Diagnostic Criteria for Detection of Vestibular Schwannomas in the VA Population

Natural History of Hearing Loss in Sporadic Vestibular Schwannoma

Hearing loss is the most common and earliest symptom of sporadic vestibular schwannoma (VS). The most common pattern of hearing loss is asymmetric sensorineural hearing loss. Throughout its natural history, patients with serviceable hearing (SH) maintain SH at 94% to 95% after 1 year, 73% to 77% after 2 years, 56% to 66% after 5 years, and 32% to 44% after 10 years. For patients newly diagnosed with VS, it is likely their hearing will worsen despite small initial tumor size or lack of tumor growth.

MRI Screening in Vestibular Schwannoma: A Deep Learning-based Analysis of Clinical and Audiometric Data

Objective

To find a more objective method of assessing which patients should be screened for a vestibular schwannoma (VS) with magnetic resonance imaging (MRI) using a deep-learning algorithm to assess clinical and audiometric data.

Materials and Methods

Clinical and audiometric data were collected for 592 patients who received an audiogram between January 2015 and 2020 at Duke University Health Center with and without VS confirmed by MRI. These data were analyzed using a deep learning-based analysis to determine if the need for MRI screening could be assessed more objectively with adequate sensitivity and specificity.

Results

Patients with VS showed slightly elevated, but not statistically significant, mean thresholds compared to those without. Tinnitus, gradual hearing loss, and aural fullness were more common in patients with VS. Of these, only the presence of tinnitus was statistically significant. Several machine learning algorithms were used to incorporate and model the collected clinical and audiometric data, but none were able to distinguish ears with and without confirmed VS. When tumor size was taken into account the analysis was still unable to distinguish a difference.

Conclusions

Using audiometric and clinical data, deep learning-based analyses failed to produce an adequately sensitive and specific model for the detection of patients with VS. This suggests that a specific pattern of audiometric asymmetry and clinical symptoms may not necessarily be predictive of the presence/absence of VS to a level that clinicians would be comfortable forgoing an MRI.

Machine Learning for Vestibular Schwannoma Diagnosis Using Audiometrie Data Alone

OBJECTIVE

The aim of this study is to compare machine learning algorithms and established rule-based evaluations in screening audiograms for the purpose of diagnosing vestibular schwannomas. A secondary aim is to assess the performance of rule-based evaluations for predicting vestibular schwannomas using the largest dataset in the literature.

STUDY DESIGN

Retrospective case-control study.

SETTING

Tertiary referral center.

PATIENTS

Seven hundred sixty seven adult patients with confirmed vestibular schwannoma and a pretreatment audiogram on file and 2000 randomly selected adult controls with audiograms.

INTERVENTIONS

Audiometric data were analyzed using machine learning algorithms and standard rule-based criteria for defining asymmetric hearing loss.

MAIN OUTCOME MEASURES

The primary outcome is the ability to identify patients with vestibular schwannomas based on audiometric data alone, using machine learning algorithms and rule-based formulas. The secondary outcome is the application of conventional rule-based formulas to a larger dataset using advanced computational techniques.

RESULTS

The machine learning algorithms had mildly improved specificity in some fields compared with rule-based evaluations and had similar sensitivity to previous rule-based evaluations in diagnosis of vestibular schwannomas.

CONCLUSIONS

Machine learning algorithms perform similarly to rule-based evaluations in identifying patients with vestibular schwannomas based on audiometric data alone. Performance of established rule-based formulas was consistent with earlier performance metrics, when analyzed using a large dataset.

Vibration-induced nystagmus and head impulse test screening for vestibular schwannoma

LEVEL OF EVIDENCE

II-2.

BACKGROUND

Vestibular schwannomas are benign tumors of the eight cranial nerve that may cause asymmetric sensorineural hearing loss (ASHL) and vestibular dysfunction.

OBJECTIVE

The aim of this study was to assess the role of the video head impulse test (vHIT) and vibration-induced nystagmus (VIN) test in diagnosing vestibular schwannoma in a population of patients with Asymmetric sensorineural hearing loss.

MATERIAL AND METHODS

For this prospective case-control study, 23 consecutive patients with ASHL and normal magnetic resonance were enrolled in the control group, and 33 consecutive patients with ASHL and vestibular schwannoma were enrolled in the case group. Gold standard was magnetic resonance imaging. Audiometry, vHIT, and VIN tests were performed for each patient. Significance of VIN and vHIT testing was determined by evaluation of their sensitivity, specificity, and correlation with vestibular function tests.

