Conservative Management Of Acoustic Neuromas

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Keyhole retrosigmoid approach for large vestibular schwannomas: strategies to improve outcomes

OBJECTIVE There are numerous treatment strategies in the management for large vestibular schwannomas, including resection only, staged resections, resections followed by radiosurgery, and radiosurgery only. Recent evidence has pointed toward maximal resection as being the optimum strategy to prevent tumor recurrence; however, durable tumor control through aggressive resection has been shown to occur at the expense of facial nerve function and to risk other approach-related complications. Through a retrospective analysis of their single-institution series of keyhole neurosurgical approaches for large vestibular schwannomas, the authors aim to report and justify key techniques to maximize tumor resection and reduce surgical morbidity. METHODS A retrospective chart review was performed at the Centre for Minimally Invasive Neurosurgery. All patients who had undergone a keyhole retrosigmoid approach for the resection of large vestibular schwannomas, defined as having a tumor diameter of ≥ 3.0 cm, were included in this review. Patient demographics, preoperative cranial nerve status, perioperative data, and postoperative follow-up were obtained. A review of the literature for resections of large vestibular schwannomas was also performed. The authors' institutional data were compared with the historical data from the literature. RESULTS Between 2004 and 2017, 45 patients met the inclusion criteria for this retrospective chart review. When compared with findings in a historical cohort in the literature, the authors' minimally invasive, keyhole retrosigmoid technique for the resection of large vestibular schwannomas achieved higher rates of gross-total or near-total resection (100% vs 83%). Moreover, these results compare favorably with the literature in facial nerve preservation (House-Brackmann I-II) at follow-up after gross-total resections (81% vs 47%, p < 0.001) and near-total resections (88% vs 75%, p = 0.028). There were no approach-related complications in this series. CONCLUSIONS It is the experience of the senior author that complete or near-complete resection of large vestibular schwannomas can be successfully achieved via a keyhole approach. In this series of 45 large vestibular schwannomas, a greater extent of resection was achieved while demonstrating high rates of facial nerve preservation and low approach-related and postoperative complications compared with the literature.

[Clinical and radiological evolution of a group of untreated acoustic neuromas]

INTRODUCTION

The acoustic neuroma is a benign tumour that originates in the vestibular branch of the eighth cranial nerve. The main treatment is surgery, but many authors suggest that with elderly patients or in small neuromas we can opt for watchful waiting.

METHODS

This was a retrospective study from 2007 to 2013 that included 27 patients diagnosed of acoustic neuroma that had not been treated due to the size of the tumour, age and comorbidities, or by patient choice. We evaluated overall condition, hearing thresholds, degree of canal paresis and central disorders.

RESULTS

After 6 years of follow up, clinical manifestations of 18 patients remained unchanged, 5 patients underwent hearing loss and developed tinnitus, 2 cases had more intense tinnitus and 2 cases had dizziness. The radiological controls by magnetic resonance imaging showed that the initial maximum diameters (5-16mm) increased by 1.7mm on average, with annual growth rates below 0.5mm.

CONCLUSION

In selected cases, such as for small neuromas and in elderly patients, the conservative option of close monitoring with magnetic resonance imaging is an important alternative given that, in our cases, clinical features and radiological image did not suffer major changes. If there were any such changes, therapeutic options could be proposed.

Acoustic tumor observation and failure to follow-up

OBJECTIVE

To review the clinical course of patients undergoing observation for their acoustic tumor with evaluation of the incidence and contributing variables to failure to follow-up.

STUDY DESIGN

Case series with chart review and telephone interview.

SETTING

Single subspecialty practice.

SUBJECTS AND METHODS

One hundred twenty-two patients underwent an observation period after their unilateral acoustic tumor was diagnosed. Follow-up patterns were noted and multiple patient variables were analyzed to determine risk factors that contributed to risk of failing to keep prescribed follow-up. Telephone interviews and/or public record reviews were conducted to determine the reasons for failing to follow-up.

RESULTS

Fifty-two (42.6%) patients failed to keep prescribed follow-up. No preoperative patient or tumor variables were correlated with the risk of failure to follow-up. The investigators were able to contact and interview 20 patients to determine reasons for not keeping follow-up. Of these patients, nine (45%) electively chose not to follow-up, six (30%) did not appear to have a clear understanding of their diagnosis or treatment options despite adequate counseling, and five (25%) had medical problems that took precedence over the acoustic tumor. Very few patients elected to reschedule follow-up even after contact was made.

CONCLUSION

Failure to follow-up is a serious problem with acoustic tumor observation protocols. It is difficult to detect which patients are at risk for noncompliance. Patient noncompliance with observation protocols should be considered when determining the most appropriate treatment for each acoustic tumor patient.

The natural history of untreated sporadic vestibular schwannomas: a comprehensive review of hearing outcomes

Object

Observation is an important consideration when discussing management options for patients with vestibular schwannoma (VS). Most data regarding clinical outcomes after conservative management come from modestsized series performed at individual centers. The authors performed an analysis of the published literature on the natural history of VSs with respect to hearing outcome. Their objective was to provide a comprehensive and unbiased description of outcomes in patients whose disease was managed conservatively.

Methods

The authors identified a total of 34 published studies containing hearing outcome data in patients with VSs < 25 mm in largest diameter who underwent observation management. The effects of initial tumor size and tumor growth rate on hearing function at latest follow-up were analyzed. Data from individual and aggregated cases were extracted from each study. Patients with poorer hearing (American Association of Otolaryngology–Head and Neck Surgery Classes C or D, or Gardner-Robertson Classes III, IV, or V) at the time of presentation were excluded.

Results

A total of 982 patients met the inclusion criteria for this analysis, with a mean initial tumor size of 11.3 ± 0.68 mm. The mean growth rate was 2.9 ± 1.2 mm/year. The length of follow-up for these studies ranged from 26 to 52 months. Patients with preserved hearing at latest follow-up had a statistically larger initial tumor size than those whose hearing declined during the observation period (11.5 ± 2.3 mm vs 9.3 ± 2.7 mm, p < 0.0001), but the 2-mm difference of means was at the limit of imaging resolution and observer reliability. In contrast, patients with lower rates of tumor growth (≤ 2.5 mm/year) had markedly higher rates of hearing preservation (75 vs 32%, p < 0.0001) compared with patients with higher tumor growth rates. Interestingly, the authors' analysis found no difference in the rate of reported intervention for patients in either group (16 vs 18%, p = not significant).

Conclusions

These data suggest that a growth rate of > 2.5 mm/year is a better predictor of hearing loss than the initial tumor size for patients undergoing observation management of VSs < 25 mm in largest diameter.

