceable hearing (all p < 0.001). The optimal tumor size threshold to distinguish between GTR and less than GTR was 17 mm of CPA extension (c-index 0.73). In the immediate postoperative period, the size threshold between HB grade I and HB grade > I was 17 mm of CPA extension (c-index 0.65). At the most recent evaluation, the size threshold between HB grade I and HB grade > I was 23 mm (c-index 0.68) and between class A/B and C/D hearing was 18 mm (c-index 0.68). Tumors within 3 mm of the 17-mm CPA threshold displayed similarly strong c-indices. Among purely intracanalicular tumors, linear size was not found to portend worse outcomes for all measures.

CONCLUSIONS

The probability of incurring less optimal microsurgical outcomes begins to significantly increase at 14-20 mm of CPA extension. Although many factors ultimately influence decision-making, when considering timing of microsurgical resection, using a size threshold range as depicted in this study offers an evidence-based approach that moves beyond reflexively recommending treatment for all tumors after detecting ≥ 2 mm of tumor growth on serial MRI studies.

Outcomes of Initial Observation Versus Upfront Microsurgical Resection for Small to Medium-sized Vestibular Schwannomas

OBJECTIVE

To assess postoperative outcomes and predictive factors of patients observed prior to microsurgery and those undergoing upfront resection for small and medium-sized VS.

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center.

PATIENTS

VS patients who had microsurgery from 2003 to 2018 for tumors up to 2.5 cm.

MAIN OUTCOME MEASURES

Postoperative outcomes including facial nerve function and interventions, complications, extent of resection, and salvage therapy.

RESULTS

Of 220 patients, 120 were initially observed, and 100 pursued upfront microsurgery. There was no significant association between initial observation and upfront microsurgery for postoperative facial nerve function at 2 to 3 weeks (p = 0.18) or 12 months (p = 0.5), facial nerve intervention (p = 0.5), major/minor complications (p = 0.48/0.63), recurrence (p = 0.8), subtotal resection (p = 0.6), or salvage therapy (p = 0.9). Time from initial consultation to surgery did not significantly impact outcomes. Intrameatal tumors were more likely to be observed (odds ratios [OR] 2.93; 95% CI 1.53-5.63; p = 0.001). Patients with larger tumor volume (OR 0.52; 95% CI 0.37-0.72; p < 0.0001), brainstem compression (OR 0.28; 95% CI 0.09-0.91; p = 0.03), or higher PTA were less likely to undergo observation (OR 0.99; 95% CI 0.97-0.997; p = 0.02). On multivariable analysis, predictive factors for observation were smaller tumor volume (OR 0.53; 95% CI 0.38-0.75; p < 0.001), lower PTA (OR 0.99; 95% CI 0.98-0.999; p = 0.04), and diabetes (OR 2.54; 95% CI 0.95-6.83; p = 0.06).

CONCLUSIONS

Patients with worse hearing, larger tumor volume, and brainstem compression were more likely to pursue upfront microsurgery. A watchful waiting period does not appear to worsen outcomes and can be considered for patients with better hearing and smaller tumors without brainstem compression.

Natural History of Growing Sporadic Vestibular Schwannomas During Observation: An International Multi-Institutional Study

OBJECTIVE

Active treatment of small- or medium-sized vestibular schwannoma during wait-and-scan management is currently recommended at most centers globally once growth is detected. The primary aim of the current study was to characterize the natural history of growing sporadic vestibular schwannoma during observation.

STUDY DESIGN

Cohort study.

SETTING

Four tertiary referral centers across the United States and Denmark.

PATIENTS

Patients with two prior MRI scans demonstrating ≥2 mm of linear growth who continued observational management.

INTERVENTION

Observation with serial imaging.

MAIN OUTCOME MEASURE

Subsequent linear growth-free survival (i.e., an additional ≥2 mm of growth) following initial growth of ≥2 mm from tumor size at diagnosis.

RESULTS

Among 3,402 patients undergoing observation, 592 met inclusion criteria. Median age at initial growth was 66 years (IQR 59-73) for intracanalicular tumors (N = 65) and 62 years (IQR 54-70) for tumors with cerebellopontine angle extension (N = 527). The median duration of MRI surveillance following initial detection of tumor growth was 5.2 years (IQR 2.4-6.9) for intracanalicular tumors and 1.0 year (IQR 1.0-3.3) for cerebellopontine angle tumors. For intracanalicular tumors, subsequent growth-free survival rates (95% CI; number still at risk) at 1, 2, 3, 4, and 5 years following the initial MRI that demonstrated growth were 77% (67-88; 49), 53% (42-67; 31), 46% (35-60; 23), 34% (24-49; 17), and 32% (22-47; 13), respectively. For cerebellopontine angle tumors, subsequent growth-free survival rates were 72% (68-76; 450), 47% (42-52; 258), 32% (28-38; 139), 26% (21-31; 82), and 22% (18-28; 57), respectively. For every 1 mm increase in magnitude of growth from diagnosis to tumor size at detection of initial growth, the HRs associated with subsequent growth were 1.64 (95% CI 1.25-2.15; p < 0.001) for intracanalicular tumors and 1.08 (95% CI 1.01-1.15; p = 0.02) for cerebellopontine angle tumors.

