Sporadic Vestibular Schwannoma Size and Location Do not Correlate With the Severity of Hearing Loss at Initial Presentation

The Influence of Asymmetric Hearing Loss on Peripheral and Central Auditory Processing Abilities in Patients With Vestibular Schwannoma

OBJECTIVES

Asymmetric or unilateral hearing loss (AHL) may cause irreversible changes in the processing of acoustic signals in the auditory system. We aim to provide a comprehensive view of the auditory processing abilities for subjects with acquired AHL, and to examine the influence of AHL on speech perception under difficult conditions, and on auditory temporal and intensity processing.

DESIGN

We examined peripheral and central auditory functions for 25 subjects with AHL resulting from vestibular schwannoma, and compared them to those from 24 normal-hearing controls that were matched with the AHL subjects in mean age and hearing thresholds in the healthy ear. Besides the basic hearing threshold assessment, the tests comprised the detection of tones and gaps in a continuous noise, comprehension of speech in babble noise, binaural interactions, difference limen of intensity, and detection of frequency modulation. For the AHL subjects, the selected tests were performed separately for the healthy and diseased ear.

RESULTS

We observed that binaural speech comprehension, gap detection, and frequency modulation detection abilities were dominated by the healthy ear and were comparable for both groups. The AHL subjects were less sensitive to interaural delays, however, they exhibited a higher sensitivity to sound level, as indicated by lower difference limen of intensity and a higher sensitivity to interaural intensity difference. Correlations between the individual test scores indicated that speech comprehension by the AHL subjects was associated with different auditory processing mechanisms than for the control subjects.

CONCLUSIONS

The data suggest that AHL influences both peripheral and central auditory processing abilities and that speech comprehension under difficult conditions relies on different mechanisms for the AHL subjects than for normal-hearing controls.

Tumor biomechanical stiffness by magnetic resonance elastography predicts surgical outcomes and identifies biomarkers in vestibular schwannoma and meningioma

Variations in the biomechanical stiffness of brain tumors can not only influence the difficulty of surgical resection but also impact postoperative outcomes. In a prospective, single-blinded study, we utilize pre-operative magnetic resonance elastography (MRE) to predict the stiffness of intracranial tumors intraoperatively and assess the impact of increased tumor stiffness on clinical outcomes following microsurgical resection of vestibular schwannomas (VS) and meningiomas. MRE measurements significantly correlated with intraoperative tumor stiffness and baseline hearing status of VS patients. Additionally, MRE stiffness was elevated in patients that underwent sub-total tumor resection compared to gross total resection and those with worse postoperative facial nerve function. Furthermore, we identify tumor microenvironment biomarkers of increased stiffness, including αSMA + myogenic fibroblasts, CD163 + macrophages, and HABP (hyaluronic acid binding protein). In a human VS cell line, a dose-dependent upregulation of HAS1-3, enzymes responsible for hyaluronan synthesis, was observed following stimulation with TNFα, a proinflammatory cytokine present in VS. Taken together, MRE is an accurate, non-invasive predictor of tumor stiffness in VS and meningiomas. VS with increased stiffness portends worse preoperative hearing and poorer postoperative outcomes. Moreover, inflammation-mediated hyaluronan deposition may lead to increased stiffness.

Age, preoperative tumor volume and widening of the internal acoustic meatus are independent factors associated with poor preoperative hearing in vestibular schwannoma patients - results of a single-center retrospective analysis

Preoperative hearing function shows wide variations among patients diagnosed with vestibular schwannoma. Besides the preoperative tumor size there are other factors that influence the preoperative hearing function that are frequently discussed. A comprehensive analysis of a large cohort of vestibular schwannomas has the potential to describe new insights and influence the preoperative management. We analyzed clinical factors, imaging data and the expression of the proliferation marker MIB1 as potential influencing factors on the preoperative hearing function in a retrospective cohort of 523 primary sporadic vestibular schwannomas. The results of the preoperative audiometry were quantified using the Gardner-Robertson Score. Uni- and multivariate analyses were performed. Serviceable hearing (Gardner-Robertson class 1 or 2) was documented in 391 patients (74.8%). Factors associated with non-serviceable hearing (Gardner-Robertson class 3-5) were patients of older age (p < 0.0001), larger preoperative tumor volume (p = 0.0013) and widening of the internal acoustic meatus compared to the healthy side (p = 0.0353). Gender and differences in the expression of the proliferation marker MIB1 had no influence on preoperative hearing. In the multivariate nominal logistic regression older age (OR 27.60 (CI 9.17-87.18), p < 0.0001), larger preoperative tumor volume (OR 20.20 (CI 3.43-128.58), p = 0.0011) and widening of the internal acoustic canal (OR 7.86 (CI 1.77-35.46), p = 0.0079) remained independent factors associated with non-serviceable hearing. Widening of the internal acoustic canal is an independent factor for non-serviceable preoperative hearing in vestibular schwannoma patients together with older age and larger preoperative tumor volume.