Spontaneous regression of vestibular schwannomas after resection of contralateral tumor in neurofibromatosis Type 2

The authors report on 2 patients with bilateral vestibular schwannomas (VSs) who underwent unilateral surgical tumor removal. One patient was followed up for 4 years, the other for 9; in both cases, the contralateral VS regressed markedly without any additional treatment during the follow-up period. Serial MR imaging was performed to monitor the untreated tumor, which in both cases involved the only hearing ear. The tumors were assessed volumetrically. The contralateral tumors appeared to enlarge mildly at initial follow-up and then, with no treatment, regressed (to 23% of the original maximum volume in Case 1 and to 15% of the original maximum in Case 2). The largest posterior fossa diameter decreased from 30.1 mm to 18.6 mm in Case 1 over 4 years and from 27 mm to 16 mm over 8 years in Case 2. Hearing declined only mildly during follow-up in both patients.

These cases demonstrate the first well-documented, long-term, spontaneous VS regressions in patients with neurofibromatosis Type 2. They underline the importance of careful observation of VS involving the only hearing ear in the management of bilateral VS to determine the natural growth pattern of the tumors. The mechanism of the dramatic spontaneous tumor regression is uncertain.

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

Object

The object of this study was to evaluate the natural history, pattern, and occurrence of tumor growth and its consequences for treatment of small-sized vestibular schwannomas (VSs).

Methods

From 1990 to 2005, 386 patients underwent conservative management for VS because of the following: age > 60 years, poor health/medical risks, risk of deterioration of good hearing, small tumor size, minimal or no incapacitating symptoms, and/or patient preference. Tumor size was measured by MR imaging according to the guidelines of the Committee on Hearing and Equilibrium. The first MR imaging study was performed 1 year after diagnosis, and subsequent imaging was performed yearly or every 2 years depending on the appearance of new symptoms, tumor growth, or both.

Results

Sixty-one patients were lost to follow-up the first year after presentation. Of the 325 patients for whom 1-year follow-up data were available, 39 showed tumor growth ≥ 3 mm. Conservative management was discontinued for these 39 patients. The patients who returned for follow-up were evaluated at 1- or 2-year intervals depending on tumor growth. The authors extrapolated to obtain data for 2-year intervals, yielding data for 160, 56, 21, and 8 patients at 3, 5, 7, and 9 years after initial presentation, respectively. The overall mean tumor growth rate (±standard deviation) was 1.15 ± 2.4 mm/year. This rate was estimated by pooling all values of tumor growth that had been determined for all patients and dividing by the total number of “events,” with each assessment constituting an event. In 58.6% of patients, the annual tumor growth rate was < 1 mm/year; in 29.2%, 1–3 mm/year; and in 12.2%, ≥ 3 mm/ year. The growth rates of intrameatal (1.02 ± 1.8 mm/year) and extrameatal (1.40 ± 3.1 mm/year) tumors did not differ significantly. No significant association was found between tumor growth rate and sex, age, initial hearing status, or initial tumor grade. Delay in diagnosis was the only significant factor associated with tumor growth rate. During follow-up, conservative management was discontinued for 77 (23.7%) of the 325 patients for whom at least 12-month follow-up data were available; surgery was performed in 60 (77.9%) and radiation therapy in 17 (22.1%).

Conclusions

The results of this study support the role of a conservative “wait-and-scan” policy of management for small-sized VSs because most have a slow growth rate. Long-term neuroimaging follow-up is needed even with non-growing tumors.

The natural history of vestibular schwannoma

OBJECTIVE

The incidence of vestibular schwannomas (VSs) approaches 20 per million/yr. As treatment may depend on tumor growth, there is a demand of a treatment strategy based on hard data on the growth pattern of these tumors. This article reports growth data registered prospectively in 552 patients.

STUDY DESIGN

Of the 1,818 consecutive patients, diagnosed with VS during the period from 1975 to 2005, 729 patients were allocated to observation by repetitive magnetic resonance imaging. At least two scans had been performed in 552 patients at the time of data analysis. Two hundred thirty patients had a tumor confined to the internal acoustic meatus, whereas 322 patients had a tumor with an extrameatal extension. Growth to extrameatal extension was the definition for growth in intrameatal tumors, whereas a largest diameter change of more than 2 mm was the criteria for growth/shrinkage of extrameatal tumors. The mean observation time was 3.6 years (range, 1-15 yr).

RESULTS

Seventeen percent of the intrameatal tumors grew, whereas significantly more of the extrameatal tumors displayed growth during the period (28.9%). Growth occurred within the first 5 years after diagnosis. No correlation could be demonstrated between tumor growth rate, sex, or age.

CONCLUSION

VS growth occurs within the first 5 years after diagnosis in a limited number of tumors, primarily in tumors with an extrameatal extension. We found no relation between tumor growth and sex or age. These findings justify primary observation of small tumors. A treatment strategy is proposed for this disease, focusing on the patient group allocated to observation.

Spontaneous regression of a growing vestibular schwannoma

A 75-year-old woman presented with a small right vestibular schwannoma which enlarged and then spontaneously regressed during conservative management. The tumor increased in size from 5.2 to 16.7 mm over 7 years with worsening symptoms of tinnitus, dizziness, and headache. The tumor then regressed to 8.2 mm and the symptoms improved for 4 years without further treatment. Changes in tumor growth should be carefully monitored during conservative management of patients with vestibular schwannoma.

Systematic review of the natural history of vestibular schwannoma

OBJECT

Magnetic resonance (MR) imaging now permits diagnosis of increasing numbers of small, minimally symptomatic vestibular schwannomas (VSs). Because VS growth patterns over time are very important in refining treatment strategies, these matters were systematically reviewed.

METHODS

An extensive MEDLINE search was performed to cull studies on VS growth according to sequential imaging. The percentages of growing and regressing tumors and lesions requiring treatment during follow-up periods were calculated. Factors associated with differences among studies were identified. Twenty-six studies including 1340 patients met all inclusion criteria. The overall frequency of VS growth during a mean follow-up period of 38 months was 46% (95% confidence interval [CI] 43-48%) and that of regression was 8% (95% CI 6-10%). The mean annual tumor growth rate was 1.2 mm/year. Furthermore, the percentage of cases requiring treatment during follow up was 18% (95% CI 16-21%). According to results of a sensitivity analysis, evaluation by serial MR imaging (39%, 95% CI 35-43%) and a prospective study design (29%, 95% CI 21-37%) were associated with less frequent reported tumor growth.

