Conservative management of 386 cases of unilateral vestibular schwannoma: tumor growth and consequences for treatment

Scoring System Assessing Risks of Growth in Sporadic Vestibular Schwannoma

BACKGROUND AND OBJECTIVES

Surveillance studies offer sparse knowledge of predictors of future growth in sporadic vestibular schwannomas (VS).Our aim was identification of these risk factors. We propose a scoring system to estimate the risk of growth in sporadic vestibular schwannoma.

METHODS

This retrospective study is based on the demographic and radiological data of 615 adult patients under the surveillance for single VS in our center. Univariate analysis, multivariate regression, and Kaplan-Meier analysis were used when appropriate. The regression coefficient-based "VS score" was calculated based on Cox proportional-hazards regression.

RESULTS

During surveillance, 285 tumors (46%) remained stable, 314 tumors (51%) grew, and 16 tumors (3%) shrank. The significant risks factors for future growth identified both in univariate and multivariate analyses were younger age at onset, cystic morphology, larger tumor volume, and cisternal location (as per Hannover grade). The proportion of growing tumors was 40%, 75%, and 96% among the homogeneous VS, primary cystic, and VS transformed to cystic, respectively. Moreover, tumor growth during the 1st year was significant predictor of continuous growth. Our "VS score" includes variables such as age, sex, morphology, and Hannover grade. The score extends between -3 and 6 points. Kaplan-Meier, confusion matrix, and receiver operating characteristic analysis proved high accuracy of our scoring model.

CONCLUSION

Our retrospective study revealed that younger age, cystic morphology, cisternal extent, larger volume, and growth during 1st year were strong predictors of future growth. Moreover, we propose a scoring system that accurately estimates the risks of future tumor growth.

Vestibular schwannoma unveiled by pregnancy: A case report and literature review

BACKGROUND

Vestibular schwannomas - benign tumours originating from the vestibular nerve - are rare during pregnancy. The intricate interplay between the gravid uterus, maternal physiology and neoplastic growth imposes complexities that demand a careful and tailored approach.

CASE REPORT

This article reports a case of a pregnant woman in her 30 s diagnosed with a large vestibular schwannoma exhibiting brainstem compression, peritumoral oedema and cranial nerve encasement at 36 + 5 weeks of gestation. A multi-disciplinary team collaborated to devise a treatment plan considering the delicate balance between fetal well-being and the urgent need for intervention. A conservative approach involving close monitoring, corticosteroid therapy to manage peritumoral oedema, and detailed fetal assessments was initially employed. As the patient neared full term, a carefully planned caesarean section was performed, followed by a successful craniotomy to resect the vestibular schwannoma. Both the mother and the newborn showed favourable outcomes postoperatively. In addition, a literature review of cases of vestibular schwannoma in pregnancy was undertaken to inform optimal management strategies and enhance understanding of this complex scenario.

CONCLUSION

This case highlights the complexity of managing vestibular schwannomas in pregnant women, and underscores the importance of a tailored, collaborative approach. The condition was resolved successfully, emphasizing the significance of timely diagnosis, meticulous planning and a patient-centred approach in these rare and intricate cases.

Tumor shape as a prognostic factor for the growth of intracanalicular vestibular schwannoma: a long-term observational study

PURPOSE

To evaluate the predictive factors of tumor growth in patients with vestibular schwannoma (VS) managed with the wait-and-scan approach.

METHODS

The data of 31 patients diagnosed with intracanalicular VS and followed for > 5 years were retrospectively analyzed. VS was diagnosed according to MRI findings and tumor growth was monitored. Tumor growth was defined as an increase of 2 mm or more in the maximal tumor diameter. The association between the initial tumor size and shape and tumor growth was assessed.

RESULTS

Tumor growth was observed in 16 of 31 patients (51.6%) over a mean follow-up duration of 7.3 years. The initial tumor size was not statistically correlated with tumor growth. However, fusiform or cylindrical tumors exhibited higher growth rates than oval or round tumors. Additionally, a significant correlation was observed between cerebellopontine angle extension and tumor shape.

CONCLUSION

In this study, 51.6% of the patients with intracanalicular VS who were managed with the wait-and-scan strategy over a follow-up period of > 5 years showed tumor growth. Tumor shape, especially fusiform or cylindrical shape, was found to be a significant predictor of tumor growth.

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

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

Assessing Tumor Volume for Sporadic Vestibular Schwannomas: A Comparison of Methods of Volumetry

INTRODUCTION

The size of vestibular schwannomas (VS) is a major factor guiding the initial decision of treatment and the definition of tumor control or failure. Accurate measurement and standardized definition are mandatory; yet no standard exist. Various approximation methods using linear measures or segmental volumetry have been reported. We reviewed different methods of volumetry and evaluated their correlation and agreement using our own historical cohort.

METHODS

We selected patients treated for sporadic VS by Gammaknife radiosurgery (GKRS) in our department. Using the stereotactic 3D T1 enhancing MRI on the day of GKRS, 4 methods of volumetry using linear measurements (5-axis, 3-axis, 3-axis-averaged, and 1-axis) and segmental volumetry were compared to each other. The degree of correlation was evaluated using an intraclass correlation test (ICC 3,1). The agreement between the different methods was evaluated using Bland-Altman diagrams.

RESULTS

A total of 2,188 patients were included. We observed an excellent ICC between 5-axis volumetry (0.98), 3-axis volumetry (0.96), and 3-axis-averaged volumetry (0.96) and segmental volumetry, respectively, irrespective of the Koos grade or Ohata classification. The ICC for 1-axis volumetry was lower (0.72) and varied depending on the Koos and Ohata subgroups. None of these methods were substitutable.

CONCLUSION

Although segmental volumetry is deemed the most accurate method, it takes more effort and requires sophisticated computation systems compared to methods of volumetry using linear measurements. 5-axis volumetry affords the best adequacy with segmental volumetry among all methods under assessment, irrespective of the shape of the tumor. 1-axis volumetry should not be used.

Giant schwannoma on the lower leg: A case report and review of the literature

INTRODUCTION AND IMPORTANCE

Peripheral nerve sheath tumors are common neoplasm with different biological features ranging from benign to malignant. The majority of these tumors are smaller than 5 cm, whereas those larger are termed giant schwannomas. When localized in the lower legs, the maximum length of the schwannoma is less than 10 cm. We report a case of giant schwannoma of the leg and its management.

CASE PRESENTATION

A 11-year-old boy presented with a 13 cm × 5 cm firm, smooth, well-defined margin mass in the posterior-medial aspect of right leg. The tumor was fusiform, well capsulated, multi-lobulated soft tissue with 13 cm × 4 cm × 3 cm in size at the biggest region. On MRI the tumor was low signal, isointense with adjacent tissue on T1S, hyper-intense on T2-FS sequences and surrounded by a thin fat-like intense rim. Biopsy findings were considered most consistent with Schwannoma (Antoni A). Tumor resection was performed. The mass appeared capsulated, white, and glistening with 132 mm × 45 mm × 34 mm in size. Postoperative course was uneventful without neurological deficit.

CLINICAL DISCUSSION AND CONCLUSION

Schwannomas are the most common peripheral nerve sheath tumors that derived almost entirely from Schwann cells. Schwannomas usually affect the head and neck region, localization in the lower extremity is rare. When located in lower extremity, the maximum diameter of 5 cm is described in most studies. Clinical presentation of schwannomas is unclear and unspecific. Diagnosis is based on ultrasound, MRI, and histology. The recommended treatment for schwannoma is surgical enucleation or resection without damaging the involved nerve.

