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To evaluate outcomes following salvage microsurgery (MS) and salvage stereotactic radiosurgery (SRS) after failure of primary treatment for vestibular schwannomas (VS).Retrospective chart review.Tertiary referral center.Patients with more than 1 intervention for their VS were divided into 4 groups: MS followed by SRS (n = 61), MS followed by MS (n = 9), SRS followed by MS (n = 7), and SRS followed by SRS (n = 7), and outcomes were evaluated.A total of 77 patients were included (84 procedures). In group 1 (MS then SRS), 3% developed a decline in facial function, 3% developed trigeminal sensory loss, and 13% patients had gradual improvement of facial nerve function following SRS. Group 2 (MS then MS) had the highest rates of facial nerve deterioration, although all but 1 patient achieved a House-Brackmann score of II or III. Gross-total resection (GTR) was achieved in 56% of patients. When a different approach was used for salvage resection, GTR occurred more commonly, and facial nerve outcomes were similar. In group 3 (SRS then MS), GTR occurred in 43% of cases, and 2 of 7 patients developed worsened facial function. In group 4 (SRS then SRS), no patient developed facial weakness after reirradiation, and 1 developed a trigeminal nerve deficit.For MS recurrences/residuals, SRS is the mainstay of treatment and does not preclude facial function recovery. If salvage microsurgery is required, an alternate approach should be considered. For SRS failures, when MS is required, less-than GTR may be preferable, and reirradiation is a potential safe alternative.

Sporadic vestibular schwannomas (VS) can be treated using radiation therapy, microsurgical resection or a wait‐and‐scan approach. In general, small VS are usually followed (wait‐and‐scan) until a significant amount of growth per year is seen. In a recent study, 212 cases of VS were observed over time; 66% showed growth, of which 30% were fast growing (doubling in size in a year). 1 Frischer et al examined cases of VS after radiosurgery (Gamma Knife), and found a tumour control rate of 92% after 5 years of follow‐up. 2 However, among patients with initial Gardner‐Robertson class 1 or 2 hearing, only 55% maintained serviceable hearing (class 1 or 2) after 2 years, and 34% after 10 years. Several other studies have reported similar results. 3 , 4 A recent meta‐analysis concluded that among patients who undergo microsurgical treatment with a hearing‐preserving technique, 35–49% still have serviceable hearing five years later. 5 The above‐mentioned findings support the conclusion that most VS will require treatment after some period of observation. However, the currently available treatment options carry a high risk of loss of serviceable hearing. Some authors believe that the possibility of cochlear implantation in the setting of VS should completely change the treatment strategy for this disease. 6 However, patient outcomes with cochlear implants (CI) show a wide variation—with some patients having no auditory perception, while others exhibit open‐set speech understanding. 7 The intraoperative testing of cochlear nerve function using electrically evoked brainstem response audiometry (eABR) provides a means of objectively assessing cochlear nerve conduction, and has been increasingly applied in this setting. 7 , 8 In the present study, we aimed to assess outcomes of patients undergoing VS resection and CI, and to develop a new scoring system to preoperatively identify suitable patients for this treatment course. Appropriate preoperative classification of patients can have important impacts on patient counseling and expectations.

Objective Radiation therapy is a mainstay in the treatment of numerous neoplasms. Numerous publications have reported good clinical outcomes for primary radiation therapy for Vestibular Schwannomas (VS). However, there are relatively few pathologic specimens of VSs available to evaluate post‐radiation, which has led to a relative dearth in research on the cellular mechanisms underlying the effects of radiation therapy on VSs. Methods Here we review the latest literature on the complex biological effects of radiation therapy on these benign tumors—including resistance to oxidative stress, mechanisms of DNA damage repair, alterations in normal growth factor pathways, changes in surrounding vasculature, and alterations in immune responses following radiation. Results Although VSs are highly radioresistant, radiotherapy is often successful in arresting their growth. Conclusion By better understanding the mechanisms underlying these effects, we could potentially harness such mechanisms in the future to potentiate the clinical effects of radiotherapy on VSs. Level of Evidence N/A., Although Vestibular Schwannomas (VS) are highly radioresistant, radiotherapy is often successful in arresting their growth. Here we review the latest literature on the complex biological effects of radiation therapy on these benign tumors—including resistance to oxidative stress, mechanisms of DNA damage repair, alterations in normal growth factor pathways, changes in surrounding vasculature, and alterations in immune responses following radiation. By better understanding the mechanisms underlying these effects, we could potentially harness such mechanisms in the future to potentiate the clinical effects of radiotherapy on VSs.

OBJECTIVES/HYPOTHESIS Cerebellopontine angle (CPA) and internal auditory canal (IAC) lipomas are rare, benign tumors comprising 0.08% of all intracranial tumors and can be mistaken for other, more common lesions of the CPA/IAC such as vestibular schwannoma. The purpose of this study was to review the literature and assess the evolution of CPA/IAC lipoma diagnosis and management. In addition, we present 17 new lipomas, matching the largest known case series of this rare tumor. STUDY DESIGN Retrospective case series and systematic review. METHODS Systematic review of the literature was performed using PubMed and Google Scholar. References from identified articles were also reviewed to identify potential additional manuscripts. Manuscripts and abstracts were reviewed to identify unique cases. For the case series, the charts of all CPA/IAC lipoma patients seen at a single institution from 2006-2019 were manually reviewed. Logistic regression and chi-squared analysis were performed where appropriate. RESULTS A total of 219 unique lipomas have been reported in the literature, including 17 presented in this study. Surgical management has been performed in 46% of cases and has been conducted less often in recent decades, likely due to improved radiographic diagnostic capabilities and understanding of surgical outcomes. Surgical management is associated with worse neurologic outcomes (P = .002) and has become less common in recent decades. Although growth is unlikely, it has been demonstrated in patients into their 30s. CONCLUSIONS Accurate radiographic diagnosis is imperative for appropriate patient management, as CPA/IAC lipomas should typically be managed through observation and serial imaging whereas vestibular schwannomas and other CPA/IAC lesions may require microsurgical or radiosurgical intervention depending on growth and symptomatology. Laryngoscope, 131:2081-2087, 2021.

