Intraoperative assessment of cochlear nerve functionality in various vestibular schwannoma scenarios: Lessons learned.

The use of cochlear implants (CIs) is on the rise for patients with vestibular schwannoma (VS). Besides CI following tumor resection, new scenarios such as implantation in observed and/or irradiated tumors are becoming increasingly common. A significant emerging trend is the need of intraoperative evaluation of the functionality of the cochlear nerve in order to decide if a CI would be placed. The purpose of this paper is to explore the experience of a tertiary center with the application of the Auditory Nerve Test System (ANTS) in various scenarios regarding VS patients. The results are compared to that of the studies that have previously used the ANTS in this condition. Patients with unilateral or bilateral VS (NF2) who were evaluated with the ANTS prior to considering CI in a tertiary center between 2021 and 2023 were analyzed. The presence of a robust wave V was chosen to define a positive electrical auditory brainstem response (EABR). Two patients underwent promontory stimulation (PromStim) EABR previous to ANTS evaluation. Seven patients, 2 NF-2 and 5 with sporadic VS were included. The initial scenario was simultaneous translabyrinthine (TL) tumor resection and CI in 3 cases while a CI placement without tumor resection was planned in 4 cases. The ANTS was positive in 4 cases, negative in 2 cases, and uncertain in one case. Two patients underwent simultaneous TL and CI, 1 patient simultaneous TL and auditory brainstem implant, 3 patients posterior tympanotomy with CI, and 1 patient had no implant placement. In the 5 patients undergoing CI, sound detection was present. There was a good correlation between the PromStim and ANTS EABR. The literature research yielded 35 patients with complete information about EABR response. There was one false negative and one false positive case; that is, the 28 implanted cases with a present wave V following tumor resection had some degree of auditory perception in all but one case. The ANTS is a useful intraoperative tool to asses CI candidacy in VS patients undergoing observation, irradiation or surgery. A positive strongly predicts at least sound detection with the CI.

Disparities in Sporadic Vestibular Schwannoma Initial Presentation Between a Public Safety Net Hospital and Tertiary Academic Medical Center at the Same Zip Code 2010 to 2020.

INTRODUCTION: Treatment of vestibular schwannoma (VS) has been extensively studied, but a gap in knowledge exists demonstrating how racial and socioeconomic status influence VS presentation. Our institution has a unique setting with a public safety net hospital (PSNH) and tertiary academic medical center (TAMC) in the same zip code, which we study to evaluate initial VS presentation disparities in patient populations presenting to these hospital settings. METHODS: Retrospective chart review was performed of all adult patients (n = 531) presenting 2010 to 2020 for initial VS evaluation at TAMC (n = 462) and PSNH (n = 69). Ethnicity, insurance, maximum tumor size, audiometry, initial treatment recommendation, treatment received, and follow up were recorded and statistical analysis performed to determine differences. RESULTS: Average age at diagnosis (51.7 ± 13.6 TAMC vs 52.3 ± 12.4 PSNH) and gender (58.4% TAMC vs 52.2% PSNH female) were similar. Patients' insurance (TAMC 75.9% privately insured vs PSNH 82% Medicaid) and racial/ethnic profiles (TAMC 67.7% White and 10.0% Hispanic/Latinx, vs PSNH 4.8% White but 59.7% Hispanic/Latinx) were significantly different. Tumor size was larger at PSNH (20.2 ± 13.3 mm) than TAMC (16.6 ± 10.0 mm). Hearing was more impaired at PSNH than TAMC (mean pure tone average 58.3 dB vs 43.9 dB, word recognition scores 52.3% vs 68.2%, respectively). Initial treatment recommendations and treatment received may include more than 1 modality. TAMC patients were offered 66.7% surgery, 31.2% observation, and 5.2% radiation, while PSNH patients offered 50.7% observation, 49.3% surgery, and 8.7% radiation. TAMC patients received 62.9% surgery, 32.5% observation, and 5.3% radiation, while PSNH patients received 36.2% surgery, 59.4% observation, and 14.5% radiation. Follow up and treatment at the same facility was not significantly different between hospitals. CONCLUSIONS: Hearing was worse and tumor size larger in patients presenting to PSNH. Despite worse hearing status and larger tumor size, the majority of PSNH patients were initially offered observation, compared to TAMC where most patients were initially offered surgery.

Cost considerations for vestibular schwannoma screening and imaging: a systematic review.

