Single Institutional Experience With Observing 564 Vestibular Schwannomas: Factors Associated With Tumor Growth

Losartan May Not Prevent Vestibular Schwannoma Growth or Related Hearing Loss During Observation

OBJECTIVE

To evaluate the impact of losartan on vestibular schwannoma (VS) growth and related hearing loss during observation.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral center.

PATIENTS

Sporadic VS patients undergoing initial observation with at least two magnetic resonance imaging and audiologic examinations.

INTERVENTION

Losartan.

MAIN OUTCOME MEASURES

Endpoints included VS growth, quantitative audiologic changes, survival free of tumor growth, and survival free of nonserviceable hearing. Patient characteristics and endpoints were compared by losartan use.

RESULTS

Seventy-nine patients were included, of which 33% were taking losartan. Tumor growth was observed in 50% of patients in the losartan group and 36% in the non-losartan group (p = 0.329). Survival analysis failed to show a significant difference in the hazard rate of VS growth between groups (hazard ratio, 1.38; 95% confidence interval, 0.70-2.70; p = 0.346). Throughout observation, mean decreases in normalized pure-tone average were 5.5 and 9.3 dB in the losartan and non-losartan groups, respectively (p = 0.908). Mean decreases in normalized word recognition score were 11.0 and 16.6% in the losartan and non-losartan groups, respectively (p = 0.757). Nonserviceable hearing developed in 19% of patients in the losartan group and 28% in the non-losartan group (p = 0.734). Survival analysis did not demonstrate a significant difference in the hazard rate of developing nonserviceable hearing between groups (hazard ratio, 1.71; 95% confidence interval, 0.56-5.21; p = 0.337).

CONCLUSIONS

Losartan use may not reduce the risk of VS growth or hearing loss during observation. A randomized trial would be ideal to further identify the true effect on growth and hearing.

Evaluation of subjective visual vertical and horizontal in patients with acoustic neuroma based on virtual reality

Objective

To investigate potential differences in absolute deviation values of subjective visual vertical and horizontal between unilateral acoustic neuroma patients and healthy young adults under varying degrees of static head tilt, as well as the impact of proprioception on these values, with the aim of determining the effect of acoustic neuroma on gravity sensory pathway function in patients.

Methods

We recruited 22 patients diagnosed with unilateral acoustic neuroma and 25 healthy young adults and employed virtual reality technology to assess the absolute deviation values of subjective visual vertical (SVV) and subjective visual horizontal (SVH) under eight different static tilted head positions (Head centered (0° tilt), PdP, Head tilt 15°, 30°, 45° to the left and right), then compare and analyze intergroup differences.

Results

In the Head-centered position, both SVV and SVH absolute deviated values were significantly higher in the AN group compared to healthy young adults. The AN group exhibited significantly higher absolute deviation values of SVV compared to the healthy group when tilting their head 30° left and right. Additionally, when tilting their heads to the right at 15° and 45° the AN group showed significant increases in SVH absolute deviated values compared to healthy adults. The SVV and SVH absolute deviation values of LAN and SAN groups did not reach statistical significance. The results of the SVV test for PDP position did not show any significant differences among all groups. However, the SVH test revealed that the absolute deviation values of the LAN group was significantly higher than that of healthy individuals.

Conclusion

Our study shows that the gravity sensing function of patients with unilateral acoustic neuroma is affected to different degrees, however, the degree of gravity sensing function damage of patients has little relationship with tumor size. When acoustic neuroma is larger than 2 cm, the effect of proprioception on patients' SVH outcome is noteworthy. So, we should pay attention to the postoperative follow-up of patients with acoustic neuroma and the evaluation of vestibular rehabilitation effect. Meanwhile, for patients opting for conservative treatment, it is imperative to monitor the dynamic changes in vestibular function and seize timely opportunities for intervention.

Comparing Linear and Volumetric Tumor Measurements During Observation of Growing Sporadic Vestibular Schwannomas

OBJECTIVE

To assess the correlation between linear and volumetric changes in vestibular schwannomas (VS).

STUDY DESIGN

Retrospective imaging review was performed on patients diagnosed with sporadic VS from 2000 to 2019 who demonstrated linear growth on observation with serial magnetic resonance imaging (MRI).

SETTING

Two large tertiary care centers.

METHODS

Changes in diameter on serial MRI scans, measured by 1995 American Academy of Otolaryngology-Head and Neck Surgery guidelines, were compared to changes in volume, calculated by segmentation.

RESULTS

Ninety-two patients had VS confined to the internal auditory canal (IAC) with 236 MRIs analyzed, and 108 patients had VS involving the cerebellopontine angle (CPA) with 193 MRIs analyzed. The Spearman rank correlation coefficients between changes in diameter and volume for IAC and CPA tumors were 0.43 (p < .001) and 0.65 (p < .001), respectively. Linear diameter increases of 1 to <2 mm corresponded to a median volume change of 32% (interquartile range [IQR]: 6%-86%) for IAC tumors, compared to 23% (IQR: 13%-40%) for CPA tumors. Linear diameter increases of 2 to <3 mm (ie, the minimum linear diameter change classically considered "true growth") corresponded to a median volume change of 42% (IQR: 23%-100%) and 47% (IQR: 26%-69%) for IAC and CPA tumors, respectively.

CONCLUSION

Changes in linear diameter significantly correlated with changes in volume for IAC and CPA tumors, although diameter changes that did not meet the definition of linear growth (<2 mm) had corresponding median volume changes in excess of 20% for both IAC and CPA tumors.

The Effect of Metformin on Vestibular Schwannoma Growth: A Systematic Review and Meta-analysis

OBJECTIVES

To systematically review and evaluate metformin's potential impact on vestibular schwannoma (VS) growth.

DATA SOURCES

PubMed, Cochrane Library, and Embase.

REVIEW METHODS

A retrospective cohort study was performed on sporadic VS patients undergoing initial observation who had at least two magnetic resonance imaging studies. Patients were stratified by metformin use during the observation period. Primary endpoint was VS growth, defined as at least a 2 mm increase in diameter. Survival free of tumor growth was evaluated between groups. Systematic review and meta-analysis were performed to produce a pooled odds ratio [OR]. Study heterogeneity was assessed and post-hoc power analysis was performed.

RESULTS

A total of 123 patients were included, of which 17% were taking metformin. Median patient age was 56.6 years (range, 25.1-84.5). There were no statistically significant differences between the groups. Survival analysis did not demonstrate a statistically significant difference in time to VS growth between groups (hazard ratio = 0.61, 95% confidence interval [CI] = 0.29-1.29). Furthermore, logistic regression analysis did not demonstrate a statistically significant difference between groups in the odds of VS growth (OR = 0.46, 95% CI = 0.17-1.27). Systematic review identified 3 studies. Meta-analysis suggested that metformin reduces the odds of developing VS growth (pooled OR = 0.45, 95% CI = 0.29-0.71). Studies demonstrated low between-study heterogeneity. Power analysis demonstrated a sample size of 220 patients with equal randomization would be required to prospectively identify a true difference with 80% power.

CONCLUSIONS

Metformin use may reduce the odds of VS growth. A randomized trial would be ideal to identify an unbiased estimate of metformin's effect on VS growth. Laryngoscope, 133:2066-2072, 2023.

Factors associated with hearing outcomes after a middle fossa approach in 131 consecutive patients with vestibular schwannomas

OBJECTIVE

The middle fossa approach is an effective option for the treatment of small (Koos grade I and II) vestibular schwannomas (VSs) when the goal is hearing preservation. The authors evaluated the rates of hearing preservation and examined the factors associated with improved hearing outcomes after the middle fossa approach for VSs.

METHODS

In this retrospective, single-center cohort study evaluating the clinical outcomes after resection of small VSs using the middle fossa approach, consecutive adult patients (> 18 years) who underwent surgery between January 2000 and December 2021 were included. Clinical and imaging characteristics were analyzed, including baseline hearing status, duration of surgery, anesthetic parameters, and imaging characteristics of the surgically treated tumors.