Upfront Radiosurgery vs a Wait-and-Scan Approach for Small- or Medium-Sized Vestibular Schwannoma: The V-REX Randomized Clinical Trial

Importance

Current guidelines for treating small- to medium-sized vestibular schwannoma recommend either upfront radiosurgery or waiting to treat until tumor growth has been detected radiographically.

Objective

To determine whether upfront radiosurgery provides superior tumor volume reduction to a wait-and-scan approach for small- to medium-sized vestibular schwannoma.

Design, Setting, and Participants

Randomized clinical trial of 100 patients with a newly diagnosed (<6 months) unilateral vestibular schwannoma and a maximal tumor diameter of less than 2 cm in the cerebellopontine angle as measured on magnetic resonance imaging. Participants were enrolled at the Norwegian National Unit for Vestibular Schwannoma from October 28, 2014, through October 3, 2017; 4-year follow-up ended on October 20, 2021.

Interventions

Participants were randomized to receive either upfront radiosurgery (n = 50) or to undergo a wait-and-scan protocol, for which treatment was given only upon radiographically documented tumor growth (n = 50). Participants underwent 5 annual study visits consisting of clinical assessment, radiological examination, audiovestibular tests, and questionnaires.

Main Outcomes and Measures

The primary outcome was the ratio between tumor volume at the trial end at 4 years and baseline (V4:V0). There were 26 prespecified secondary outcomes, including patient-reported symptoms, clinical examinations, audiovestibular tests, and quality-of-life outcomes. Safety outcomes were the risk of salvage microsurgery and radiation-associated complications.

Results

Of the 100 randomized patients, 98 completed the trial and were included in the primary analysis (mean age, 54 years; 42% female). In the upfront radiosurgery group, 1 participant (2%) received repeated radiosurgery upon tumor growth, 2 (4%) needed salvage microsurgery, and 45 (94%) had no additional treatment. In the wait-and-scan group, 21 patients (42%) received radiosurgery upon tumor growth, 1 (2%) underwent salvage microsurgery, and 28 (56%) remained untreated. For the primary outcome of the ratio of tumor volume at the trial end to baseline, the geometric mean V4:V0 was 0.87 (95% CI, 0.66-1.15) in the upfront radiosurgery group and 1.51 (95% CI, 1.23-1.84) in the wait-and-scan group, showing a significantly greater tumor volume reduction in patients treated with upfront radiosurgery (wait-and-scan to upfront radiosurgery ratio, 1.73; 95% CI, 1.23-2.44; P = .002). Of 26 secondary outcomes, 25 showed no significant difference. No radiation-associated complications were observed.

Conclusion and relevance

Among patients with newly diagnosed small- and medium-sized vestibular schwannoma, upfront radiosurgery demonstrated a significantly greater tumor volume reduction at 4 years than a wait-and-scan approach with treatment upon tumor growth. These findings may help inform treatment decisions for patients with vestibular schwannoma, and further investigation of long-term clinical outcomes is needed.

Trial Registration

ClinicalTrials.gov Identifier: NCT02249572.

Management of Vestibular Schwannoma with Normal Hearing

INTRODUCTION

This work aimed to study the management of vestibular schwannoma (VS) patients with normal hearing (NH).

METHODS

A retrospective study was undertaken in a Quaternary referral center for skull base pathologies. Among 4,000 VS patients 162 met our strict audiological criteria for NH. These patients were divided into 2 management groups, wait and scan (W&S) (45/162, 25%) and operated patients (123/162, 75%), and 6 patients were included in both groups.

RESULTS

Our management strategy achieved the goals for treatment of VS. First goal, all tumors were completely removed except for 2 intentional residuals. Second goal, facial nerve (FN) function preservation (House Brackmann I, II, and III) was 95.9%. Third goal, possible hearing preservation (HP) attempts occurred in (50/122) (40.9%) with an HP rate in 44% of the patients. Additionally, there were only 2 cases of postoperative complications with no CSF leakage. The prospect of HP in NH patients did not differ with respect to tumor size. However, patients with normal preoperative ABR seemed to have better chances of HP and good FN function and vice versa. HP rate was superior for the MCFA as opposed to the RS + RLA. W&S group demonstrated hearing stability in 88.9% of the patients and FN function stability of HB I in 100% of the patients.

CONCLUSIONS

Surgical resection is a reasonable and definitive management option for VS with NH. Nevertheless, choosing to manage cases with observation remains an appropriate management option for NH patients. ABR might be considered as an adjuvant tool indicating better prognosis for HP.

Surgery versus radiosurgery for vestibular schwannoma: Shared decision making in a multidisciplinary clinic

Background

Our neurosurgical unit adopted a model of shared decision-making (SDM) based on multidisciplinary clinics for vestibular schwannoma (VS). A unique feature of this clinic is the interdisciplinary counseling process with a surgeon presenting the option of surgery, an oncologist radiosurgery or radiotherapy, and a specialist nurse advocating for the patient.

Methods

This is a retrospective cohort study. All new patients seen in the combined VS clinic and referred from the skull base multidisciplinary team (MDT) from beginning of June 2013 to end of January 2019 were included. Descriptive statistics and frequency analysis were carried out for the full cohort.

Results

Three hundred and fifty-four patients presenting with new or previously untreated VS were included in the analysis. In our cohort, roughly one-third of patients fall into each of the treatment strategies with slightly smaller numbers of patients undergoing surgery than watch, wait and rescan (WWR) ,and SRS (26.6% vs. 32.8% and 37.9%, respectively).

Conclusion

In our experience, the combined surgery/oncology/specialist nurse clinic streamlines the patient experience for those with a VS suitable for either microsurgical or SRS/radiotherapy treatment. Decision-making in this population of patients is complex and when presented with all treatment options patients do not necessarily choose the least invasive option as a treatment. The unique feature of our clinic is the multidisciplinary counseling process with a specialist nurse advocating and guiding the patient. Treatment options are likely to become more rather than less complex in future years making combined clinics more valuable than ever in the SDM process.

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.

Evaluation of Carotid Space Schwannoma Using Ultrasonography: Characteristics and Role in Defining the Nerve of Origin

OBJECTIVES

We aimed to evaluate the ultrasonography (US) characteristics of carotid space schwannoma and their role in identifying the nerve of origin.

METHODS

This prospective study enrolled patients with cervical carotid space schwannoma accessible by US. The US characteristics of vagus nerve schwannomas (VNSs) and sympathetic nerve schwannomas (SNSs) were assessed; a carotid space schwannoma was defined as a VNS if the tumor originated in the mid-vagal region and an SNS if it arose posterior to the intact vagus nerve, displacing the vagus nerve anteriorly.

RESULTS

Twenty patients with carotid space schwannoma were enrolled. The vagus and sympathetic nerves were identified as the nerve of origin in 12 and 8 patients, respectively. VNSs were centered at levels II, III, and IV in 5, 3, and 4 patients, respectively, while SNSs were centered at levels II (7 patients) and IV (1 patient) (P = .105). The maximal diameters were 3.2 and 4.8 cm for VNSs and SNSs, respectively (P = .011). Internal vascularity was absent and low in 9 and 3 VNSs, respectively, and low and intermediate in 4 SNSs each (P = .002). Twelve patients with VNSs underwent active surveillance without immediate surgery; no adverse events occurred during the 55.2-month follow-up period. Eight patients with potential SNSs underwent surgery, confirming the sympathetic nerve as the nerve of origin.

