An international comparison of diagnostic and management strategies for vestibular schwannoma

Subclassification of the Koos grade 2 vestibular schwannoma into 2a and 2b for individualized patient care: a validity and reliability study

OBJECTIVE

Vestibular schwannoma (VS) growth of ≥2 mm during serial MRI observation, irrespective of size, is the benchmark for treatment initiation in almost all centers. Although the probability of less optimal outcomes significantly increases in VS closer to the brainstem, early intervention does not improve long-term quality of life. Moving beyond the recommendation of definitive treatment for all VS after detected growth, we subclassified Koos 2 tumors based on extrameatal extension and relation to the brainstem. The aim of the current study was to evaluate the Koos 2 subclassification's validity and the inter-and intra-rater reliability of the entire Koos classification.

METHODS

Six experts, including neurosurgeons, otorhinolaryngologists and radiologists from two tertiary referral centers, classified 43 VS MRI scans. Validity of the Koos 2 subclassification was evaluated by the percentage agreement against the multidisciplinary skull base tumor board management advice. Inter- and intra-rater reliability were calculated using the intraclass correlation coefficient (ICC).

RESULTS

Validity was almost perfect in Koos 2a VSs with a 100% agreement and 87.5% agreement for Koos 2b. Inter-rater reliability for all Koos grades was significantly excellent (ICC 0.91; 95%CI 0.866 to 0.944, p= <0.001). Five raters had an excellent intra-rater reliability (ICC > 0.90; p= <0.01) and one rater had a good intra-rater reliability (ICC 0.88; 95% CI 0.742 to 0.949).

CONCLUSIONS

Although multiple factors influence decision-making, the classification of Koos 2a and 2b with excellent inter- and intra-rater reliability, can aid in recommending treatment initiation, moving beyond detected tumor growth, aiming to optimize patient centered care.

Orbital schwannoma management: a case report, literature review, and potential paradigm shift

PURPOSE

To present a case of orbital schwannoma and assess the literature on treatment modalities.

METHODS

A MEDLINE literature search for cases of orbital schwannomas was performed using the PubMed search tool using the search terms "orbital schwannoma" and "orbital neurilemmoma." Papers were included if they were peer-reviewed, published in English, discussed management, and included the search terms. Each article was rated using the scale developed by the British Centre for Evidence-Based Medicine. In addition, we present a case report of an orbital schwannoma.

RESULTS

A total of 428 articles were found. 102 met the criteria for inclusion. Only two articles met Level 1 evidence and 16 were important to the clinical care process. We report a case of a biopsy-proven orbital schwannoma managed conservatively with observation over a 4-year period due to risk of cosmetic disfigurement with tumor removal. There has been no change in tumor size and no associated complications during follow up.

CONCLUSIONS

There is a paucity of data on the natural history of orbital schwannomas. Based on our review of the literature, we recommend observation for asymptomatic or minimally symptomatic orbital schwannomas with minimal growth over an extended period of time. For rapidly growing tumors or large tumors affecting key structures causing visual loss, diplopia, aesthetic disfigurement, or patient discomfort, a more aggressive approach may be necessary.

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.

Vestibular Schwannoma Practice Patterns: An International Cross-specialty Survey

OBJECTIVE

To assess vestibular schwannoma (VS) practice patterns among providers.

STUDY DESIGN

Cross-sectional survey.

SETTING

8th Quadrennial International Conference on Vestibular Schwannoma and Other CPA Tumors.

SUBJECTS

Clinicians who specialize in the management of VS.

MAIN OUTCOME MEASURES

Responses to questions on the management and anticipated outcomes of VS for a series of common clinical scenarios were compared by specialty (otolaryngology versus neurosurgery), level of experience, scope of practice (surgery versus radiation and surgery), and geographic location of practice (United States versus international).