Vestibular schwannomas (VSs) were proposed to arise from the glial-Schwann cell junction within the internal auditory canal (IAC). However, otopathology studies indicate that VS may arise anywhere along the course of the vestibular nerve. Recent studies suggested that the majority of tumors are located centrally within the IAC with an equal distribution near the porus acusticus and the fundus. However, these studies analyzed tumors of all sizes, obscuring their precise origin. Herein, we aim to quantify the position of small intracanalicular tumors (

Background Neurofibromatosis type 2 (NF2) is an autosomal dominant, multiple neoplasia syndrome characterized by bilateral vestibular schwannomas (VSs). Endoglin is a proliferation-associated protein expressed in angiogenic endothelial cells. The aim of this study was to investigate endoglin expression in a series of NF2-associated VSs, as compared with a group of sporadic VSs. Methods Using image analysis, vessel cross-sectional area (AA) and density (VD) were calculated from CD105 expression in 7 NF2-associated VSs and 14 size-matched sporadic VSs. Results There were no significant differences between NF2-associated VSs and sporadic cases in terms of AA (P = .28), or VD (P = .39). A positive correlation emerged between tumor growth rate (measured on contrast-enhanced MRI) and VD in the cohort of NF2-associated VSs (rho = 0.95, P = .05). Conclusions Further investigations are needed to ascertain the feasibility of (a) measuring circulating endoglin levels to monitor tumor growth rate and (b) targeting tumor neoangiogenesis with anti-endoglin approaches in NF2-associated VS.

OBJECTIVES/HYPOTHESIS To determine if volumetric growth prior to gamma knife (GK) radiosurgery predicts long-term tumor control. STUDY DESIGN Retrospective cohort study. METHODS Sporadic vestibular schwannomas (VS) treated with GK between 2002 and 2014 at a single tertiary care center were identified. Patients were included if they had over 6 months of pretreatment observation and over 1.5 years of posttreatment follow-up. Volumetric tumor analysis was performed on T1 postcontrast imaging. Pretreatment and posttreatment volume change was calculated. Tumors with over 20% volume increase were classified as growing. RESULTS There were 62 patients included in this study; 48 had pretreatment growth and 14 had no pretreatment growth. Median tumor volume was 0.58 ± 1.8 cm3 and median follow-up was 3.3 ± 2.0 years. For tumors with and without pretreatment growth, salvage treatment rates were 2% and 7% (P = .35), and posttreatment radiologic stability rates were 73% and 86%, respectively (P = .33). Median pretreatment growth was 27 ± 33% per year for tumors with posttreatment radiographic growth and 18 ± 26% per year for tumors without posttreatment radiographic growth (P = .99). CONCLUSIONS Pretreatment growth was not associated with increased salvage treatment or posttreatment radiographic progression rates in VS following GK. LEVEL OF EVIDENCE 4 Laryngoscope, 129:743-747, 2019.

Unlike adult neurofibromatosis type 2 (NF2), which presents with symptoms related to bilateral vestibular schwannomas, children with NF2 most frequently present with ocular, dermatological, and neurological symptoms. Arteriopathy, a well-established feature in neurofibromatosis type 1, is not a widely recognized feature of NF2. Here we report three children with NF2 with cerebral arteriopathy and/or arterial ischaemic stroke. Bevacizumab, a vascular endothethial growth factor inhibitor, is an established treatment for rapidly growing vestibular schwannomas; however, it carries a risk of both ischaemic and haemorrhagic stroke. Thus, the role of screening and risk to benefit ratio of bevacizumab in NF2 merit further consideration. WHAT THIS PAPER ADDS: Children with neurofibromatosis type 2 (NF2) may be at increased risk of cerebral vasculopathy and arterial ischaemic stroke. Targeted magnetic resonance angiography should be performed in children with NF2 who are being considered for bevacizumab therapy.

OBJECTIVES/HYPOTHESIS To determine if aspirin intake is associated with reduced growth of vestibular schwannomas (VS). To determine the prevalence of contraindications to regular aspirin in patients with VS. STUDY DESIGN Retrospective, observational case-control study. METHODS The study utilized a postal questionnaire and telephone interviews to determine aspirin exposure. Propensity score matching was used to control for age, sex, and tumor size. Cases were defined as patients with VS proven to have grown on serial magnetic resonance imaging (MRI). Controls were defined as patient with VS stable on serial MRI. Prevalence of regular aspirin use was compared in patients with growing VS versus stable VS. Absolute and relative contraindications to aspirin intake were recorded. RESULTS Six hundred fifty-three patients with VS were contacted, and responses were received by 67% (220 cases and 217 controls). The mean tumor size was 11.3 mm (9.0 mm and 13.3 mm in controls and cases, respectively). Aspirin exposure was more common in stable VS than growing VS (22.1% vs. 17.3%). However, following matching to control for covariates, aspirin was not found to be associated with VS stability (P = .475). Multiple logistic regression (analysis of variance) found tumor size to be the only factor strongly associated with tumor growth (P

Objectives/hypothesis The objectives of this study were to evaluate the diagnostic accuracy of constructive interference steady state (CISS) sequencing compared to gadolinium-enhanced T1 (GdT1) magnetic resonance imaging (MRI) to screen for small vestibular schwannomas (VSs), and to assess the overall diagnostic confidence of neuroradiologists in their ability to accurately diagnose or rule out VSs using CISS imaging compared to a GdT1 MRI STUDY DESIGN: Retrospective chart review. Methods Chart review from 2011 to 2015 was performed for VS/benign cerebellopontine angle tumors. Two blinded, board-certified neuroradiologists each independently reviewed the axial CISS sequence and answered a set of questions that determined their confidence in diagnosis of VS. Next, each neuroradiologist independently reviewed the corresponding GdT1 MRI sequence and completed the same questionnaire. Results The majority of the lesions were in the lateral internal auditory canal, with eight intralabyrinthine tumors. The overall sensitivity of CISS for both readers was 93.5%. All tumor locations had high sensitivities except for the intralabyrinthine location (62.3%). Four of the eight total intralabyrinthine lesions were missed by at least one reader. Each reader was highly confident in diagnosing VSs with CISS, which approximated that of GdT1 MRI. Conclusions This study's results showed that CISS examinations for screening of small VS approximated that of GdT1. Neuroradiologists had high sensitivity, perfect specificity, and felt confident in ruling out a VS on CISS sequence while feeling extremely confident in diagnosing one on CISS. Intralabyrinthine lesions and lesions ≤3.0 mm are most at risk for not being detected on CISS examinations. Level of evidence 4 Laryngoscope, 128:2128-2132, 2018.