Vestibular schwannomas (VS) account for approximately 8% of all intracranial neoplasms. Importantly, the cost of the diagnostic workup for VS, including the screening modalities most commonly used, has not been thoroughly investigated. Our aim is to conduct a systematic review of the published literature on costs associated with VS screening. A systematic review of the literature for cost of VS treatment was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The terms "vestibular schwannoma," "acoustic neuroma," and "cost" were queried using the PubMed and Embase databases. Studies from all countries were considered. Cost was then corrected for inflation using the US Bureau of Labor Statistics Inflation Calculator, correcting to April 2022. The search resulted in an initial review of 483 articles, of which 12 articles were included in the final analysis. Screening criteria were used for non-neurofibromatosis type I and II patients who complained of asymmetric hearing loss, tinnitus, or vertigo. Patients included in the studies ranged from 72 to 1249. The currency and inflation-adjusted mean cost was $418.40 (range, $21.81 to $487.03, n = 5) for auditory brainstem reflex and $1433.87 (range, $511.64 to $1762.15, n = 3) for non-contrasted computed tomography. A contrasted magnetic resonance imaging (MRI) scan was found to have a median cost of $913.27 (range, $172.25-$2733.99; n = 8) whereas a non-contrasted MRI was found to have a median cost of $478.62 (range, $116.61-$3256.38, n = 4). In terms of cost reporting, of the 12 articles, 1 (8.3%) of them separated out the cost elements, and 10 (83%) of them used local prices, which include institutional costs and/or average costs of multiple institutions. Our findings describe the limited data on published costs for screening and imaging of VS. The paucity of data and significant variability of costs between studies indicates that this endpoint is relatively unexplored, and the cost of screening is poorly understood.

Socioeconomic Disparities in the Pursuit of Care at a High-Volume Institution for Surgical Resection of Vestibular Schwannomas.

OBJECTIVE: Increased institutional surgical resection case volume for vestibular schwannomas (VSs) has been associated with improved patient outcomes, including reduced risk of prolonged hospital stay and readmission. Socioeconomic disparities in the pursuit of care at these high-volume institutions remain unknown. STUDY DESIGN: Retrospective cohort epidemiological study. SETTING: National Cancer Database, a hospital-based registry of over 1,500 facilities in the United States. PATIENTS: Adult VS patients (age, >18 years) treated surgically. INTERVENTIONS: High- versus low-volume facilities, defined using a facility case volume threshold of 25 cases per year. A risk-adjusted restricted cubic spline model was previously used to identify this risk threshold beyond which the incremental benefit of increasing case volume began to plateau. MAIN OUTCOME MEASURES: Sociodemographic factors, including race, ethnicity, income, insurance status, and rurality. Multivariable analyses were adjusted for patient and tumor characteristics, including age, sex, Charlson-Deyo score, and tumor size. RESULTS: A totoal of 10,048 patients were identified (median [interquartile range] age = 51 [41-60] years, 54% female, 87% Caucasian). Patients with Spanish/Hispanic ethnicity (OR = 0.71, 95% confidence interval [CI] = 0.52-0.96), income below median (OR = 0.63, 95% CI = 0.55-0.73]), and Medicare, Medicaid, or other government insurance versus private insurance (OR = 0.63, 95% CI = 0.53-0.74) had reduced odds of treatment at a high-volume facility. Further sensitivity analyses in which facility volume was operationalized continuously reinforced direction and significance of these associations. CONCLUSIONS: Socioeconomic disparities exist in the propensity for VS patients to be treated at a high-volume facility. Further work is needed to understand the nature of these associations and whether interventions can be designed to mitigate them.

CLINICAL-AND-FUNCTIONAL ASSESSMENT OF THE EARLY POSTOPERATIVE OUTCOME OF SURGICAL TREATMENT OF PATIENTS WITH VESTIBULAR SCHWANNOMA.