CONCLUSIONS

US facilitates identification of the nerve of origin in cervical carotid space schwannoma. VNSs are more frequent in infrahyoid locations and tend to be smaller in size with lower vascularity compared with SNSs on US.

Spontaneous regression of solid-cystic vestibular schwannoma: A case report

Background:

Vestibular schwannomas (VSs) are one of the most common tumors of the cerebellopontine angle and internal meatus, the evolution of this type of tumors is defined as unpredictable, it can enlarge or present a spontaneous regression as described in rare cases.

Case Description:

We report the case of a 50-year-old woman who presented with a large right full cystic VS revealed by a balance disorder associated with deafness in the right ear which spontaneously regressed. The patient was lost to follow-up for 3 years, the symptomatology improved, and the tumor clearly regressed without any surgical treatment.

Conclusion:

Spontaneous regression of solid-cystic VS is possible but rare, it can be part of conservative treatment, which requires regular follow-up.

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.

Hemorrhagic vestibular schwannoma: a case example of vestibular apoplexy syndrome. Illustrative case

BACKGROUND

Acute intratumoral hemorrhage within a vestibular schwannoma, or vestibular apoplexy, is a rare condition. Unlike the typical insidious vestibulopathy typically caused by vestibular schwannoma growth, patients with vestibular apoplexy have an acute and severe presentation with nausea and emesis in addition to severe vertigo and hearing loss. Here, the authors present an illustrative case demonstrating this rare clinical condition and an operative video detailing the surgical management.

OBSERVATIONS

A 76-year-old man presented to the emergency department with acute-onset dizziness, left-ear fullness, double vision, gait ataxia, emesis, and facial numbness. Imaging revealed a 2.8-cm hemorrhagic left cerebellopontine angle lesion extending into the left internal auditory canal, consistent with hemorrhagic vestibular schwannoma. The patient subsequently underwent a retrosigmoid craniotomy for resection of the hemorrhagic mass, and by 1 month after surgery, all his presenting symptoms had resolved, allowing his return to daily activities.

LESSONS

Vestibular schwannomas typically present with decreased hearing and chronic vestibulopathy. Acute presentation should raise the suspicion for an apoplectic event, and surgical debulking may lead to improvement in most vestibular symptoms.

Treatment for vestibular schwannoma: Systematic review and single arm meta-analysis

OBJECTIVE

Vestibular schwannoma is a benign tumor in the schwannoma cells of the 8th cranial nerve. It causes symptoms like tinnitus, vertigo and end up with loss of hearing so the appropriate treatment is very important. There are many treatment techniques including conservative, surgery and radiosurgery. We aimed to systematically review and single arm meta-analysis the different treatment techniques of vestibular schwannoma.

METHODS

A comprehensive literature search using thirteen databases including PubMed, Scopus, and Web of Science was performed. All clinical trials about treatment vestibular schwannoma were included and single arm meta-analyzed. We assessed the risk of bias using ROBIN-I's tool and scale of Council Australia's Cancer Guidelines Wiki. The protocol was registered in PROSPERO (CRD42018089784) and has been updated on 17 April 2019.

RESULTS

A total of 35 clinical trials studies were included in the final analysis. The pooled proportion of stable hearing capability in patients receiving gamma knife radiosurgery (GKRS) was 64% (95% CI: 52%-74%). GKRS favored increased hearing capability 10% (95% CI: 7%-16%). Regarding tumor size, GKRS is the most protective method 53% (95% CI: 37%-69%). Complications occurred most commonly in single fractional linac stereotactic radiosurgery (SFSRT) 37% (95% CI: 12%-72%).

CONCLUSION

Our analysis suggested gamma knife radiosurgery could be the most ideal treatment for vestibular schwannoma based on stabilizing hearing capability, increasing hearing capability, decreasing tumor size and complications.

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.

Comparing the Precision and Reliability Between Three Radiographic Techniques for Measuring Sporadic Vestibular Schwannomas

RATIONALE AND OBJECTIVES

Several methods exist for measuring vestibular schwannoma (VS) size radiographically. Our aim was to compare the precision and reproducibility of three different radiographic measurement techniques for assessing VS tumor size.

MATERIAL AND METHODS

Twenty patients with unilateral, sporadic VS previously untreated were identified. All patients had thin-slice T1 weighted, postcontrasted magnetization prepared rapid acquisition gradient echo images. Three measurement techniques were performed using within-subject and between-subject comparison. Experimental comparison of interobserver agreement between techniques was calculated. Interobserver intraclass correlation coefficients, repeatability coefficients, and relative smallest detectable difference were calculated and compared.

RESULTS

Mean tumor measurements were: 10.3 mm (maximum linear dimension, [MLD]), 495.9 mm³ (orthogonal volumetric analysis, [OVA]), and 572.1 mm³ (segmented volumetric analysis, [SVA]). Interobserver correlation coefficient was excellent for all measurement techniques, but highest for segmented volumetric analysis. Repeatability coefficient was 1.44 mm for MLD, 298.9 mm³ for OVA, and 174.8 mm³ for SVA. The smallest detectable difference was 13.9% for MLD, 60.2% for OVA, and 30.6% for SVA. A subgroup analysis was performed for small tumors (<14 mm) and large tumors (>14 mm) and demonstrated increased precision of segmented volumetric analysis for larger tumors.

CONCLUSION

Semi-automated segmented volumetric analysis appears more precise than either linear measurement or orthogonal volumetric analysis for reporting VS tumor size, and becomes increasingly precise for larger tumors. Tumor volume and tumor volume change over time using SVA may be more sensitive in surveilling VS than current measurement techniques.

Schwannoma in the extremity: clinical features and microscopic intra-capsular enucleation

Objective: Schwannomas are the most common type of neoplasm of the peripheral nerves. Enucleation is a standard surgical procedure; however, it occasionally results in iatrogenic nerve injury, even with atraumatic procedures. Herein, we present the clinical characteristics of schwannoma arising in the extremities and discuss the clinical outcomes of extra- and intra-capsular enucleation.

Patients and Methods: We reviewed 122 schwannomas treated at our institute. Schwannomas arising from the minor nerve (n=30) or intramuscularly (n=15) were operated using the extra-capsular technique. Of the 77 major nerve schwannomas, 62 schwannomas were treated using the intra-capsular technique and 15 schwannomas using the extra-capsular technique.

Results: Neurological deficits following enucleation were significantly lower using the intra-capsular technique than with the extra-capsular technique. The patient age, duration of symptoms, maximum tumor diameter, and site of occurrence were not associated with subsequent neurological deficits. With both techniques, no tumor recurrence was observed at the final follow-up.

Conclusion: These results support the use of intra-capsular micro-enucleation as a safe and reliable treatment for every type of schwannoma. To minimize the risk of nerve injury, en bloc resection should not be used because the main purpose of schwannoma surgery is the relief of symptoms, not tumor resection.

Case series of vestibular schwannoma patients with no asymmetry in hearing

OBJECTIVE

(1) Describe the presenting symptoms and tumor characteristics of patients who are diagnosed with a vestibular schwannoma (VS) with normal hearing or symmetric hearing loss, and (2) report the prospective growth and treatment of each tumor.

