Systematic review of the natural history of vestibular schwannoma

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

OBJECTIVE

To characterize the risk and predictors of growth during observation of vestibular schwannomas (VS).

STUDY DESIGN

Retrospective case series.

SETTING

Single academic, tertiary care center.

PATIENTS

Five hundred sixty-four consecutive VS patients who underwent at least two magnetic resonance imaging (MRI) studies before intervention.

INTERVENTION(S)

Serial MRI studies.

MAIN OUTCOME MEASURE(S)

Tumor growth, defined as a ≥2 mm increase in the maximum tumor diameter between consecutive MRI studies, or between the first and last study.

RESULTS

A total of 1296 patients (1995-2015) with VS were identified. Of those, 564 patients (median age 59.2 years; 53.5% female) were initially observed and underwent multiple MRI studies (median follow-up 22.9 months, interquartile range [IQR] 11.7-42.7). The median maximum tumor diameter at presentation was 1.00 cm (IQR 0.6-1.51 cm). In all, 40.8% of tumors demonstrated growth and 32.1% underwent intervention (21.5% microsurgery, 10.5% radiation) during the surveillance period. Multivariable Cox regression analysis showed that for each tumor, the risk of growth or intervention was significantly increased for larger initial VS diameters (HR = 2.22; 95% CI: 1.90-2.61) and when disequilibrium was a presenting symptom (HR = 1.70; 95% CI: 1.30-2.23). Patient age, sex, aspirin use, and presenting symptoms of asymmetric hearing loss, tinnitus, and vertigo were not associated with tumor growth.

CONCLUSION

To date, this is the largest series of observed VS reported in the literature. Risk of VS growth is significantly increased among patients who present with larger tumors and who have concomitant disequilibrium.IRB:: 151481.

DEFINE PROFESSIONAL PRACTICE GAP AND EDUCATIONAL NEED

No cohort with this sample size has assessed vestibular schwannoma growth rates in conjunction with this number of variables.

LEARNING OBJECTIVE

To characterize vestibular schwannoma growth rates and predictors of growth.

"Wait and scan" management of patients with vestibular schwannoma and the relevance of non-contrast MRI in the follow-up

Vestibular schwannoma (VS) is a slow-growing benign neoplasm. There has been an evolution in the management of VS from active treatments (microsurgery and stereotactic radiotherapy) to conservative management (wait and scan). Regular MRI scanning is necessary to monitor tumor progression. Conservative management causes significantly less complications and offers a higher quality of life compared with active treatments. The mean growth rate of VS varies from 0.4 to 2.9 mm/year, and spontaneous shrinkage is observed in 3.8 percent of tumors during observation. If significant growth occurs, active treatment is considered. Significant growth is defined as an increase of at least 3 mm in the largest extrameatal diameter in any plane between the first and last available scans. The vestibulocochlear nerve is surrounded by cerebrospinal fluid, which provides natural contrast for MRI; thus, gadolinium may not be needed to detect VS. Specific sequences have high sensitivity, specificity, and accuracy for detection of progression. Hypointense signal in the ipsilateral inner ear fluid might be a useful sign to distinguish VS from meningioma. In this paper, we summarize the current status of research on conservative management and non-contrast MRI for the detection of VS.

Surgical outcomes of middle fossa approach in intracanalicular vestibular schwannoma

CONCLUSION

Middle fossa approach (MFA) shows a hearing preservation rate of 86% and facial nerve function was preserved with HB grade I or II in 93%. MFA is a good treatment option for intra-canalicular vestibular schwannomas when surgical excision is needed.

BACKGROUND

Surgical outcomes of vestibular schwannoma have progressively improved with the advancement of microsurgical instruments. MFA is known to have better chances to preserve hearing, while it has limited access to the posterior fossa, limitation of tumor size, and higher risk of post-operative facial nerve weakness.

OBJECTIVES

To investigate surgical outcomes and clinical efficiency of MFA in vestibular schwannoma.

METHODS

A retrospective study was done in 14 patients who underwent MFA for vestibular schwannoma in Asan Medical Center.

RESULTS

The median age at diagnosis was 46.3 years. At initial presentation, 57% of the patients had vertigo, 43% hearing disturbance, and 64% tinnitus. The mean tumor size was 9.7 mm. The tumors were completely resected in 86% of the patients. Hearing was post-operatively preserved in 12 patients and two patients lost their hearing following surgery. Facial nerve function post-operatively remained unchanged in 12 patients (86%).

Giant Trigeminal Schwannoma Presenting with Obstructive Hydrocephalus

Trigeminal schwannomas represent between 0.07% and 0.36% of all intracranial tumors and 0.8% to 8% of intracranial schwannomas. Selection of the appropriate management strategy requires an understanding of the tumor’s natural history and treatment outcomes. This report describes the case of a 36-year-old male who presented with a three-month history of progressive headaches, dizziness, loss of balance, decreased sleep, and cognitive decline. Magnetic resonance imaging revealed a large enhancing lesion centered around the left Meckel’s cave and extending into both the middle and the posterior fossa with obstructive hydrocephalus secondary to compression of the fourth ventricle. Resection of the posterior fossa component of the tumor was performed in order to relieve the mass effect upon the brainstem without attempting a radical removal of the middle fossa component and a potential risk of further cognitive impairment. The pathological exam confirmed the diagnosis of a trigeminal schwannoma. The residual tumor showed progressive spontaneous volumetric shrinkage after a subtotal surgical resection. This case shows the value of a planned conservative surgery in complex schwannomas and highlights the challenges in interpreting the treatment responses in these benign tumors, whether approached surgically or with stereotactic radiation techniques.