The incidence of vestibular schwannoma (VS) increased largely within the last 50 years from 1,5 cases per 100 thousand persons to 4,2 (for the last decade). The approaches to the management of VS patients vary significantly in different medical centers and different countries. The search for the consensus in selecting strategy of VS treatment based on systemic clinical-and-functional assessment of treatment outcome is topical nowadays. The aim of study - to analyze the clinical-and-functional early postoperative outcome of the surgical treatment of vestibular schwannoma depending on the stage of the disease. The findings of the examination and the outcomes of the surgical treatment of 27 VS patients were retrospectively analyzed. The patients were treated at the Department of Subtentorial Neurosurgery of the State Institution "Romodanov Institute of Neurosurgery of the NAMS of Ukraine" in 2018-2019. According to Koos classification, three groups of the patients were delineated for the analysis of the results of the study, namely, group 1 (Koos II) - 8 (29,6 %) patients; group 2 (Koos III) - 6 (22,2 %); and group 3 (Koos IV) - 13 (48,2 %). The complex clinical examination, in particular clinical-and-instrumental otoneurological examination and the evaluation of the neurological status according to the Scale for the assessment of the functional treatment outcome were performed preoperatively and early postoperatively. The data were statistically processed. In the patients with small tumors (group 1, Koos II), the socially useful hearing on the affected side was preserved preoperatively necessitating the caution for selecting the treatment strategy in these patients. When pre- and postoperative clinical symptoms were compared in group 1, the statistically significant worsening of the hearing to the socially non-useful, the unilateral subjective tinnitus, the dysfunction of the facial nerve, the decreased sense of taste/loss of taste on the anterior 2/3 of the tongue on the affected side were found. Upon the surgical treatment, the rate of the neurological deficit increased, and the severity grade of the neurological deficit increased by about 10 points. The overall preoperative score in group 3 (Koos IV) was significantly different from that in other groups. The progression of the disease to the stage of Koos IV results in the neurological deficit that is equivalent by the set of the neurological symptoms and their severity to that in early postoperative period in patients with Koos III. In group 3, the rate of the dysfunction of the facial nerve and the caudal group of the cranial nerves increased postoperatively with concomitant decreased sense of taste/loss of taste on the anterior 2/3 of the tongue on the affected side and statocoordinatory impairments. The overall preoperative score differed significantly between all groups. In group 3, the postoperative overall score did not differ from preoperative one, although the postoperative overall score in group 3 (Koos ІV) differed significantly from that in other two groups. The proposed scale for the assessment of the functional outcome of the VS treatment is versatile and represents the integral element of the systemic assessment of the clinical-and-functional status of VS patient. There are good reasons to integrate proposed scale into the general scheme of the medical care for VS patients allowing for the objective assessment of the otoneurological patterns in the patients in the dynamics of the treatment. The analysis of our own findings and the literature data proved the relevance of the problem requiring further task-oriented scientific inquiry. The important aspects of the problem relate to the optimization and improvement of the diagnostic and treatment strategy according to the principles of individualization and multimodality allowing for increasing the level of consensus and improving the functional outcome of the treatment.

Labyrinthine Fluid Signal Intensity on T2-Weighted MR Imaging in Patients With Vestibular Schwannomas Undergoing Proton Radiotherapy: A Longitudinal Assessment.

OBJECTIVE: In vestibular schwannoma patients, a loss of signal intensity (SI) on T2-weighted magnetic resonance imaging (MRI) has been reported within the ipsilateral labyrinth. The purpose of this study was to quantitatively evaluate the occurrence and course of this intensity loss in relation to proton radiotherapy and its possible association with hearing loss. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary referral center. PATIENTS: Patients who received proton therapy for a vestibular schwannoma and underwent at least two high-resolution T2-weighted cisternographic sequence (constructive interference in steady state/fast imaging employing steady-state acquisition/DRIVE) MRIs and audiometry assessments. MAIN OUTCOME MEASURES: Relative T2 SIs from the vestibules and basal/apical cochlear turns of the labyrinth, bilaterally. RESULTS: Ninety-five MRI scans from 34 patients were included. The apical turn of the ipsilateral cochlea showed a lower mean cochlear SI than on the contralateral side (±3.5 versus 5.0). The mean relative cochlear SI did not significantly change after proton radiotherapy. The ipsilateral vestibule showed a higher SI than the cochlea. The relative mean cochlear SI was not directly correlated to (the degree of) hearing loss before or after proton radiotherapy, nor did it predict future hearing loss. CONCLUSION: The relative mean cochlear SI on cisternographic T2-MRI in vestibular schwannoma patients is diminished on the treated side, when compared with the ipsilateral vestibule and the contralateral cochlea/vestibule. The SI of the ipsilateral cochlea does not further decrease after proton radiotherapy and seems to be related to the tumor rather than the therapy. The diminished cochlear SI does not correlate with subsequent loss of hearing.

Anticipating Facial Nerve Position Using Three-Dimensional Tractography During the Preoperative Assessment of Cerebellopontine Angle Tumors.

OBJECTIVE: We aim to evaluate the usefulness of preoperative facial nerve tractography in determining the facial nerve position in cerebellopontine angle tumor resection and its value in helping to preserve facial nerve function during surgery. METHODS: A prospective study was designed to include patients presenting with cerebellopontine angle tumors. Three-dimensional reconstruction of facial nerve tractography was performed and added to the usual preoperative testing in all patients. Facial nerve position was compared between tractography results and surgical findings. Moreover, facial nerve function was evaluated at baseline and during follow-up. RESULTS: Fifteen patients were included for analysis. Complete resection was obtained in 5 patients, near-total resection was achieved in 8 patients, and partial resection in 2 patients. We found a strong statistically significant concordance between the preoperative facial nerve tractography reconstruction and the intraoperative findings (complete concordance in 86.66% of all the cases; κ = 0.784; P < 0.0001). Facial nerve anatomic structure was preserved in all patients during surgery. At 6 months follow-up, 66.66% of patients had a facial nerve normal function or a mild dysfunction. CONCLUSIONS: Preoperative facial nerve tractography reconstruction showed a high correlation with intraoperative findings. Preoperative tractography information regarding facial nerve position and its cisternal course is valuable information and could help the surgeon in increasing the safety of the procedure during cerebellopontine angle tumor surgery.