CONCLUSIONS

Although their applicability may be limited to relatively elderly patients with small tumors, data revealing a limited frequency of VS enlargement and an infrequent necessity for eventual therapy should assist decision-making in the treatment of small VSs causing minimal symptoms.

Unilateral Acoustic Neuromas: Long-Term Hearing Results in Patients Managed with Fractionated Stereotactic Radiotherapy, Hearing Preservation Surgery, and Expectantly

INTRODUCTION

Hearing preservation is invariably a consideration when exploring treatment options for acoustic neuromas. We reviewed the long-term hearing results of patients who were treated using 1) hyperfractionated stereotactic radiotherapy (HSR), 2) hearing preservation tumor excision surgery (HPTES), and 3) expectantly (no treatment).

METHODS AND MATERIALS

Single institution retrospective chart review of 42 patients managed with HSR (1993-2003), 113 patients in whom HPTES was carried out, and 86 patients who were untreated (1974-2003). Hearing levels were graded according to the Gardner-Robertson classification.

RESULTS

The percent of patients managed with HSR initially who had serviceable hearing (class 1-2) was 68.8%. This fell to 6.7% in the follow-up interval. Of the group treated with HPTES, 100% had preoperative serviceable hearing. This dropped to 15.9% in the follow-up interval. The percent of patients managed expectantly who initially had serviceable hearing was 77.3%. This dropped to 33.3% during the follow-up interval. Mean follow-up periods were 4.0, 9.5, and 6.8 years in the HSR, HPTES, and expectant groups, respectively.

CONCLUSIONS

Hearing acuity statistically worsened over the long term (P < .01) in all three groups. There was a significant proportion of patients in whom hearing deteriorated from serviceable to nonserviceable hearing (P < .01) during the follow-up interval. The decline was most significant in the groups treated with HPTES and HSR compared with the group treated expectantly (P < .05). Hearing outcomes, in our experience, continue to be poor, but this is especially so in patients treated with HPTES or HSR.

Conservative management of vestibular schwannomas - second review of a prospective longitudinal study

Vestibular schwannomas have been traditionally managed with microsurgical removal and in recent years, stereotactic radiotherapy. However, there is a group of patients in whom a conservative management approach might represent a desirable alternative. The aim of this study was to determine the natural history and outcome following the conservative management of 72 patients with unilateral vestibular schwannomas. This is a prospective cohort review of a previously published group of patients [Clin. Otolaryngol. (2000) 25, 28-39] with unilateral vestibular schwannoma that were initially analysed at our institution in 1998 [Walsh R.M., Bath A.P., Bance M.L. et al., Clin. Otolaryngol. (2000) 25, 28]. The mean duration of follow-up was 80 months (range 52-242 months). All the patients in the study underwent serial magnetic resonance imaging (MRI) for assessment of tumour growth. Patients were deemed to have failed conservative management if there was evidence of rapid radiological tumour growth and/or increasing signs and symptoms, which necessitated active intervention. The mean tumour growth rate for the entire group at the second review was 1 mm/year (range -0.84-9.65 mm/year). The mean growth rate for cerebellopontine angle tumours (1.3 mm/year) was significantly greater than that of internal auditory canal (IAC) tumours (0 mm/year) (P = 0.005). The majority of tumours (87.14%) grew <2 mm/year. There was significant tumour growth seen in 38.9%, no or insignificant growth in 41.7%, and negative growth in 19.4%. Twenty-three patients (32%) failed conservative management at the second review. There was no difference in the outcome of these failed patients in comparison with patients who underwent primary treatment without a period of conservative management. The mean growth rate of tumours in patients that failed conservative management (3.1 mm/year) was significantly greater than that in patients who did not fail (0.2 mm/year) (P < 0.001). No factors predictive of tumour growth or failure of conservative management were identified. Hearing deterioration with pure tone averages (0.5, 1, 2, 3 kHz) and speech discrimination scores occurred irrespective of tumour growth. This prospective study further emphasizes the role of conservative management in selected cases of vestibular schwannomas. Tumours in this study confined to the IAC typically demonstrated minimal or no growth on serial MRI scanning. Regular follow-up with interval scanning is mandatory in all patients.

Quality of Life in patients with vestibular schwannomas managed conservatively

Since the era of magnetic resonance imaging (MRI) scanning, vestibular schwannomas are being diagnosed earlier, growth has been shown to be static in up to 70% of cases and patients have admitted to a reduced quality of life following acoustic neuroma surgery. The aim of this study was to assess the quality of life in patients with vestibular schwannomas managed conservatively. Fifty patients with a vestibular schwannoma were identified who were being managed by interval MRI scanning. Fifty patients attending the general otolaryngology clinic with similar symptoms were prospectively recruited. Each group was assessed using the short form 36 (SF-36) health survey. Both groups were adequately age and sex matched and the SF-36 scores were comparable across all eight health domains.

The efficacy of corticosteroids in restoring hearing in patients undergoing conservative management of acoustic neuromas

OBJECTIVE

To evaluate the role of corticosteroids in restoring hearing in patients undergoing conservative management of acoustic neuromas.

STUDY DESIGN

Prospective cohort.

SETTING

Tertiary referral center.

PATIENTS

Seven patients with acute hearing loss secondary to an acoustic neuroma.

INTERVENTION

Oral prednisone (1 mg/kg for 1 to 2 weeks) within a week of onset of hearing loss.

MAIN OUTCOME MEASURES

Audiometric assessment at the time of presentation and after corticosteroid therapy.

RESULTS

All seven patients had pure tone reception threshold improvements ranging from 10 to 50 dB in at least two frequencies or more. Speech discrimination thresholds improved after therapy in all seven patients, with gains of 4 to 38% points.

CONCLUSIONS

Patients with acoustic neuromas who are being treated with a "watchful waiting" approach should receive corticosteroid treatment at the first signs of hearing deterioration. An evaluation to rule out a retrocochlear lesion is mandated in patients with sudden hearing loss, regardless of whether the hearing loss responds to corticosteroid treatment. Older data documenting the efficacy of corticosteroids in the treatment of sudden hearing loss may need to be reevaluated, given that many of these studies were conducted before MRI was available.