Stereotactic Radiosurgery versus Natural History in Patients with Growing Vestibular Schwannomas

Objective To describe our experience with stereotactic radiosurgery and its efficacy on growing tumors, and then to compare this result with the natural history of a similar cohort of non-radiation-treated lesions. Study Design A retrospective chart review and cohort comparison. Methods The long-term control rates of patients having undergone radiosurgery were collected and calculated, and this population was then compared with a group of untreated patients from the same period of time with growing lesions. Results A total of 61 patients with growing vestibular schwannomas treated with radiosurgery were included. After a mean of 160 months, we observed a control rate of 85.2%. When compared with a group of 36 patients with growing tumors who were yet to receive treatment (previously published), we found a corrected control rate or relative risk reduction of only 76.8%. Conclusion Radiosurgery for growing vestibular schwannomas is less effective than previously reported in unselected series. Although radiosurgery still has a role in managing this disease, consideration should be given to the actual efficacy that may be calculated when the natural history is known. We hope other centers will similarly report their experience on this cohort of patients.

Vestibular schwannoma atypically invading temporal bone

Vestibular schwannoma (VS) usually present the widening of internal auditory canal (IAC), and these bony changes are typically limited to IAC, not extend to temporal bone. Temporal bone invasion by VS is extremely rare. We report 51-year-old man who revealed temporal bone destruction beyond IAC by unilateral VS. The bony destruction extended anteriorly to the carotid canal and inferiorly to the jugular foramen. On histopathologic examination, the tumor showed typical benign schwannoma and did not show any unusual vascularity or malignant feature. Facial nerve was severely compressed and distorted by tumor, which unevenly eroded temporal bone in surgical field. Vestibular schwannoma with atypical invasion of temporal bone can be successfully treated with combined translabyrinthine and lateral suboccipiral approach without facial nerve dysfunction. Early detection and careful dissection of facial nerve with intraoperative monitoring should be considered during operation due to severe adhesion and distortion of facial nerve by tumor and eroded temporal bone.

Growth of Primary and Remnant Vestibular Schwannomas: A Three-Year Follow-Up Study

OBJECTIVE

Vestibular schwannomas (VSs) are benign, slowly growing tumors. The management strategy, however, remains unclear for both primary VS and remnant VS after subtotal or partial resection. In this study, we analyzed the radiographical tumor growth to elucidate factors possibly predicting growth or regrowth of their tumors.

METHODS

We retrospectively analyzed the data of 76 patients with diagnoses of VS at a single tertiary academic referral center. The primary VS group consisted of 43 patients with conservative management, and the remnant VS group included 33 patients with tumor remnant after surgery. All patients were followed up with serial magnetic resonance imaging without intervention. The primary end point in this study was significant tumor growth at the end of the 3-year follow-up period.

RESULTS

Multivariate analysis revealed that remnant VS was less likely to grow than primary VS (odds ratio: 0.27, 95% confidence interval: 0.09-0.84). Tumor volume was correlated with tumor growth; larger tumors grew more frequently than small tumors in both primary and remnant VS groups with marginal (P = 0.05) and definite (P = 0.007) significance, respectively. The receiver operating characteristic curves plotted for tumor growth identified the optimum cutoff points of tumor volumes with greater sensitivity and specificity for remnant VS than for primary VS (sensitivity: 80% vs. 59%, specificity: 87% vs. 76%, respectively).

CONCLUSIONS

Small remnant VS after surgery could be conservatively managed without additional treatment, and relatively large remnant VS should be followed up with close serial imaging or might be a possible candidate for radiosurgery during the early postoperative period.

Stereotactic radiotherapy for vestibular schwannoma

BACKGROUND

Vestibular schwannomas (acoustic neuromas) are common benign tumours that arise from the Schwann cells of the vestibular nerve. Management options include observation with neuroradiological follow-up, microsurgical resection and stereotactic radiotherapy.

OBJECTIVES

To assess the effect of stereotactic radiotherapy compared to observation, microsurgical resection, any other treatment modality, or a combination of two or more of the above approaches for vestibular schwannoma.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials; PubMed; EMBASE; CINAHL; Web of Science; CAB Abstracts; ISRCTN and additional sources for published and unpublished trials. The date of the search was 24 July 2014.

SELECTION CRITERIA

Randomised controlled trials (RCTs) exploring the efficacy of stereotactic radiotherapy compared with observation alone, microsurgical resection or any other possible treatment or combination of treatments in patients with a cerebellopontine angle tumour up to 3 cm in diameter, presumed to be a vestibular schwannoma.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration.

MAIN RESULTS

No studies met the inclusion criteria for this review.