Objectives/Hypothesis There is a large variation in vestibular rehabilitation (VR) results depending on type of therapy, adherence, and the appropriateness for the patient's level of function. A novel adaptive vestibular rehabilitation (AVR) program was developed and evaluated. Study Design Technology and procedure development, and prospective multicenter trial. Methods Those with complete unilateral vestibular hypofunction and symptomatic at least 3 months with a Dizziness Handicap Inventory (DHI) >30 were eligible. Patients were given a device to use with their own computer. They were instructed to use the program daily, with each session lasting about 10 minutes. The task consisted of reporting orientation of the letter C, which appeared when their angular head velocity exceeded a threshold. The letter size and head velocity required were adjusted based on prior performance. Performance on the task was remotely collected by the investigator as well as a weekly DHI score. Results Four patients aged 31 to 74 years (mean = 51 years) were enrolled in this feasibility study to demonstrate efficacy. Two had treated vestibular schwannomas and two had vestibular neuritis. Starting DHI was 32 to 56 (mean = 42), which was reduced to 0 to 16 (mean = 11.5) after a month of therapy, a clinically and statistically significant (P < .05) improvement. The three who continued therapy an additional month improved to a DHI of 4. Conclusions This AVR method has advantages over traditional VR in terms of cost and customization for patient ability and obtained a major improvement in symptoms. This study demonstrated a clinically and statistically significant decrease in symptoms after 4 weeks of therapy. Level of Evidence 2b Laryngoscope, 2017

Author(s): Mahboubi, Hossein; Maducdoc, Marlon M; Yau, Amy Y; Ziai, Kasra; Ghavami, Yaser; Badran, Karam W; Al-Thobaiti, Majid; Brandon, Bryan; Djalilian, Hamid R | Abstract: ObjectiveTo understand the differences in characteristics of neurofibromatosis type 2 (NF2) and sporadic patients with surgically excised vestibular schwannomas in the state of California.Study designCross-sectional.Setting, subjects, and methodsThe records of all patients who underwent vestibular schwannoma excision between 1997 and 2011 were extracted from the California Hospital Inpatient Discharge Databases (CHIDD). NF2 cases were identified using ICD-9-CM diagnosis code 237.72, neurofibromatosis, type 2. All other cases were recoded as sporadic. Trends in total number and population-adjusted rates (per 1 million California residents) of surgery, demographics, hospital case volume, state of residency, complications, length of stay, total charges, expected source of payment, and disposition were examined.ResultsVestibular schwannoma (VS) excision was performed on 7017 patients, of which 464 patients (6.6%) had NF2. The population-adjusted surgery rate declined from 11.8 to 6.2 (P l .001) for sporadic cases and from 0.3 to 0.2 (P = .01) for NF2 cases over the study period. NF2 was associated with younger age (mean, 32.9 vs 51.3), higher rate of other complications (8.8% vs 4.4%) and facial nerve complications (32.3% vs 16.8%), higher total charges (median $70,106 vs $46,395), longer stay (median 5 vs 4), and high volume hospitals (80.4% vs 48.8%) (all P l .001).ConclusionThe surgery rates for vestibular schwannoma excision for both sporadic and NF2 patients have declined, but the decline is more prominent for sporadic cases. NF2 patients tend to be younger and have a longer hospitalization and possibly higher corresponding hospital charges compared to patients with sporadic VS.

Schwannomatosis is a recently delineated inherited condition that has clinical overlap with neurofibromatosis type 2 (NF2). Diagnostic criteria have been developed to distinguish schwannomatosis from NF2, but the existence of mosaic NF2, which may closely mimic schwannomatosis, makes even these criteria problematic. In particular, it is not clear why there is a relative sparing of the cranial nerves from schwannomas in schwannomatosis. We have identified two individuals with schwannomatosis and a unilateral vestibular schwannoma (VS), where a diagnosis of NF2 has been excluded. A third case with an identified SMARCB1 mutation was reported by two radiologists to have a VS, but this was later confirmed as a jugular schwannoma. These cases question whether the current exclusion of a VS from the clinical diagnosis of schwannomatosis is justified.

OBJECTIVES/HYPOTHESIS: Gamma knife radiosurgery (GKRS) has become an important treatment modality for vestibular schwannomas. The primary aim of this study was to investigate whether tumor growth at the moment of GKRS has any correlation with the outcome. The secondary aim was to identify clinical predictors of radioresistance in vestibular schwannoma patients treated with GKRS. STUDY DESIGN: One hundred vestibular schwannoma patients, treated with GKRS, were divided into two groups: 1) proven tumor growth preceding GKRS; and 2) previous history of growth unknown. GKRS outcome was defined in two ways. According to the first definition, GKRS was said to have failed when additional treatment had taken place. According to the second one, a volume decrease >20% after 2 years marked successful treatment. METHODS: Correlations between outcome and growth status were determined with SPSS software. Furthermore, the study assessed how different variables (patient data, history, tumor characteristics, imaging, and audiovestibular examinations) correlated with the outcome of GKRS. RESULTS: No significant difference regarding success and failure of GKRS was found between the two patient groups. The mean reduction in tumor volume after GKRS was less pronounced in patients in whom tumor growth was demonstrated before treatment, but this finding was not significant. No significant predictors (P < .05) could be identified in this data set. CONCLUSIONS: This study found no indication that growth at the moment of GKRS influences therapeutic outcome, nor did it identify any predictors of the outcome after GKRS in vestibular schwannoma patients.