Management of Acoustic Neuromas in the Elderly: Retrospective Study

The wide availability of gadolinium-enhanced magnetic resonance imaging (MRI-Gd) has led to the discovery of an increasing number of small and less symptomatic acoustic neuromas in elderly patients. We conducted a retrospective study in order to obtain data on outcomes and complications associated with different management strategies that would be useful in establishing a management guideline. We identified 44 patients aged 65 to 77 years with acoustic neuromas who had been managed with either surgery or simple observation with MRI-Gd imaging. Of the entire group, 36 patients had tumors larger than 1 cm, and they underwent surgery (most via the translabyrinthine approach). Complete removal of the tumor was achieved in 34 of these patients (94.4%). At the 1-year follow-up, grade VI facial nerve paralysis was evident in only two of 35 evaluable patients (5.7%). Postsurgical complications occurred in five patients (13.9%), including one death. The remaining eight patients had tumors 1 cm or smaller, and they were managed with periodic MRI-Gd scanning. At the 5-year follow-up, no tumor growth was seen in six of these patients. The other two patients exhibited a tumor growth rate of less than 2 mm per year. No patient in the observation group required surgical intervention.

Is clinical growth index a reliable predictor of tumour growth in vestibular schwannomas?

We have assessed the clinical growth index as an indicator of tumour growth rate in 50 patients with a vestibular schwannoma. Clinical growth index was calculated by measuring the length of history and dividing it by the maximum tumour diameter. Total tumour volumes were also measured from all MRI examinations and an effective tumour volume doubling time was calculated. Radiological growth measurements demonstrated involution in 10/50 patients. The median volume doubling time was 1.65 years (range 20.9-46.3 months, skewness 1.72 years). The median clinical growth index was 0.030 cm per month (range 0-0.270 cm per month, skewness 2.398). There was no significant correlation between volume doubling time and clinical growth index. Identification of rapidly growing tumours with clinical growth index >0.025 cm/month had a positive predictive value of 61%, negative predictive value of 48%, false-positive rate of 30% and false-negative rate of 52%. In conclusion, we have shown that the growth rate of vestibular schwannoma is not related to the clinical growth index and we recommend that this measure should be abandoned in the clinical management of patients where conservative management regimes are being considered.

Diagnostic imaging

Imaging technology continues to advance and simplify the diagnosis of neurotologic pathology. Namely, high-resolution magnetic resonance imaging has provided detailed evaluation of the internal auditory canal and membranous labyrinth. Conversely, the role of high-resolution magnetic resonance imaging as a screening tool remains controversial. Functional imaging studies, such as functional magnetic resonance imaging and single photon emission computed tomography are beginning to find significant roles in the evaluation of patients with cochlear implants. General imaging principles and imaging strategies for specific pathologic conditions of the temporal bone are also discussed.

Acoustic neuroma. Assessment and management

Acoustic neuroma results from abnormal proliferation of Schwann cells. These tumors originate in the region of Scarpa's ganglion at the junction of peripheral and central myelin of the vestibular nerve located in the internal auditory canal (IAC). The bony confine of the IAC houses the VII and the VIII cranial nerves. The presence of tumor mass compresses these structures. The growing tumor mass may also prolapses into the cerebellopontine angle (CPA). With continued growth, the tumor eventually compresses on the brain stem and cerebellum. Despite the benign nature of these tumors, the clinical course of this disease may be fraught with complications.

Diagnostic imaging

Imaging technology continues to advance and simplify the diagnosis of neurotologic pathology. Namely, high resolution magnetic resonance imaging has provided detailed evaluation of the internal auditory canal and membranous labyrinth. Conversely, the role of high resolution magnetic resonance imaging as a screening tool remains controversial. Functional imaging studies such as functional magnetic resonance imaging and single photon emission computed tomography are beginning to find significant roles in the evaluation of cochlear implant patients. General imaging principles and imaging strategies for specific temporal bone pathologies are also discussed.

Vestibular schwannoma growth in patients with neurofibromatosis Type 2: a longitudinal study

OBJECT

The factors that determine the growth rates of vestibular schwannomas (VSs) in patients with neurofibromatosis Type 2 (NF2) are unknown. The authors undertook this study to determine if clinical factors or type of constitutional NF2 mutation were associated with VS growth rates in cases of NF2.

METHODS

The authors reviewed serial gadolinium-enhanced magnetic resonance (MR) images of the head and full spine of 37 patients with sporadic NF2 who had been observed over periods ranging from 0.2 to 8 years (median 3.9 years) at a specialized referral clinic for NF2. A box model was used to calculate VS volumes so that tumor growth rates could be estimated. Temperature-gradient gel electrophoresis was used to screen for constitutional NF2 mutations. The VS growth rates tended to decrease with increasing patient age at onset of signs or symptoms (r2 = 0.23, p = 0.003) and at the time the baseline gadolinium-enhanced MR image was obtained (r2 = 0.38, p < 0.001). The authors did not find significant associations between VS growth rates and the number of non-VS cerebral or spinal tumors or different types of constitutional NF2 mutations.

CONCLUSIONS

There is considerable variability in growth rates of VSs in patients with NF2, but they tend to be higher in patients who are younger at onset of signs or symptoms.

Predictors of vestibular schwannoma growth in patients with neurofibromatosis Type 2

OBJECT

The results of two longitudinal studies of growth rates of vestibular schwannomas (VSs) in patients with neurofibromatosis Type 2 (NF2) differ as to whether VS growth rates decrease or increase with increasing patient age. The authors undertook this study to assess the relationship between VS growth rates and patient age and type of constitutional NF2 mutation; they also examined variability in VS growth rates among multiple patients in families with NF2.

METHODS

Gadolinium-enhanced magnetic resonance images obtained in 18 patients with inherited NF2 from 11 unrelated families were retrospectively analyzed. The patients had been observed for a median of 4 years. Volumes of the VSs were measured using a two-component box model (intrameatal and extrameatal parts measured separately). Single-strand conformation polymorphism analysis and Southern blot analysis were used to identify constitutional NF2 mutations. Growth rates of the VSs were highly variable, but tended to decrease with increasing patient age both at onset of signs or symptoms of NF2 (r2 = 0.35, p = 0.026) and at diagnosis (r2 = 0.33, p = 0.012). The VS growth rates did not vary significantly with the type of constitutional NF2 mutation or the number of non-VS cerebral or spinal tumors. The VS growth rates were highly variable within families and did not correspond to clinical indices of NF2 disease severity, such as patient age at symptom onset and the number of non-VS cerebral and spinal tumors.

CONCLUSIONS

The growth rates of VSs in patients with NF2 are highly variable, but tend to decrease with increasing patient age. Clinical treatment of multiple patients in families with NF2 cannot be based on the expectations of similar VS growth rates, even when other clinical aspects of disease severity are similar.

[Asymptomatic acoustic neurinoma associated with hypophyseal macroadenoma]

The widespread use of gadolinium-enhanced MRI (Gd-MRI) in our hospitals has supposed an increase in detection of asymptomatic acoustic neuromas (AN) as incidental finding. Concurrent primary intracranial tumors of different cell types are extremely uncommon.