AUTHORS' CONCLUSIONS

There is no high quality evidence in the literature from RCTs to determine whether stereotactic radiotherapy is better than microsurgical resection or observation alone for patients with a vestibular schwannoma. In the absence of such evidence, the treatment method should be chosen on an individual basis, taking into consideration the patient's preferences, clinician experience and the availability of radiotherapeutic equipment. With the growing availability of radiotherapeutic equipment, randomised controlled trials should be undertaken to evaluate the role of stereotactic radiotherapy in comparison with other treatment options.

Clinical Practice Guideline

Objective

Tinnitus is the perception of sound without an external source. More than 50 million people in the United States have reported experiencing tinnitus, resulting in an estimated prevalence of 10% to 15% in adults. Despite the high prevalence of tinnitus and its potential significant effect on quality of life, there are no evidence-based, multidisciplinary clinical practice guidelines to assist clinicians with management. The focus of this guideline is on tinnitus that is both bothersome and persistent (lasting 6 months or longer), which often negatively affects the patient’s quality of life. The target audience for the guideline is any clinician, including nonphysicians, involved in managing patients with tinnitus. The target patient population is limited to adults (18 years and older) with primary tinnitus that is persistent and bothersome.

Purpose

The purpose of this guideline is to provide evidence-based recommendations for clinicians managing patients with tinnitus. This guideline provides clinicians with a logical framework to improve patient care and mitigate the personal and social effects of persistent, bothersome tinnitus. It will discuss the evaluation of patients with tinnitus, including selection and timing of diagnostic testing and specialty referral to identify potential underlying treatable pathology. It will then focus on the evaluation and treatment of patients with persistent primary tinnitus, with recommendations to guide the evaluation and measurement of the effect of tinnitus and to determine the most appropriate interventions to improve symptoms and quality of life for tinnitus sufferers.

Action Statements

The development group made a strong recommendation that clinicians distinguish patients with bothersome tinnitus from patients with nonbothersome tinnitus. The development group made a strong recommendation against obtaining imaging studies of the head and neck in patients with tinnitus, specifically to evaluate tinnitus that does not localize to 1 ear, is nonpulsatile, and is not associated with focal neurologic abnormalities or an asymmetric hearing loss. The panel made the following recommendations: Clinicians should (a) perform a targeted history and physical examination at the initial evaluation of a patient with presumed primary tinnitus to identify conditions that if promptly identified and managed may relieve tinnitus; (b) obtain a prompt, comprehensive audiologic examination in patients with tinnitus that is unilateral, persistent (≥ 6 months), or associated with hearing difficulties; (c) distinguish patients with bothersome tinnitus of recent onset from those with persistent symptoms (≥ 6 months) to prioritize intervention and facilitate discussions about natural history and follow-up care; (d) educate patients with persistent, bothersome tinnitus about management strategies; (e) recommend a hearing aid evaluation for patients who have persistent, bothersome tinnitus associated with documented hearing loss; and (f) recommend cognitive behavioral therapy to patients with persistent, bothersome tinnitus. The panel recommended against (a) antidepressants, anticonvulsants, anxiolytics, or intratympanic medications for the routine treatment of patients with persistent, bothersome tinnitus; (b) Ginkgo biloba, melatonin, zinc, or other dietary supplements for treating patients with persistent, bothersome tinnitus; and (c) transcranial magnetic stimulation for the routine treatment of patients with persistent, bothersome tinnitus. The development group provided the following options: Clinicians may (a) obtain an initial comprehensive audiologic examination in patients who present with tinnitus (regardless of laterality, duration, or perceived hearing status); and (b) recommend sound therapy to patients with persistent, bothersome tinnitus. The development group provided no recommendation regarding the effect of acupuncture in patients with persistent, bothersome tinnitus.

Primary culture of human Schwann and schwannoma cells: improved and simplified protocol

Primary culture of human Schwann cells (SCs) and vestibular schwannoma (VS) cells are invaluable tools to investigate SC physiology and VS pathobiology, and to devise effective pharmacotherapies against VS, which are sorely needed. However, existing culture protocols, in aiming to create robust, pure cultures, employ methods that can lead to loss of biological characteristics of the original cells, potentially resulting in misleading biological findings. We have developed a minimally manipulative method to culture primary human SC and VS cells, without the use of selective mitogens, toxins, or time-consuming and potentially transformative laboratory techniques. Schwann cell purity was quantified longitudinally using S100 staining in SC cultures derived from the great auricular nerve and VS cultures followed for 7 and 12 weeks, respectively. SC cultures retained approximately ≥85% purity for 2 weeks. VS cultures retained approximately ≥80% purity for the majority of the span of 12 weeks, with maximal purity of 87% at 2 weeks. The VS cultures showed high level of biological similarity (68% on average) to their respective parent tumors, as assessed using a protein array featuring 41 growth factors and receptors. Apoptosis rate in vitro negatively correlated with tumor volume. Our results, obtained using a faster, simplified culturing method than previously utilized, indicate that highly pure, primary human SC and VS cultures can be established with minimal manipulation, reaching maximal purity at 2 weeks of culture. The VS cultures recapitulate the parent tumors' biology to a great degree, making them relevant models to investigate VS pathobiology.

Conservative management of vestibular schwannomas of 15 to 31 mm intracranial diameter

Objective:

To study the natural course of vestibular schwannomas 15 to 31 mm in diameter.