BACKGROUND: The radiosurgical treatment of vestibular schwannomas in patients with neurofibromatosis type 2 (NF2) is controversial. The authors investigated the radiologically proven tumor control rate after gamma knife radiosurgery. The factors that affect tumor control and serviceable hearing preservation were analyzed. METHODS: Thirty-six lesions in 30 patients were included. The median lengths of the clinical and radiologic follow-ups were 48.5 months and 36.5 months, respectively. The median tumor volume was 3.2 cm3. The mean marginal dose was 12.1 grays (Gy) (range, 8–14 Gy) at an isodose line of 50%±0.6%. The Kaplan-Meier method and Cox proportional hazards model were used for the statistical analyses. RESULTS: The actuarial tumor control rate was 81%, 74%, and 66%, respectively, in the first, second, and fifth years. Five tumors required a salvage surgery because of tumor control failure. A low marginal dose and a young age at radiosurgery were associated with poor tumor control. Of the 16 tumors with which ipsilateral hearing was serviceable, the actuarial serviceable hearing preservation rates were 50%, 45%, and 33%, respectively, in the first, second, and fifth years. Better ipsilateral hearing (Gardner-Robertson grade 1, compared with grade 2) at the time of radiosurgery was associated with significantly greater serviceable hearing preservation. CONCLUSIONS: Gamma knife radiosurgery for vestibular schwannomas in NF2 patients provided 5-year tumor control in approximately two-thirds of patients and preserved serviceable hearing in approximately one-third. The rates of other cranial nerve deficits were low, and no secondary malignancy was observed. Radiosurgery should be included in treatment options for NF2 patients. Cancer 2009. © 2009 American Cancer Society.

Seventy-two patients with a unilateral vestibular schwannoma have been treated conservatively for a median of 121 months. They have been followed prospectively by serial clinical examination, MRI scans and audiometry. Twenty-five patients (35%, 95% CI: 24-47) failed conservative management and required active intervention during the study. No factors predictive of tumour growth or failure of conservative management could be identified. Seventy-five per cent of failures occurred in the first half of the 10-year study. The median growth rate for all tumours at 10 years was 1 mm/year (range -0.53-7.84). Cerebellopontine angle tumours grew faster (1.4 mm/year) than intracanalicular tumours (0 mm/year, P < 0.01); 92% had growth rates under 2 mm/year. Hearing deteriorated substantially even in tumours that did not grow, but did so faster in tumours that grew significantly (mean deterioration in pure tone average at 0.5, 1, 2 and 3 kHz was 36 dB; speech discrimination scores deteriorated by 40%). Patients who failed conservative management had clinical outcomes that were not different from those who underwent primary treatment without a period of conservative management.

Objective: A preliminary study to investigate the intra-observer and inter-observer variability of measurements of vestibular schwannoma volume using an area-tracing and linear dimension measurement method. Design: Prospective blinded measurements by two observers (one a consultant and one a sub-specialty trainee in neuroradiology). Setting: Ambulatory patients with known vestibular schwannoma attending a tertiary referral centre. Participants: Twenty-three patients with 26 vestibular schwannomas aged 29–80 years old. Main outcome measure: Quantification of the variability in measured volume due to intra- and inter-observer measurement differences, expressed as reliability coefficients within which 95% of repeated measurements are calculated to lie from each other in relative percentage terms. Results: For the linear measurement method, intraobserver variability was calculated to have a reliability coefficient of 65% and for interobserver variability this was 155%. For the area tracing method, the corresponding coefficients were 26% for intraobserver variability and 44% for interobserver variability. Conclusions: Volume measurements in vestibular schwannoma are variable even when the measurements are made by the same observer on identical images. The area tracing method, commonly regarded as the gold standard, is less variable than a linear method but still introduces more variability than commonly realized (for 95% of patients, repeated measurements by the same observer lie within around 25% of each other). Manual area tracing is not widely used in practice because it is time consuming and reliable automated methods are eagerly awaited.

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.

Tumor-specific alterations at the p53 gene locus in 30 human vestibular schwannomas (VS) comprising 10 confirmed NF2 cases and 20 sporadic cases were analyzed. We found loss of heterozygosity (LOH) at the first intron of the p53 gene locus in 54% of the informative cases. This is the first report showing LOH at the p53 gene locus in a significant number of human VS and both sporadic and NF2 cases show the LOH event. Increased levels of normal size p53 mRNA and p53 protein were found in all the tumors analyzed. Thus p53 appears to be deregulated in all the tumors suggesting that p53 alterations may be associated with tumor progression in VS. There was a negative significant correlation of patients' age and percentage of Ser 392 phosphorylated p53 protein. The tumor samples obtained from younger patients of 35 yr and below showed higher percentage of Ser 392 phosphorylated p53 protein compared to the tumors of older patients. The increased percentage of Ser 392 phosphorylated p53 protein indicates that it could be involved in the acceleration of tumor growth in the younger patients. Our results suggest that age dependent phosphorylation of p53 protein and deregulation of p53 gene has a role in the development of human vestibular schwannomas.

BACKGROUND AND PURPOSE Unruptured anterior inferior cerebellar artery (AICA) aneurysms are rare but potentially lethal cerebellopontine angle (CPA) lesions that may be misdiagnosed as vestibular schwannomas when they present with vestibulo-cochlear symptoms. METHODS We report two cases of unruptured but symptomatic AICA aneurysms initially referred to us as atypical vestibular schwannomas requiring surgery. Two discriminant MR features are described. RESULTS One patient refused treatment. The other was successfully treated by coil occlusion. CONCLUSIONS Caution is advised before suspecting a CPA mass to be a purely extra-canalicular schwannoma, given its extreme rarity. Deafness and cerebellar ischemia may be prevented if AICA aneurysms are correctly identified preoperatively. In the absence of specific arterial imaging, two MR features may distinguish them from vestibular schwannomas: (1) the absence of internal auditory canal enlargement and (2) the “blurry dot sign,” representing blood flow artefacts on pre- and postcontrast studies.

Growth rate of non-vestibular intracranial schwannomas A group of nine patients with non-vestibular intracranial neuromas (four jugular, four facial, one trigeminal) underwent an interval scanning management policy, with serial annual magnetic resonance (MR) imaging. Tumour volume was assessed by manual measurement of the tumour area by MR imaging. Tumour volume was assessed by manual measurement of the tumour area on MR imaging axial cuts. The mean tumour size at presentation was 4.6 cm3 (range 0.7–17.8 cm3). During a mean follow-up of 36 months (range 22–50 months), five out of nine tumours grew significantly at a rate of more than 5% of their initial volume per year. Only those tumours growing at a rate of more than 20% initial volume per year exhibited symptom progression. During a 36-month period of interval scanning, just over 50% of non-vestibular intracranial neuromas exhibited significant growth. Symptom progression was found to be a strong indicator of a high growth rate. This proportion exhibiting growth is higher than that demonstrated by unilateral sporadic vestibular schwannomas, but less than in patients with neurofibromatosis II. Early treatment of non-vestibular intracranial neuromas should therefore be considered.