CLINICAL CASE

A 23 year-old woman complained of irregular menstrual cycles and galactorrhea for two years. A Gd-MRI scan showed a pituitary macroadenoma and an AN of 1.4 cm. with intracanalicular and cisternal extension. The patient did not have any otologic or neuro-otologic symptoms or signs. Audiograms revealed bilateral normal hearing. The results of acoustic reflex test and electronystagmographic caloric tests were normal. The AN underwent radiosurgery treatment.

DISCUSSION

The literature about atypical AN is reviewed, giving a particular concern on asymptomatic cases. We only have found one case of association between AN and pituitary adenoma. The real prevalence of AN in general population is discussed.

Assessment of vestibular schwannoma growth: application of a new measuring protocol to the results of a longitudinal study

This study pertains to a group of 44 patients with unilateral vestibular schwannoma who did not undergo surgery. Prospectively, the dimensions of the tumor were depicted at regular intervals by means of magnetic resonance imaging and then judged independently by an otolaryngologist and a neuroradiologist. Retrospectively, the size of the tumor was quantified by measuring the maximum surface of the lesion in the axial plane. The retrospective surface measurements confirmed the assessments made in the prospective part of the study: growth in 18% of the patients and shrinkage in 7%; 75% remained unchanged. This approach is a pragmatic means to determine whether the size of a tumor has changed over the course of time.

Incidence and growth pattern of vestibular schwannomas in a Danish county, 1977-98

During a period of 21 years 162 acoustic neuromas or vestibular schwannomas (VS) were diagnosed in the county of Aarhus. During this period the incidence increased gradually, probably due to improvement of the quality of computed tomography imaging (CTI), and more widely available access to magnetic resonance imaging (MRI). Sixty-four patients were followed up by repeated CTI or MRI, whereas the remaining patients were referred for immediate operation. Six of the observed patients had their tumours removed after demonstration of continuous tumour growth. The observation of 64 tumours over periods between 5 months and 15 years provided useful information on the natural history of sporadic VS. Our results showed that 14 VS (22%) regressed, 35 VS (55%) did not grow or had only minimal growth (growth rate up to 1 mm/year), whereas 15 VS (23%) grew > 1 mm/year. All VS with positive growth had regular growth patterns.

A clinical study of vestibular schwannomas in type 2 neurofibromatosis

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.

Current management of acoustic neuromas: review of surgical approaches and outcomes

The management options for patients with acoustic neuromas is discussed with a review of 164 patients assessed and treated between 1994 and 1998. Twenty-one patients have neurofibromatosis type II. In 33 cases initial observation was undertaken with repeated imaging. Surgical removal of 122 tumours was performed in 121 patients. Eleven of these patients have NF2, of whom three underwent Auditory Brainstem Implantation. Hearing preservation tumour removal was attempted in 37 and was successful in 20 (54%). The middle cranial fossa approach was used in ten cases with 100% successful hearing preservation. The retrosigmoid approach was used in 27 cases with 36% successful hearing preservation. Non-hearing preservation tumour removal was performed in 85 cases where hearing was poor or the tumour measured more than 2 cm within the cerebellopontine angle. The translabyrinthine approach was used in 80 of these patients. Postoperative facial nerve outcome was dependent on tumour size. All 38 patients with tumours </= 1.5 cm have normal (Grade 1) facial function. For all sized tumours, 90% of patients have good facial function (82% Grade 1, 8% Grade 2), 7% of patients have moderate function (6% Grade 3 and 1% Grade 4) and only 3% of patients have poor function (2% Grade 5, 1% Grade 6). Lasting complications were minimal with no operative mortality and eight patients (6.4%) suffering CSF fistulae. Seven patients in this series have had stereotactic radiation with variable outcome. The radiobiology of both single dose and fractionated stereotactic radiation is described and the current role of stereotactic radiation in the management of acoustic neuromas is discussed. Surgical tumour removal by an experienced multi-disciplinary team remains the primary treatment modality for acoustic neuromas. The middle cranial fossa approach is recommended for management of intracanalicular tumours. The translabyrinthine approach facilitates facial nerve preservation, particularly in patients with large tumours.

Tumor growth and audiometric change in vestibular schwannomas managed conservatively

OBJECTIVE

To prospectively define the correlation between changes in tumor volume and audiometric function in vestibular schwannomas managed conservatively.

STUDY DESIGN

Prospective longitudinal study.

METHODS

Twenty-one patients (age range, 15-84 y; mean age, 63.3 y) with newly diagnosed vestibular schwannomas were enrolled between 1994 and 1999 in a protocol at The Ohio State University Hospital (Columbus, OH) to evaluate the correlation between tumor volume and audiometric change during a period of observation. Patients were evaluated yearly by clinical examination, a standardized internal auditory canal magnetic resonance imaging scan with gadolinium contrast for volumetric analysis, and audiometric function testing. Demographic data, historical features, neurofibromatosis type 2 (NF2) status, initial testing results, and serial testing results were recorded.

RESULTS

An increase in tumor volume occurred in 14 of the 21 patients (66%). The pattern of volumetric change was found to be extremely variable. Multiple regression analysis revealed significant correlations of changes in tumor volume with changes in pure-tone average and speech discrimination score (P < .0001 and P = .0021, respectively). Change in tumor volume had greater effect on pure-tone average and speech discrimination score in patients initially with class D audiometric function when compared with those initially in class A (P = .0083 and P = .0245, respectively). The presence of NF2 had an independent protective effect against deterioration of the pure-tone average when compared with patients without NF2 (P = .0125).

CONCLUSIONS

This study demonstrated a significant correlation between a change in volume and auditory deterioration in vestibular schwannomas being managed with a trial of observation. A given change in tumor volume appeared to have a greater effect on pure-tone average and speech discrimination score as initial auditory classification declined.

A meta-analysis comparing outcomes of microsurgery and gamma knife radiosurgery

OBJECTIVES/HYPOTHESIS

Surgery has been the most common treatment for acoustic neuromas, but gamma knife radiosurgery has emerged as a safe and efficacious alternative to microsurgery. This meta-analysis compares the outcomes of the two modalities.

STUDY DESIGN

A retrospective MEDLINE search was used to find all surgical and gamma knife studies published from 1990 to 1998 and strict inclusion criteria were applied.