"To implant or not to implant": electrically evoked auditory brainstem response audiometry for decision-making in vestibular schwannoma resection with CI

Vestibular schwannomas (VS) are often associated with debilitating hearing loss. Therefore, preservation and rehabilitation of hearing have become major therapeutic goals of VS management. Recently, cochlear implantation (CI) has been established as an effective treatment option for VS-associated hearing loss. Nevertheless, the integrity and proper function of the cochlear nerve must be evaluated before conducting CI to ensure optimal CI outcomes. Various methods to determine cochlear nerve integrity and functionality have emerged in the last few years. Of these, the use of electrically evoked auditory brainstem response audiometry (eABR) in particular has been proven to be a meaningful tool for monitoring cochlear nerve health during VS surgery. Here, the cochlear nerve can be electrically stimulated using an intracochlear test electrode before, during, and after tumor extirpation. Subsequently, the resulting brainstem responses can be measured and interpreted accordingly to obtain direct information on the cochlear nerve function. This allows for continuous monitoring of cochlear nerve function throughout the course of VS surgery and aids in the decision-making for CI candidacy. Finally, in the case of preserved brainstem responses, CI can be performed instantly after VS extirpation. This simultaneous approach offers several advantages over two-staged procedures and has been shown to be an efficient and safe procedure for restoring hearing after VS removal.

Spontaneous Regression of a Large Vestibular Schwannoma: Is Nonoperative Management Reasonable?

Vestibular schwannomas (VSs) are the most common cerebellopontine tumors. The natural history of smaller-sized VSs (<30 mm) has been well-studied, leading to the recommendation of a "watch and wait" approach. However, large VSs (>30 mm) have not been extensively studied, mainly because of their rarity. As such, most patients are conventionally offered surgery which carries a significant risk of neurological morbidity. Here, we report a case of a giant VS (>40 mm) in a 30-year-old man who regressed spontaneously. He was lost to follow-up for 18 years and, upon re-presentation, the symptomatology drastically improved and repeat imaging demonstrated a marked reduction in tumor size. Referring to similar cases in other studies, we postulate that most large and giant VSs undergo a phase of growth and stasis, followed by regression due to shifts in the balance between tumorigenic and regressive factors. Taken together with emerging molecular data, further studies are required to better understand the history of large and giant VSs to shape more personalized treatment options. This potentially includes non-operative management as a tenable option.

Immune Profiling of Secreted Factors from Human Vestibular Schwannoma Cells and Tumor-associated Macrophages

OBJECTIVES

This study compared the immune-related secretory capacity of human vestibular schwannoma (VS) and tumor-assisted macrophages (TAMs) with their normal counterparts (Schwann cells [SC] and peripheral blood monocyte-derived macrophages [Mo-MFs], respectively), and examined relationships with presurgical hearing and tumor size.

METHODS

VS tumors (n = 16), auditory nerve (n = 1), blood (n = 9), and great auricular nerves (n = 3) were used. SCs (S100B+ ) and TAMs (CD68+ ) were isolated from VS tissue for culture. The secreted levels of 65 immune-related factors were measured and compared using unpaired t-tests with Welch correction (schwannoma vs. SCs) or Mann-Whitney tests (TAMs and Mo-MFs). Associations between factor concentration and word recognition (WR), pure-tone average (PTA), and tumor size were evaluated with Spearman correlation.

RESULTS

Secreted factors with significantly higher concentrations in schwannoma versus SC supernatants included IL-2 and BAFF, whereas MMP-1, IL-6, FGF-2, VEGF-A, MIP-3α, and GRO-α concentrations were significantly higher in TAMs versus Mo-MFs (all p < 0.05). Worse WR was significantly associated with higher secretion of fractalkine, eotaxin-3, CD30, and IL-16 by VS cells; IP-10, eotaxin-3, multiple interleukins, GM-CSF, SCF, and CD30 by TAMs; and TNF-α and MIP-1α by Mo-MFs (all p < 0.05). Worse PTA was significantly correlated with higher secretion of IL-16 by VS cells (p < 0.05). Larger tumor size was significantly correlated with higher secretion of eotaxin by VS cells, and of IL-7, IL-21, and LIF by TAMs (all p = 0.017).