Neurofibromatosis 2 (NF2) is an autosomal-dominant disease caused by genetic mutations of the NF2 gene on chromosome 22. Patients are often diagnosed according to the presence of bilateral vestibular schwannomas and other tumors in the brain and spinal cord. In children, NF2 can present early with ocular findings and cutaneous tumors. We report here a 9-year-old girl who presented with multiple pigmented, slightly tender plaques on her scalp, face, and back that were revealed by histopathology to be plexiform schwannomas. We suspected NF2 and sent the patient’s blood for genetic testing, which confirmed our diagnosis.

Objectives:(1) Compare noncontrast steady-state free precession (SSFP, also called FIESTA, CISS, and bFFE) magnetic-resonance imaging (MRI) to contrast-enhanced full sequence MRI for initial evaluation of retrocochlear pathology. (2) Assess the sensitivity and specificity of SSFP alone versus complete contrast-enhanced MRI as the gold standard.Methods:Retrospective review of a tertiary care center radiology imaging database from 2006 to present was performed. Based on statistical power analysis, 50 studies with identified vestibular schwannomas and 53 studies with normal internal auditory canal (IAC) findings were included. Four expert reviewers performed blinded, randomized evaluation of non-contrast SSFP sequence and contrast-enhanced MRI studies to evaluate for retrocochlear pathology. MRI reports from the original studies were used as the gold standard. Using XLSTAT™ statistical software, data were analyzed using a 2-sided z-test of one proportion for each reviewer’s sensitivity and specificity agains...

Objectives:(1) Analyze the recent trends in radiosurgery for vestibular schwannomas (VS). (2) Determine the number of VS treated with radiosurgery since 1990 in the United States.Methods:Large databases were obtained by contacting the manufacturers of the 2 main radiosurgical machines used to treat VS in the United States. Analysis of de-identified data from Leksell Gamma Knife reporting was carried out to investigate the treatment trends for VS. The main variable investigated was the number of VS treated by radiosurgery in the United States. Extrapolations were made to the available data to estimate the trends of radiosurgical treatment.Results:The number of VS treated by radiosurgery has been increasing. In the US, radiosurgery for treatment of VS was approximately 150 to 200 per year from 1991 to 1993. However, VS cases treated by radiosurgery were approximately 1520 and 1490 in 2011 and 2012, respectively. This indicates an approximate average annual rate of increase of about 4.7% (SD: 8.6%). Currentl...

Evaluation of the proliferation activity of neuromas has a practical meaning when there are doubts about the complete resection of the tumor. Evaluation of the clinical aspects connected with increased proliferation activity may have a much broader application. The aim of this study was to correlate selected clinical and radiologic aspects of vestibular schwannomas with the results of the Ki-67 index. The studied group included 23 males and 20 females. Unilateral neuromas were stated in 38 cases (mean age, 52.2 years) and bilateral tumors in 5 cases (mean age, 44.2 years). The immunohistochemical tests (Ki-67) were performed on the specimens preserved in formalin and stored in paraffin. The Ki-67 index was estimated in a semiquantitative study. The mean value of Ki-67 index was 1.86%. In case of unilateral neuromas (n = 38), the average Ki-67 index was 1.74%. In 5 cases of bilateral tumors, the index amounted to 2.79% (P = 0.278). No significant correlation was found by comparing the value of the Ki-67 index with the age of patients (P = 0.410: r = 0.128). Significant differences in the value of the Ki-67 index were noted in the sub-groups of tumors that were evaluated radiologically as growing and stable. The mean value of Ki-67 index was 3.17% in the first subgroup; in stable neuromas, it was significantly lower, amounting to 1.11% (P = 0.020). Such results may confirm that the growth rate of vestibular schwannomas varies and may explain the difficulties in estimating the growth of neuromas on the basis of clinical aspects only. (Otolaryngol Head Neck Surg 2000;123:779-83.)

All 13 patients with neurofibromatosis 2 (NF2) who presented over a period of 17 years at the Institute of Neurological Sciences, Glasgow were reviewed and compared to patients with sporadic vestibular schwannomas. The NF2 patients presented at a younger age than those with sporadic vestibular schwannomas. A significant number had normal pure tone audiograms and a small number also had normal auditory brainstem responses at presentation. Vestibular schwannomas in NF2 patients grow more often and more rapidly than sporadic unilateral ones. They are more liable to infiltrate the cochlear and facial nerves making hearing and facial nerve preservation more difficult to achieve. Because the relatives of these patients often have normal audiograms and normal auditory brain stem responses in the presence of a schwannoma, our recommended method of screening of relatives of NF2 patients is magnetic resonance image scanning with Gd-DTPA enhancement.

Stereotactic Body Radiation Therapy (SBRT) was introduced clinically more than twenty years ago, and many subsequent publications have reported safety and efficacy data. The AAPM Working Group on Biological Effects of Hypofractionated Radiotherapy/SBRT (WGSBRT) extracted published treatment outcomes data from extensive literature searches to summarize and construct tumor control probability (TCP) and normal tissue complication probability (NTCP) models for six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session, we present the WGSBRT’s work for cranial sites, and recurrent head and neck cancer. From literature-based data and associated models, guidelines to aid with safe and effective hypofractionated radiotherapy treatment are being determined. Further, the ability of existing and proposed radiobiological models to fit these data is considered as to the ability to distinguish between the linear-quadratic and alternative radiobiological models such as secondary cell death from vascular damage, immunogenic, or bystander effects. Where appropriate, specific model parameters are estimated. As described in “The lessons of QUANTEC,” (1), lack of adequate reporting standards continues to limit the amount of useful quantitative information that can be extracted from peer-reviewed publications. Recommendations regarding reporting standards are considered, to enable such reviews to achieve more complete characterization of clinical outcomes. 1 Jackson A, Marks LB, Bentzen SM, Eisbruch A, Yorke ED, Ten Haken RK, Constine LS, Deasy JO. The lessons of QUANTEC: recommendations for reporting and gathering data on dose-volume dependencies of treatment outcome. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S155–60. Learning Objectives: 1. Describe the techniques, types of cancer and dose schedules used in treating recurrent H&N cancers with SBRT 2. List the radiobiological models that compete with the linear-quadratic model in explaining the results of hypofractionated RT 3. Describe the dose/volume metrics that are considered safe in SBRT treatment of tumors near the optic structures. 4. Discuss the efficacy of hypofractionation and dosing schedules used in treating vestibular schwannomas 5. Identify some difficulties in modeling TCP and NTCP for cranial tumors treated with hypofractionation. One moderator, Dr. Grimm, designed and holds intellectual property rights to the DVH Evaluator software tool which is an FDA-cleared product in commercial use, and can analyze some of this data. No others have relevant conflicts of interest.