RESULTS

Among the 131 included patients, 102 had valid and discoverable pre- and postoperative audiology assessments. The mean follow-up was 26 months (range 1-180 months). There were 85 patients with serviceable hearing preoperatively, defined as American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B, of whom 78% retained class A or B hearing at the last follow-up. Binary logistic regression demonstrated that preoperative hearing AAO-HNS class (OR 0.19, 95% CI 0.05-0.77; p = 0.02), overlap between fundus and cochlea (OR 0.32, 95% CI 0.11-0.96; p = 0.04), and duration of anesthesia (OR 0.98, 95% CI 0.97-0.99; p = 0.03) were independent predictors of hearing outcomes. Additionally, 75% of patients with high diffusion-weighted imaging signal in the tumor (p = 0.009) and 67% of patients with the tumor originating at the modiolus of the cochlea (p = 0.004) had poor hearing outcomes.

CONCLUSIONS

The hearing preservation rates after microsurgical resection of small VSs using the middle fossa approach are high, with 78% of patients maintaining AAO-HNS class A or B hearing. Poor hearing status at baseline, longer duration of anesthesia, and large overlap between the fundus of the internal auditory canal and the cochlea were independently associated with unfavorable hearing outcomes. Imaging characteristics can be used to stratify patients' risk of hearing loss.

Automated Whole Cochlear T2 Signal Demonstrates Weak Correlation with Hearing Loss in Observed Vestibular Schwannoma

INTRODUCTION

We sought to evaluate the correlation between whole cochlear T2 signal changes obtained with a novel automated segmentation method and hearing levels, both at diagnosis and over time, in patients with observed vestibular schwannoma.

METHODS

This retrospective correlation study within an academic medical center neurotology practice evaluated 127 patients with vestibular schwannoma observed over time, each with ≥2 MRI scans (367 total) and ≥2 audiograms (472 total). 86 patients had T2-weighted sequences with sufficient resolution for cochlear signal analysis, yielding 348 unique timepoint intervals. The main outcome measure was correlation of the ipsilateral-to-contralateral ratio of whole cochlear T2 signal with hearing outcomes as measured by pure tone average (PTA) and word recognition score (WRS).

RESULTS

Whole cochlear T2 signal ratios did not show a correlation with hearing levels at diagnosis. Change in signal ratio over time showed weak correlation with changes in PTA, but not WRS, over time. Cochlear signal ratio did not precede changes in hearing but did follow changes in both PTA and WRS.

CONCLUSION

Whole cochlear T2 signal ratios were weakly correlated with changes in hearing in patients with observed vestibular schwannoma. The technology of automated segmentation and signal processing holds promise for future evaluation of clinical entities causing cochlear signal changes.

Dosimetric predictive factors for facial nerve paralysis after cyberknife® stereotactic radiotherapy for vestibular schwannomas: A single institution experience of 88 patients

PURPOSE

To identify dosimetric predictive factors of facial nerve paralysis for patients with vestibular schwannomas (VS) treated in a single institution with Cyberknife® (CK) hypofractionated stereotactic radiotherapy (SRT).

METHODS AND MATERIALS

Eighty-eight patients were treated from 2010 to 2020. Different treatment schedules were used over that period, some prescribed to the 80% isodose line (4 × 5 Gy, 3 × 7 Gy, 3 × 8 Gy and 5 × 5 Gy) and one to the 70% isodose line (3 × 7.7 Gy). Local control tumor and facial nerve toxicity were recorded, as well as various dosimetric indicators.

RESULTS

Median follow-up 37 months (range, 7-96). Of the 88 stereotactic treatments, 20 patients (23%) developed objectively diagnosed radiation-induced facial nerve paralysis. The 2-year and 5-year local tumor control were respectively 95% and 88%, and the overall 2-year facial nerve preservation was 76%. Prescriptions with a maximum dose point (Dmax) of 33 Gy were at a substantially higher risk of facial paralysis than prescriptions with a Dmax less than or equal to 30 Gy (HR = 4.51, 95% CI = [1.04;19.6], p = 0.045). The 2-years cumulative incidences of facial paralysis were 32% [20%;44%] in the case of a 33 Gy Dmax, against 7% [1%;21%] otherwise. We identified four significative dosimetric predictive factors for radiation-induced facial nerve dysfunction: a GTV minimal dose over 22 Gy (EQD2 = 45.5 Gy, p = 0.019), a GTV mean dose over 29 Gy (EQD2 = 73.5 Gy, HR = 2.84, 95% CI = [1.10;7.36], p = 0.024), a PTV mean dose over 27 Gy (EQD2 = 64.8 Gy, HR = 10.52, 95% CI = [1.39;79.76], p = 0.002) and a PTV maximal dose of 32 Gy (EQD2 = 87.5 Gy,HR = 5.09, 95% CI = [1.17;22.15], p = 0.013).

CONCLUSION

We identified four dosimetric predictive factors for post-treatment facial paralysis. Increasing the doses of hypofractionated stereotactic radiotherapy for vestibular schwannomas leads to higher facial nerve toxicity and may lead to lower local control rates than other published series. Our three-hypofractionated regimens may have also played a role in these results.

Diagnosis and Treatment of Peripheral and Cranial Nerve Tumors with Expert Recommendations: An EUropean Network for RAre CANcers (EURACAN) Initiative

The 2021 WHO classification of the CNS Tumors identifies as "Peripheral nerve sheath tumors" (PNST) some entities with specific clinical and anatomical characteristics, histological and molecular markers, imaging findings, and aggressiveness. The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is particularly low due to the rarity, and drawn recommendations accordingly. Tumor diagnosis is primarily based on hematoxylin and eosin-stained sections and immunohistochemistry. Molecular analysis is not essential to establish the histological nature of these tumors, although genetic analyses on DNA extracted from PNST (neurofibromas/schwannomas) is required to diagnose mosaic forms of NF1 and SPS. MRI is the gold-standard to delineate the extension with respect to adjacent structures. Gross-total resection is the first choice, and can be curative in benign lesions; however, the extent of resection must be balanced with preservation of nerve functioning. Radiotherapy can be omitted in benign tumors after complete resection and in NF-related tumors, due to the theoretic risk of secondary malignancies in a tumor-suppressor syndrome. Systemic therapy should be considered in incomplete resected plexiform neurofibromas/MPNSTs. MEK inhibitor selumetinib can be used in NF1 children ≥2 years with inoperable/symptomatic plexiform neurofibromas, while anthracycline-based treatment is the first choice for unresectable/locally advanced/metastatic MPNST. Clinical trials on other MEK1-2 inhibitors alone or in combination with mTOR inhibitors are under investigation in plexiform neurofibromas and MPNST, respectively.

Vestibular, Central, and Non-Vestibular Etiologies of Vertigo and Disequilibrium: A Rural Hospital-Based Cross-Sectional Comparative Analysis

INTRODUCTION

Vertigo/dizziness is defined as disturbed postural awareness and could range from a feeling of sensation of spinning of self or surrounding. Dizziness or disturbed postural awareness is a common presentation in varying age groups. Vertigo has varied clinical presentations. Classically, there are four vertigo syndromes: vertigo, imbalance/disequilibrium, presyncope/lightheadedness, and psychogenic dizziness. The present study was conducted to examine the various etiologies involved in these syndromes and to help unmask the overlaps between them. This study also aimed to further classify the etiologies underlying these vertigo syndromes and overlaps into peripheral or vestibular, central, and non-vestibular. This would help develop a comprehensive management protocol for vertigo of any origin.

METHODS

A prospective observational cross-sectional study was undertaken in a rural hospital in Central India. We studied patients with giddiness and categorized them into vertigo syndromes according to the site of origin of vertigo. We also compared overlaps in the presentation of vertigo.