Methods:

A retrospective study of 45 patients conservatively managed with interval scanning was performed. Outcome measures were: changes in tumour size, clinical features and hearing. A tumour was considered to be growing if it increased in size by more than 2 mm.

Results:

Initial tumour sizes ranged from 15 to 31 mm, with a mean (± standard deviation) diameter of 20.1 ± 4.3 mm. The duration of follow up ranged from 6 months to 14 years (median, 3 years). Tumours grew in 11 cases (24.4 per cent), remained stable in 30 cases (66.7 per cent) and regressed in 4 cases (8.9 per cent). The overall mean tumour growth rate was 0.9 ± 2.2 mm per year; in growing tumours, it was 3.6 ± 2.9 mm per year.

Conclusion:

Outcomes were similar to those reported for smaller tumours. These findings suggest that patients with medium or moderately large tumours can be safely offered an initial period of conservative management before intervention is considered.

Methodology and reporting of meta-analyses in the neurosurgical literature

OBJECT

Neurosurgeons are inundated with vast amounts of new clinical research on a daily basis, making it difficult and time-consuming to keep up with the latest literature. Meta-analysis is an extension of a systematic review that employs statistical techniques to pool the data from the literature in order to calculate a cumulative effect size. This is done to answer a clearly defined a priori question. Despite their increasing popularity in the neurosurgery literature, meta-analyses have not been scrutinized in terms of reporting and methodology.

METHODS

The authors performed a literature search using PubMed/MEDLINE to locate all meta-analyses that have been published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Accepted checklists for reporting (PRISMA) and methodology (AMSTAR) were applied to each meta-analysis, and the number of items within each checklist that were satisfactorily fulfilled was recorded. The authors sought to answer 4 specific questions: Are meta-analyses improving 1) with time; 2) when the study met their definition of a meta-analysis; 3) when clinicians collaborated with a potential expert in meta-analysis; and 4) when the meta-analysis was the only focus of the paper?

RESULTS

Seventy-two meta-analyses were published in the JNS Publishing Group journals and Neurosurgery between 1990 and 2012. The number of published meta-analyses has increased dramatically in the last several years. The most common topics were vascular, and most were based on observational studies. Only 11 papers were prepared using an established checklist. The average AMSTAR and PRISMA scores (proportion of items satisfactorily fulfilled divided by the total number of eligible items in the respective instrument) were 31% and 55%, respectively. Major deficiencies were identified, including the lack of a comprehensive search strategy, study selection and data extraction, assessment of heterogeneity, publication bias, and study quality. Almost one-third of the papers did not meet our basic definition of a meta-analysis. The quality of reporting and methodology was better 1) when the study met our definition of a meta-analysis; 2) when one or more of the authors had experience or expertise in conducting a meta-analysis; 3) when the meta-analysis was not conducted alongside an evaluation of the authors' own data; and 4) in more recent studies.

CONCLUSIONS

Reporting and methodology of meta-analyses in the neurosurgery literature is excessively variable and overall poor. As these papers are being published with increasing frequency, neurosurgical journals need to adopt a clear definition of a meta-analysis and insist that they be created using checklists for both reporting and methodology. Standardization will ensure high-quality publications.

Conservative management of bilateral vestibular schwannomas in neurofibromatosis type 2 patients: hearing and tumor growth results

BACKGROUND

As new treatment modalities develop for the management of vestibular schwannomas (VS) in patients with neurofibromatosis type 2, it remains crucial to ascertain the natural history of the disease.

OBJECTIVE

To determine the relationship between hearing and tumor growth in patients undergoing conservative VS management.

METHODS

Patients harboring bilateral VS with at least 1 year of radiological follow-up were selected. Conservative management was proposed based on the small tumor size and/or serviceable hearing at presentation. Tumor size was calculated by using the 2-component box model and reported as mean tumor diameter. Hearing was evaluated by using pure-tone average and the American Academy of Otololaryngologists and Head and Neck Surgery classification.

RESULTS

Forty-six patients harboring 92 VS were included. The mean clinical and radiological follow-up times were 6.0 and 4.2 years, respectively. The mean tumor diameter was 13 mm at presentation and 20 mm at the end of follow-up. Mean tumor growth rate was 1.8 mm/year. During follow-up, 17 patients (37%) underwent surgery for VS. Surgery-free rate for VS was 88% at 5 years. The number of patients with at least 1 serviceable ear was 39 (85%) at presentation and 34 (74%) at the end of follow-up, including 22 (66%) with binaural serviceable hearing maintained. There was no statistical correlation between tumor growth rate and preservation of serviceable hearing. Tumor growth rates and age at presentation were inversely correlated.

CONCLUSION

This study illustrates the high variability among neurofibromatosis type 2 patients regarding hearing status and VS growth rate and justifies the choice of initial conservative management in selected cases.

ABBREVIATIONS

: AAO-HNS, American Academy of Otololaryngologists and Head and Neck Surgery classificationMTD, mean tumor diameterNF2, neurofibromatosis type 2PTA, pure-tone averageSDS, speech discrimination scoreVS, vestibular schwannomas.

Contemporary surgical management of vestibular schwannomas: analysis of complications and lessons learned over the past decade

BACKGROUND

Despite advanced microsurgical techniques, more refined instrumentation, and expert team management, there is still a significant incidence of complications in vestibular schwannoma surgery.