Novel Multiportal Approach to the Internal Auditory Canal for Hearing-Preserving Surgery: Feasibility Assessment in Dissections.

OBJECTIVE: State-of-the-art, minimally invasive endoscopic transcanal surgery of the internal auditory canal (IAC) sacrifices the cochlea with complete hearing loss. With a combination of the transcanal infracochlear and transmastoid retrolabyrinthine approaches, we aim to preserve hearing and enable minimally invasive surgical treatment of vestibular schwannoma. In this study, we investigate the anatomical indications and the feasibility of both approaches in dissections, in human whole head specimens. METHODS: We operated whole head anatomical specimens with a four-handed technique, using the retrolabyrinthine approach as the main surgical corridor and the infracochlear approach for endoscopic visualization. We tested 4 different powered surgical systems. We collected intraoperative data on the size of the access windows, the surgical freedom, and the exposed area of the IAC. Finally, we evaluated the outcome in postoperative computed tomography scans. RESULTS: Six out of 14 sides were anatomically suitable and qualified for the surgery based on preoperative computed tomography. In all attempted sides, the IAC could be reached and opened, leaving the ossicular chain and the labyrinth intact. 51%-75% of the length and 22%-40% of the circumference of the IAC could be exposed. All tested instruments were beneficial at different stages of the surgery. The four-handed technique enabled good maneuverability of the instruments. CONCLUSIONS: The combined multiportal approach to the IAC is feasible with a good surgical exposure and full anatomical preservation of hearing. State-of-the-art surgical instruments in specimens with suitable anatomy are sufficient to perform this approach.

On the effect of dose delivery temporal domain on the biological effectiveness of central nervous system CyberKnife radiosurgery applications: theoretical assessment using the concept of biologically effective dose.

OBJECTIVE: The diversity in technical configuration between clinically available radiosurgery systems, results in accordingly diverse treatment times for the same physical dose prescription, spanning from several min to more than 1 h. This, combined with evidence supporting the impact of dose delivery temporal pattern on the bio-effectiveness of low-LET radiation treatments, challenges the 'acute exposure' assumption adopted clinically to estimate the biological outcome of a given treatment scheme under the concept of biologically effective dose (BED).Approach: In this work, the treatment plans of 30 patients underwent CyberKnife radiosurgery for vestibular schwannoma (VS), prescribing a marginal dose of 13 Gy to the tumor, were retrospectively reviewed and the corresponding dose distributions were resolved in the temporal domain. For this purpose, the dose delivery timeline for each treatment was calculated based on relevant treatment plan data and technical specifications of the CyberKnife system, while dosimetry data were independently acquired on a CT-based digital model of each patient using an in-house developed dose calculation algorithm.Main results: Results showed that CyberKnife delivers highly inhomogeneous dose rate distributions in the temporo-spatial domain. This influences the delivered BED levels due to alterations in the sublethal damage repair (SLR) occurring within the treatment session. Using a BED framework involving SLR effects, it was shown that each physical dose iso-surface is associated with a BEDslrrange. For the patient cohort studied, a typical range of 2%, with respect to the mean BEDslrvalue was found at 1σ.Significance: The marginal BEDslrdelivered to the tumor by the prescription dose iso-surface deteriorates with treatment time, involving both beam-on time and beam-off gaps. For treatment time,T, between 21 and 50 min, this can be expressed byBEDslr(Gy2.47)=-0.35±2.8%∙Tmin+(76.74±0.4%).Compared to the acute exposure approach, a BED 'loss' of 21% is associated with the delivery of 13 Gy to the VS-tumor in 35 min.

Quantitative assessment of brainstem distortion in vestibular schwannoma and its implication in occurrence of hydrocephalus.