CONCLUSIONS

Differential secretion of immune-related factors was observed in schwannoma versus normal SCs and in TAMs versus Mo-MFs, some of which were correlated with worse hearing and larger VS tumors.

LEVEL OF EVIDENCE

N/A Laryngoscope, 134:S1-S14, 2024.

Natural History of Serviceable Hearing During Active Surveillance of Nongrowing Sporadic Vestibular Schwannoma Supports Consideration of Initial Wait-and-Scan Management

OBJECTIVE

The treatment paradigm of vestibular schwannoma (VS) focuses on preservation of neurologic function, with small tumors increasingly managed with active surveillance. Often, tumor size and hearing outcomes are poorly correlated. The aim of the current work was to describe the natural history of hearing among patients with nongrowing VS during observational management.

STUDY DESIGN

Historical cohort study.

PATIENTS

Adults with sporadic VS.

INTERVENTION

Wait-and-scan management.

MAIN OUTCOME MEASURE

Maintenance of serviceable hearing (SH) after diagnosis.

RESULTS

Among 228 patients with nongrowing VS, 157 patients had SH at diagnosis. Rates of maintaining SH (95% CI; number still at risk) at 1, 3, and 5 years after diagnosis were 94% (89-98; 118), 81% (74-89; 65), and 78% (71-87; 42), respectively. Poorer hearing at diagnosis (hazard ratio [HR] per 10 dB hearing level increase in pure-tone average of 2.51, p < 0.001; HR per 10% decrease in word recognition score of 1.70, p = 0.001) was associated with increased likelihood of developing non-SH during observation. When controlling for baseline hearing status, tumors measuring 5 mm or greater in the internal auditory canal or with cerebellopontine angle extension were associated with significantly increased risk of developing non-SH (HR, 4.87; p = 0.03). At 5 years after diagnosis, 95% of patients with nongrowing intracanalicular VS measuring less than 5 mm maintained SH.

CONCLUSIONS

Hearing worsens during periods of nongrowth in sporadic VS. Patients with small (<5 mm) intracanalicular tumors demonstrate robust maintenance of SH over time, reinforcing the consideration of initial observation in this patient subset.

Matrix metalloproteinase 9: An emerging biomarker for classification of adherent vestibular schwannoma

Background

The progression of vestibular schwannoma (VS) is intricately linked with interactions between schwannoma cells and the extracellular matrix. Surgical resection of VS is associated with substantial risks as tumors are adherent to the brainstem and cranial nerves. We evaluate the role of matrix metalloproteinase 9 (MMP9) in VS and explore its potential as a biomarker to classify adherent VS.

Methods

Transcriptomic analysis of a murine schwannoma allograft model and immunohistochemical analysis of 17 human VS were performed. MMP9 abundance was assessed in mouse and human schwannoma cell lines. Transwell studies were performed to evaluate the effect of MMP9 on schwannoma invasion in vitro. Plasma biomarkers were identified from a multiplexed proteomic analysis in 45 prospective VS patients and validated in primary culture. The therapeutic efficacy of MMP9 inhibition was evaluated in a mouse schwannoma model.

Results

MMP9 was the most highly upregulated protease in mouse schwannomas and was significantly enriched in adherent VS, particularly around tumor vasculature. High levels of MMP9 were found in plasma of patients with adherent VS. MMP9 outperformed clinical and radiographic variables to classify adherent VS with outstanding discriminatory ability. Human schwannoma cells secreted MMP9 in response to TNF-α which promoted cellular invasion and adhesion protein expression in vitro. Lastly, MMP9 inhibition decreased mouse schwannoma growth in vivo.

Conclusions

We identify MMP9 as a preoperative biomarker to classify adherent VS. MMP9 may represent a new therapeutic target in adherent VS associated with poor surgical outcomes that lack other viable treatment options.