OBJECTIVE

To analyze complications from the microsurgical treatment of vestibular schwannoma by an expert surgical team and to propose strategies for minimizing such complications.

METHODS

Surgical outcomes and complications were evaluated in a consecutive series of 410 unilateral vestibular schwannomas treated from 2000 to 2009. Clinical status and complications were assessed postoperatively (within 7 days) and at the time of follow-up (range, 1-116 months; mean, 32.7 months).

RESULTS

Follow-up data were available for 357 of the 410 patients (87.1%). Microsurgical tumor resection was performed through a retrosigmoid approach in 70.7% of cases. Thirty-three patients (8%) had intrameatal tumors and 204 (49.8%) had tumors that were <20 mm. Gross total resection was performed in 306 patients (74.6%). Hearing preservation surgery was attempted in 170 patients with tumors <20 mm, and good hearing was preserved in 74.1%. The main neurological complication was facial palsy (House-Brackmann grade III-VI), observed in 14% of patients (56 cases) postoperatively; however, 59% of them improved during the follow-up period. Other neurological complications were disequilibrium in 6.3%, facial numbness in 2.2%, and lower cranial nerve deficit in 0.5%. Nonneurological complications included cerebrospinal fluid leaks in 7.6%, wound infection in 2.2%, and meningitis in 1.7%.

CONCLUSION

Many of these complications are avoidable through further refinement of operative technique, and strategies for avoiding complications are proposed.

Phase II study of everolimus in children and adults with neurofibromatosis type 2 and progressive vestibular schwannomas

BACKGROUND

Activation of the mammalian target of rapamycin (mTOR) signaling pathway is thought to be a key driver of tumor growth in Merlin (NF2)-deficient tumors. Everolimus is an oral inhibitor of mTOR complex 1 (mTORC1) with antitumor activity in a variety of cancers.

METHODS

We conducted a single-institution, prospective, 2-stage, open-label phase II study to estimate the response rate to everolimus in neurofibromatosis type 2 (NF2) patients with progressive vestibular schwannoma (VS). Ten eligible patients were enrolled, including 2 pediatric patients. Everolimus was administered at a daily dose of 10 mg (adults) or 5 mg/m(2)/day (children <18 y) orally in continuous 28-day courses, for up to 12 courses. Response was assessed every 3 months with MRI, using 3-dimensional volumetric tumor analysis, and audiograms. Nine patients were evaluable for the primary response, defined as ≥15% decrease in VS volume. Hearing response was evaluable as a secondary endpoint in 8 patients.

RESULTS

None of the 9 patients with evaluable disease experienced a clinical or MRI response. No objective imaging or hearing responses were observed in stage 1 of the trial, and the study was closed according to predefined stopping rules.

CONCLUSION

Everolimus is ineffective for the treatment of progressive VS in NF2 patients. We are currently conducting a pharmacokinetic/pharmacodynamic ("phase 0") study of everolimus in presurgical VS patients to elucidate the biological basis for apparent treatment resistance to mTORC1 inhibition in these tumors.

ABR in the diagnosis of vestibular schwannomas: a meta-analysis

PURPOSE

The aim of this study is to rigorously evaluate the role of auditory brainstem response (ABR) testing in the diagnosis of vestibular schwannomas (VS).

MATERIALS AND METHODS

Searches were conducted in multiple online databases, supplemented by hand searches. From the studies chosen for final inclusion, relevant data were extracted and meta-analysis of pooled data was performed.

RESULTS

623 studies were identified from which 43 met inclusion criteria for analysis (1978 to 2009) including 3314 patients. Pooled sensitivity for ABR detection of vestibular schwannomas was 93.4% (95% CI 92.6-94.3, P=0.0000). For tumors less than 1cm (8 studies, 176 patients) sensitivity was 85.8% (95% CI 80.6-90.1, P=0.0116). For tumors greater than 1cm (6 studies, 251 patients) pooled sensitivity was 95.6% (95% CI 93.1-98.2, P=0.0660). Sensitivity of ABR to detect extracanalicular tumors was higher than for intracanalicular tumors, though pooled data were not statistically valid. Pooled specificity (8 studies, 2432 patients) was 82.0% (95% CI 80.5-83.6, P=0.0000).

CONCLUSIONS

Although MRI remains the gold standard, emerging trends towards more conservative management coupled with limited financial resources may prompt many clinicians to review the role of ABR testing in screening for retrocochlear pathology. In light of the high sensitivity and specificity of ABR testing for VS, we strongly urge its reconsideration as a useful diagnostic tool for patients with clinically suspected VS.

An update on unilateral sporadic small vestibular schwannoma

Advances in neuroimaging have increased the detection rate of small vestibular schwannomas (VSs, maximum diameter < 25 mm). Current management modalities include observation with serial imaging, stereotactic radiosurgery, and microsurgical resection. Selecting one approach over another invites speculation, and no standard management consensus has been established. Moreover, there is a distinct clinical heterogeneity among patients harboring small VSs, making standardization of management difficult. The aim of this article is to guide treating physicians toward the most plausible therapeutic option based on etiopathogenesis and the highest level of existing evidence specific to the different cohorts of hypothetical case scenarios. Hypothetical cases were created to represent 5 commonly encountered scenarios involving patients with sporadic unilateral small VSs, and the literature was reviewed with a focus on small VS. The authors extrapolated from the data to the hypothetical case scenarios, and based on the level of evidence, they discuss the most suitable patient-specific treatment strategies. They conclude that observation and imaging, stereotactic radiosurgery, and microsurgery are all important components of the management strategy. Each has unique advantages and disadvantages best suited to certain clinical scenarios. The treatment of small VS should always be tailored to the clinical, personal, and social requirements of an individual patient, and a rigid treatment protocol is not practical.