METHODS

This is a retrospective cohort study of acoustic neuroma patients who were found to have a VS and normal or symmetric hearing loss at a single tertiary care academic center from 1999 to 2012. Medical records were reviewed collecting the following information: patient demographics, symptoms, MRI characteristics, and treatment modality.

RESULTS

15/195 (7.7%) patients met criteria for the study. Dizziness was the most common presenting symptom occurring in 9 subjects (60%), followed by headache in 6 (40%), vision changes in 5 (33%), tinnitus in 5 (33%), and unilateral hearing loss in 1 (7%). The average tumor size was 1.07 cm (range 0.3-2.2 cm). Eight (53%) patients presented with intracanalicular tumors. Growth was observed in 6 subjects (40%) with average growth rate in those who exhibited mean growth of 1.8 mm per year. Treatment consisted of surgical removal in 4 cases (27%), gamma knife therapy in 1 (7%), and observation or loss to follow-up in 10 (66%).

CONCLUSIONS

The incidence of VS with normal hearing was 7.7% Patients with VSs who do not exhibit unilateral hearing loss present most commonly with dizziness. Most of our patients had small, intracanalicular tumors with the largest tumor measuring 2.2 cm in greatest dimension. Of those who were managed conservatively with repeat imaging and observation, most showed tumor growth.

Tufts Medical Center Experience With Long-Term Follow-Up of Vestibular Schwannoma Treated With Gamma Knife Stereotactic Radiosurgery: Novel Finding of Delayed Pseudoprogression

Purpose

Our purpose was to evaluate the long-term outcomes of patients with vestibular schwannoma (VS) treated with Gamma Knife stereotactic radiosurgery (GKSRS) with modern techniques, with attention to posttreatment tumor growth dynamics, dosimetric predictors, and late toxicities.

Methods and Materials

One hundred twelve patients with VS were treated with GKSRS with a median dose of 12.5 Gy to the 50% isodose line treated between 2004 and 2015, with patients followed up to 15 years. Target and organ-at-risk doses were recorded, and tumor diameter/volume, audiologic decline, and trigeminal/facial nerve preservation were tracked from treatment onward.

Results

GKSRS yielded local control of 5, 10, and 15 years at 96.9%, 90.0%, and 87.1% respectively. Pseudoprogression was found in 45%, with a novel pattern detected with peak swelling at 31 months. Pseudoprogression was associated with smaller tumor diameter at treatment and fewer treatment isocenters, but not with the development of any toxicity, nor was it predicted by any dosimetric factor. Median time to hearing loss was 3.4 years with actuarial hearing preservation at 2, 5, and 10 years of 66.5%, 43.1%, and 37.6%, with rate of hearing loss correlating with maximum cochlea and modiolus doses. Trigeminal and facial nerve preservation rates were 92.7% and 97.6%, respectively. Increasing maximum tumor dose was associated with facial paresthesia.

Conclusions

Modern GKSRS is a safe and effective treatment for VS on long-term follow-up, with high levels of facial and trigeminal nerve preservation. A novel pattern of pseudoprogression has been identified suggesting longer imaging follow-up may be needed before initiating salvage in those without symptomatic progression. Several tumor and dosimetric predictors have been suggested for the development of different toxicities, requiring further evaluation.

Adherence to Long-Term Follow-up in Patients With Sporadic Vestibular Schwannomas Managed With Serial Observation

Objectives

To examine the long-term adherence to serial imaging of patients with sporadic vestibular schwannoma and analyze factors associated with being lost to follow-up.

Study Design

Retrospective chart review with telephone interview.

Setting

Single tertiary care center.

Methods

Patients with a sporadic vestibular schwannoma and started on observational surveillance management between January 2005 and December 2010 were included. Demographic data, tumor size, hearing and vestibular changes, and follow-up length were recorded. Patient factors were analyzed for association with being lost to follow-up.

Results

In total, 122 patients were included with a median length of follow-up of 5 months (range, 0-146). After initial surveillance, 22.1% (n = 27) of patients had a change in management to either microsurgery or radiosurgery. Of the remaining 77.9% (n = 95), nearly half (44.2%, n = 42) never returned for a second visit, and all but 3 were eventually lost to follow-up. There was no association between sex, race, age at diagnosis, initial tumor size, insurance status, household income, or driving distance to hospital and being lost to follow-up. Of 26 interviewed patients initially lost to follow-up, 11 (42.3%) sought care at another institution, 5 (19.2%) chose to no longer receive care, 1 (3.8%) had transportation difficulties, and 9 (36.4%) had poor understanding of their diagnosis or instructions.

Conclusions

The length of follow-up for patients undergoing surveillance of sporadic vestibular schwannoma varies widely, and patients are commonly lost to follow-up. Further efforts should be made to identify at-risk patients and provide adequate education to improve long-term surveillance.

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.

Natural History of Growing Sporadic Vestibular Schwannomas During Observation: An International Multi-Institutional Study

OBJECTIVE

Active treatment of small- or medium-sized vestibular schwannoma during wait-and-scan management is currently recommended at most centers globally once growth is detected. The primary aim of the current study was to characterize the natural history of growing sporadic vestibular schwannoma during observation.

STUDY DESIGN

Cohort study.

SETTING

Four tertiary referral centers across the United States and Denmark.

PATIENTS

Patients with two prior MRI scans demonstrating ≥2 mm of linear growth who continued observational management.

INTERVENTION

Observation with serial imaging.

MAIN OUTCOME MEASURE

Subsequent linear growth-free survival (i.e., an additional ≥2 mm of growth) following initial growth of ≥2 mm from tumor size at diagnosis.

RESULTS

Among 3,402 patients undergoing observation, 592 met inclusion criteria. Median age at initial growth was 66 years (IQR 59-73) for intracanalicular tumors (N = 65) and 62 years (IQR 54-70) for tumors with cerebellopontine angle extension (N = 527). The median duration of MRI surveillance following initial detection of tumor growth was 5.2 years (IQR 2.4-6.9) for intracanalicular tumors and 1.0 year (IQR 1.0-3.3) for cerebellopontine angle tumors. For intracanalicular tumors, subsequent growth-free survival rates (95% CI; number still at risk) at 1, 2, 3, 4, and 5 years following the initial MRI that demonstrated growth were 77% (67-88; 49), 53% (42-67; 31), 46% (35-60; 23), 34% (24-49; 17), and 32% (22-47; 13), respectively. For cerebellopontine angle tumors, subsequent growth-free survival rates were 72% (68-76; 450), 47% (42-52; 258), 32% (28-38; 139), 26% (21-31; 82), and 22% (18-28; 57), respectively. For every 1 mm increase in magnitude of growth from diagnosis to tumor size at detection of initial growth, the HRs associated with subsequent growth were 1.64 (95% CI 1.25-2.15; p < 0.001) for intracanalicular tumors and 1.08 (95% CI 1.01-1.15; p = 0.02) for cerebellopontine angle tumors.

CONCLUSIONS

Growth detected during observation does not necessarily portend future growth, especially for slowly growing tumors. Because early treatment does not confer improved long-term quality of life outcomes, toleration of some growth during observation is justifiable in appropriately selected cases.