CONCLUSIONS

Growth detected during observation does not necessarily portend future growth, especially for slowly growing tumors. Because early treatment does not confer improved long-term quality of life outcomes, toleration of some growth during observation is justifiable in appropriately selected cases.

Guidelines in the management of CNS tumors

INTRODUCTION

Evidence-based, clinical practice guidelines in the management of central nervous system tumors (CNS) continue to be developed and updated through the work of the Joint Section on Tumors of the Congress of Neurological Surgeons (CNS) and the American Association of Neurological Surgeons (AANS).

METHODS

The guidelines are created using the most current and clinically relevant evidence using systematic methodologies, which classify available data and provide recommendations for clinical practice.

CONCLUSION

This update summarizes the Tumor Section Guidelines developed over the last five years for non-functioning pituitary adenomas, low grade gliomas, vestibular schwannomas, and metastatic brain tumors.

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.

What is the Required Frequency of MRI Scanning in the Wait and Scan Management?

The wait and scan policy is being increasingly used as the first measure after the diagnosis of a vestibular schwannoma (VS) using magnetic resonance imaging (MRI). As part of the European Academy of Otology and Neuro-Otology (EAONO) position statement on VS, the frequency of imaging has been studied in the literature. Among 163 studies, 29 fulfilled the inclusion criteria and were scored using the Grading of Recommendations, Assessment, Development, and Evaluation system. Because tumor growth rate during the first 5 years of follow-up is predictive of further growth during the upcoming years, a protocol for wait and scan is useful for centers dealing with this condition. The EAONO proposal is that after the initial diagnosis by MRI, a first new MRI would take place after 6 months, annually for 5 years, and then every other year for 4 years, followed by a lifelong MRI follow-up every 5 years. The first early MRI is to screen for fast-growing tumors, and the lifelong follow-up with tapered intervals is to detect late repeated growth.

Screening for vestibular schwannoma in the context of an ageing population

Objective

To review the literature regarding screening for vestibular schwannoma in the context of demographic changes leading to increasing numbers of elderly patients presenting with asymmetric auditory symptoms.

Methods

A systematic review of the literature was performed, with narrative synthesis and statistical analysis of data where appropriate.

Results

Vestibular schwannomas diagnosed in patients aged over 70 years exhibit slower growth patterns and tend to be of smaller size compared to those tumours in younger age groups. This fact, combined with reduced life expectancy, renders the probability of these tumours in the elderly requiring active treatment with surgery or stereotactic radiotherapy to be extremely low. Vestibular schwannomas in the elderly are much more likely to be managed by serial monitoring with magnetic resonance imaging. The weighted yield of magnetic resonance imaging in the diagnosis of vestibular schwannoma in all age groups is 1.18 per cent, with almost 85 scans required to diagnose 1 tumour.

Conclusion

An evidence-based approach to the investigation of asymmetric hearing loss and tinnitus in the elderly patient can be used to formulate guidelines for the rational use of magnetic resonance imaging in this population.

Early Radiosurgery Improves Hearing Preservation in Vestibular Schwannoma Patients With Normal Hearing at the Time of Diagnosis

PURPOSE

Vestibular schwannomas (VS) are increasingly diagnosed in patients with normal hearing because of advances in magnetic resonance imaging. We sought to evaluate whether stereotactic radiosurgery (SRS) performed earlier after diagnosis improved long-term hearing preservation in this population.

METHODS AND MATERIALS

We queried our quality assessment registry and found the records of 1134 acoustic neuroma patients who underwent SRS during a 15-year period (1997-2011). We identified 88 patients who had VS but normal hearing with no subjective hearing loss at the time of diagnosis. All patients were Gardner-Robertson (GR) class I at the time of SRS. Fifty-seven patients underwent early (≤2 years from diagnosis) SRS and 31 patients underwent late (>2 years after diagnosis) SRS. At a median follow-up time of 75 months, we evaluated patient outcomes.

RESULTS

Tumor control rates (decreased or stable in size) were similar in the early (95%) and late (90%) treatment groups (P=.73). Patients in the early treatment group retained serviceable (GR class I/II) hearing and normal (GR class I) hearing longer than did patients in the late treatment group (serviceable hearing, P=.006; normal hearing, P<.0001, respectively). At 5 years after SRS, an estimated 88% of the early treatment group retained serviceable hearing and 77% retained normal hearing, compared with 55% with serviceable hearing and 33% with normal hearing in the late treatment group.

CONCLUSIONS

SRS within 2 years after diagnosis of VS in normal hearing patients resulted in improved retention of all hearing measures compared with later SRS.

Imaging of brain tumors

Neuroimaging plays a crucial role in diagnosis of brain tumors and in the decision-making process for therapy. Functional imaging techniques can reflect cellular density (diffusion imaging), capillary density (perfusion techniques), and tissue biochemistry (magnetic resonance [MR] spectroscopy). In addition, cortical activation imaging (functional MR imaging) can identify various loci of eloquent cerebral cortical function. Combining these new tools can increase diagnostic specificity and confidence. Familiarity with conventional and advanced imaging findings facilitates accurate diagnosis, differentiation from other processes, and optimal patient treatment. This article is a practical synopsis of pathologic, clinical, and imaging spectra of most common brain tumors.