Clinical features of intracranial vestibular schwannomas

The aim of the present study was to discuss the clinical features of intracranial vestibular schwannomas and to evaluate the symptoms and signs as well as their correlation with tumor extension. The records of 1,009 patients who were treated in Shanghai Huashan Hospital were reviewed retrospectively. According to the Samii classification of 1997, the patients were grouped into a T3 and a T4 group based on the radiological findings. We focused our analysis on the incidence of subjective disturbances versus objective morbidity, and symptomatology versus tumor size and extension. Of the 1,009 cases, 424 patients (42.0%) were defined as T3 while 585 patients (58%) were defined as T4. The most frequent clinical symptoms were hearing loss (85.8%), facial numbness (48.9%), ataxia (44.6%), tinnitus (40.1%), deafness (26.3%) and facial paralysis (21.1%). The ratios of gender, vertigo and facial paralysis were significantly different between the T3 and T4 groups (P<0.05); however, none of the clinical symptoms had a positive likelihood ratio (PLR) greater than 10 for T4 prediction. The most frequent cranial nerve disturbance was associated with the cochlear nerve (92.6%) and trigeminal nerve (53.5%). Disturbance of the facial nerve was more severe in T3 than T4 patients (P<0.05). Hearing deficit, facial paresthesia, ataxia and tinnitus are key symptoms of huge vestibular schwannomas. Cochlear, trigeminal and facial nerves were the most commonly affected cranial nerves in cases of large tumors. Gender and tumor size were associated with tumor extension. Although the predictive value was limited, the symptoms of vertigo, facial paralysis and hearing loss may be indicators of tumor growth.

Natural history of intradural-extramedullary spinal cord tumors

The objective of the present study was to investigate the natural history of intradural-extramedullary spinal cord tumors. Nine cases of intradural-extramedullary tumors were observed over the 2 years. The physical and magnetic resonance imaging (MRI) examination were performed in the first examination and every other year. Tumors were classified as the schwannoma type and the meningioma type based on the MRI findings. The tumor volume was calculated by the craniocaudal length on a sagittal image and maximum transverse diameter on an axial image of MRI, every year. The annual growth rate, which was defined as the change in the volume each year compared to the volume of the previous year, was examined. There were six cases in the schwannoma type and three cases in the meningioma type. The schwannoma type tumors presented several growth patterns: unchanging, continuous slight growth, and initial slight growth followed by rapid growth during the observation period (6.7 ± 2.7 years), while the meningioma type tumors presented the continuous growth pattern during the observation period (4.3 ± 2.5 years). The average annual growth rate was 2.3 ± 5.5% in the schwannoma type and 7.0 ± 8.5% in the meningioma type. Schwannoma type tumors showed relatively less change in their size and would be observed for a longer time.

Incidental vestibular schwannomas: a review of prevalence, growth rate, and management challenges

With the relatively recent increase in the use of MRI techniques, there has been a concurrent rise in the number of vestibular schwannomas (VSs) detected as incidental findings. These incidental VSs may be prevalent in up to 0.02%–0.07% of individuals undergoing MRI and represent a significant portion of all diagnosed VSs. The management of these lesions poses a significant challenge for practitioners. Most incidental VSs tend to be small and associated with minimal symptoms, permitting them to be managed conservatively at the time of diagnosis. However, relatively few indicators consistently predict tumor growth and patient outcomes. Furthermore, growth rates have been shown to vary significantly over time with a large variety of long-term growth patterns. Thus, early MRI screening for continued tumor growth followed by repeated MRI studies and clinical assessments throughout the patient's life is an essential component in a conservative management strategy. Note that tumor growth is typically associated with a worsening of symptoms in patients who undergo conservative management, and many of these symptoms have been shown to significantly impact the patient's quality of life. Specific indications for the termination of conservative management vary across studies, but secondary intervention has been shown to be a relatively safe option in most patients with progressive disease. Patients with incidental VSs will probably qualify for a course of conservative management at diagnosis, and regular imaging combined with the expectation that the tumor and symptoms may change at any interval is crucial to ensuring positive long-term outcomes in these patients. In this report, the authors discuss the current literature pertaining to the prevalence of incidental VSs and various considerations in the management of these lesions. It is hoped that by incorporating an understanding of tumor growth, patient outcomes, and management strategies, practitioners will be able to effectively address this challenging disease entity.