Determinants of Vestibular Schwannoma Growth

OBJECTIVE

Management of vestibular schwannomas (VS) involves surgery, radiotherapy, or surveillance, based on patient and tumor factors. We recently described conditional probability as a more accurate method for stratifying VS growth risk. Building on this, we now describe determinants of VS growth, allowing clinicians to move toward a more personalized approach to growth-risk profiling.

METHODS

Retrospective analysis of a prospectively collected database in a tertiary referral skull base unit between 2005 and 2014. Inclusion of patients with unilateral VS managed on surveillance protocol for a minimum of 5 years. Analysis of patient age, sex, tumor location, tumor size, and symptomology using conditional probability.

RESULTS

A total of 340 patients met inclusion criteria. The conditional probability of growth of extracanalicular VS was significantly higher versus intracanalicular (IC) VS (30% versus 13%, p < 0.001) as was small-sized VS versus IC VS (28 versus 13%, p = 0.002), but only in the first year after diagnosis. Sex, age, and presenting symptoms did not significantly affect VS growth.

CONCLUSION

In our series, extracanalicular VS were more likely to grow than IC VS and small-sized VS more likely to grow than IC VS, but only in the first year after diagnosis. Conversely, sex, age, and presenting symptoms did not affect the conditional probability of VS growth.

Postural Sway Predicts Growth in Untreated Vestibular Schwannoma: A Retrospective Volumetric Study

BACKGROUND

One in three vestibular schwannomas (VS) will grow within 3 years after diagnosis, but no reliable baseline parameter has been found to predict such growth.

OBJECTIVE

To determine if postural sway is associated with growth of untreated VS.

METHODS

Patients with newly diagnosed sporadic VS assigned to a wait-and-scan protocol were identified from a prospectively maintained database. Postural sway was measured by posturography at baseline and patients were classified as steady or unsteady. Observer-blinded volumetric tumor measurements were performed on the diagnostic MRI and a 3-year control MRI. Tumor growth quantified as relative growth (%) and volume-doubling time (VDT and VDT-1) were investigated as dependent variables against baseline parameters.

RESULTS

Out of 204 VS patients, 53 (26%) were classified as unsteady on the platform at baseline. Median tumor volume was 0.32 cm3 (range 0.02-4.79), and 51% demonstrated significant growth within 3 years. Unsteady patients had significantly faster-growing tumors, with a mean relative growth of 172.5% compared to 79.5% in steady patients (p < 0.006). Seventy-seven percent of unsteady patients had >20% volume increase, compared to 42% in steady patients (p < 0.001). Mean VDT-1 was 0.65 doublings per year for unsteady patients, and 0.22 for steady patients (p < 0.001). Multivariate regression analysis including demographic and clinical parameters showed an OR of 5.6 (95% CI 2.6, 11.8) for growth in unsteady patients.

CONCLUSIONS

This is the first demonstrated association between a measurable parameter and future growth in untreated VS. Our findings may help clinicians identify patients with a higher risk for tumor growth and provide closer monitoring or early treatment.

Useful hearing preservation is improved in vestibular schwannoma patients who undergo stereotactic radiosurgery before further hearing deterioration ensues

INTRODUCTION

The present study evaluates whether hearing deterioration during observation reduces serviceable hearing preservation rates after stereotactic radiosurgery (SRS) in vestibular schwannoma (VS) patients with useful hearing.

METHODS

We retrospectively analyzed 1447 VS patients who underwent SRS between 1992 and 2017. We identified 100 VS patients who had Grade I Gardner- Robertson (GR) hearing at initial diagnosis but were observed without surgery or SRS. We compared hearing after SRS in 67 patients who retained GR Grade I hearing from initial diagnosis to SRS (the hearing maintenance or HM group) to 33 patients whose hearing worsened from GR grade I to grade II (the hearing deterioration or HD group). We also investigated whether a decline in pure tone average (PTA) or speech discrimination score (SDS) before SRS affected hearing preservation after SRS.

RESULTS

The serviceable hearing (GR I and II) preservation in HM patients was 80%s, 63%, and 51% at 3, 5, and 10 years, respectively. The serviceable hearing preservation in HD patients was 40%, 33%, and 20% at 3, 5, and 10 years, respectively. In multivariate analysis, younger age (< 55 years, p = 0.045) and HM during observation (p = 0.001) improved serviceable hearing preservation rates. Patients whose PTA increased ≥ 15 dB (p = 0.024) or whose SDS declined ≥ 10% (p = 0.019) had reduced serviceable hearing preservation rates.

CONCLUSIONS

Hearing deterioration during observation before SRS reduced long term hearing preservation rate in VS patients with GR grade I hearing at initial diagnosis. SRS before hearing deterioration was recommended for hearing preservation.

Intracanalicular Vestibular Schwannoma: A Systematic Review and Meta-analysis of Therapeutics Outcomes

OBJECTIVE

To perform a systematic review and meta-analysis summarizing the current evidence on the management of intracanalicular vestibular schwannoma.

DATA SOURCES

Embase (1947-), Medline (1946-), Cochrane library (1947-), Scopus (2010-), and CINAHL (1961-) were searched from 1969 to October 5, 2019 (50 years).

STUDY SELECTION

A search strategy was performed to identify patients with vestibular schwannoma confined to the internal auditory canal without extension to the cerebellopontine angle. Studies with patients aged less than 18, Neurofibromatosis type 2, revision cases, and non-English language were excluded.

DATA EXTRACTION

A standardized collection sheet was used for the extracted data and a quality assessment was performed using the Newcastle-Ottawa Scale with the comparability criterion omitted.

DATA SYNTHESIS

Seventy-one studies were included with 24 on observation, 14 on radiotherapy, and 34 on surgery. The primary outcome was serviceable hearing preservation. Secondary outcomes were preservation of facial nerve function, growth, involution, and dizziness. Sub-analysis on the type of surgery and type of radiotherapy were performed. Excel 2016 with MIX 2.0 Pro add-on package was used to analyze the data and create forest plots. Data were presented in proportion with a 95% confidence interval.

CONCLUSIONS

Serviceable hearing was observed in 31% of patients after observation, 56% after radiotherapy, and 51% after surgical treatment with mean follow-up time of 4.04 years, 4.92 years, and 2.23 years, respectively. Facial nerve function was found to be best preserved in both observation and radiotherapy groups. Vestibular schwannoma growth occurred in 33% of patients under observation. Involution occurred in 2% of patients under observation and in 38% after radiotherapy.

Clinical risk factor analysis of bilateral vestibular schwannoma's growth pattern inconsistency in individual NF2 patients

OBJECTIVE

Although bilateral vestibular schwannomas (VSs) in individual NF2 patients have the same NF2 gene mutation, they often show different growth patterns. We attempted to identify factors associated with this growth pattern inconsistency.

PATIENTS AND METHODS

Cranial MR images of 120 untreated VSs in 60 NF2 patients were carefully reviewed for their growth rates. Growth pattern analysis was performed on 68 VSs in 34 NF2 patients followed up for more than three years with at least three cranial MR scans.

RESULTS

Patient age and tumor volume were significantly associated with NF2 VS absolute growth rates (p < 0.05). Bilateral VS growth patterns in individual NF2 patients were the same in 18 (52.9 %) and different in 16 (47.1 %) patients. Patients with consistent bilateral growth patterns were significantly younger than the inconsistent patients (21.8 ± 5.8 years vs. 30.8 ± 13.1 years, p = 0.014). The bilateral VS volume consistency rates were significantly higher in patients with consistent growth patterns than in patients with inconsistent growth patterns (10/18 vs. 3/16, p = 0.028).