RESULTS

Out of the 80 patients that were studied, vertigo with disequilibrium was observed in 72.50% of the patients. Non-vestibular vertigo of cervicogenic origin was the common cause of vertigo seen in 36.25% of the patients occurring alone or in association with vestibular vertigo. Among patients with overlaps, vestibular vertigo with non-vestibular vertigo was the most common etiology observed in 89.65% of the patients with overlaps.

CONCLUSION

The syndrome of "vertigo with disequilibrium" was the commonest presentation in the patients studied, followed by "vertigo syndrome" as an isolated symptom, not associated with "disequilibrium." Ours is probably the first study to report this observation of overlaps of two syndromes, with diagnostic implications.

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.

Natural History of Brachial Plexus, Peripheral Nerve, and Spinal Schwannomas

BACKGROUND

Management of sporadic schwannomas is often dictated by a patient's clinical presentation and the tumor's behavior. For patients who are managed nonsurgically, there are little data available about the expected natural history.

OBJECTIVE

To evaluate the natural history and growth patterns of extracranial schwannomas including tumors of the distal peripheral nerves, spine, and brachial plexus.

METHODS

A retrospective review was performed to identify patients with nonsyndromic extracranial schwannomas at a single tertiary care institution diagnosed between 2002 and 2019. Patient data and tumor characteristics including volume were recorded.

RESULTS

Two hundred twenty-seven patients were identified (mean age 51 years, 42% male, average of 27.8-month follow-up). Tumor location was distal peripheral nerve in 82, brachial plexus in 36, and paraspinal in 109. At the time of diagnosis, peripheral lesions were significantly larger than spinal (59 m 3 vs 13 cm 3 ) and brachial plexus lesions (15 cm 3 ). Distinct growth patterns were seen with both distal peripheral nerve and spinal lesions; 34/82 peripheral nerve lesions had fast growth (β = 0.176%/day), and 48 had slow growth (β = 0.021%/day; P < .01). Spinal schwannomas similarly had 30 fast-growing (β = 0.229%/day), 16 moderate-growing (β = 0.071%/day), and 63 slow-growing (β = 0.022%/day; P = .03) subtypes. The brachial plexus had relatively homogeneous growth patterns (β = 0.065%/day). Females had 2.9 times greater odds of having the fast-growing subtype.

CONCLUSION

Distinct growth patterns were seen in extracranial sporadic schwannomas based on tumor location and patient demographics. Fast (>80% volume change per year) vs slow (5%-10% per year) tumor growth can often be ascertained within 2 follow-up images. Awareness of these patterns might have implications for patient counseling and therapeutic decision-making.

Spontaneous Volumetric Tumor Regression During Wait-and-Scan Management of 952 Sporadic Vestibular Schwannomas

OBJECTIVE

Spontaneous tumor shrinkage during wait-and-scan management of sporadic vestibular schwannoma is generally considered an uncommon phenomenon. However, most data informing this understanding stem from single-slice linear tumor measurements taken in the axial imaging plane. The objective of the current work was to characterize the regression capacity of sporadic vestibular schwannomas using volumetric tumor measurements.

STUDY DESIGN

Retrospective cohort study using slice-by-slice, three-dimensional volumetric tumor measurements.

SETTING

Three tertiary referral centers.

PATIENTS

Patients with sporadic vestibular schwannoma.

INTERVENTIONS

Wait-and-scan.

MAIN OUTCOME MEASURES

Regression-free survival rates with regression defined as a decrease of at least 20% of the tumor volume.

RESULTS

Among 952 patients undergoing a total of 3,505 magnetic resonance imaging studies during observation, 123 experienced volumetric tumor regression after diagnosis at a median of 1.2 years (interquartile range, 0.6-2.9 yr). Volumetric regression-free survival rates (95% confidence interval; number still at risk) at 1, 3, and 5 years after diagnosis were 94% (92-95%; 662), 86% (83-89%; 275), and 78% (73-82%; 132), respectively. Among 405 patients who demonstrated an initial period of tumor growth but continued wait-and-scan management, 48 experienced volumetric regression at a median of 1.2 years (interquartile range, 0.8-2.6 yr) after initial growth. Volumetric regression-free survival rates at 1, 3, and 5 years after initial growth were 94% (92-97%; 260), 84% (79-89%; 99), and 75% (67-83%; 43), respectively. Ultimately, only 82 of the 952 patients studied showed exclusively volumetric tumor regression (i.e., without any periods of tumor growth) by the time of last follow-up.

CONCLUSION

Spontaneous volumetric tumor shrinkage during wait-and-scan management occurs more frequently than suggested by previous studies using linear tumor measurements and can even occur after previous episodes of documented tumor growth. These data further highlight the dynamic nature of vestibular schwannoma growth. To this end, the application of natural history data to patient management requires a nuanced approach that parallels the complex tumor behavior of vestibular schwannoma.

Wait and Scan Management of Intra-canalicular Vestibular Schwannomas: Analysis of Growth and Hearing Outcome

OBJECTIVE

To report on the results of intracanalicular vestibular schwannomas (ICVS) that were managed by wait and scan and to analyze the possible predictors of tumor growth and hearing deterioration throughout the observation period.

STUDY DESIGN

A retrospective case series.

SETTING

Quaternary referral center for skull base pathologies.

PATIENTS

Patients with sporadic ICVS managed by wait and scan.

INTERVENTION

Serial resonance imaging (MRI) with size measurement and serial audiological evaluation.

MAIN OUTCOME MEASURE

Tumor growth defined as 2 mm increase of maximal tumor diameter, further treatment, and hearing preservation either maintain initial modified Sanna hearing class, or maintain initial serviceable hearing (class A/B).

RESULTS

339 patients were enrolled. The mean follow-up was 36.5±31.7 months with a median of 24 months. Tumor growth occurred in 141 patients (40.6%) either as slow growth (SG) in 26.3% of cases or fast growth (FG) in 15.3% of cases. Intervention was performed in only 64 cases (18.8%). Out of 271 patients who underwent hearing analysis, 86 patients (33.5%) showed hearing deterioration to a lower hearing class of the modified Sanna classification. Tumor growth and older age were predictors of hearing deterioration. Of the 125 cases with initial serviceable hearing (Class A/B), 91 cases (72.8%) maintained serviceable hearing at last follow-up. Tumor growth and a worse initial pure tone average (PTA) were predictors of hearing deterioration.

CONCLUSIONS

Wait and scan management of ICVS is a viable option and only 18.8% of patients needed further treatment. Hearing tends to deteriorate over time.

A 2 and 5-Year Longitudinal Analysis of 671 Consecutive Patients Diagnosed with Unilateral Vestibular Schwannoma

OBJECTIVE

To analyse the 2 and 5-year outcomes of a cohort of patients with newly diagnosed vestibular schwannoma patients.

STUDY DESIGN

Longitudinal cohort study.

SETTING

Tertiary skull base referral unit.

PATIENTS

Six hundred and seventy-one consecutive patients referred to the Cambridge Skull Base Unit between 2005 and 2010.

MAIN OUTCOME MEASURES

1) Treatment outcomes, 2) hearing preservation, 3) facial nerve function, and 4) gross tumor control.

RESULTS

At initial diagnosis, 440/671(65.6%) of patients entered a watch, wait and rescan (WWR) pathway, 208/671 (31%) underwent primary microsurgical excision and 23/671 (3.4%) primary radiotherapy. Of patients who entered WWR, 144/440 (32.7%) exhibited tumor growth necessitating secondary intervention at a mean of 22.7 months; 67.4% had radiotherapy and 32.6% surgery. Radiotherapy was successful at achieving tumor control in 95% of cases. Primary surgery via the translabyrinthine route was performed in the majority of cases allowing for a radiologically clear surgical resection in 93% of cases.