PURPOSE: Anatomical distortion directly affects the clinical status of patients with vestibular schwannomas (VSs). It may vary for a given tumor size due to variability in posterior fossa anatomy. We aimed to quantitatively assess brainstem distortion (BSD) and review its role in occurrence of hydrocephalus associated with VSs. METHODS: Sixty-six patients with small (<3 cm, n= 8; 12.1%); large (3-4 cm; n= 26; 39.4%) and giant (>4 cm; n= 32; 48.5%) VSs were included. Cystic VSs were excluded. Tumor size, tumor-extent, linear displacement (LD; distance between line bisecting pons (line 1) and posterior fossa midline (line 2)) and angular distortion (AD; angle subtended between lines 1 and 2) in axial-T2-MRI section through pons, and their effect on hydrocephalus were assessed. RESULTS: Significant BSD occurred in a younger age (p value = .004/.003), larger-sized tumor (p value = .001/.002), hydrocephalus (p value = .001/.001), trigeminal (V) nerve palsy (p value = .004/.003) and long tract signs (p value = .001/.034). Tumors crossing midline had significant association with hydrocephalus (p value = .003). LD increased progressively even for 4-5 cm-sized tumors while AD stabilized. Receiver operating characteristic (ROC) curve revealed that diagnostic accuracy of LD (area under the ROC curve (AUROC): 78.9% (95% CI: 67.2%, 90.5%, p < .001)), AD (AUROC:77.6% (95% CI:65.8%, 89.5%, p < .001)) and LD × AD (AUROC:80.3% (95% CI: 69.2%, 91.2%, p < .001)) for predicting occurrence of hydrocephalus was better than tumor size (AUROC: 66.7% (95% CI: 53.5%, 79.9%, p < .05). Cut-off values of LD and AD for predicting occurrence of hydrocephalus were 6.25 mm and 14.6°, respectively. Hydrocephalus was significantly more when both LD was greater than  6.25 mm and AD was greater than 14.5° (p value = .034). The role of LD and AD in influencing hydrocephalus was greater than categorization based on tumor size (Spearman's correlation coefficient: 0.535 and 0.248, respectively). Hydrocephalus occurred at a lesser cut-off value of LD and AD when compared to long tract signs. CONCLUSIONS: LD and AD values in VSs have a significantly greater influence in the development of hydrocephalus compared to tumor size, and may aid, more reliably, in the prediction of hydrocephalus.

Auditory brainstem response prior to MRI compared to standalone MRI in the detection of vestibular schwannoma: A modelling study.

OBJECTIVES: To determine the cost-effectiveness of auditory brainstem response prior to MRI (ABR-MRI) compared to standalone MRI to diagnose vestibular schwannoma. DESIGN: A state transition model was developed to simulate costs and effects (quality-adjusted life years [QALY]) for both diagnostic strategies for patients suspected of a vestibular schwannoma. Model input was derived from literature, hospital databases and expert opinions. Scenario and sensitivity analyses addressed model uncertainty. RESULTS: Over a lifetime horizon, ABR-MRI resulted in a limited cost-saving of €68 or €98 per patient (dependent on MRI sequence) and a health loss of 0.005 QALYs over standalone MRI. ABR-MRI, however, did miss patients with other important pathology (2% of the population) that would have been detected when using standalone MRI. In total, €14 203 or €19 550 could be saved per lost QALY if ABR-MRI was used instead of standalone MRI. The results were sensitive to the detection rate of vestibular schwannoma and health-related quality of life of missed patients. CONCLUSION: The cost-saving with ABR-MRI does not seem to outweigh the number of missed patients with VS and other important pathologies that would have been detected when using standalone MRI.

Growing versus non-growing vestibular schwannomas: assessment of natural history.

OBJECTIVE: Vestibular schwannomas can demonstrate great heterogeneity in their behaviour; approximately one-third will grow and two-thirds will not. This study aimed to determine whether there are factors present at diagnosis that can help predict outcomes. METHODS: This retrospective cohort study compared data from 735 patients from the past 20 years. Analysis of serial magnetic resonance imaging was carried out to place patients into growing and non-growing cohorts. Factors including size, age, follow-up time and presence of balance symptoms were compared. RESULTS: The median size of a growing vestibular schwannoma at diagnosis was 13 mm, whereas the non-growing median size was 10.65 mm (p < 0.001). Balance symptoms were present in 60.76 per cent of growing vestibular schwannoma patients but only in 38.75 per cent of patients with non-growing vestibular schwannomas (p < 0.001). CONCLUSION: This study highlights initial tumour size and balance symptoms as potential predictors of whether or not a vestibular schwannoma will grow; these results better facilitate our understanding of vestibular schwannoma natural history.

Volumetry and Surgical Grading Systems for Vestibular Schwannoma Size Assessment and their Relationship to Postoperative Facial Nerve Function.