CONCLUSIONS

Patient age and volume consistency are the clinical risk factors for bilateral NF2 VS growth pattern inconsistencies. Bilateral VSs in young NF2 patients tend to have the same growth patterns. These findings may help us to predict the future clinical behavior of small NF2 VSs based on the past clinical history of the large ones.

Tracking Spontaneous Vestibular Schwannoma Regression with Volumetric Measurements

OBJECTIVE

To characterize a series of patients with MRI evidence of spontaneous vestibular schwannoma (VS) regression.

STUDY DESIGN

Retrospective case series.

METHODS

Retrospective review between 2012 and 2020 from a single, tertiary-care center of all patients with an untreated, sporadic VS and spontaneous regression in volumetric tumor size over the course of observation. The main outcome measures included VS size and location, presenting symptoms, medication use, changes in pure-tone averages and word recognition scores.

RESULTS

The 13 treatment-naïve patients (62% female, mean age 67.1 years) with spontaneous VS regression represented 3.9% of all patients undergoing observation with serial imaging during the study period. Median tumor size from initial MRI was 529.0 mm³ (range: 108 mm³ -13,180 mm³ ). The mean interval between MRI measurements was 5.5 years (SD 4.4 years). The average percent decrease in tumor size was 36.1% (SD 21.9%) and the average rate of volume decrease was 15.8 mm³ /yr (SD 25.4 mm³ /yr). Five patients were classified as having major regression, defined by a relative decrease in volume of >40%, while eight patients had minor regression (<40% relative volume reduction). No significant differences in initial tumor size, rate of regression, or audiometric changes were observed between the major and minor regression cohorts.

CONCLUSIONS

Patients with evidence of a spontaneously shrinking VS have a heterogeneous presentation. Due to the scarcity of this phenomenon, predicting which tumors will eventually undergo regression remains unclear. Employing volumetric measurements to compare serial MRI scans may improve the accuracy of detecting shrinking tumors.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1647-E1652, 2021.

Volumetric growth rates of untreated vestibular schwannomas

OBJECTIVE

There remains a large discrepancy among surgeons in expectations of vestibular schwannoma (VS) growth. The anticipated growth rate of a VS and its potential clinical impact are important factors when deciding whether to observe the lesion over time or to intervene. Previous studies of VS natural growth remain limited, mostly confined to linear measurements, often without high-resolution, thin-sequence imaging. The present study comprehensively assessed natural tumor growth rates using volumetric measurements.

METHODS

Between 2012 and 2018, 212 treatment-naïve patients diagnosed with a unilateral VS were evaluated. A total of 699 MR images were assessed, with a range of 2-11 MR images per patient. All MR images preceded any intervention, with patients subsequently being observed through completion of data analysis (36%) or treated with stereotactic radiosurgery (32%) or microsurgical resection (32%). To determine precise tumor volumes, the tumor area was outlined on every slice, and the products of the area and slice thickness were summed (99% of scans were ≤ 1-mm slice thickness). A multilevel model with random effects was used to assess the mean volume change over time. Each tumor was categorized as one of the following: growing (volume increase by more than 20% per year), fast growing (volume increase by more than 100% per year), stable (volume change between 20% decrease and 20% increase per year), and shrinking (volume decrease by more than 20% per year).

RESULTS

The mean VS volumetric growth rate was 33.5% per year (95% CI 26.9%-40.5%, p < 0.001). When assessing the frequencies of individual tumor annual growth rates, 66% demonstrated growth (30% fast growing), 33% were stable, and 1% exhibited shrinking over an average interval of 25 months. Larger tumors were associated with increased absolute growth, but there was no relationship between tumor size and proportional growth rate. There was also no relationship between patient age and tumor growth rate.

CONCLUSIONS

This study comprehensively assessed VS volumetric growth rates using high-resolution images and was conducted in a large and diverse patient sample. The majority of the tumors exhibited growth, with about one-third growing at a rate of 100% per year. These findings may contribute to a consensus understanding of tumor behavior and inform clinical decisions regarding whether to intervene or observe.

Natural history of peripheral nerve schwannomas

BACKGROUND

Little information about the natural history of peripheral nerve schwannomas exists in the literature. The aim of this study was to determine the natural history of those tumors both in sporadic and schwannomatosis cases to determine their growth rates and patterns.

METHODS

In 44 patients from 3 surgical centers, hospital charts, follow-up records, and imaging studies were reviewed. Of these patients, 7 had sporadic schwannomatosis. Histological diagnosis was obtained in 37 patients (84%). Tumor growth rates were determined by calculating the absolute and relative growth rates.

RESULTS

On the 47 tumors analyzed, the median tumor size at diagnosis was 1.8 cm³, and the majority of tumors were located in the lower limb (62%). The absolute growth rate ranged from - 1.13 to 23.17 cm³/year (mean, 1.69 cm³/year). Relative annual growth rates ranged from - 9 to 166%/year (mean, 33.9%/year). There was no clear correlation between initial tumor size, age at diagnosis, and tumor growth rate. Six patients (13%) harbored "fast-growing" tumors (absolute growth rate > 2 cm³/year and relative growth rate > 35%/year) while 19% of tumors demonstrate no growth or negative growth. In schwannomatosis patients, each tumor displayed a distinct growth pattern.

CONCLUSION

This study confirms the slow-growing nature of most, but not all, peripheral nerve schwannomas. Additional studies are mandatory to explore the environmental factors influencing growth in sporadic cases and the precise growth patterns in schwannomatosis cases to detect the rare cases of malignant transformation and pave the way to the evaluation of future clinical trials.

Simultaneous cochlear implantation and removal of acoustic neuroma: implications for hearing

OBJECTIVE

To present our data evaluating the feasibility of simultaneous cochlear implantation with resection of acoustic neuroma.

METHODS

This paper describes a case series of eight adult patients with a radiologically suspected acoustic neuroma, treated at a tertiary referral centre in Newcastle, Australia, between 2012 and 2015. Patients underwent cochlear implantation concurrently with removal of an acoustic neuroma. The approach was translabyrinthine, with facial nerve monitoring and electrically evoked auditory brainstem response testing. Standard post-implant rehabilitation was employed, with three and six months' follow-up data collected. The main outcome measures were: hearing, subjective benefit of implant, operative complications and tumour recurrence.

RESULTS

Eight patients underwent simultaneous cochlear implantation with resection of acoustic neuroma over a 3-year period, and had 25-63 months' follow up. There were no major complications. All patients except one gained usable hearing and were daily implant users.

CONCLUSION

Simultaneous cochlear implantation with resection of acoustic neuroma has been shown to be a safe treatment option, which will be applicable in a wide range of clinical scenarios as the indications for cochlear implantation continue to expand.

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.

Gamma knife surgery in the treatment of intracanalicular vestibular schwannomas

OBJECTIVE

According to the literature, gamma knife surgery (GKS) is a promising method for intracanalicular vestibular schwannoma (IVS) management, providing excellent tumor growth control rates (91%-100%) and good hearing preservation rates (41%-76%), but this evidence originates primarily from a small series of patients. The aim of this study was to present the outcomes of GKS in the largest group of patients with IVS studied to date, with particular emphasis on the long-term outcomes of treatment.