CONCLUSION

The Cambridge philosophy of treating the newly diagnosed vestibular schwannoma aims at preserving functional status where possible. In patients with small tumors it is recommended that they are placed on to a WWR pathway, of which 67.3% will not exhibit any growth by 5 years. If small tumors grow more than 2 mm by serial scanning, radiotherapy offers a high rate of tumor control. In patients with larger tumors more than 20 mm we would advocate microsurgical excision by the translabyrinthine route which offers excellent functional outcomes and gross tumor control.

[Vestibular schwannomas - baseline and progress diagnostics]

Vestibular (vestibulocochlear) schwannomas are rare, benign schwannomas of the cerebellopontine angle, the internal auditory canal, or the inner ear. They can occur with or without clinical symptoms. The most common symptoms are unilateral or side-differentiated hearing loss with or without tinnitus and balance disorders. Initial symptomatology is nonspecific in the basic functional diagnosis, raising the question of when a hearing or balance disorder should be thought of as a differential diagnosis of vestibular schwannoma and what diagnostic pathway is appropriate. This concerns not only the confirmation of the diagnosis and the recording of all dysfunctions of the involved cranial nerves in the initial basic diagnostics, but also the procedure in the course and follow-up diagnostics - especially in patients who are subject to an observation strategy. Today, imaging alone is no longer sufficient for differentiated and individualized patient counseling. Due to the increasing detection of smaller tumors on MRI and the growing proportion of nearly asymptomatic patients, a shift in thinking from pure imaging monitoring to a detailed analysis of auditory and vestibular function is timely. In this educational article, diagnostic pathways for a sufficient patient consultation will be compiled. Ultimately, functional examination techniques from follow-up and progression diagnostics will also be included.

A Subset of Intracanalicular Vestibular Schwannomas Demonstrates Minimal Growth Over a 10-Year Period

OBJECTIVE

Vestibular schwannomas (VS) commonly undergo magnetic resonance imaging (MRI) surveillance, but long-term data to support the ideal frequency is limited. Herein, we aim to investigate intracanalicular VS growth predictors and long-term growth rates (GR).

STUDY DESIGN

Retrospective chart review.

SETTING

Two tertiary care centers.

PATIENTS

Sporadic intracanalicular VS with initial conservative management and at least two sequential MRIs.

INTERVENTION

Serial MRI.

MAIN OUTCOME MEASURES

VS were categorized by baseline internal auditory canal tertile sublocalization (fundus, midpoint, porus) and size (≤100, 100-200, >200 mm3). Throughout follow-up, volumetric GR (mm3/yr) were determined (baseline-3 yrs, 3-5 yrs, 5-10 yrs) and treatment rates were assessed.

RESULTS

Ninety-nine intracanalicular VS were identified (mean follow-up of 6.1 ± 4.5 yrs). Mean GR before 5-year follow-up were comparable for baseline tertile involvement and size. After 5-year follow-up, mean GR of VS involving the fundus at baseline were lower than those involving the midpoint and fundus (6.17 ± 21.16 and 119.74 ± 117.57 mm3/yr, respectively; p = 0.034). Mean GR of VS with less than or equal to 100 mm3 at baseline (-7.29 ± 25.44 mm3/yr) were lower than those with 100 to 200 mm3 (86.55 ± 103.99 mm3/yr; p = 0.011) and more than 200 mm3 (45.70 ± 35.71 mm3/yr; p = 0.031). Vestibular schwannomas involving the midpoint and fundus had greater treatment rates compared with VS involving only the fundus (p < 0.001).

CONCLUSIONS

Baseline tertile involvement and size may predict long-term intracanalicular VS growth where fundal tumors or those less than or equal to 100 mm3 exhibit little long-term growth. Extending surveillance after 5-year follow-up may be reasonable for fundal VS.

The Natural History of Small Vestibular Schwannomas

Objective

The incidence of vestibular schwannomas is increasing, and the average tumor size at diagnosis is decreasing. Therefore, understanding the specific growth pattern of small vestibular schwannomas is becoming increasingly important to guide clinical management. The objectives of this study were to evaluate the growth patterns of very small intracanalicular vestibular schwannomas measuring ≤ 4 mm in linear diameter and to assess the likelihood of these lesions ever requiring treatment. 

Methods

A retrospective review was performed. A search of all MRI brain and internal auditory canal studies suggestive of a vestibular schwannoma from 1995 to 2019 was performed at our institution. This resulted in 372 cases, which were then evaluated for the presence of a vestibular schwannoma measuring ≤ 4 mm. All patients had to have at least one follow-up MRI to be included. Images were reviewed by a neuroradiologist.

Results

Eight ≤ 4 mm vestibular schwannomas were found that met all search criteria. The distribution of tumor sizes was as follows: three 2 mm, one 3 mm and four 4 mm. None of the ≤ 4 mm vestibular schwannomas identified demonstrated any significant growth in the linear dimension defined as greater than 2 mm of growth over observation times of 1-13 years (mean 6.3 years). None of the lesions ever required a treatment intervention per available medical records.

Conclusion

None of the ≤ 4 mm intracanalicular vestibular schwannomas identified in this study grew significantly or required treatment. Overall, the findings in this study suggest that vestibular schwannomas measuring ≤ 4 mm are unlikely to grow and ever require treatment.

Long-term natural history and patterns of sporadic vestibular schwannoma growth: A multi-institutional volumetric analysis of 952 patients

BACKGROUND

The current study aims to characterize the natural history of sporadic vestibular schwannoma volumetric tumor growth, including long-term growth patterns following initial detection of growth.

METHODS

Volumetric tumor measurements from 3505 serial MRI studies were analyzed from unselected consecutive patients undergoing wait-and-scan management at three tertiary referral centers between 1998 and 2018. Volumetric tumor growth was defined as a change in volume ≥20%.

RESULTS

Among 952 patients undergoing observation, 622 experienced tumor growth with initial growth-free survival rates (95% CI) at 1, 3, and 5 years following diagnosis of 66% (63-69), 30% (27-34), and 20% (17-24). Among 405 patients who continued to be observed despite demonstrating initial growth, 210 experienced subsequent tumor growth with subsequent growth-free survival rates at 1, 3, and 5 years following initial growth of 77% (72-81), 37% (31-43), and 24% (18-31). Larger tumor volume at initial growth (HR 1.13, P = .02) and increasing tumor growth rate (HR 1.31; P < .001) were significantly associated with an increased likelihood of subsequent growth, whereas a longer duration of time between diagnosis and detection of initial growth was protective (HR 0.69; P < .001).

CONCLUSIONS

While most vestibular schwannomas exhibit an overall propensity for volumetric growth following diagnosis, prior tumor growth does not perfectly predict future growth. Tumors can subsequently grow faster, slower, or demonstrate quiescence and stability. Larger tumor size and increasing tumor growth rate portend a higher likelihood of continued growth. These findings can inform timing of intervention: whether upfront at initial diagnosis, after detection of initial growth, or only after continued growth is observed.

Vestibular Schwannomas in Young Patients: A 12-Year Experience in a Single Center

OBJECTIVE

This study evaluated the characteristics of vestibular schwannomas (VS) in young patients, including clinical features, treatment, prognosis, and histopathologic characteristics.

METHODS

We retrospectively reviewed medical records and follow-up data for 36 pediatric patients <21 years of age who were surgically treated for VS in the Chinese PLA General Hospital between 2008 and 2019.

RESULTS

Mean patient age was 17.4 years. Mean tumor size was 2.8 cm. Hearing loss (n = 32, 88.9%) and tinnitus (n = 20, 55.6%) were the most common symptoms. Ten patients (27.8%) had impaired facial nerve function after surgery. Gross total resection (GTR) was achieved in 26 cases (72.2%). The median tumor Ki-67 level was 5%. Tumor size was related to incomplete tumor resection (odds ratio, 0.2; 95% confidence interval, 0.1-0.9) and postoperative facial nerve dysfunction (odds ratio, 24.9; 95% confidence interval, 1.2-539.1). Tumor size was nonlinearly associated with prognosis and 2.2 cm corresponded to the inflection point at which the probability of tumor remnant and postoperative facial nerve dysfunction significantly increased. The GTR and low Ki-67 groups achieved better 3-year tumor control rate. Histopathologic findings confirmed the presence of cellular schwannoma subtype in young patients.