Expectant management of vestibular schwannoma: a retrospective multivariate analysis of tumor growth and outcome

We conducted a retrospective observational study to assess the consequences of conservative management of vestibular schwannoma (VS). Data were collected from tertiary neuro-otological referral units in United Kingdom. The study included 59 patients who were managed conservatively with radiological diagnosis of VS. The main outcome measures were growth rate and rate of failure of conservative management. Multivariate analysis sought correlation between tumor growth and (i) demographic features, (ii) tumor characteristics. The mean tumor growth was 0.66 mm/y. 11 patients (19%) required intervention. Mean time to intervention was 37 months with two notable late "failures" occurring at 75 and 84 months. Tumors extending into the cerebellopontine angle (CPA) grew significantly faster than intracanalicular tumors (p = 0.0045). No association was found between growth rate and age, sex, tumor laterality, facial nerve function, and grade of hearing loss. Conservative management is acceptable for a subset of patients. Tumors extending into the CPA at diagnosis grow significantly faster than intracanalicular tumors. No growth within 5 years of surveillance does not guarantee a continued indolent growth pattern; surveillance must therefore continue.

Incidence of vestibular schwannoma and incidental findings on the magnetic resonance imaging and computed tomography scans of patients from a direct referral audiology clinic

OBJECTIVE

To identify the incidence of vestibular schwannoma amongst patients referred from a direct referral audiology clinic, and also the number of incidental findings, as seen on magnetic resonance imaging or computed tomography scans.

METHOD

Prospective data collection for patients referred from a direct referral audiology clinic due to audiological evidence of asymmetrical hearing loss. The audiograms, magnetic resonance imaging and computed tomography scans of patients with diagnosed vestibular schwannoma were subsequently reviewed.

RESULTS

A total of 4100 patients were seen during the study period, with 396 scans performed. Six (1.5 per cent) patients had vestibular schwannoma, while 12 (3 per cent) had significant incidental findings.

CONCLUSION

Patients referred from the direct referral audiology clinic had a low incidence of vestibular schwannoma detection. Their detection rate for significant incidental findings was similar to previous reports. If the current protocol had not been in place, over 300 patients would have been needlessly added to the ENT clinic list. Thus, general practitioner referral to direct referral audiology clinics provides a cost-effective way of managing asymmetrical sensorineural hearing loss in older patients. The number of such clinics could be expanded.

Growth of untreated vestibular schwannoma: a prospective study

Object

Small vestibular schwannomas (VSs) are often conservatively managed and treated only upon growth. Growth is usually reported in mm/year, but describing the growth of a 3D structure by a single diameter has been questioned. As a result, VS growth dynamics should be further investigated. In addition, baseline clinical parameters that could predict growth would be helpful. In this prospective study the authors aimed to describe growth dynamics in a cohort of conservatively managed VSs. They also compared different growth models and evaluated the ability of baseline parameters to predict future growth.

Methods

Between 2000 and 2006, 178 consecutive patients with unilateral de novo small-sized VSs identified among the Norwegian population of 4.8 million persons were referred to a tertiary care center and were included in a study protocol of conservative management. Tumor size was defined by MR imaging–based volume estimates and was recorded along with clinical data at regular visits. Mixed-effects models were used to analyze the relationships between observations. Three growth models were compared using statistical diagnostic tests: a mm/year–based model, a cm3/year–based model, and a volume doubling time (VDT)-based model. A receiver operating characteristic curve analysis was used to determine a cutoff for the VDT-based model for distinguishing growing and nongrowing tumors.

Results

A mean growth rate corresponding to a VDT of 4.40 years (95% CI 3.49–5.95) was found. Other growth models in this study revealed mean growth rates of 0.66 mm/year (95% CI 0.47–0.86) and 0.19 cm3/year (95% CI 0.12–0.26). Volume doubling time was found to be the most realistic growth model. All baseline variables had p values > 0.09 for predicting growth.

Conclusions

Based on the actual measurements, VDT was the most correct way to describe VS growth. The authors found that a cutoff of 5.22 years provided the best value to distinguish growing from nongrowing tumors. None of the investigated baseline predictors were usable as predictors of growth.

Factors associated with hearing preservation after Gamma Knife surgery for vestibular schwannomas in patients who retain serviceable hearing

Object

Gamma Knife surgery (GKS) has been a safe and effective treatment for small- to medium-sized vestibular schwannomas (VSs) over relatively long-term outcomes. However, even with recent radiosurgical techniques, hearing results following GKS remain unsatisfactory. The purpose of this study was to evaluate the hearing preservation rate as well as factors related to hearing preservation in patients with VSs and serviceable hearing who were treated with GKS.

Methods

Among patients with Gardner-Robertson (GR) Class I or II serviceable hearing and VSs treated with GKS between 1991 and 2009, 117 were evaluable via periodic MR imaging and audiometry.

Results

The median age at the time of GKS was 52 years. Four patients (3%) had undergone prior surgery. Fifty-six patients (48%) had GR Class I hearing and 61 (52%) had GR Class II hearing at the time of GKS. The median tumor volume was 1.9 cm3. The median maximum and tumor margin radiation doses were 24 and 12 Gy, respectively. The median follow-up periods for MR imaging and audiometry were 74 and 38 months, respectively. The overall tumor control rate was 97.5%. Actuarial 3-, 5-, and 8-year hearing preservation rates were 55%, 43%, and 34%, respectively. On multivariate analysis, GR hearing class at the time of GKS and the mean cochlear dose affected hearing preservation significantly. In a limited number of patients who were treated using the most recent dose planning techniques and who had GR Class I hearing before treatment, the 3- and 5-year hearing preservation rates increased to 80% and 70%, respectively.