RESULTS

For tumors less than 4 cm in diameter, there is no difference in hearing preservation (P = .82) or facial nerve outcome (P = .2). Surgery on all sized tumors has a significantly lower complication rate than radiosurgery performed on tumors smaller than 4 cm (P = 3.2 x 10(-14)). Surgery also has a lower major morbidity rate than gamma knife radiosurgery (P = 2.4 x 10(-14)). Tumor control was defined as no tumor recurrence or no tumor regrowth. Surgery has superior tumor control when tumors are totally resected (P = 9.02 x 10(-11)). Assuming that all partially resected tumors will recur, surgery still retains a significant advantage over radiosurgery for tumor control (P = .028).

CONCLUSION

Data from these studies date back to the late 1960s and do not completely reflect outcomes using current imaging and procedures. A major difficulty encountered in this study is inconsistent data reporting. Future surgical and radiation reports should use standardized outcomes scales to allow valid statistical comparisons. In addition, long-term results from gamma knife radiosurgery using lower dosimetry have not been reported. Surgery should remain the therapy of choice for acoustic neuromas until tumor control rates can be established.

Translabyrinthine removal of large acoustic neuromas in young adults

OBJECTIVE

the authors reviewed the clinical manifestations and the surgical outcomes in a series of young patients who underwent removal of large acoustic neuromas via the translabyrinthine approach.

METHODS

40 young adults who underwent a translabyrinthine removal of acoustic neuromas 3 cm or greater in size were analyzed. The patient's age ranged from 17 to 30 years. The mean size of tumor was 4.25 cm.

RESULTS

the primary symptoms are similar to those in adult but usually less intense. The average interval time between the primary symptom and the diagnosis was 17 months. A high percentage of preoperative normal hearing (35%) and good facial function (100%) were noted. Translabyrinthine approach was used in all cases. Total removal was realised in 39 patients (97.5%). The facial nerve was anatomically preserved in 37 patients (92.5%). Twenty-six patients (65%) had a good facial function (House-Brackmann grade I or II) immediately or at 1 month after surgery, 11 patients (28%) achieved grade III or IV. Three patients underwent an immediate nerve repair after tumor removal. All of them recovered to grade III or IV 1 year after surgery. Postoperative complications were minimal.

CONCLUSIONS

young adults may have a rapid growth rate but usually have minimal symptoms even with a large acoustic neuroma. The translabyrinthine approach has been used successfully in removal of large acoustic tumors of young patients, with the good result of facial nerve preservation and long-term tumor control.

Distinguishing and treating causes of central vertigo

A patient's dizziness can be caused by a peripheral vestibular disorder, VIIIth nerve compression, brain stem ischemia, or cerebellar stroke. Clues from the history and physical examination are mentioned, and diagnostic entities, such as demyelination, cerebrovascular disease, migraine, Arnold-Chiari malformation, cerebellar degeneration, and neoplastic disease are discussed. Treatment options are outlined so that therapeutic and diagnostic trials can be initiated. Guidelines are offered for when to image the brain or posterior circulation vasculature and when a patient with acute vertigo should be admitted for observation.

The role of conservative management of vestibular schwannomas

Although microsurgery is generally regarded as the conventional treatment of choice for most vestibular schwannomas, there remains a group of patients in whom a conservative management approach may be a desirable alternative. The aim of this study was to determine the natural history and outcome following the conservative management of 72 patients with unilateral vestibular schwannomas. The reasons for conservative management included poor general health, age, patient preference, small tumour size, minimal or no symptoms, and tumour in the only/better hearing ear. The mean duration of follow-up was 39.8 months (range 12-194 months). All patients underwent serial magnetic resonance imaging (MRI) for assessment of tumour growth. Patients were deemed to have failed conservative management if there was evidence of continuous or rapid radiological tumour growth and/or increasing symptoms or signs. The mean tumour growth rate, according to the 1995 guidelines of the American Academy of Otolaryngology/Head and Neck Surgery, was 1.16 mm/year (range: 0.75 9.65 mm/year). Approximately 83% of tumours grew at < 2 mm/year. Significant tumour growth was seen in 36.4%, no or insignificant growth in 50%, and negative growth in 13.6% of tumours. The growth rate of CPA tumours (1.4 mm/year) was significantly greater than that of IAC tumours (0.2 mm/year) (P = 0.001). Failure of conservative management, in which active treatment was required, occurred in 15.3%. The outcome of these patients appeared to be as favourable to a comparable group who underwent primary treatment, without a period of conservative management. The mean growth rate of tumours in patients who failed conservative management (4.2 mm/year) was significantly greater than that in patients who did not fail (0.5 mm/year) (P < 0.01). No factors predictive of tumour growth or failure of conservative management were identified. Deterioration of mean pure tone average (0.5, 1, 2, 3 kHz) and speech discrimination scores occurred regardless of whether radiological tumour growth was demonstrated or not. This study suggests that in a select number of cases of vestibular schwannoma, a conservative management approach may be appropriate. Regular follow-up with serial MRI is mandatory. Deterioration of auditory function occurs even in the absence of tumour growth.

Consequences to hearing during the conservative management of vestibular schwannomas

OBJECTIVE

To estimate the risk of loss of serviceable hearing during the conservative management of vestibular schwannomas.

STUDY DESIGN

Retrospective case review.

METHODS

Twenty-five patients with a radiological diagnosis of unilateral vestibular schwannoma were managed conservatively for a mean duration of 43.8 months (range, 12-194 mo). The pure-tone average (PTA) (0.5, 1, 2, and 3 kHz) and speech discrimination scores (SDS) were measured at regular intervals throughout the entire duration of follow-up. Serviceable hearing was defined using two criteria: 70% SDS/30 dB PTA (the 70/30 rule) and 50% SDS/50 dB PTA (the 50/50 rule). The size and growth rate of tumors were determined according to the American Academy of Otolaryngology-Head and Neck Surgery guidelines (1995). Intervention was recommended if there was evidence of continuous or rapid radiological tumor growth, and/or increasing symptoms or signs suggestive of tumor growth.

RESULTS

The risk of loss of serviceable hearing for the total group was 43% using the 70/30 rule and 42% using the 50/50 rule. Tumor growth was considered significant (> 1 mm) in 8 tumors (32%) and nonsignificant in 17 (68%). The risk of loss of serviceable hearing for the tumor-growth group was 67% using the 70/30 rule and 80% using the 50/50 rule. In contrast, the risk of loss of serviceable hearing for the no tumor-growth group was 25% using the 70/30 rule and 14% using the 50/50 rule. No audiological factors predictive of tumor growth were identified.

CONCLUSIONS

There is a significant risk of loss of serviceable hearing during the conservative management of vestibular schwannomas. This risk appears to be greater in tumors that demonstrate significant growth.