METHODS

The study included 136 consecutive patients with unilateral IVS, who underwent GKS in 2011-2015. Mean age of the patients was 54 ± 12.6 years. All patients were operated on with a 192-source cobalt-60 gamma knife unit. All patients had complete follow-up documentation and the mean duration of the follow-up was 52 ± 13.8 months (6-83 months). Neurological status (facial and trigeminal nerve), hearing and instability/dizziness presence were determined prior to GKS, immediately after the procedure, and during the follow-up visits.

RESULTS

Tumor growth control was obtained in 124/136 (~91.2%) patients. Hearing improvement was observed in 32/136 (23.5%) patients, and there was a distinct cluster of 9 patients (6.6%) regaining serviceable hearing after GKS, whereas in 36 patients (26.5%) was stable. Four patients developed facial nerve dysfunction, including 3 periodic hemifacial spasm and 1 partial paresis, which resolved spontaneously within 12 months of GKS. None of the operated patients showed new, debilitating neurological deficits, including trigeminal sensory disturbances or hydrocephalus.

CONCLUSIONS

GKS is a highly effective treatment for IVS, associated with low morbidity and good tumor growth control.

Treatment Outcomes and Dose Rate Effects Following Gamma Knife Stereotactic Radiosurgery for Vestibular Schwannomas

BACKGROUND

Gamma Knife radiosurgery (GKRS; Elekta AB) remains a well-established treatment modality for vestibular schwannomas. Despite highly effective tumor control, further research is needed toward optimizing long-term functional outcomes. Whereas dose-rate effects may impact post-treatment toxicities given tissue dose-response relationships, potential effects remain largely unexplored.

OBJECTIVE

To evaluate treatment outcomes and potential dose-rate effects following definitive GKRS for vestibular schwannomas.

METHODS

We retrospectively reviewed 419 patients treated at our institution between 1998 and 2015, characterizing baseline demographics, pretreatment symptoms, and GKRS parameters. The cohort was divided into 2 dose-rate groups based on the median value (2.675 Gy/min). Outcomes included clinical tumor control, radiographic progression-free survival, serviceable hearing preservation, hearing loss, and facial nerve dysfunction (FND). Prognostic factors were assessed using Cox regression.

RESULTS

The study cohort included 227 patients with available follow-up. Following GKRS 2-yr and 4-yr clinical tumor control rates were 98% (95% CI: 95.6%-100%) and 96% (95% CI: 91.4%-99.6%), respectively. Among 177 patients with available radiographic follow-up, 2-yr and 4-yr radiographic progression-free survival rates were 97% (95% CI: 94.0%-100.0%) and 88% (95% CI: 81.2%-95.0%). The serviceable hearing preservation rate was 72.2% among patients with baseline Gardner-Robertson class I/II hearing and post-treatment audiological evaluations. Most patients experienced effective relief from prior headaches (94.7%), tinnitus (83.7%), balance issues (62.7%), FND (90.0%), and trigeminal nerve dysfunction (79.2%), but not hearing loss (1.0%). Whereas GKRS provided effective tumor control independently of dose rate, GKRS patients exposed to lower dose rates experienced significantly better freedom from post-treatment hearing loss and FND (P = .044).

CONCLUSION

Whereas GKRS provides excellent tumor control and effective symptomatic relief for vestibular schwannomas, dose-rate effects may impact post-treatment functional outcomes. Further research remains warranted.

EAONO position statement on Vestibular Schwannoma: Imaging Assessment Question: How should growth of Vestibular Schwannoma be defined?

The relevance of defining the growth of vestibular schwannoma (VS) is that any significant VS growth may impact treatment strategy. A conservative treatment strategy is often proposed as a primary treatment option in the management of VS. Several authors have demonstrated that a significant proportion of VSs do not grow, and those that do, usually grow slowly. Surgical and/or radiosurgical treatment options may be offered to the patient according to the VS growth. Therefore, defining the VS growth is a determinant in managing treatment strategies. A comprehensive literature search was performed to examine the definition of tumor growth for VS. The literature review was conducted using PubMed and Embase databases dated back to 20 years (1995-2015) and was updated until February 2015. VS growth should be measured on contrast-enhanced T1-weighted images. Although there the overall quality of the present studies is low, all highlight a significant VS growth of > 2 mm, and/or 1.2 cm3, and/or 20% change in volume, and/or the square of the product of the 2 orthogonal diameters. We suggest that VS growth should instead change management strategies when a 3-mm increase in diameter on two consecutive MRI scans are performed 1 year apart.

What is the Required Frequency of MRI Scanning in the Wait and Scan Management?

The wait and scan policy is being increasingly used as the first measure after the diagnosis of a vestibular schwannoma (VS) using magnetic resonance imaging (MRI). As part of the European Academy of Otology and Neuro-Otology (EAONO) position statement on VS, the frequency of imaging has been studied in the literature. Among 163 studies, 29 fulfilled the inclusion criteria and were scored using the Grading of Recommendations, Assessment, Development, and Evaluation system. Because tumor growth rate during the first 5 years of follow-up is predictive of further growth during the upcoming years, a protocol for wait and scan is useful for centers dealing with this condition. The EAONO proposal is that after the initial diagnosis by MRI, a first new MRI would take place after 6 months, annually for 5 years, and then every other year for 4 years, followed by a lifelong MRI follow-up every 5 years. The first early MRI is to screen for fast-growing tumors, and the lifelong follow-up with tapered intervals is to detect late repeated growth.

Long-Term Hearing Preservation Outcomes for Small Vestibular Schwannomas: Retrosigmoid Removal Versus Observation

OBJECTIVE

Management of small vestibular schwannomas (VSs) consists of three options: serial observation, radiosurgery, and microsurgery. The authors reported the long-term hearing outcomes after retrosigmoid tumor removal in 110 patients and hearing follow-up outcomes in 160 serial observation patients with small VSs to explore the appropriate management strategy and predictive factors of hearing preservation for small VSs.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

In this study, 110 patients with small VS (purely intracanalicular/cerebellopontine angle tumor ≤15 mm) during a 15-year period, from January 2001 to December 2015, were candidates for hearing preservation surgery through retrosigmoid approach, while 160 patients were candidates for serial observation. The main outcome measure was preservation of hearing under different hearing levels, assessed with the classification of American Academy of Otolaryngology-Head and Neck Surgery.

RESULTS

Preoperative hearing levels of the 110 study patients were Class A in 49 patients, Class B in 43 patients, and Class C in 18 patients. In all surgery patients (n = 110), 97.3% (107/110) patients maintained the same level during postoperative follow-up (mean follow-up time was 49.1 ± 28.2 mo) and 86 (78.2%) had complete radiologic and audiometric data at least 4 years follow-up for review. In the 4 years follow-up surgery group (n = 86), postoperative hearing levels were Class A, B, C, and D for 22, 11, 18, and 35 patients, and postoperative rates of preservation of serviceable and useful hearing were 59.3% (51/86) and 47.1% (33/70), respectively. In serial observation group, mean follow-up time was 35.2 ± 33.1 months; mean tumor size at presentation was 8.6 ± 4.3 mm; overall mean tumor growth rate was 1.08 ± 2.3 mm/yr; serviceable hearing preservation rate of 98 patients was 54.1% (53/98) at the 5-year end point and 48.7% (37/76) at the 7-year end point.