Conclusions

For the majority of patients with small- to medium-sized VSs, GKS was an effective and reasonable alternative to resection with satisfactory long-term tumor control. Factors related to hearing preservation included a GR Class I hearing pre-GKS and a lower mean cochlear radiation dose. To retain serviceable hearing, it is important to apply GKS treatment while patients retain GR Class I hearing.

Gamma knife radiosurgery for vestibular schwannomas: tumor control and functional preservation in 70 patients

OBJECTIVE

We present the previously unreported outcomes of 70 patients treated with Gamma knife radiosurgery for vestibular schwannoma (VS), including comprehensive analysis of clinical outcomes and the effects of lower marginal doses.

METHODS

We performed a retrospective study of patients treated for VS at Gamma knife of Spokane between 2003 and 2008. Endpoints measured include tumor control, hearing preservation, and facial nerve preservation, including the effect of tumor size and marginal dose. Statistical analysis was performed with Wilcoxon signed-rank test, paired Student t test, Mann-Whitney U test, Kendall's rank correlation, Fisher exact test, and Liddell's exact χ(2) test for matched pairs.

RESULTS

With a mean follow-up of 26 months, 93.8% of tumors either shrank or remained static after receiving a mean marginal dose of 12.7 Gy. Tumor control was independent of marginal dose or tumor size. Hearing preservation was achieved in 64% of patients with serviceable function before the treatment. Hearing changes were independent of dose or tumor size. Preservation of good facial nerve function was achieved in 95% of patients. Post-treatment hydrocephalus occurred in 4.4% of patients, but no other significant morbidities were elucidated.

CONCLUSIONS

In the treatment of VS, contemporary radiosurgical techniques and the use of marginal doses below 13 Gy offer excellent tumor control, at high rates relative to surgical intervention. These findings are independent of marginal dose and tumor size. Patients should be informed about the benefits and risks of radiosurgery and microsurgery before choosing an intervention. Further analysis of post-treatment outcomes should be encouraged as follow-up times increase and the treatment protocols continue to evolve.

Ewing's Sarcoma/Peripheral Primitive Neuroectodermal Tumor in the Cerebellopontine Angle : Diagnosis and Treatment

Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is an unusual malignancy with aggressive behavior. ES/PNET in the cerebellopontine angle (CPA) is extremely uncommon, and we report on a rare case here. A 31-year-old man presented with one month history of left facial palsy, hearing loss, swallowing difficulty, and hoarseness. Magnetic resonance images showed a large mass in the left CPA and a small one in the right cerebellar hemisphere. The patient underwent a surgery for the CPA mass lesion, and the pathology was compatible with ES/PNET. Radiation therapy and chemotherapy were administered. In contrast to the initial radiologic findings resembling vestibular schwannoma or meningioma, ES/PNET had several distinct clinical features. A patient with a CPA mass and presenting unusual clinical features should be suspected of having a rare malignancy.

Hearing preservation in the resection of vestibular schwannomas: patterns of hearing preservation and patient-assessed hearing function

Object

No extant literature documents the analysis of patient perceptions of hearing as a corollary to objective audiometric measures in patients with vestibular schwannoma (VS), or acoustic neuroma. Therefore, using objective audiometric data and patient perceptions of hearing function as outlined on a questionnaire, the authors evaluated the hearing of patients who underwent VS resection.

Methods

This investigation involved a retrospective review of 176 patients who had undergone VS resections in which hearing preservation was a goal. Both pre- and postoperative audiometry, expressed as a speech discrimination score (SDS) and pure tone threshold average (PTA), were performed, and the results were analyzed. Intraoperative auditory brainstem responses were also recorded. Eighty-seven of the patients (49.4%) completed a postoperative questionnaire designed to assess hearing function in a variety of social and auditory situations. Multiple linear regression analyses were completed to compare available audiometric results with questionnaire responses for each patient.

Results

One hundred forty-two patients (80.7%) had PTA and SDS audiometric data pertaining to the surgically treated ear; 94 of these patients (66.2%) had measurable postoperative hearing, as defined by a PTA < 120 dB or SD > 0%. Eighty-seven patients (49.4%) completed the retrospective questionnaire, and 74 of them had complete audiometric data and thus were included in a comparative analysis. Questionnaire data showed major postoperative subjective hearing decrements, even among patients with the same pre- and postoperative objective audiometric hearing status. Moreover, the subscore reflecting hearing while exposed to background noise, or the “cocktail party effect,” characterized the most significant patient-perceived hearing deficit following VS resection.

Conclusions

The authors' analysis of a patient-perceived hearing questionnaire showed that hearing during exposure to background noise, or the cocktail party effect, represents a significant postoperative hearing deficit and that patient perception of this deficit has a strong relation with audiometric data. Furthermore, questionnaire responses revealed a significant disparity between subjective hearing function and standard audiometrics such that even with similar levels of audiometric data, subjective measures of hearing, especially the cocktail party effect, decreased postoperatively. The authors posit that the incorporation of patient-perceived hearing function evaluation along with standard audiometry is an illustrative means of identifying subjective hearing deficits after VS resection and may ultimately aid in specific and subsequent treatment for these patients.