RESULTS

Responses from 110 participants were analyzed. Overall, 53% of respondents were otolaryngologists, 60% had greater than 10 years of experience, and 57% practiced within the United States. In total, 86% of respondents would pursue initial observation for themselves if diagnosed with a 4 mm distal intracanalicular VS; however, practicing radiosurgeons were more likely to select stereotactic radiosurgery for this scenario compared with providers who solely practice surgery (14 versus 0%; p = 0.032). Otolaryngologists and neurosurgeons alike report that radiosurgery should not be considered a long-term hearing preservation strategy.Otolaryngologists were more optimistic regarding microsurgical hearing preservation outcomes for small distal intracanalicular tumors compared with neurosurgeons (11 versus 3% selected a high likelihood of maintaining class A/B hearing; p = 0.007). Ninety-five percent of respondents prioritized facial nerve outcome over complete disease removal in the context of microsurgical resection of large tumors.

CONCLUSIONS

Management decision-making and expected outcomes for various clinical scenarios were largely similar among providers; however, variances in several key clinical areas exist. This study points to the feasibility of developing a widely accepted consensus statement among VS experts across specialties.

Development of a diagnostic model to identify patients at high risk for cerebellopontine angle lesions

Purpose

To develop a diagnostic model to identify patients at high risk of a CPA lesion.

Methods

A consecutive cohort of patients with AAD referred by a general practitioner, who underwent their first MRI examination of the CPA between 2005 and 2015 was included. Demographics, symptoms, findings during physical examination, and pure-tone audiometry were used as potential predictors. The presence of a CPA lesion was used as outcome.

Results

We analyzed data of 2,214 patients, detecting 73 CPA lesions in 69 (3.1%) patients. The final model contained eleven variables, namely gender [male] [OR 1.055 (95% CI 0.885–1.905)], sudden onset of hearing loss [OR 0.768 (95% CI 0.318–0.992)], gradual onset of hearing loss [OR 1.069 (95% CI 0.500–1.450)], unilateral tinnitus [OR 0.682 (95% CI 0.374–0.999)], complaints of unilateral aural fullness [OR 1.006 (95% CI 0.783–2.155)], instability [OR 1.006 (95% CI 0.580–2.121)], headache [OR 0.959 (95% CI 0.059–1.090)], facial numbness [OR 2.746 (95% CI 0.548–11.085)], facial nerve dysfunction during physical examination [OR 1.024 (95% CI 0.280–3.702)], and asymmetry in BC at 1 kHz [OR 1.013 (95% CI 1.000–1.027)] and 4 kHz [OR 1.008 (95% CI 1.000–1.026)].

Conclusion

The proposed diagnostic model is a first step in selecting patients with a high risk of a CPA lesion among those with AAD. It needs to be externally validated prior to its implementation in clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00405-021-06778-6.

Vestibular schwannomas with spontaneous shrinkage: about 35 cases

PURPOSES

The first aim is to describe the epidemiological, clinical, and radiological characteristics of regressive vestibular schwannomas (VS), based on volumetric measurements on MRI to define which regressions are significant. The secondary aim is to look for a correlation between a shrinkage of the tumor and the medical history, and the presence of clinical symptoms.

METHODS

We first selected all patients presenting with a VS who underwent two or more MRI of the internal auditory canal on the same 3 T MRI machine retrospectively between January 2013 and June 2018. All MRI images were evaluated independently by two radiologists. The volumetric analysis was performed contrast-enhanced 2D spin-echo T1-weighted sequence and expressed in cubic centimeters.

RESULTS

Thirty-five patients presented with a regressive VS on MRI (14%). The annual mean shrinkage rate was 0.08 cm³/year. Eighty percent of the patients present both a shrinkage by more than 0.01 cm³/year and a decrease of the initial tumor volume by more than 20%. The majority of patients are asymptomatic or presented moderate balance disorders, which remained stable or improved over time. Tinnitus was observed in 47% and was stable or improved in the majority of cases and the mean annual mean hearing loss was by < or = 4 dB/year.

CONCLUSION

Out of 247 VS, 14% decreased using follow-up (by > or = 2 MRI), and a spontaneous shrinkage greater than 0.01 cm³/year and greater than 20% could be considered significant.