Stereotactic Body Radiation Therapy (SBRT) was introduced clinically more than twenty years ago, and many subsequent publications have reported safety and efficacy data. The AAPM Working Group on Biological Effects of Hypofractionated Radiotherapy/SBRT (WGSBRT) extracted published treatment outcomes data from extensive literature searches to summarize and construct tumor control probability (TCP) and normal tissue complication probability (NTCP) models for six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session, we present the WGSBRT’s work for cranial sites, and recurrent head and neck cancer. From literature-based data and associated models, guidelines to aid with safe and effective hypofractionated radiotherapy treatment are being determined. Further, the ability of existing and proposed radiobiological models to fit these data is considered as to the ability to distinguish between the linear-quadratic and alternative radiobiological models such as secondary cell death from vascular damage, immunogenic, or bystander effects. Where appropriate, specific model parameters are estimated. As described in “The lessons of QUANTEC,” (1), lack of adequate reporting standards continues to limit the amount of useful quantitative information that can be extracted from peer-reviewed publications. Recommendations regarding reporting standards are considered, to enable such reviews to achieve more complete characterization of clinical outcomes. 1 Jackson A, Marks LB, Bentzen SM, Eisbruch A, Yorke ED, Ten Haken RK, Constine LS, Deasy JO. The lessons of QUANTEC: recommendations for reporting and gathering data on dose-volume dependencies of treatment outcome. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S155–60. Learning Objectives: 1. Describe the techniques, types of cancer and dose schedules used in treating recurrent H&N cancers with SBRT 2. List the radiobiological models that compete with the linear-quadratic model in explaining the results of hypofractionated RT 3. Describe the dose/volume metrics that are considered safe in SBRT treatment of tumors near the optic structures. 4. Discuss the efficacy of hypofractionation and dosing schedules used in treating vestibular schwannomas 5. Identify some difficulties in modeling TCP and NTCP for cranial tumors treated with hypofractionation. One moderator, Dr. Grimm, designed and holds intellectual property rights to the DVH Evaluator software tool which is an FDA-cleared product in commercial use, and can analyze some of this data. No others have relevant conflicts of interest.

Stereotactic Body Radiation Therapy (SBRT) was introduced clinically more than twenty years ago, and many subsequent publications have reported safety and efficacy data. The AAPM Working Group on Biological Effects of Hypofractionated Radiotherapy/SBRT (WGSBRT) extracted published treatment outcomes data from extensive literature searches to summarize and construct tumor control probability (TCP) and normal tissue complication probability (NTCP) models for six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session, we present the WGSBRT’s work for cranial sites, and recurrent head and neck cancer. From literature-based data and associated models, guidelines to aid with safe and effective hypofractionated radiotherapy treatment are being determined. Further, the ability of existing and proposed radiobiological models to fit these data is considered as to the ability to distinguish between the linear-quadratic and alternative radiobiological models such as secondary cell death from vascular damage, immunogenic, or bystander effects. Where appropriate, specific model parameters are estimated. As described in “The lessons of QUANTEC,” (1), lack of adequate reporting standards continues to limit the amount of useful quantitative information that can be extracted from peer-reviewed publications. Recommendations regarding reporting standards are considered, to enable such reviews to achieve more complete characterization of clinical outcomes. 1 Jackson A, Marks LB, Bentzen SM, Eisbruch A, Yorke ED, Ten Haken RK, Constine LS, Deasy JO. The lessons of QUANTEC: recommendations for reporting and gathering data on dose-volume dependencies of treatment outcome. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S155–60. Learning Objectives: 1. Describe the techniques, types of cancer and dose schedules used in treating recurrent H&N cancers with SBRT 2. List the radiobiological models that compete with the linear-quadratic model in explaining the results of hypofractionated RT 3. Describe the dose/volume metrics that are considered safe in SBRT treatment of tumors near the optic structures. 4. Discuss the efficacy of hypofractionation and dosing schedules used in treating vestibular schwannomas 5. Identify some difficulties in modeling TCP and NTCP for cranial tumors treated with hypofractionation. One moderator, Dr. Grimm, designed and holds intellectual property rights to the DVH Evaluator software tool which is an FDA-cleared product in commercial use, and can analyze some of this data. No others have relevant conflicts of interest.

Stereotactic Body Radiation Therapy (SBRT) was introduced clinically more than twenty years ago, and many subsequent publications have reported safety and efficacy data. The AAPM Working Group on Biological Effects of Hypofractionated Radiotherapy/SBRT (WGSBRT) extracted published treatment outcomes data from extensive literature searches to summarize and construct tumor control probability (TCP) and normal tissue complication probability (NTCP) models for six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session, we present the WGSBRT’s work for cranial sites, and recurrent head and neck cancer. From literature-based data and associated models, guidelines to aid with safe and effective hypofractionated radiotherapy treatment are being determined. Further, the ability of existing and proposed radiobiological models to fit these data is considered as to the ability to distinguish between the linear-quadratic and alternative radiobiological models such as secondary cell death from vascular damage, immunogenic, or bystander effects. Where appropriate, specific model parameters are estimated. As described in “The lessons of QUANTEC,” (1), lack of adequate reporting standards continues to limit the amount of useful quantitative information that can be extracted from peer-reviewed publications. Recommendations regarding reporting standards are considered, to enable such reviews to achieve more complete characterization of clinical outcomes. 1 Jackson A, Marks LB, Bentzen SM, Eisbruch A, Yorke ED, Ten Haken RK, Constine LS, Deasy JO. The lessons of QUANTEC: recommendations for reporting and gathering data on dose-volume dependencies of treatment outcome. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S155–60. Learning Objectives: 1. Describe the techniques, types of cancer and dose schedules used in treating recurrent H&N cancers with SBRT 2. List the radiobiological models that compete with the linear-quadratic model in explaining the results of hypofractionated RT 3. Describe the dose/volume metrics that are considered safe in SBRT treatment of tumors near the optic structures. 4. Discuss the efficacy of hypofractionation and dosing schedules used in treating vestibular schwannomas 5. Identify some difficulties in modeling TCP and NTCP for cranial tumors treated with hypofractionation. One moderator, Dr. Grimm, designed and holds intellectual property rights to the DVH Evaluator software tool which is an FDA-cleared product in commercial use, and can analyze some of this data. No others have relevant conflicts of interest.