CONCLUSIONS

Tumor size is an important factor affecting the prognosis of VS in young patients. For large VS, surgical treatment should be the first choice, rather than wait-and-scan. VS in young patients shows high tumor proliferation and a tendency to relapse. The cellular schwannoma subtype requires special attention; an accurate histopathologic diagnosis is necessary for young patients with VS, and a closer follow-up strategy should be adopted for cellular VS.

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

OBJECTIVE

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

STUDY DESIGN

Retrospective cohort.

SETTING

Tertiary referral center.

PATIENTS

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

Decision making on vestibular schwannoma treatment: predictions based on machine-learning analysis

Decision making on the treatment of vestibular schwannoma (VS) is mainly based on the symptoms, tumor size, patient's preference, and experience of the medical team. Here we provide objective tools to support the decision process by answering two questions: can a single checkup predict the need of active treatment?, and which attributes of VS development are important in decision making on active treatment? Using a machine-learning analysis of medical records of 93 patients, the objectives were addressed using two classification tasks: a time-independent case-based reasoning (CBR), where each medical record was treated as independent, and a personalized dynamic analysis (PDA), during which we analyzed the individual development of each patient's state in time. Using the CBR method we found that Koos classification of tumor size, speech reception threshold, and pure tone audiometry, collectively predict the need for active treatment with approximately 90% accuracy; in the PDA task, only the increase of Koos classification and VS size were sufficient. Our results indicate that VS treatment may be reliably predicted using only a small set of basic parameters, even without the knowledge of individual development, which may help to simplify VS treatment strategies, reduce the number of examinations, and increase cause effectiveness.

Growth of vestibular schwannoma: long-term follow-up study using survival analysis

BACKGROUND

A vestibular schwannoma (VS) is a benign nerve sheath tumor derived from the vestibular nerves. The growth rate of VS during long-term follow-up has not yet been fully evaluated. We aimed to investigate the growth rate of newly diagnosed VS and the related predictive factors for tumor growth.

METHODS

A retrospective review was performed using VS patients who underwent at least two magnetic resonance imaging (MRI) scans before tumor growth was observed. Tumor growth was defined as a size increase of more than 2 mm in the longest diameter of the tumor. To assess the growth rate of VS and related factors, we assessed tumor growth using survival analysis. Survival analysis to assess the growth rate and Cox regression analysis were performed to find related factors.

RESULTS

The study included 118 patients. The mean age of patients was 57.0 ± 12.9 years. During the observation period, the 5-year cumulative growth incidence rate was 41.3% by survival analysis. Extrameatal tumor location and hearing loss were found to be associated with an increased hazard ratio (HR) for tumor growth.

CONCLUSION

After long-term observation of VS, 41.3% of VS patients presented cumulative growth incidence rate in the first 5 years after diagnosis. Extrameatal tumor location and hearing changes were related to subsequent tumor growth.

Vestibular Schwannoma Measurements-Is Volumetric Analysis Clinically Necessary?

OBJECTIVE

1) To compare vestibular schwannoma maximum linear dimensions and calculated volume with measured volume in accurately determining tumor volume and growth. 2) To determine natural growth history of vestibular schwannomas utilizing volumetric measurements in an observed patient population.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary academic referral.

PATIENTS

One hundred fifty two adults with a vestibular schwannoma who underwent observational management with sequential magnetic resonance imaging (MRI) scans (496 scans).

INTERVENTION

MRI scans.

MAIN OUTCOME MEASURES

Tumor volume calculated from linear dimensions compared with measured volume. The percentage change in tumor size (linear or volume) between consecutive MRI scans.

RESULTS

The percentage change in tumor size between consecutive MRIs is significantly different between maximum linear dimension (MLD) and measured tumor volume (p = 0.03), but no difference exists in the percentage change between measured and calculated tumor volume (p = 0.882 for three linear measurements, p = 0.637 for two linear measurements). The overall number of growing tumors is 57.2% (n = 87) with an average growth rate of 62.6%. If a criterion for growth of 20% change is used, 32.2% of tumors monitored by linear volume would have demonstrated growth while 57.2% of tumors with measured volume demonstrated growth.

CONCLUSION

Maximum linear dimensions are a significantly less sensitive measure of tumor growth compared with measured volumes. Calculated tumor volume utilizing three linear measurements is an accurate predictor of both measured tumor volume and tumor growth.

EANO guideline on the diagnosis and treatment of vestibular schwannoma

The level of evidence to provide treatment recommendations for vestibular schwannoma is low compared with other intracranial neoplasms. Therefore, the vestibular schwannoma task force of the European Association of Neuro-Oncology assessed the data available in the literature and composed a set of recommendations for health care professionals. The radiological diagnosis of vestibular schwannoma is made by magnetic resonance imaging. Histological verification of the diagnosis is not always required. Current treatment options include observation, surgical resection, fractionated radiotherapy, and radiosurgery. The choice of treatment depends on clinical presentation, tumor size, and expertise of the treating center. In small tumors, observation has to be weighed against radiosurgery, in large tumors surgical decompression is mandatory, potentially followed by fractionated radiotherapy or radiosurgery. Except for bevacizumab in neurofibromatosis type 2, there is no role for pharmacotherapy.

Predicting Hearing Outcomes in Conservatively Managed Vestibular Schwannoma Patients Utilizing Magnetic Resonance Imaging

OBJECTIVE

Management of small vestibular schwannomas has evolved to where observation with interval imaging is an accepted treatment strategy. Loss of residual hearing is a known complication of observation. Magnetic resonance imaging (MRI) may provide critical information to assist in determining which tumors are at highest risk of hearing loss. We wished to determine what effect fundal cap size and cochlear fluid-attenuated inversion recovery (FLAIR) signal had on the progression of hearing loss in a large cohort of observed subjects.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary academic referral center.

PATIENTS

Three hundred ninety-three adults with a vestibular schwannoma who underwent expectant management with serial audiograms and MRI.

INTERVENTIONS

Audiogram and MRI.

MAIN OUTCOME MEASURES

Hearing outcomes included pure-tone average and word discrimination score (WRS). Cochlear FLAIR signal was measured as a ratio between the affected and nonaffected cochlea. Cerebrospinal fluid fundal cap was measured from the most lateral aspect of the tumor to the fundus of the internal auditory canal.

RESULTS

An increased cochlear FLAIR ratio was associated with a worse initial WRS (p = 0.0001, β=-0.25). A multivariate regression analysis demonstrated the variables fundal cap and initial WRS to significantly predict change in WRS over time. The larger the fundal cap size, the smaller the change in the WRS (p = 0.047, β=-0.35).

CONCLUSIONS

Cerebrospinal fluid fundal cap size predicts the natural history of hearing in vestibular schwannoma patients. The presence of a smaller fundal cap is correlated with a greater risk of progression of hearing loss and should be a variable considered in the management of small vestibular schwannomas.

Identifying Factors Associated with the Growth of Vestibular Schwannomas: A Systematic Review

BACKGROUND

Surveillance imaging is a valid management option for selected vestibular schwannomas (VS). An ideal protocol for radiologic monitoring would highlight growth-related risk factors and tailor management accordingly. This study aims to identify variables associated with the growth of sporadic VS to enhance surveillance imaging, enable early intervention, and optimize outcomes.

METHODS

The review was conducted according to the PRISMA guidelines. A systematic review of 5 databases (PubMed, Ovid, Cochrane Library, Web of Science, and Google Scholar) was performed to identify negative and positive growth predictors of sporadic vestibular schwannomas. The search was limited to studies reported between January 2015 and January 2020. We conducted an individual patient data meta-analysis using a 1-stage multivariate mixed-effect logistic regression model.