Development of a model to predict vestibular schwannoma growth: An opportunity to introduce new wait and scan strategies

Objectives

To develop a prediction model to predict vestibular schwannoma (VS) growth for patients in a wait and scan (W&S) strategy.

Design

Retrospective cohort study.

Setting

Tertiary hospital (Radboud university medical center, Nijmegen, the Netherlands).

Participants

Patients with unilateral VS, entering a W&S strategy and at least one follow‐up MRI available. Data on demographics, symptoms, audiometry and MRI characteristics at time of diagnosis were collected from medical records.

Main outcome measures

Following multiple imputation, a multivariable Cox regression model was used to select variables, using VS growth (≥2 mm) as outcome. Decision curve analyses (DCA) were performed to compare the model to the current strategy.

Results

Of 1217 analysed VS patients, 653 (53.7%) showed growth during follow‐up. Balance complaints (HR 1.57 (95% CI: 1.31‐1.88)) and tinnitus complaints in the affected ear (HR 1.36 (95% CI: 1.15‐1.61)), Koos grade (Koos 1 is reference, Koos 2 HR 1.03 (95% CI: 0.80‐1.31), Koos 3 HR 1.55 (95% CI: 1.16‐2.06), Koos 4 HR 2.18 (95% CI: 1.60‐2.96)), time since onset of symptoms (IQR HR 0.83 (95% CI: 0.77‐0.88) and intrameatal diameter on MRI (IQR HR 1.67 (95% CI: 1.42‐1.96)) were selected as significant predictors. The model's discrimination (Harrell's C) was 0.69 (95% CI: 0.67‐0.71), and calibration was good. DCA showed that the model has a higher net benefit than the current strategy for probabilities of VS growth of >12%, 15% and 21% for the first consecutive 3 years, respectively.

Conclusions

Patients with balance and tinnitus complaints, a higher Koos grade, short duration of symptoms and a larger intrameatal diameter at time of diagnosis have a higher probability of future VS growth. After external validation, this model may be used to inform patients about their prognosis, individualise the W&S strategy and improve (cost‐)effectiveness.

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.

Management and Outcomes of Sporadic Vestibular Schwannoma: A Longitudinal Study Over 12 Years

OBJECTIVES

To evaluate the management of sporadic vestibular schwannomas (VS) with a 12-year follow-up.

STUDY DESIGN

Retrospective study of all VS patients initially treated in 2005 in a tertiary referent center.

METHODS

Initial decision making for microsurgical resection (MSR) or wait-and-scan (WaS) was according to VS size and hearing; subsequently, MSR or stereotactic radiosurgery (SRS) was proposed dependent on VS growth and size, hearing, and patient's age or willingness.

RESULTS

Two hundred and one sporadic VS were included. The first management apportionment was 120 WaS (61.5%), 72 MSR (37%), three SRS (1.5%), and six others refused MSR and were lost to follow-up (LFU). Within 1 year, 95 (47%) VS were surgically removed; 17 (8.5%) were treated by SRS; and 35 (17.5%) were LFU. The proportions for SRS and LFU were virtually unchanged for the following years, and the proportion under MSR increased slightly within 3 years and then remained stable. Finally, at 12 years, 104 (51.5%) cases had been operated on, 21 (10.5%) treated by SRS, 23 (11.5%) still under WaS, and 53 (26.5%) LFU, which were mainly intracanalicular. The initially and subsequently operated cases presented similar hearing preservation rates and good facial nerve function outcomes.

CONCLUSION

This longitudinal study of a large number of VS, which were diagnosed over a short period of time and followed for 12 years, provides new information on both the natural history of these benign tumors and individual patient concerns. This study recommends use of the WaS policy for small and mid-sized VS before active therapeutic decision making.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:E970-E976, 2021.

Middle-ear cholesteatoma co-existing with labyrinthine fistula and vestibular schwannoma

BACKGROUND

Many conditions, among them vestibular schwannoma and middle ear cholesteatoma with lateral semicircular canal destruction, may be associated with asymmetrical sensorineural hearing loss (SNHL) and vertigo. However, the probability that these two distinct disease entities causing the same symptoms occur in a single patient is very low, approximately 1 per 28 billion per 1 year.