CONCLUSION

Tumor removal should be the first treatment option for patients with small VSs and preserved hearing, especially for young patients with good hearing; retrosigmoid approach is an effective and safe approach for small VSs removal with excellent functional outcomes; better preoperative hearing predicted a higher rate of postoperative hearing preservation; patients without fundal extension were more likely to achieve hearing preservation than those with fundal extension, but no difference had been detected when retrosigmoid removal assisted with endoscope was performed; patients with small tumors originating from SVN were more likely to achieve hearing preservation compared with those with IVN-originating tumors.

Decision Making in the Wait-and-Scan Approach for Vestibular Schwannomas: Is There a Price to Pay in Terms of Hearing, Facial Nerve, and Overall Outcomes?

BACKGROUND

The wait-and-scan modality has emerged as an important strategy in the management of vestibular schwannoma (VS) as it has been demonstrated that many tumors grow slowly or do not show any growth over long periods.

OBJECTIVE

To analyze long-term outcomes of wait-and-scan in the treatment of patients with VS, discuss the factors contributing to the decision making, determine the inherent risks of the policy, and compare our results with literature.

METHODS

In total, 576 patients with sporadic unilateral VS who were managed with wait-and-scan were reviewed retrospectively. Of these, a subset of 154 patients with 5-yr follow-up was separately analyzed. The tumor characteristics including patterns of growth, rate of growth, hearing outcomes, and likely factors affecting the above parameters were analyzed.

RESULTS

The mean period of follow-up was 36.9 ± 30.2 mo. The mean age was 59.2 ± 11.6 yr. Thirteen different patterns of tumor growth were observed. Eighty-four (54.5%) of 154 tumors with 5-yr follow-up showed no growth throughout 5 yr. Fifty-six (36.4%) tumors showed mixed growth rates. Only 57 (37%) patients had serviceable hearing at the start of follow-up, but 32 (56.1%) maintained it at the end of follow-up. One hundred fifty (26%) of the 576 patients who failed wait-and-scan had to be taken up for surgery.

CONCLUSION

While there may be no price to pay in wait-and-scan as far as hearing is concerned, this may not be the case for facial nerve outcomes, wherein the results may be better if the patients are taken earlier for surgery.

Screening for vestibular schwannoma in the context of an ageing population

Objective

To review the literature regarding screening for vestibular schwannoma in the context of demographic changes leading to increasing numbers of elderly patients presenting with asymmetric auditory symptoms.

Methods

A systematic review of the literature was performed, with narrative synthesis and statistical analysis of data where appropriate.

Results

Vestibular schwannomas diagnosed in patients aged over 70 years exhibit slower growth patterns and tend to be of smaller size compared to those tumours in younger age groups. This fact, combined with reduced life expectancy, renders the probability of these tumours in the elderly requiring active treatment with surgery or stereotactic radiotherapy to be extremely low. Vestibular schwannomas in the elderly are much more likely to be managed by serial monitoring with magnetic resonance imaging. The weighted yield of magnetic resonance imaging in the diagnosis of vestibular schwannoma in all age groups is 1.18 per cent, with almost 85 scans required to diagnose 1 tumour.

Conclusion

An evidence-based approach to the investigation of asymmetric hearing loss and tinnitus in the elderly patient can be used to formulate guidelines for the rational use of magnetic resonance imaging in this population.

Accelerated Internal Auditory Canal Screening Magnetic Resonance Imaging Protocol With Compressed Sensing 3-Dimensional T2-Weighted Sequence

BACKGROUND AND PURPOSE

High-resolution T2-weighted sequences are frequently used in magnetic resonance imaging (MRI) studies to assess the cerebellopontine angle and internal auditory canal (IAC) in sensorineural hearing loss patients but have low yield and lengthened examinations. Because image content in the Wavelet domain is sparse, compressed sensing (CS) that uses incoherent undersampling of k-space and iterative reconstruction can accelerate MRI acquisitions. We hypothesized that an accelerated CS T2 Sampling Perfection with Application optimized Contrasts using different flip angle Evolution (SPACE) sequence would produce acceptable diagnostic quality for IAC screening protocols.

MATERIAL AND METHODS

Seventy-six patients underwent 3 T MRI using conventional SPACE and a CS T2 SPACE prototype sequence for screening the IACs were identified retrospectively. Unilateral reconstructions for each sequence were separated, then placed into mixed folders for independent, blinded review by 3 neuroradiologists during 2 sessions 4 weeks apart. Radiologists reported if a lesion was present. Motion and visualization of specific structures were rated using ordinal scales. McNemar, Wilcoxon, Cohen κ, and Mann-Whitney U tests were performed for accuracy, equivalence, and interrater and intrarater reliability.

RESULTS

T2 SPACE using CS reconstruction reduced scan time by 80% to 50 seconds and provided 98.7% accuracy for IAC mass detection by 3 raters. Radiologists preferred conventional images (0.7-1.0 reduction on 5-point scale, P < 0.001), but rated CS SPACE acceptable. The 95% confidence for reduction in any cerebellopontine angle, IAC, or fluid-filled inner ear structure assessment with CS SPACE did not exceed 0.5.

CONCLUSIONS

Internal auditory canal screening MRI protocols can be performed using a 5-fold accelerated T2 SPACE sequence with compressed sensing while preserving diagnostic image quality and acceptable lesion detection rate.

Subtotal resection of cervical schwannomas and growth rate of residual tumors

OBJECTIVE

The objective of this study was to elucidate the features and surgical outcomes of cervical schwannomas.

METHODS

The authors retrospectively reviewed the records of 90 patients who underwent surgically treated cervical schwannomas from January 1995 to December 2017, with an emphasis on MRI findings such as tumor location, tumor size, extent of tumor resection, and growth of a residual tumor.

RESULTS

This study included 51 men (56.7%) and 39 women (43.3%) with a mean age of 44.5 years (range 7-77 years). Dumbbell-shaped tumors comprised 62 (68.9%) of 90 cases and gross-total resection (GTR) was achieved in 59 (65.6%) of 90 cases. All nondumbbell tumors (n = 28) underwent GTR. Only 1 case of recurrence in the GTR group showed a gradual increase in size (by 8.9 mm) during the 150-month follow-up period. For the regrowth patients in the subtotal resection group, the mean percentage increase in tumor size was 47.5% ± 33.1% and the mean growth rate was 5.8 ± 4.6 mm/year during the 20.3-month follow-up period. However, the size of residual tumor spontaneously decreased by a mean of 8.3% ± 11.1% during the 48.4-month follow-up period in the nonregrowth group.

CONCLUSIONS

These findings suggested that frequent MRI follow-up examinations are required for residual schwannomas in the cervical spine for at least 2 years, and continuous MRI follow-ups are also required thereafter.

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.

The Role of Particle Therapy for the Treatment of Skull Base Tumors and Tumors of the Central Nervous System (CNS)

Radiation therapy (RT) is a mainstay in the interdisciplinary treatment of brain tumors of the skull base and brain. Technical innovations during the past 2 decades have allowed for increasingly precise treatment with better sparing of adjacent healthy tissues to prevent treatment-related side effects that influence patients' quality of life. Particle therapy with protons and charged ions offer favorable kinetics with sharp dose deposition in a well-defined depth (Bragg-Peak) and a steep radiation fall-off beyond that maximum. This review highlights the role of particle therapy in the management of primary brain tumors and tumors of the skull base.