Stereotactic Body Radiation Therapy (SBRT) was introduced clinically more than twenty years ago, and many subsequent publications have reported safety and efficacy data. The AAPM Working Group on Biological Effects of Hypofractionated Radiotherapy/SBRT (WGSBRT) extracted published treatment outcomes data from extensive literature searches to summarize and construct tumor control probability (TCP) and normal tissue complication probability (NTCP) models for six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session, we present the WGSBRT’s work for cranial sites, and recurrent head and neck cancer. From literature-based data and associated models, guidelines to aid with safe and effective hypofractionated radiotherapy treatment are being determined. Further, the ability of existing and proposed radiobiological models to fit these data is considered as to the ability to distinguish between the linear-quadratic and alternative radiobiological models such as secondary cell death from vascular damage, immunogenic, or bystander effects. Where appropriate, specific model parameters are estimated. As described in “The lessons of QUANTEC,” (1), lack of adequate reporting standards continues to limit the amount of useful quantitative information that can be extracted from peer-reviewed publications. Recommendations regarding reporting standards are considered, to enable such reviews to achieve more complete characterization of clinical outcomes. 1 Jackson A, Marks LB, Bentzen SM, Eisbruch A, Yorke ED, Ten Haken RK, Constine LS, Deasy JO. The lessons of QUANTEC: recommendations for reporting and gathering data on dose-volume dependencies of treatment outcome. Int J Radiat Oncol Biol Phys. 2010 Mar 1;76(3 Suppl):S155–60. Learning Objectives: 1. Describe the techniques, types of cancer and dose schedules used in treating recurrent H&N cancers with SBRT 2. List the radiobiological models that compete with the linear-quadratic model in explaining the results of hypofractionated RT 3. Describe the dose/volume metrics that are considered safe in SBRT treatment of tumors near the optic structures. 4. Discuss the efficacy of hypofractionation and dosing schedules used in treating vestibular schwannomas 5. Identify some difficulties in modeling TCP and NTCP for cranial tumors treated with hypofractionation. One moderator, Dr. Grimm, designed and holds intellectual property rights to the DVH Evaluator software tool which is an FDA-cleared product in commercial use, and can analyze some of this data. No others have relevant conflicts of interest.

Vestibular schwannomas account for 84% of cerebellopontine angle (CPA) lesions. The remaining CPA tumours comprise a fascinating group of lesions which may present in a similar fashion. Fortunately, advances in neuroradiology have increased our diagnostic accuracy of these lesions. This paper describes the surgical results of a series of 69 CPA lesions which were not vestibular schwannomas. The majority of these unusual CPA tumours were meningiomas, cholesteatomas and neuromas of other cranial nerves in the posterior fossa.

Objective: Compare 3D conformal volumetric analysis (3DCVA) versus traditional linear measurements on serial MRI imaging of vestibular schwannomas (VS) for determination and assessment of accurate tumor volume and growth rates.Method: Retrospectively identified VS patients followed with serial 0.7-3.0 Tesla MRI were included. Maximal linear dimensions were obtained from gadolinium-contrasted T1 sequences from 3 serial MRI scans per RECIST guidelines. Volumetric analysis was performed with semiautomated 3DCVA. Annual tumor growth rate and percentage change were compared for linear and volumetric measurements.Results: The average time span during which the serial MRI scans were obtained was 2.86 years in this initial retrospective analysis of 11 patients. The linear growth measurements averaged 0.5 mm/y, corresponding to a 6.4% average change per year. With 3DCVA the average tumor growth rate was 5mm3/y, corresponding to 3.7 mm/y growth in each dimension. There was an average increase in tumor volume of 29%...

Smith, Miriam J Hadfield, Kristen D Ramsden, Richard T Rutherford, Scott A King, Andrew T Newman, William G Evans, D Gareth Research Support, Non-U.S. Gov't United States American journal of medical genetics. Part A Am J Med Genet A. 2010 Jun;152A(6):1586-7. doi: 10.1002/ajmg.a.33409.

Vestibular schwannomas have been noted to have increased frequency and aggressivity in female patients, suggesting a possible role of estrogen. This study evaluated the effects of estrogen and tamoxifen on the growth of human vestibular schwannoma tissue implanted in subcutaneous pockets of nude mice. Animals were implanted with 1 of 3 human vestibular schwannomas and observed for 28 days. Mice were then separated into 3 treatment groups: controls, estrogen (receiving 1.7 mg of 17B-estradiol), and estrogen + tamoxifen (receiving 1.7 mg of 17B-estradiol + 10 mg of tamoxifen), and treated for 28 days. Mice treated with estrogen showed increased growth that was statistically significant (P < 0.05) when compared with that of both the controls and the animals treated with estrogen + tamoxifen. Controls and animals treated with estrogen + tamoxifen showed a general trend of decreased volume during the treatment period. These early results support the hypothesis that estrogen modulates the growth of vestibular schwannomas in the nude mouse model and that these effects can be blocked by tamoxifen administration.

Purpose: To compare the plan quality and organs at risk (OAR) sparing of volumetric modulated art therapy (VMAT) and Gamma Knife for stereotactic radiosurgery (SRS) of pituitary adenomas and vestibular schwannomas (VS). Methods: VMAT radiosurgery plans (SmartArc) were made using Pinnacle’s (version 9.10, Phillips) new Auto-Plan tool for eight vestibular schwannoma (VS) and eight pituitary adenoma patients previously treated with Gamma Knife Perfexion (GK) system. VMAT plans were made with three non-coplanar arcs using 3 angles, 6MV, FFF mode at 1400 MU per min dose rate and millennium HD MLC. All plans were normalized to deliver prescription dose (Rx) to at least 99.5 percent of the target volume. Results: For pituitary cases (1.07 – 20.71cc), respectively for GK and VMAT plans, mean conformity index (CI) was 1.62 ± 0.23 Gy and 1.51 ± 0.21 Gy (p = 0.05); mean gradient index (GI) was 2.76 ± 0.14 and 3.15 ± 0.43 Gy (p < 0.05); mean brainstem maximum dose was 9.13 ± 3.50 Gy and 7.31 ± 2.01 Gy (p < 0.05); mean optic nerve maximum dose was 9.66 ± 1.0 Gy and 7.67 ± 2.58 Gy (p < 0.05); and mean treatment time of 68 min and 4 min. For VS (0.47 – 5.26cc), respectively for GK and VMAT plans, CI was 1.39 ± 0.23 Gy and 1.57 ± 0.28 Gy (p < 0.05); GI was 3.71 ± 1.83 and 3.60 ± 0.84 Gy (p = 0.82); brainstem maximum dose was 11.67 ± 4.56 Gy and 12.22 ± 4.56 Gy (p = 0.12), cochlea mean dose was 7.31 ± 2.7 Gy and 6.75 ± 3.88 Gy (p = 0.52); and mean treatment time of 40 min and 4 min. Conclusion: VMAT plan quality and OAR sparing were comparable to GK plans with a shorter treatment time. Samuel Chao is a member of Varian Speakers Bureau, Gennady Neyman is a consultant for Elekta Instrument A/B