Identification of immune-related candidate biomarkers in plasma of patients with sporadic vestibular schwannoma

Vestibular schwannoma (VS) is an intracranial tumor arising from neoplastic Schwann cells and typically presenting with hearing loss. The traditional belief that hearing deficit is caused by physical expansion of the VS, compressing the auditory nerve, does not explain the common clinical finding that patients with small tumors can have profound hearing loss, suggesting that tumor-secreted factors could influence hearing ability in VS patients. We conducted profiling of patients' plasma for 66 immune-related factors in patients with sporadic VS (N > 170) and identified and validated candidate biomarkers associated with tumor size (S100B) and hearing (MCP-3). We further identified a nine-biomarker panel (TNR-R2, MIF, CD30, MCP-3, IL-2R, BLC, TWEAK, eotaxin, and S100B) with outstanding discriminatory ability for VS. These findings revealed possible therapeutic targets for VS, providing a unique diagnostic tool that may predict hearing change and tumor growth in VS patients, and may inform the timing of tumor resection to preserve hearing.

miR-431 secreted by human vestibular schwannomas increases the mammalian inner ear's vulnerability to noise trauma

Introduction

Vestibular schwannoma (VS) is an intracranial tumor that arises on the vestibular branch of cranial nerve VIII and typically presents with sensorineural hearing loss (SNHL). The mechanisms of this SNHL are postulated to involve alterations in the inner ear's microenvironment mediated by the genetic cargo of VS-secreted extracellular vesicles (EVs). We aimed to identify the EV cargo associated with poor hearing and determine whether its delivery caused hearing loss and cochlear damage in a mouse model in vivo.

Methods

VS tissue was collected from routinely resected tumors of patients with good (VS-GH) or poor (VS-PH) pre-surgical hearing measured via pure-tone average and word recognition scores. Next-generation sequencing was performed on RNA isolated from cultured primary human VS cells and EVs from VS-conditioned media, stratified by patients' hearing ability. microRNA expression levels were compared between VS-PH and VS-GH samples to identify differentially expressed candidates for packaging into a synthetic adeno-associated viral vector (Anc80L65). Viral vectors containing candidate microRNA were infused to the semicircular canals of mice to evaluate the effects on hearing, including after noise exposure.

Results

Differentially expressed microRNAs included hsa-miR-431-5p (enriched in VS-PH) and hsa-miR-192-5p (enriched in VS-GH). Newborn mice receiving intracochlear injection of viral vectors over-expressing hsa-miR-431-GFP, hsa-miR-192-GFP, or GFP only (control) had similar hearing 6 weeks post-injection. However, after acoustic trauma, the miR-431 group displayed significantly worse hearing, and greater loss of synaptic ribbons per inner hair cell in the acoustically traumatized cochlear region than the control group.

Conclusion

Our results suggest that miR-431 contributes to VS-associated hearing loss following cochlear stress. Further investigation is needed to determine whether miR-431 is a potential therapeutic target for SNHL.

Automated Radiomic Analysis of Vestibular Schwannomas and Inner Ears Using Contrast-Enhanced T1-Weighted and T2-Weighted Magnetic Resonance Imaging Sequences and Artificial Intelligence

OBJECTIVE

To objectively evaluate vestibular schwannomas (VSs) and their spatial relationships with the ipsilateral inner ear (IE) in magnetic resonance imaging (MRI) using deep learning.

STUDY DESIGN

Cross-sectional study.

PATIENTS

A total of 490 adults with VS, high-resolution MRI scans, and no previous neurotologic surgery.

INTERVENTIONS

MRI studies of VS patients were split into training (390 patients) and test (100 patients) sets. A three-dimensional convolutional neural network model was trained to segment VS and IE structures using contrast-enhanced T1-weighted and T2-weighted sequences, respectively. Manual segmentations were used as ground truths. Model performance was evaluated on the test set and on an external set of 100 VS patients from a public data set (Vestibular-Schwannoma-SEG).

MAIN OUTCOME MEASURES

Dice score, relative volume error, average symmetric surface distance, 95th-percentile Hausdorff distance, and centroid locations.

RESULTS

Dice scores for VS and IE volume segmentations were 0.91 and 0.90, respectively. On the public data set, the model segmented VS tumors with a Dice score of 0.89 ± 0.06 (mean ± standard deviation), relative volume error of 9.8 ± 9.6%, average symmetric surface distance of 0.31 ± 0.22 mm, and 95th-percentile Hausdorff distance of 1.26 ± 0.76 mm. Predicted VS segmentations overlapped with ground truth segmentations in all test subjects. Mean errors of predicted VS volume, VS centroid location, and IE centroid location were 0.05 cm 3 , 0.52 mm, and 0.85 mm, respectively.

CONCLUSIONS

A deep learning system can segment VS and IE structures in high-resolution MRI scans with excellent accuracy. This technology offers promise to improve the clinical workflow for assessing VS radiomics and enhance the management of VS patients.