BACKGROUND AND STUDY AIMS: Treatment modalities in vestibular schwannoma (VS) are difficult to compare since different techniques for size measurements are used. The purpose of this study was to evaluate the relation between different tumor size grading systems regarding their compatibility as well as the relationship to facial nerve outcome facilitating comparisons of different studies. MATERIAL AND METHODS: In this retrospective study, preoperative magnetic resonance imaging of 100 patients with surgically treated VS was evaluated regarding total tumor volume and anatomical extension based on the Koos and Samii classification, as well as volumetric and maximal diameter measures. Three-dimensional constructive interference in steady state (3D-CISS) and T1 postcontrast volumetric interpolated breath-hold examination (VIBE) sequences were used. Facial nerve function was evaluated according to the House-Brackmann (HB) scale 6 months following complete tumor removal via the retrosigmoid approach. RESULTS: Tumor size showed a moderate influence on postsurgical facial nerve function with correlations not exceeding 0.4. Severe palsy was observed mainly in patients with large tumors with Koos grade 4, Samii grade 4b, respectively a volume of at least 6 cm3 or a maximum diameter of 2.4 cm for HB ≥ 3 and a volume of 7.5 cm3 and maximum diameter of 3.2 cm for HB ≥ 4. In regard to volumetry, the Koos and Samii grading systems were highly comparable, whereas the maximal diameter showed consistently lower correlation values. CONCLUSIONS: The results of our study allow direct comparison of studies on surgery versus radiotherapy of VS. The data allow for translation of tumor sizes based on different grading systems. Comparison of microsurgical, radiotherapeutic and radiosurgical approaches should concentrate on patients with large tumors. Whereas smaller tumors were rarely associated with severe facial palsy, large tumors did not exclude the possibility of weak or no palsy 6 months after surgery.

Lifetime Cost and Quality-Adjusted Life-Years Across Management Options for Small- and Medium-Sized Sporadic Vestibular Schwannoma.

OBJECTIVE: Despite the growing emphasis on healthcare costs, limited data address this aspect of care within the vestibular schwannoma (VS) literature. We sought to determine which strategy confers the lowest lifetime cost and greatest quality-adjusted life-years (QALYs) for patients with small- to medium-sized sporadic VS tumors. STUDY DESIGN: A Markov model was created to determine the most cost-effective management algorithm. Tumor characteristics, magnetic resonance imaging surveillance schedule, treatment outcomes, and health-related quality of life values were derived from previously published data. Cost estimates were based on CMS Fee Schedule reimbursement rates. SETTING: Economic Evaluation Service within the Kern Center for the Science of Healthcare Delivery. PATIENTS: Patients diagnosed with small- to medium-sized sporadic VS. INTERVENTIONS: Upfront microsurgery following diagnosis, upfront radiosurgery following diagnosis, observation with microsurgery reserved for observed tumor growth, and observation with radiosurgery reserved for observed tumor growth. RESULTS: Across patient ages at time of diagnosis ranging from 18 to 70 years, observation with subsequent radiosurgery used for tumor growth was the most cost-effective management algorithm while upfront microsurgery was the least. When presented with a hypothetical 50-year-old patient, the strategy with the lowest lifetime cost and highest QALYs was observation with subsequent radiosurgery reserved for tumor growth ($32,161, 14.11 QALY), followed by observation with microsurgery reserved for tumor growth ($34,503, 13.94 QALY), upfront radiosurgery ($43,456, 14.02 QALY), and lastly, upfront microsurgery ($47,252, 13.60 QALY). Sensitivity analyses varying mortality rates, estimated costs, health-related quality of life, and progression to nonserviceable hearing demonstrated consistent ranking among treatments. CONCLUSIONS: When considering initial management of small- and medium-sized sporadic VSs, neither lifetime cost nor QALYs support upfront microsurgery or radiosurgery, even for younger patients. Initial observation with serial imaging, reserving radiosurgery or microsurgery for patients exhibiting tumor growth, confers the greatest potential for optimized lifetime healthcare cost and QALY outcomes.

Assessment of Tumor Volume Dynamics and Outcome After Radiosurgery for the Treatment of Vestibular Schwannoma: A Single-Center Experience.

OBJECTIVE: To assess the factors affecting early local and audiometric outcomes in vestibular schwannoma (VS) patients treated with stereotactic radiosurgery (SRS). STUDY DESIGN: A retrospective review of medical records. SETTING: Tertiary referral center. PATIENTS: Records of all adult patients who underwent SRS between 2010 and 2016 for the treatment of VS were retrospectively reviewed. Patients treated with microsurgery or multi-fractionation schemes, and those who had neurofibromatosis type 2, were excluded. INTERVENTION: SRS, tumor volume/size measurements. MAIN OUTCOME MEASURES: The impact of tumor volume dynamics on the early local and hearing-related outcomes, together with the factors that influence them following SRS, and comparison of different tumor size measurement methods. RESULTS: From 2010 to 2016, 53 patients underwent single fraction SRS of 12 Gy. Median follow-up time was 32 months (range, 6-79). At the last follow-up, only one patient had clinical progression. Age less than or equal to 65 years (p = 0.04; odds ratio [OR]: 0.17; 95% confidence interval [CI]: 0.03-0.93) and baseline pure-tone average (PTA) level less than or equal to 30 dB (p = 0.03; OR: 0.90; 95% CI: 0.84-0.96) were associated with maintenance of serviceable hearing. On multivariate analysis, PTA remained significant (p = 0.01; OR: 0.04; 95% CI: 0.003-0.45). In patients with a loss of serviceable hearing, the mean volume increase tended to be higher than in the patients whose hearing was maintained. The linear measurement method underestimated, and the A × B × C/2 equation overestimated, the radiological progression compared with 3D-volumetric delineations. CONCLUSION: During the median observation period of almost 3 years, we reported our early outcome results. Tumor volume increase may have an impact on serviceable hearing loss after SRS. Currently there is no widely accepted method for the evaluation of post-SRS response. Linear measurement and the A × B × C/2 equation produce less reliable estimates of radiological progression compared with 3D-volumetric delineations. Accurate volume measurements with 3D delineations should be considered as part of clinical routine for assessing progression and deciding on salvage therapies.