RESULTS

A total of 437 studies were identified, of which 25 met our criteria for full-text analysis. Articles that measured VS with comparable methods were determined eligible for meta-analysis inclusion. The selected articles were highly heterogeneous in their use of grading scales and assessment of tumor size. Our review showed that size at diagnosis (odds ratio, 1.15; 95% confidence interval, 1.11-1.18; P < 0.0001) and intracanalicular localization (odds ratio, 0.49; 95% confidence interval, 0.26-0.90; P = 0.023) were associated with VS growth.

CONCLUSIONS

The factors most frequently reported as being associated with growth within the literature were size of VS at diagnosis and localization of an intracanalicular component. Greater attention should be placed on these criteria within the surveillance imaging algorithm for VS.

Predicting Potential of Rapid Tumor Growth in Small to Medium Vestibular Schwannomas on the Basis of Sway Assessed Using Posturography

OBJECTIVE

The relationship between quantitative posturography results and growth of vestibular schwannomas (VSs) during conservative management has not been studied. We aimed to clarify the relationship between the presence of disequilibrium based on posturographic measurement and VS growth.

METHODS

This retrospective, single-center study included 53 patients with VSs (Koos stage I or II) managed conservatively after initial diagnosis. Radiographic progression was considered present if 20% volumetric growth was observed over the imaging interval. Posturography was performed at initial diagnosis, and sway velocity (SV) and sway area were calculated. Tumor growth-free survival was estimated using the Kaplan-Meier method.

RESULTS

Mean follow-up period was 2.87 ± 2.58 years, up to tumor growth detection or last follow-up magnetic resonance imaging. Tumor growth incidence was 40.8% and 61.2% at 2 and 5 years, respectively. Cerebellopontine angle extension and SV with eyes open were related to tumor growth. Tumor growth-free survival of patients with cerebellopontine angle extension and patients with intracanalicular tumor at 2 years was 37.3% and 76.4%, respectively. Tumor growth-free survival of patients with SV >2.06 cm/second and patients with SV ≤2.06 cm/second at 2 years was 30.8% and 68.9%, respectively. The Cox hazard model demonstrated a significant risk for future tumor growth with SV >2.06 cm/second (relative risk, 2.475; 95% confidence interval, 1.11-5.37, P = 0.027).

CONCLUSIONS

We demonstrated a positive correlation between SV with eyes open and future tumor growth. Posturographic data are objective and quantitative; thus, SV may be a potential predictor of future growth of VSs.

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.

Vestibular Schwannoma Tumor Size and Growth Rate Predict Response with Gamma Knife Stereotactic Radiosurgery

Objective The aim of this study is to determine if pretreatment growth of sporadic vestibular schwannomas (VS) predicts postradiosurgery response.

Methods This study was a retrospective chart review at a tertiary referral center of patients with VS that had at least two pretreatment magnetic resonance imaging (MRI) studies at least 6 months apart and underwent Gamma Knife radiosurgery with a minimum of 14 months postradiosurgery imaging surveillance. Tumor linear measurements and volumetric segmentation were assessed before and after radiosurgery. The main outcome measure was persistent enlargement following radiosurgery, defined as 2 mm enlargement in greatest axial diameter or 20% enlargement in volume without size regression.

Results Thirty-five patients met the inclusion criteria. Patients were observed for median pre- and posttreatment intervals of 29.5 and 40.6 months, respectively. Median dose to the tumor margin was 13 Gy. Postradiosurgery enlargement occurred in six (17.1%) and nine (25.7%) patients based on linear and volumetric enlargement definitions, respectively. Pseudoprogression—defined as tumor enlargement—followed by linear or volumetric regression that occurred in 34.3% of tumors, reaching a maximum size at a median time of 6.3 months (3.3–8.4) postradiosurgery. When controlling for age, gender, and radiation dose, preradiosurgery tumor volume less than 0.3 cm3 (odds ratio [OR]: 59.7, p = 0.012) and preradiosurgery tumor diameter growth rate greater than or equal to 2.5 mm/year (OR: 19.3, p = 0.045) were associated with persistent postradiosurgery tumor enlargement.

Conclusion Smaller pretreatment tumor volume and greater linear tumor growth rates were associated with postradiosurgery tumor enlargement when controlling for age, gender, and radiation dose.

Level of Evidence :This study indicates that the level of evidence is V.

Association of Metformin With the Growth of Vestibular Schwannomas

Objective

To assess whether medication use, specifically statin, metformin, and aspirin, affects the growth of vestibular schwannomas (VSs).

Study Design

Retrospective case series.

Setting

Single tertiary care academic hospital.

Subjects and Methods

Patients were enrolled if they were diagnosed with sporadic VS and had at least 2 magnetic resonance imaging (MRI) studies at a minimum of 6 months apart prior to any intervention. Electronic medical records were reviewed for demographic and medication data. Tumor volumes on MRI studies were assessed via BrainLab iPlan. The primary endpoint was VS tumor growth, defined as a 20% increase in tumor volume, between consecutive MRI studies or between the first and last available MRI study. Predictors of volumetric growth, specifically statin, aspirin, or metformin use, were analyzed with t tests, chi-square test, univariate logistic regression, and multivariate logistic regression.

Results

A total of 387 patients met inclusion criteria, 53.5% of whom were women. For all patients, the mean age was 60.6 years (range, 18.2-89.2 years); the mean axial tumor diameter, 11.9 mm (range, 1.7-32.0 mm); and the mean tumor volume, 0.85 cm3 (range, 0.01-13.1 cm3). In review of the electronic medical record, 46 patients (11.9%) were taking metformin; 145 (37.5%), a statin; and 117 (30.2%), aspirin. Among patients taking metformin, 39.1% (18/46) exhibited volumetric growth, as opposed to 58.2% (198/340) of nonusers ( P = .014). Metformin (odds ratio, 0.497; P = .036) is significantly associated with reduced VS growth when controlling for aspirin, statin, and tumor size on multivariate logistic regression.

Conclusion

Metformin use is associated with reduced volumetric VS growth.

MRI monitoring of small and medium-sized vestibular schwannomas: predictors of growth

Background: Vestibular schwannomas are among the most common intracranial tumours. Their growth is difficult to predict.Objectives: To study the evolution of small and medium-sized vestibular schwannomas (VSs) and identify factors predictive of growth.Material and methods: This was a retrospective longitudinal study at a tertiary referral centre from January 2011 to January 2018. The inclusion criteria were radiological diagnosis of sporadic unilateral VS of stage I or II. Radiological and clinical data were analysed descriptively and by multivariate logistic regression to identify factors predictive of growth.Results: A total of 1105 cases were discussed in multidisciplinary meetings and 336 patients were included with a mean age of 57.8 years and a mean follow-up time of 24 months. Around two thirds of these patients (62.8%) had non-progressive tumours. Factors identified as predictive of VS growth were the size at diagnosis (OR = 2.622, 95% CI, 1.50-4.66; p = .001) and internal auditory canal filling (OR = 7.672; 95% CI, 4.52-13.43; p < .001).Conclusions and significance: Monitoring is the primary treatment modality for small or medium-sized VSs. As reported here for the first time, internal auditory canal filling is significantly associated with VS growth.

Automated Detection of Vestibular Schwannoma Growth Using a Two-Dimensional U-Net Convolutional Neural Network

OBJECTIVES/HYPOTHESIS

To determine if an automated vestibular schwannoma (VS) segmentation model has comparable performance to using the greatest linear dimension to detect growth.

STUDY DESIGN

Case-control Study.

METHODS

Patients were selected from an internal database who had an initial gadolinium-enhanced T1-weighted magnetic resonance imaging scan and a follow-up scan captured at least 5 months later. Two observers manually segmented the VS to compute volumes, and one observer's segmentations were used to train a convolutional neural network model to automatically segment the VS and determine the volume. The results of automatic segmentation were compared to the observer whose measurements were not used in model development to measure agreement. We then examined the sensitivity, specificity, and area under the receiver-operating characteristic curve (AUC) to compare automated volumetric growth detection versus using the greatest linear dimension. Growth detection determined by the external observer's measurements served as the gold standard.