The comparable tumour microenvironment in sporadic and NF2-related schwannomatosis vestibular schwannoma

Bilateral vestibular schwannoma is the hallmark of NF2-related schwannomatosis, a rare tumour predisposition syndrome associated with a lifetime of surgical interventions, radiotherapy and off-label use of the anti-angiogenic drug bevacizumab. Unilateral vestibular schwannoma develops sporadically in non-NF2-related schwannomatosis patients for which there are no drug treatment options available. Tumour-infiltrating immune cells such as macrophages and T-cells correlate with increased vestibular schwannoma growth, which is suggested to be similar in sporadic and NF2-related schwannomatosis tumours. However, differences between NF2-related schwannomatosis and the more common sporadic disease include NF2-related schwannomatosis patients presenting an increased number of tumours, multiple tumour types and younger age at diagnosis. A comparison of the tumour microenvironment in sporadic and NF2-related schwannomatosis tumours is therefore required to underpin the development of immunotherapeutic targets, identify the possibility of extrapolating ex vivo data from sporadic vestibular schwannoma to NF2-related schwannomatosis and help inform clinical trial design with the feasibility of co-recruiting sporadic and NF2-related schwannomatosis patients. This study drew together bulk transcriptomic data from three published Affymetrix microarray datasets to compare the gene expression profiles of sporadic and NF2-related schwannomatosis vestibular schwannoma and subsequently deconvolved to predict the abundances of distinct tumour immune microenvironment populations. Data were validated using quantitative PCR and Hyperion imaging mass cytometry. Comparative bioinformatic analyses revealed close similarities in NF2-related schwannomatosis and sporadic vestibular schwannoma tumours across the three datasets. Significant inflammatory markers and signalling pathways were closely matched in NF2-related schwannomatosis and sporadic vestibular schwannoma, relating to the proliferation of macrophages, angiogenesis and inflammation. Bulk transcriptomic and imaging mass cytometry data identified macrophages as the most abundant immune population in vestibular schwannoma, comprising one-third of the cell mass in both NF2-related schwannomatosis and sporadic tumours. Importantly, there were no robust significant differences in signalling pathways, gene expression, cell type abundance or imaging mass cytometry staining between NF2-related schwannomatosis and sporadic vestibular schwannoma. These data indicate strong similarities in the tumour immune microenvironment of NF2-related schwannomatosis and sporadic vestibular schwannoma.

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.

Intraoperative Cochlear Nerve Monitoring in Vestibular Schwannoma Microsurgery

Monitoring the cochlear nerve during vestibular schwannoma (VS) microsurgery depends on the hearing status and surgical approach. Traditional hearing preservation VS microsurgery relies on acoustically driven auditory brainstem response (ABR) and cochlear nerve action potential. Both modalities have advantages and disadvantages that need to be understood for proper implementation. When hearing is lost or the approach violates the otic capsule, electrically evoked monitoring methods may be used. Evoked ABR (eABR) is feasible and safe but may be limited by artifact. Combining eABR with near-field measures such as electrocochleography or neural telemetry shows promise.

The NLRP3 inflammasome as a target for sensorineural hearing loss

Sensorineural hearing loss is the most common type of hearing loss in adults and occurs due to damage of the inner ear caused by a range of factors including ageing, excessive noise, toxins, and cancer. Auto-inflammatory disease is also a cause of hearing loss and there is evidence that inflammation could contribute to hearing loss in other conditions. Within the inner ear there are resident macrophage cells that respond to insults and whose activation correlates with damage. The NLRP3 inflammasome is a multi-molecular pro-inflammatory protein complex that forms in activated macrophages and may contribute to hearing loss. The aim of this article is to discuss the evidence for the NLRP3 inflammasome and associated cytokines as potential therapeutic targets for sensorineural hearing loss in conditions ranging from auto-inflammatory disease to tumour-induced hearing loss in vestibular schwannoma.

Increased Labyrinthine T1 Postgadolinium Signal Intensity Is Associated with the Degree of Ipsilateral Sensorineural Hearing Loss in Patients with Sporadic Vestibular Schwannoma

BACKGROUND AND PURPOSE

Vestibular schwannomas are benign, generally slow-growing tumors, commonly presenting with hearing loss. Alterations in the labyrinthine signal are seen in patients with vestibular schwannoma; however, the association between imaging abnormalities and hearing function remains poorly defined. The purpose of this study was to determine whether labyrinthine signal intensity is associated with hearing in patients with sporadic vestibular schwannoma.