Preoperative Differences in Intracranial Facial Versus Vestibular Schwannomas: A Four Nerve Assessment.

OBJECTIVES: Assesses whether preoperative functional testing can distinguish vestibular schwannomas from facial nerve schwannomas medial to the labyrinthine segment. STUDY DESIGN: Retrospective cohort. METHODS: Retrospectively review surgically managed intracranial facial and vestibular schwannomas between January 2015 and December 2019 at two tertiary care centers. Patients with neurofibromatosis 2 and surgery for recurrence were excluded. Preoperative functional testing to include House-Brackmann scores, electroneuronography (ENoG), cervical vestibular evoked myogenic potentials (cVEMP), caloric testing, acoustic brainstem responses (ABRs), acoustic reflexes, and audiograms was compared between the two groups of schwannomas. RESULTS: Twelve facial and 128 vestibular schwannomas met inclusion criteria. In only one case was a facial schwannoma diagnosed preoperatively from imaging. No statistically significant difference was found in preoperative House-Brackmann scores, ENoG, cVEMP, caloric testing, ABRs, or acoustic reflexes. Pure tone average was worse in the vestibular schwannoma group (63 dB [95% CI: 58-68 dB] vs. 46 dB [95% CI: 34-58 dB], P = .01), and the difference was more apparent in the lower frequencies. Word recognition score was better in the facial schwannoma group (66% [95% CI: 45-86%] vs. 41% [95% CI: 34-47%], P = .02). CONCLUSION: Specialized preoperative functional evaluation of the nerves of the internal auditory canal cannot reliably predict the presence of an intracranial facial schwannoma. Hearing is better in facial schwannomas, particularly in the lower frequencies. This should raise the index of suspicion for an intracranial facial schwannoma, especially in candidates for hearing preservation vestibular schwannoma surgery. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:2098-2105, 2021.

The Relationship Between the Functional Gait Assessment and Quality-of-Life Data in Patients Undergoing Vestibular Schwannoma Resection.

OBJECTIVE: To examine the relationship between the Functional Gait Assessment (FGA) and quality of life (QOL) measurements relating to balance before and after vestibular schwannoma (VS) resection and to assess the role of preoperative FGA in predicting postoperative QOL. STUDY DESIGN: A prospective clinical study of adult patients undergoing VS resection between September 2018 and December 2019. FGA was administered 1 week before and after surgery. Dizziness Handicap Inventory (DHI) and Penn Acoustic Neuroma Quality of Life (PANQOL) were administered preoperatively and at 3 months postoperatively. SETTING: Single tertiary center. PATIENTS: Patients (age ≥ 18 years old) with VS undergoing microsurgical resection. Excluded were patient with previous surgery or radiation. INTERVENTION: VS resection. MAIN OUTCOMES AND MEASURES: Primary outcome: correlation between FGA and QOL surveys. Secondary outcome: correlation between preoperative measurements of balance and postoperative PANQOL. RESULTS: One hundred thirty-eight patients were analyzed (mean age: 48 years old, 65.9% female). The translabyrinthine approach was most commonly performed. Under multivariate analysis, preoperative FGA significantly correlated with preoperative PANQOL balance score (p < 0.0001), preoperative PANQOL total score (p = 0.0002), and preoperative DHI (p < 0.0001). However, postoperative FGA did not significantly correlate with postoperative PANQOL balance or total scores (p = 0.446 and p = 0.4, respectively), or postoperative DHI (p = 0.3). Univariate analysis demonstrated that preoperative DHI and preoperative FGA were predictive of changes in postoperative PANQOL balance and total scores. However under multivariate analysis, preoperative FGA did not predict changes in postoperative PANQOL balance or total score (p = 0.24; p = 0.28, respectively). Preoperative DHI remained predictive of changes in postoperative PANQOL balance (p = 0.03) score but not of postoperative PANQOL total score (p = 0.37). CONCLUSIONS: Although FGA and QOL data significantly correlated in the preoperative setting, our results did not suggest that preoperative FGA can be used to determine postoperative QOL. Additionally, the lack of correlation between FGA and QOL measurements in the acute postoperative setting suggests that further research is needed to determine contributors to postoperative QOL.