Postoperative quality of life in vestibular schwannoma patients measured by the SF36 Health Questionnaire

OBJECTIVE

To quantify the postoperative quality of life in patients following surgical treatment for vestibular schwannoma.

STUDY DESIGN

Patient self-assessment using the short form 36 (SF36) multidimensional quality of life health questionnaire. Sex- and age-matched normalized scores were calculated using a standardized process and accepted normative data.

SETTING

Tertiary referral skull base unit.

RESULTS

An 80% response rate (90 patients) was achieved. The postoperative quality of life in vestibular schwannoma patients, as quantified by seven of the eight SF36 health scales was less than the appropriate matched healthy standard. Comparison of a variety of preoperative patients and tumor factors-different operative approaches (translabyrinthine and retrosigmoid), tumor size (group cut of points of tumor diameter 1.5 mm and 2.5 mm), patient sex, and ranking of patient age-showed no statistically significant difference in measured quality of life outcomes for each of these traditional predictors.

CONCLUSION

Reduced quality of life in patients after surgical treatment for vestibular schwannoma, coupled with the low tumor growth rates and minimal preoperative symptoms, supports a conservative approach to patient management. The advantages and disadvantages of a variety of approaches used to measure the quality of life after surgical treatment of vestibular schwannoma and their impact on clinical decision making for patients, are discussed.

A Molecular, Clinical and Immunohistochemical Study of Vestibular Schwannoma

The molecular pathogenesis of vestibular schwannoma has been investigated by determining the extent of chromosome 22 loss of heterozygosity in 77 tumors and relating these findings to clinical and immunohistochemical indexes of tumor behavior. Loss of heterozygosity was looked for at eight chromosome 22q loci. Clinical details were obtained in all 77 cases, and a clinical growth index was calculated for each tumor. The proliferative index was estimated in all tumors by using a monoclonal antibody to the proliferating cell nuclear antigen and by calculating the labeling index. Forty percent (31 of 77) of the tumors showed allele loss, and in each case this loss involved the region of the neurofibromatosis type 2 gene. No evidence was found that the presence of chromosome 22 allele loss was associated with the clinical growth index. On the log scale, however, an association was seen between the clinical growth index and the proliferating cell nuclear antigen labeling index p = 0.001). These results suggest that chromsome 22 allele loss is a frequent event in vestibular schwannoma. Tumor behavior, however, appears to be independent of the chromosome 22 mutation. It is proposed that chromosome 22 allele loss and neurofibromatosis type 2 gene inactivation is an early event, possibly involved in the initiation of tumorigenesis in vestibular schwannoma. Tumor growth appears to be independent of this mutation and is likely to be determined by other as yet undefined factors.

Non-surgical treatment of vestibular schwannoma patients

The aim of the study was to evaluate the course of vestibular schwannoma (VS) when surgery was not attempted. The tumor may be slowly growing and surgery a risk for a patient. Twenty-eight patients out of 390 VS patients during years 1981-1995 were primarily recommended a non-surgical treatment. Another 3 patients refused the operation. Altogether 23 women and 8 men were evaluated. Their age varied from 30.6 to 74.6 years (median 56.7 years). Tumor size varied from 5 to 30 mm (median 15.0 mm) at the beginning of the follow-up. Patients symptoms, condition and other illnesses were recorded. Seven patients had neurofibromatosis 2 (3 of them had one hearing ear), 2 had severe mental problems, 5 patients had their only hearing ear and 11 patients were not recommended an operation because of their age and other illnesses. Patients were controlled with MRI at intervals from 1 to 3 years. The follow-up time varied from 1 to 20 years (median 2.0 years). The average tumor growth rate among unilateral VS patients was 0.035 cm/year and among bilateral tumors the average tumor growth rate was 0.015 cm/year. Two patients were later operated on, one 2 years after diagnosis because of the tumor growth and the other one 4 years after diagnosis-she had refused an operation earlier. Two patients could not be reached. Another patient had tumor growth but because of his illnesses he got a radiation beam instead of an operation. The majority of the patients could live fairly normal lives and required no treatment. Surgery is not the only alternative to VS patients. Wait-and-see policy is also a good alternative to those who have high operation risk or who refuse an operation.

Management of 1000 vestibular schwannomas (acoustic neuromas): clinical presentation

OBJECTIVE

Despite good knowledge of the key symptoms of vestibular schwannomas and their significance for surgical results, the evolution of symptoms and signs and their relation to tumor extension still need thorough investigation.

METHODS

From 1978 to 1993, operations were performed by the same surgeon (M.S.) on 1000 vestibular schwannomas at the Neurosurgical Department of Nordstadt Hospital. The vestibular schwannomas were diagnosed in 962 patients, including 522 female patients (54%) and 440 male patients (46%); the mean age was significantly higher in female patients (47.6 yr) than in men (45.2 yr). We focused our analysis on the incidence of subjective disturbances versus objective morbidity, on the sequence of symptom onset, and on symptom duration and symptomatology versus tumor size and extension.

RESULTS

The most frequent clinical symptoms were disturbances of the acoustic (95%), vestibular (61%), trigeminal (9%), and facial (6%) nerves. Symptom duration was 3.7 years for hearing loss, 1.9 years for facial paresis, and 1.3 years for trigeminal disturbances. Symptom incidence and duration did not strictly correlate with tumor size. Key symptoms of various tumor extension classes precipitated the diagnosis, such as trigeminal disturbances in large tumors with brain stem compression or tinnitus in small neuromas. In cases of trigeminal or facial nerve symptoms, the overall duration of symptomatology was much shorter. According to the subjective perception of the patients, between only one- and two-thirds of nerve disturbances were noticed. Patients with preoperative deafness had become deaf either chronically (23%) or suddenly (3%); even in cases of moderate hearing deficit that lasts a long time, deafness can occur suddenly. The rate of tinnitus was higher in hearing than in deaf patients; however, deafness does not mean relief from tinnitus, because this symptom persists in 46% of preoperatively deaf patients. Vestibular disturbances most often occur as some unsteadiness while walking or as vertigo, and the symptoms frequently are fluctuating, not constant.

CONCLUSION

Differences in tumor biology can be underestimated and are not visible on radiological scans. For example, intrameatal tumors, despite their small size, present with a duration of symptoms that is representative of the larger tumors and are most frequently associated with vestibular symptoms and with tinnitus. Large tumors with brain stem compression present with relatively shorter symptom durations and at a younger age; both factors are suggestive of especially fast tumor growth. The clinical findings presented in this study promote new consideration of the dynamics of tumor growth and of the affected neural tissues.