MATERIALS AND METHODS

This was an institutional review board-approved retrospective review of patients from a prospectively maintained vestibular schwannoma registry imaged in 2003-2017. Signal-intensity ratios of the ipsilateral labyrinth were obtained using T1, T2-FLAIR, and postgadolinium T1 sequences. Signal-intensity ratios were compared with tumor volume and audiometric hearing threshold data including pure tone average, word recognition score, and American Academy of Otolaryngology-Head and Neck Surgery hearing class.

RESULTS

One hundred ninety-five patients were analyzed. Ipsilateral labyrinthine signal intensity including postgadolinium T1 images was positively correlated with tumor volume (correlation coefficient = 0.17, P  = .02). Among signal-intensity ratios, postgadolinium T1 was significantly positively associated with pure tone average (correlation coefficient = 0.28, P  < .001) and negatively associated with the word recognition score (correlation coefficient = -0.21, P  = .003). Overall, this result correlated with impaired American Academy of Otolaryngology-Head and Neck Surgery hearing class (P  = .04). Multivariable analysis suggested persistent associations independent of tumor volume with pure tone average (correlation coefficient = 0.25, P  < .001) and the word recognition score (correlation coefficient = -0.17, P  = .02) but not hearing class (P  = .14). No consistent significant associations were noted between noncontrast T1 and T2-FLAIR signal intensities and audiometric testing.

CONCLUSIONS

Increased ipsilateral labyrinthine postgadolinium signal intensity is associated with hearing loss in patients with vestibular schwannoma.

Functional Outcome After Simultaneous Vestibular Schwannoma Resection and Cochlear Implantation With Intraoperative Cochlear Nerve Monitoring

OBJECTIVE

Electrically evoked auditory brainstem response audiometry has emerged as a suitable option to intraoperatively assess cochlear nerve function during vestibular schwannoma resection. This study aimed to analyze the functional outcome and implant usage of patients with preserved auditory nerve responses after simultaneous translabyrinthine schwannoma resection and cochlear implantation.

STUDY DESIGN

Prospective study.

SETTING

Tertiary referral center.

METHODS

Patients with unilateral sporadic vestibular schwannoma underwent translabyrinthine tumor resection. Intraoperatively, electrically evoked auditory brainstem response audiometry was performed before and after tumor removal. Cochlear implantation was carried out if positive responses were detected after tumor removal indicating cochlear nerve function. Postoperatively, patients were biannually followed-up to assess aided sound field audiometry and word recognition as well as implant usage.

RESULTS

Overall, 26 patients with vestibular schwannoma underwent translabyrinthine schwannoma resection. Out of these patients, 15 had positive cochlear nerve responses after tumor removal and concurrently received a cochlear implant. In 13 patients with histologically confirmed vestibular schwannoma, hearing improved by 23.7 ± 33.2 decibels and word recognition by 25.0 ± 42.4% over a mean follow-up period of 18 months. Overall, 12 included patients were regular cochlear implant users.

CONCLUSION

Patients with vestibular schwannoma can benefit substantially from cochlear implantation. Intraoperative assessment of cochlear nerve function using electrically evoked auditory brainstem response audiometry can help to better identify individuals eligible for simultaneous vestibular schwannoma resection and cochlear implantation.

Identification of Immune-Related Candidate Biomarkers in Plasma of Patients with Sporadic Vestibular Schwannoma: Candidate Plasma Biomarkers in Vestibular Schwannoma

Vestibular schwannoma (VS) is intracranial tumor arising from neoplastic Schwann cells, causing hearing loss in about 95% of patients. The traditional belief that hearing deficit is caused by physical expansion of the VS, compressing the auditory nerve, does not explain the common clinical finding that patients with small tumors can have profound hearing loss, suggesting that tumor-secreted factors could influence hearing ability in VS patients. Here, we conducted profiling of patients' plasma for 67 immune-related factors on a large cohort of VS patients (N>120) and identified candidate biomarkers associated with tumor growth (IL-16 and S100B) and hearing (MDC). We identified the 7-biomarker panel composed of MCP-3, BLC, S100B, FGF-2, MMP-14, eotaxin, and TWEAK that showed outstanding discriminatory ability for VS. These findings revealed possible therapeutic targets for VS-induced hearing loss and provided a unique diagnostic tool that may predict hearing change and tumor growth in VS patients and may help inform the ideal timing of tumor resection to preserve hearing.