Objectives: Objectives: Show the importance of magnetic resonance imaging (MRI) in patients with sudden deafness (SD), evaluating the frequency and characteristics of abnormalities found. Methods: We performed MRI in 49 of 61 patients with sensorineural hearing loss treated by an otorhinolaryngologist in the emergency room from April 2001 to May 2003. Twelve patients stopped treatment or did not undergo MRI. Results: Twenty-three patients presented abnormalities on MRI. Five tumors were found, 2 suggesting meningioma, and 3 suggesting vestibular schwannomas. Subcortical and periventricular lesions hyperintense in FLAIR (fluid attenuation inversion recovery) were found in 13 patients. Five patients presented peripheral alterations that appeared as 2 types: a vestibulo-cochlear gadolinium-enhanced change observed in sequence T1, in 2 patients, and a hyperintense vestibulocochlear signal observed in sequence T2. Conclusions: In the etiologic investigation of patients with SD, MRI is becoming more important and, in this study, MRI showed abnormalities in 46.9% of these patients. It can also identify and clear up etiologic bases or suggest a physiopathologic course for the sudden onset of deafness.

Objectives: To determine whether clinically obtained auditory brainstem response (ABR) shows significant changes over time associated with the growth of vestibular schwannomas related to neurofibromatosis 2 (NF2) and to evaluate the clinical use of derived band ABR in NF2 patients. Methods: Subjects meeting the NIH NF2 diagnostic criteria were enrolled (n = 103) across 9 domestic and international investigational sites. ABR and MRI exams were conducted annually. Each site was instructed to follow a comprehensive protocol for acquiring the MRI. The sites were instructed to assess the ABR either with the usual clinical parameters or using derived band methodology. Results: Wave 5 latency data were available for 35 subjects at both baseline and year 1. Average latency values were found to be clinically normal at both evaluations (average = 6.4 ms). Subjects experienced an average change in Wave 5 from baseline to year 1 of 0.06 ms. A strong association was found between Wave 5 latency at baseline and the greatest diameter measurement of the tumor (Pearson’s correlation = 0.62, P < 0.05), where larger tumors have longer latencies. The subjects with derived band ABR were further evaluated for change over time. Conclusions: ABR wave 5 latency shows a strong association with size, the longer the latency, the larger the vestibular schwannoma, regardless of how the ABR was obtained. Across evaluations, there was a nonsignificant change in wave latencies. Clinically obtained ABR provides information regarding size but provides less information about the change in vestibular schwannomas over time. Derived band ABR offers greater measurement specificity for observing NF2 patients over time.

Surgical removal remains the primary mode of therapy for large vestibular schwannomas. The current goals of treatment are preservation of life, avoidance of brain injury and reduction of cranial nerve deficits. Although historically, poorer facial nerve outcomes are associated with removal of large vestibular schwannomas, we have demonstrated excellent facial nerve results in 94% of patients. It should be noted that in large tumors, facial nerve function is often correlated with the extent of tumor removal. In our current series, 76% of patients underwent total tumor removal and in 24%, subtotal removal was elected intraoperatively. Of the 9 patients who underwent subtotal removal, 1 patient has required revision surgery and the remaining 8 continue to be followed with serial imaging and have stable residual tumors. Total tumor removal is an important goal in order to reduce the risk of future surgery, however, consideration should be given to the risk of permanent facial nerve weakness. Facial nerve dysfunction greatly impacts quality of life and additional rehabilitation can be costly. In order to further reduce the risk of facial nerve dysfunction, alternative surg ical treatment strategies have been described when addressing the treatment of large tumors. Recent studies by Patni and Kartush (2005) demonstrated H-B grade I facial nerve function in 94% of patients following staged resection of large tumors 7 . Furthermore, treatment options

Vestibular schwannomas (acoustic neuromas) are benign, slow-growing tumors of the eight cranial nerve. For patients who undergo surgical management in whom hearing preservation is not an issue, a translabyrinthine approach to these tumors is used. However, when hearing preservation is attempted, the two widely used approaches are the retrosigmoid (RS) approach and the middle fossa (MF) approach. Prior to 1996, our institution used the RS approach for hearing preservation attempts. In an effort to improve our hearing preservation rate, in 1996 we changed to the middle fossa (MF) approach for largely intracanalicular tumors with good hearing.

In the period from 1977 to 1996 143 vestibular schwannomas were diagnosed in 138 patients in the County of Aarhus, Denmark. The natural history of vestibular schwannomas was observed in 50 patients with 52 tumours who did not undergo immediate surgical removal of their tumour due to small tumour size, advanced age, poor general health and the patients' refusal of surgery. The management included serial CT- or MR-imaging and complete otoneurological evaluation. The imaging interval was between 6 months and 2 years and depended on the recorded growth rate. Thirty-three (64%) of the tumours showed continuous growth with a mean growth rate of 1.6 mm/year. In 11 (21%) of the tumours the size was unchanged and eight (15%) remitted. The last group consisted mainly of the largest tumours. Among the tumours with positive growth, 15 (45%) had a growth rate of 1 mm/year or less. Generally, our findings showed that approximately two-thirds of all the tumours did not grow, were getting smaller or had a growth rate sufficiently small to be simply watched. Additionally, our results suggest that some symptomatic tumours will grow to a certain point whereupon stagnation or remission occurs.