RESULTS

A total of 65 patients and 130 scans were studied. The automated method of segmentation demonstrated excellent agreement with the observer whose measurements were not used for model development for the initial scan (interclass correlational coefficient [ICC] = 0.995; 95% confidence interval [CI]: 0.991-0.997) and follow-up scan (ICC = 0.960; 95% CI: 0.935-0.975). The automated method of segmentation demonstrated increased sensitivity (72.2% vs. 63.9%), specificity (79.3% vs. 69.0%), and AUC (0.822 vs. 0.701) compared to using the greatest linear dimension for growth detection.

CONCLUSIONS

In detecting VS growth, a convolutional neural network model outperformed using the greatest linear dimension, demonstrating a potential application of artificial intelligence methods to VS surveillance.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E619-E624, 2021.

Patient Demographics Influencing Vestibular Schwannoma Size and Initial Management Plans

OBJECTIVE

To explore patient demographics as to predicting vestibular schwannoma (VS) size and treatment plan within a single institution.

METHODS

Using a large tertiary referral skull base center database, all patients with sporadic VS who presented to the center between 2009 and 2018 were reviewed.

RESULTS

A total of 816 patients with VS over 18 years of age were included. The median age was 56.8 years (range: 18.6-90.9 years). The median tumor diameter at diagnosis was 11.9 mm (range: 0.6-51.1 mm). With multivariate analysis, older age was associated with decreased tumor size (0.23 mm, 95% confidence interval [CI]: 0.17-0.29), whereas married patients had larger tumors (2.5 mm, 95% CI: 0.92-4.09). When comparing observation, radiation, or surgery, older patients are more likely to pursue observation as compared with surgery and radiation (odds ratio [OR]: 1.08, 95% CI: 1.06-1.10 and OR: 1.20, 95% CI: 1.08-1.33), respectively. Married patients were less likely to pursue observation as compared with surgery (OR: 0.49, 95% CI: 0.29-0.82). Each additional mile a patient lives farther from the center increases his or her odds of pursuing treatment (OR: 1.002, 95% CI: 1.001-1.003).

CONCLUSIONS

Older age is associated with smaller tumors, whereas married patients have larger tumors at diagnosis as compared with nonmarried patients. Furthermore, married patients are more likely to pursue treatment, specifically surgery, as compared with nonmarried patients, whereas patients who live farther from the center are more likely to pursue treatment.

Long-term Effects of Conservative Management of Vestibular Schwannoma on Dizziness, Balance, and Caloric Function

Objectives

To study the development of dizziness, caloric function, and postural sway during long-term observation of untreated vestibular schwannoma patients.

Study Design

Retrospective review of a prospectively maintained longitudinal cohort.

Setting

Tertiary referral hospital.

Subjects and Methods

Patients with vestibular schwannoma undergoing wait-and-scan management were included—specifically, those who did not require treatment during a minimum radiologic follow-up of 1 year. Baseline data and follow-up included magnetic resonance imaging, posturography, bithermal caloric tests, and a dizziness questionnaire. Main outcomes were prevalence of moderate to severe dizziness, canal paresis, and postural instability at baseline and follow-up, as compared with McNemar’s test.

Results

Out of 433 consecutive patients with vestibular schwannoma, 114 did not require treatment during follow-up and were included. Median radiologic follow-up was 10.2 years (interquartile range, 4.5 years). Age ranged from 31 to 78 years (mean, 59 years; SD, 10 years; 62% women). Median tumor volume at baseline was 139 mm3(interquartile range, 314 mm3). This did not change during follow-up ( P = .446). Moderate to severe dizziness was present in 27% at baseline and 19% at follow-up ( P = .077). Postural unsteadiness was present in 17% at baseline and 21% at follow-up ( P = .424). Canal paresis was present in 51% at baseline and 56% at follow-up ( P = .664).

Conclusions

There was no significant change in the prevalence of dizziness, postural sway, or canal paresis during conservative management of vestibular schwannoma, while tumor volume remained unchanged. This indicates a favorable prognosis in these patients with regard to vestibular symptoms.

Surgery of the lateral skull base: a 50-year endeavour

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

Impact of Aspirin and Other NSAID Use on Volumetric and Linear Growth in Vestibular Schwannoma

Objectives

Conflicting research exists surrounding the utility of aspirin to prevent tumor growth in the medical management of vestibular schwannoma (VS). Recent studies demonstrated no association between aspirin and VS growth using linear tumor measurements. Given the heightened sensitivity of volumetric analyses to monitor tumor growth, the current study was conceived with the chief objective of assessing the association between aspirin or other nonsteroidal anti-inflammatory drug (NSAID) use and VS growth using volumetric analyses.

Study Design

Retrospective review.

Setting

Tertiary referral center.

Subjects and Methods

A total of 361 patients totaling 1601 volumetrically analyzed magnetic resonance imaging studies who underwent initial observation since January 1, 2003.

Results

In total, 123 (35%) patients took 81 mg aspirin daily, 23 (7%) took 325 mg aspirin daily, and 41 (11%) reported other NSAID use. Among those taking aspirin, 112 (72%) exhibited volumetric tumor growth during observation compared to 33 (80%) among other NSAID users and 137 (67%) among nonaspirin users. Patients taking aspirin or other NSAIDs were significantly older at time of diagnosis (median, 66 vs 56 years; P < .001). Neither aspirin use (hazard ratio [HR], 0.96; P = .73) nor other NSAID use (HR, 1.39; P = .081) was significantly associated with a reduced risk of volumetric tumor growth. These results were similar following age adjustment ( P = .81 and .087, respectively). When separating aspirin users by 81-mg or 325-mg dosing, neither group exhibited a reduced risk of growth ( P = .95 and .73, respectively).

Conclusion

Despite promising initial results, the preponderance of existing literature suggests that aspirin and other NSAID use does not prevent tumor growth in VS.

Long-term outcome after Gamma Knife radiosurgery for acoustic neuroma of all Koos grades: a single-center study

OBJECTIVE

The authors present long-term follow-up data on patients treated with Gamma Knife radiosurgery (GKRS) for acoustic neuroma.

METHODS

Six hundred eighteen patients were radiosurgically treated for acoustic neuroma between 1992 and 2016 at the Department of Neurosurgery, Medical University Vienna. Patients with neurofibromatosis and patients treated too recently to attain 1 year of follow-up were excluded from this retrospective study. Thus, data on 557 patients with spontaneous acoustic neuroma of any Koos grade are presented, as are long-term follow-up data on 426 patients with a minimum follow-up of 2 years. Patients were assessed according to the Gardner-Robertson (GR) hearing scale and the House-Brackmann facial nerve function scale, both prior to GKRS and at the times of follow-up.

RESULTS

Four hundred fifty-two patients (81%) were treated with radiosurgery alone and 105 patients (19%) with combined microsurgery-radiosurgery. While the combined treatment was especially favored before 2002, the percentage of cases treated with radiosurgery alone has significantly increased since then. The overall complication rate after GKRS was low and has declined significantly in the last decade. The risk of developing hydrocephalus after GKRS increased with tumor size. One case (0.2%) of malignant transformation after GKRS was diagnosed. Radiological tumor control rates of 92%, 91%, and 91% at 5, 10, and 15 years after GKRS, regardless of the Koos grade or pretreatment, were observed. The overall tumor control rate without the need for additional treatment was even higher at 98%. At the last follow-up, functional hearing was preserved in 55% of patients who had been classified with GR hearing class I or II prior to GKRS. Hearing preservation rates of 53%, 34%, and 34% at 5, 10, and 15 years after GKRS were observed. The multivariate regression model revealed that the GR hearing class prior to GKRS and the median dose to the cochlea were independent predictors of the GR class at follow-up.