Predictive Model and Online Calculator for Discharge Disposition in Brain Tumor Patients.

BACKGROUND: In the era of value-based payment models, it is imperative for neurosurgeons to eliminate inefficiencies and provide high-quality care. Discharge disposition is a relevant consideration with clinical and economic ramifications in brain tumor patients. We developed a predictive model and online calculator for postoperative non-home discharge disposition in brain tumor patients that can be incorporated into preoperative workflows. METHODS: We reviewed all brain tumor patients at our institution from 2017 to 2019. A predictive model of discharge disposition containing preoperatively available variables was developed using stepwise multivariable logistic regression. Model performance was assessed using receiver operating characteristic curves and calibration curves. Internal validation was performed using bootstrapping with 2000 samples. RESULTS: Our cohort included 2335 patients who underwent 2586 surgeries with a 16% non-home discharge rate. Significant predictors of non-home discharge were age >60 years (odds ratio [OR], 2.02), African American (OR, 1.73) or Asian (OR, 2.05) race, unmarried status (OR, 1.48), Medicaid insurance (OR, 1.90), admission from another health care facility (OR, 2.30), higher 5-factor modified frailty index (OR, 1.61 for 5-factor modified frailty index ≥2), and lower Karnofsky Performance Status (increasing OR with each 10-point decrease in Karnofsky Performance Status). The model was well calibrated and had excellent discrimination (optimism-corrected C-statistic, 0.82). An open-access calculator was deployed (https://neurooncsurgery.shinyapps.io/discharge_calc/). CONCLUSIONS: A strongly performing predictive model and online calculator for non-home discharge disposition in brain tumor patients was developed. With further validation, this tool may facilitate more efficient discharge planning, with consequent improvements in quality and value of care for brain tumor patients.

Facial Nerve Neurophysiologic Assessment in Vestibular Schwannoma Removal with Transcanal Approach: A Pilot Clinical Study.

BACKGROUND: The transcanal transpromontorial approach has been introduced to remove vestibular schwannomas. As with other techniques, preservation of the facial nerve (FN) is challenging. This pilot study described FN outcomes of patients preoperatively and postoperatively assessed with electromyography (EMG) and blink reflex (BR). METHODS: Between September 2017 and December 2018, 10 patients (5 men; 5 women; mean age, 59.8 years; age range, 25-77 years) underwent removal of vestibular schwannoma via the transcanal transpromontorial approach. FN assessment using EMG/BR and clinical evaluation with the House-Brackmann (HB) grading scale was performed preoperatively and 2 months postoperatively. If facial impairment was present postoperatively, further analysis was performed 6 months after surgery. RESULTS: All 10 patients had normal FN function on preoperative EMG/BR. After 2 months, 4 patients had normal FN function on EMG/BR, 4 patients showed a slight delay of FN responses, 1 patient had moderate dysfunction, and 1 patient had consistent damage. After 6 months, among the 6 patients with a pathologic neurophysiologic study, consistent EMG/BR improvement was shown, with complete recovery in 3 cases. At the last follow-up, 8 patients had HB grade I, 1 patient had HB grade II, and 1 patient had HB grade III in 1, showing progression toward healing in 9 of 10 cases. CONCLUSIONS: The transcanal transpromontorial approach is an effective procedure for vestibular schwannoma removal. EMG/BR represents an objective evaluation method to verify FN recovery after surgery and confirms the low impact of this surgical procedure on the FN.

Asymmetric sensorineural hearing loss and vestibular schwannoma: when to image?

PURPOSE OF REVIEW: We review the literature on the use of audiometric protocols in the guidance of when to obtain MRI for detection of vestibular schwannoma. This discussion will focus on the sensitivity, specificity, and cost-effective analysis of audiometric criteria of asymmetric sensorineural hearing loss (ASNHL) when used to decide when MRI scans should be performed. RECENT FINDINGS: The sensitivity for detecting vestibular schwannomas when invoking published audiometric protocols for triggering MRI acquisition in ASNHL ranged from 50 to 100%. Specificity of these protocols ranged from 23 to 83%. Such audiometric protocols are efficient, achieving sensitivity and specificity at these rates while reducing the screening rate to 18 to 35%. The reduced procurement of MRI while using such audiometric protocols is associated with annual cost savings of between 23 and 82%. While no definitive recommendations can be made from this review, some audiometric protocols offer a better balance of sensitivity and specificity than others. SUMMARY: Audiometric protocols for triggering MRI acquisition in ASNHL for evaluation of vestibular schwannoma can be both sensitive and specific. These are competitive measures, and so no protocol is both 100% sensitive and specific. Such protocols become less effective in populations with increased incidence of noise-induced hearing loss. Invocation of such audiometric protocols can considerably reduce the annual cost of MRI evaluation for vestibular schwannomas.