RESULTS

Regarding the vHIT, sensitivity and specificity were 45.5% and 82.6%, respectively, for horizontal canal gain, 60.6% and 87.6%, respectively, for posterior canal gain, and 45.5% and 78.3%, respectively, when analyzing superior canal gains. Regarding the VIN test, the sensitivity and specificity were 81.8% and 73.9%, respectively, when based on the presence of a VIN with any mastoid stimulation.

CONCLUSIONS

Our results suggest that using the VIN test may be an efficient approach to screen for vestibular schwannoma in patients with asymmetric sensorineural hearing loss.

SIGNIFICANCE

Our results suggest that using the VIN test may be an efficient approach to screen for vestibular schwannoma in patients with ASHL.

Facial Nerve Outcomes After Vestibular Schwannoma Microsurgical Resection in Neurofibromatosis Type 2

OBJECTIVE

The aim of this study is to investigate facial nerve outcomes after microsurgical resection in neurofibromatosis type 2 (NF2) compared to sporadic tumors.

STUDY DESIGN

Single institutional retrospective chart review.

SETTING

Tertiary referral center.

METHODS

All adult patients with NF2 vestibular schwannoma (VS) or sporadic VS who underwent microsurgical resection from 2008 to 2019 with preoperative magnetic resonance imaging (MRI) and 1 year of postsurgical follow-up were included. The primary outcome measure was postoperative House-Brackmann (HB) facial nerve score measured at first postoperative visit and after at least 10 months.

RESULTS

In total, 161 sporadic VSs and 14 NF2 VSs met inclusion criteria. Both median tumor diameter (NF2, 33.5 mm vs sporadic, 24 mm, P = .0011) and median tumor volume (NF2, 12.4 cm³ vs sporadic, 2.9 cm³, P = .0005) were significantly greater in patients with NF2. The median follow-up was 24.9 months (range, 12-130.1). Median facial nerve function after 1 year for patients with NF2 was HB 3 (range, 1-6) compared to HB 1 (range, 1-6) for sporadic VS (P = .001). With multivariate logistic regression, NF2 tumors (odds ratio [OR] = 13.9, P = .001) and tumor volume ≥3 cm³ (OR = 3.6, P = .025) were significantly associated with HB ≥3 when controlling for age, sex, extent of tumor resection, translabyrinthine approach, and prior radiation.

CONCLUSION

Tumor volume >3 cm³ and NF2 tumors are associated with poorer facial nerve outcomes 1 year following microsurgical resection.

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.

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.

Asymmetric Hearing Loss Prompting MRI Referral in a Military Population: Redefining Audiometric Criteria

Objective

To reevaluate asymmetric sensorineural hearing loss (ASNHL) criteria used to justify magnetic resonance imaging (MRI) in the evaluation of retrocochlear tumors in a military population.

Study Design

Retrospective case-control study.

Setting

Tertiary care military medical center.

Subjects and Methods

Patients with military service and a history of ASNHL prompting referral for MRI, with or without retrocochlear tumors, were compared between 2005 and 2016. Predictor variables included pure tone ASNHL, speech audiometry, and a history of noise exposure. Logistic regression models for hearing asymmetries were performed, and receiver operator curves were used to calculate sensitivity and specificity.

Results

Thirty-eight retrocochlear tumors were identified. The MRI diagnosis rate for patients with ASHNL was 0.85%. Patients with tumors were slightly older (42 vs 37 years, P = .021) and had less noise exposure (47% vs 85%, P < .001). A sensitivity of 0.83 and a specificity of 0.58 were calculated for asymmetries ≥10 dB at 2000 Hz without adjusting for noise exposure. Instituting this imaging threshold would have reduced the number of MRI scans by half while missing 16% of tumors.

Conclusion

The tumor diagnosis rate among those undergoing MRI for ASNHL is low in the military population, likely because service-related noise exposure commonly causes ASNHL. Optimal MRI referral criteria should conserve resources while balancing the risks of over- and underdiagnosis. For those with a history of military service, an asymmetry ≥10 dB at 2000 Hz among patients meeting current ANSHL referral criteria is most predictive of a retrocochlear tumor.