CONCLUSIONS

In small to medium-sized spontaneous acoustic neuromas, radiosurgery should be recognized as the primary treatment at an early stage. Although minimizing the cochlear dose seems beneficial for hearing preservation, the authors, like others before, do not recommend undertreating intracanalicular tumors in favor of low cochlear doses. For larger acoustic neuromas, radiosurgery remains a reliable management option with tumor control rates similar to those for smaller acoustic neuromas; however, careful patient selection and counseling are recommended given the higher risk of side effects. Microsurgery must be considered in acoustic neuromas with significant brainstem compression or hydrocephalus.

When Should We Stop Scanning Older Patients with Vestibular Schwannomas?

Objective  Observation is a well-accepted management for small- to medium-sized vestibular schwannomas (VSs). Although there are good data on the natural history of this disease within adults, no studies have looked specifically at those aged over 70 years. Thus, there is a need for a surveillance protocol to determine if and when we can stop imaging safely patients aged 70 years and over with a new diagnosis of VSs when managed with observation. Design  Over a 13-year period, we retrospectively analyzed all skull base unit patients with a sporadic unilateral VSs managed with an imaging surveillance protocol. All data were collected prospectively with a minimum follow-up of 5 years. Setting  Tertiary referral skull base unit Participants  Patients aged 70 years and over with sporadic VSs at diagnosis Main Outcome Measures  Main outcome measures Results  A total of 112 patients met inclusion criteria. The median age at diagnosis was 74 years (range: 70-87 years). The mean follow-up was 82 months (range: 60-144). The size of the VSs at diagnosis was intracanalicular (IC) in 46%, small in 41%, medium in 12%, and large in 2%. Growth was more likely where tumors were extracanalicular (EC) rather than IC at presentation ( p  = 0.036) and within the first 18 months after diagnosis ( p  < 0.001). Twenty-nine percent of VSs displayed growth (6% continued surveillance, 23% received active treatment). Good hearing at diagnosis did not predict tumor stability for IC or EC tumors ( p  = 0.162 and p  = 0.536). Conclusions  Since no VSs grew after 42 months from diagnosis, our data support an initial magnetic resonance imaging (MRI) at 6 months after diagnosis followed by an annual MRI for 3 years. At this point, consideration could be given to discussing discontinuation or further imaging with patients.

Main Symptom that Led to Medical Evaluation and Diagnosis of Vestibular Schwannoma and Patient-Reported Tumor Size: Cross-sectional Study in 1,304 Patients

Objectives  Although vestibular schwannomas (VS) are known to cause cranial nerve deficits, cerebellar symptoms, and hydrocephalus, the role of these symptoms as the key driver of presentation from the patient's perspective has not been described. Our objective was to survey a large, retrospective VS cohort to document the patient-reported principal initial symptom, and self-reported tumor size, and to study trends in VS patient presentation. Methods  Patients diagnosed with VS at our tertiary referral center and belonging to the Acoustic Neuroma Association (ANA) answered a questionnaire between 2015 and 2017. Demographic data, self-reported tumor size, and symptomatology were analyzed. Results  1,304 patients completed the questionnaire. Tumors were diagnosed from 1966 to 2017 at a mean 51.8 years (range: 8-86 years); 66% were female, and 1.1% had confirmed neurofibromatosis type 2 (NF2). Tumor size was reported using a 6-point scale: 0 to 1 cm (22.9%), 1 to 2 cm (28.7%), 2 to 3 cm (20.5%), 3 to 4 cm (10%), greater than 4 cm (7.2%), and unknown (10.6%). Hearing loss was the most common symptom that led to diagnosis (51.5%), followed by dizziness (17%), tinnitus (11.2%), and incidental diagnosis (10.2%); a fraction that has increased significantly in the last decade ( p  = 0.022). Larger tumors and NF2 were significantly associated with young age ( p  < 0.001). Conclusion  Our large-scale questionnaire-driven review of 1,304 patients confirms that VS presentations are stereotypical, with most individuals recalling hearing loss, dizziness, or tinnitus as their chief complaint. Many tumors were incidentally diagnosed; an expanding population, attributable to increased access to magnetic resonance imaging (MRI). Large tumors were significantly more prevalent among younger patients at diagnosis, excluding NF2 patients, suggesting a more aggressive tumor biology that remains incompletely understood.

Natural History of Sporadic Vestibular Schwannoma: A Volumetric Study of Tumor Growth

Objective

(1) Assess 3-dimensional volumetric growth of untreated sporadic vestibular schwannomas (VSs) in a large cohort of patients treated with conservative observation. (2) Compare volumetric and conventional linear diameter measurements for detecting tumor growth.

Study Design

Case series with chart review.

Setting

Tertiary skull base referral center.

Subjects and Methods

Patients with sporadic VS who elected initial conservative treatment with at least 2 serial magnetic resonance imaging (MRI) scans were included. Tumor volume was determined with 3-dimensional segmentation of MRI sequences. The volumetric threshold for tumor growth was an increase ≥20% from baseline tumor volume. Tumor size based on linear diameter was assessed with the 1995 American Academy of Otolaryngology—Head and Neck Surgery Foundation guidelines for VS outcome reporting, with growth defined as an increase ≥2 mm.

Results

A total of 361 patients were included with a median radiologic follow-up of 4.1 years (interquartile range [IQR], 2.5-6.8). At diagnosis, 232 VSs (64%) were purely intracanalicular, and 129 (36%) extended into the cerebellopontine angle. The median baseline tumor volume was 0.161 cm3 (IQR, 0.054-0.418). Overall, 69% of tumors demonstrated volumetric growth at a median of 1.1 years (IQR, 0.6-2.1) after initial MRI. In contrast, based on linear measurement assessment, 48% of tumors demonstrated growth at a median of 1.8 years (IQR, 0.8-3.1) from first MRI scan. Disequilibrium, facial hypoesthesia, aural fullness, initial tumor size, and nonincidental diagnosis were associated with tumor growth.

Conclusion

Three-dimensional volumetric assessment of VS provides a more sensitive measure of tumor growth when compared with linear diameter assessment. Through volumetric analysis, the current study revealed that a significant proportion of VSs demonstrate growth during observation.

Vestibular Schwannoma Growth With Aspirin and Other Nonsteroidal Anti-inflammatory Drugs

OBJECTIVE

To investigate whether the use of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) impact the growth of vestibular schwannoma (VS).

STUDY DESIGN

Retrospective case series.

SETTING

Single academic, tertiary care center.

PATIENTS

Patients with VS who underwent at least two magnetic resonance imaging (MRI) studies before intervention.

INTERVENTION(S)

Serial MRI studies.

MAIN OUTCOME MEASURE(S)

VS tumor growth, defined as more than or equal to 2 mm increase in the maximum tumor diameter between consecutive MRI studies, or between the first and last available study. Mean growth rate was also calculated, defined as the change in tumor size divided by length of follow-up.

RESULTS

A total of 564 VS patients met inclusion criteria, with 234 (41.2%) taking some type of NSAID. Aspirin use was not associated with VS tumor growth, presenting tumor diameter, or mean VS growth rate. Further, aspirin dosage did not impact growth outcomes or presenting tumor diameter. A total of 96 (17.0%) patients took an NSAID other than aspirin. Neither non-aspirin NSAID use nor degree of cyclooxygenase-2 (COX-2) selectivity, including aspirin, was significantly associated with VS tumor growth, presenting tumor diameter, or mean VS growth rate.

CONCLUSIONS

While previous studies have suggested a relationship between aspirin usage and VS growth, we found no significant association in our series of 564 observed VS. Furthermore, there was no apparent relationship between aspirin dosage, non-aspirin NSAID use, and COX-2 selectivity with VS growth, presenting tumor diameter at presentation, or mean VS growth rate.