Thallium chloride 201Tl combined with single photon emission computed tomography (SPECT) in the evaluation of vestibular schwannoma growth

Thallium chloride 201Tl combined with SPECT was performed in a series of 29 patients with neuroradiological evidence of vestibular schwannoma (VS). The relative tumor uptake (U) and relative tumor concentration (C) of the radiotracer 201Tl was determined, and the cerebellum served as a reference. The relative tracer concentration and uptake were correlated to tumor volume determined by gadolinium DTPA enhanced MR, to prediagnostic duration of symptoms, to tumor vascularity expressed by the average number of intratumoral vessels using the endothelial marker CD31, and to the proliferative activity in the tumors expressed by positive staining with the monoclonal antibody MIB-1 for Ki-67. A positive 201TI enhancement was detected in 17 tumors (n = 17). Tumors U and C were statistically unrelated to tumor volume (p = 0.236 and p = 0.439). SPECT demonstrated all tumors > 0.8 cm3, but it had its limitation as a diagnostic modality of small intracanalicular tumors, when compared with gadolinium DTPA enhanced MR. Relating U and C in all tumors (n = 29) and the prospectively registered data on the prediagnostic duration of symptoms, a statistical significance was found (p = 0.012 and p = 0.015). No statistically significant correlation was observed between U and C and the proliferative activity of the tumors expressed by positive staining with the monoclonal antibody MIB-1 for Ki-67 (p = 0.063 and p = 0.086). A statistically significant correlation was noted between C and U in the operated group (n = 12) and tumor vascularity expressed by the average number of the intratumoral vessels (p = 0.003 and p = 0.014). SPECT was found to be superior to MR in determining VS growth potentials as it expresses tumor vascularity, which is essential for tumor growth. It seems that we now have an in vivo functional radiological modality capable of providing data on VS vascularity and determination of growth potential in the individual tumor. A high radioactive tracer uptake in the tumor corresponded to high tumor vascularity, indicating a high growth rate and vice versa.

Growth rate characteristics of acoustic neuromas associated with neurofibromatosis type 2

Neurofibromatosis type 2 (NF2) is a dominantly inherited disorder characterized by the occurrence of bilateral acoustic neuromas (ANs and other central nervous system tumors. Magnetic resonance images and audiologic data on 22 patients with NF2 who underwent multiple studies at the National Institutes of Health between 1983 and 1993 were reviewed to determine the growth characteristics of ANs in these patients. The average growth rate of ANs in NF2 patients was 0.30 cm3 per year and was significantly higher in older patients (0.75 cm3 per year) than in younger ones (0.12 cm3 per year). Larger ANs were more commonly found in patients with concomitant spinal tumors or meningiomas. NF2 patients with spinal tumors but not meningiomas demonstrated faster growth rates than patients without additional tumor burden. The data from this study suggest that older patients or patients with associated spinal tumors have faster growing ANs and therefore should be followed closely and treated aggressively.

Conservative management of patients with small acoustic tumors

Of 432 patients referred for treatment of their cerebellopontine angle tumors, 53 with acoustic neuromas were managed initially without intervention but with adequate follow-up. Mean presenting tumor size in this subgroup of patients was 0.98 cm (range, 0.2 to 3.0 cm), and average growth rate was 0.16 cm per year. Twenty-one patients demonstrated tumor growth with a mean follow-up interval of 1.9 years. Of these 21 patients, 14 underwent microsurgical excision, 4 received radiation, 2 continued to be observed and 1 was lost to follow-up. The remaining 32 (60%) had no demonstrable growth with a mean follow-up of 2.13 years. Of these patients, 29 continue to be followed and 3 were lost to follow-up. Of the information evaluated, the only statistically significant relationship is with larger tumor size in elderly patients--most likely reflecting the propensity to opt for conservative treatment in elderly patients. Tumor growth rate was unrelated to presenting tumor size or patient age, which suggests that conservative treatment may be appropriate in selected patients.

False-Positive Magnetic Resonance Imaging of Small Internal Auditory Canal Tumors: A Clinical Radiologic, and Pathologic Correlation Study

Magnetic resonance imaging with gadolinium facilitates the early diagnosis of internal auditory canal tumors at a small enough stage to permit increasing application of hearing preservation surgical techniques. Surgeons report successful removal of tumors as small as 3 mm, which are diagnosed with enhanced magnetic resonance imaging. A retrospective study was performed to determine the risk of false-positive “tumor” diagnosis with enhanced magnetic resonance imaging. We reviewed the imaging records, office notes, and surgical records of 112 consecutive “tumors” involving the internal auditory canal treated by the Wilford Hall USAF Medical Center Neurotology Service between July 1991 and July 1994. Two categories of false-positive magnetic resonance imaging were Identified: (1) surgically confirmed absence of internal auditory canal neoplasm and (2) spontaneous resolution of the internal auditory canal lesions on subsequent, enhanced magnetic resonance images. Overall, eight false-positive scans were identified. Three were surgically confirmed as false-positive, and five resolved on subsequent Imaging studies. All cases were smaller than 6 mm and involved the distal internal auditory canal (fundus). The surgically confirmed cases were approached through a middle fossa technique with successful hearing preservation. The overall rate of surgical false-positive results was 3.5% (3 cases in 86 surgeries). However, the overall false-positive rate for intracanalicular “tumors” was 32% (8 cases in 25 intracanalicular lesions). Although hearing preservation is more likely in small lesions, the surgeon must consider the possibility that an internal auditory canal lesion smaller than 6 mm may actually represent a nonneoplastic process. Enhancing lesions limited to the internal auditory canal fundus may be treated by reimaging the patient in 6 months after the first image rather than by prompt surgical exploration.

Management of posterior cranial fossa meningiomas

Posterior cranial fossa meningiomas are relatively common extra-axial tumors with important relationships to the cochleovestibular system, facial nerve, and/or cranial base. Nevertheless, objective reporting of auditory and vestibular function is rare for this patient population, and a full discussion of the nonsurgical management is all but totally discounted in the otolaryngology literature. Nine cases (8 operative cases) are presented, with the purpose of correlating neurotologic function with precise anatomic tumor location, available by magnetic resonance imaging and computed tomography. The usefulness of this information for diagnosis and meaningful scrutiny of the operative results is discussed. A comprehensive review of posterior fossa meningiomas in terms of epidemiology, etiology, and pathology, as well as nonsurgical treatment alternatives, is provided.

Vestibular schwannoma in an only hearing ear

A vestibular schwannoma in an only hearing ear is a difficult management problem. A case is presented of a patient who had a Nucleus-22 channel device implanted into a nonfunctioning ear and auditory rehabilitation prior to resection of a large vestibular schwannoma in the contralateral ear.