METHODS

We present the case of a 40-year-old male admitted to our clinic because of chronic middle ear inflammation with concomitant tinnitus vertigo, and deafness in the right ear. The patient was diagnosed with lateral semicircular canal fistula caused by middle-ear cholesteatoma and concomitant vestibular schwannoma. Canal wall-down surgery was carried out to remove the cholesteatoma, followed by gamma knife radiosurgery for the vestibular schwannoma.

RESULTS

Vertigo and tinnitus resolved within 3 days after the ear surgery, and gamma knife treatment resulted in the complete involution of the vestibular schwannoma. The patient presented with completely dry middle-ear cavity and no recurrence of the cholesteatoma was observed during a 3-year follow-up.

CONCLUSION

As the hereby reported condition is very rare, the results cannot be compared with any similar report published previously. Nevertheless, based on the outcome, the treatment strategy seems to be both reasonable and effective.

Vestibular Schwannoma: What We Know and Where We are Heading

Vestibular schwannoma (VS) is a Schwann cell-derived tumour arising from the vestibulocochlear nerve. Although benign, it represents a threat to intracranial structures due to mass effect and carries a small risk of malignant transformation. VS therefore represents an important healthcare burden. We review the literature regarding pathogenesis, risk factors, and diagnosis of VS. The current and future potential management strategies are also discussed. A narrative review of all relevant papers known to the authors was conducted. The majority of VS remain clinically stable and do not require interventional procedures. Nevertheless, various surgical techniques exist for removing VS, the most common of which are translabyrinthine and retrosigmoid approaches. Due to surgical risks such as hearing loss, facial nerve dysfunction, post-operative headache, and cerebrospinal fluid leakage, a "watch and rescan" approach is adopted for most patients. Radiotherapy is a useful alternative and has been shown to have a similar response for growth restriction. Due to the heterogeneous nature of VS, there is a lack of consensus regarding management of tumours that are too large for conservative management but too small to indicate surgery. Emerging biologic therapies, such as Bevacizumab, Everolimus, and Lapatinib, as well as anti-inflammatories like aspirin are promising potential treatments; however, long-term evidence of their efficacy is required. The knowledge base regarding VS continues to improve. With increased understanding of the pathogenesis of these tumors, we believe future work should focus on pharmacologic intervention. Biologic therapies aimed toward improved patient outcomes are particularly promising.

In search of the most cost-effective monitoring strategy for vestibular schwannoma: A decision analytical modelling study

Objectives

To assess the cost‐effectiveness of frequently used monitoring strategies for vestibular schwannoma (VS).

Design

A state transition model was developed to compare six monitoring strategies for patients with VS: lifelong annual monitoring; annual monitoring for the first 10 years after diagnosis; scanning at 1‐5, 7, 9, 12, 15 years after diagnosis and subsequently every 5 years; a personalised monitoring strategy for small and large tumours; scanning at 1, 2 and 5 years after diagnosis and no monitoring. Input data were derived from literature and expert opinion. Quality‐adjusted life years (QALYs) and healthcare costs of each strategy were modelled over lifetime. Net monetary benefits (NMBs) were calculated to determine which strategy provided most value for money. Sensitivity analyses were performed to address uncertainty.

Results

Omitting monitoring is least effective with 18.23 (95% CI 16.84‐19.37) QALYs per patient, and lifelong annual monitoring is most effective with 18.66 (95% CI 17.42‐19.65) QALYs. Corresponding costs were €6526 (95% CI 5923‐7058) and €9429 (95% CI 9197‐9643) per patient, respectively. Lifelong annual monitoring provided the best value with a NMB of €363 765 (339 040‐383 697), but the overall probability of being most cost‐effective compared to the other strategies was still only 23%. Sensitivity analysis shows that there is large uncertainty in the effectiveness of all strategies, with largely overlapping 95% confidence intervals for all strategies.

Conclusions

Due to the largely overlapping 95% confidence intervals of all monitoring strategies for VS, it is unclear which monitoring strategy provides most value for money at this moment.