Meningiomas of the cerebellopontine angle with extension into the internal auditory canal

[Retrocochlear diagnostics for acute hearing loss and successful therapy]

A 41-year-old female patient presented due to acute onset of unilateral hearing loss 3 months previously and persistent since then. Systemic therapy with oral glucocorticoids in decreasing doses had been performed beforehand, but did not lead to any improvement. In the course of audiological diagnostics, based on subjective and objective methods, a retrocochlear hearing disorder was suspected. A meningioma was diagnosed by diagnostic imaging. Subsequent surgical removal achieved a significant hearing improvement.

Red flags alerting a posterior cranial fossa tumor from audiovestibular perspectives - a review

BACKGROUND

There is no comprehensive and up-to-date overview of audiovestibular approach to the posterior fossa tumors in the literature.

OBJECTIVE

This paper reviewed the literature relating to tumors at the posterior cranial fossa to find red flags alerting a posterior fossa lesion from audiovestibular perspectives.

METHODS

This review was developed from articles published in those journals listed on the journal citation reports. Through the PubMed database, Embase, Google Scholar, and Cochrane library, 60 articles were finally obtained based on the PRISMA guidelines for reporting reviews.

RESULTS

The presence of one red flag indicates a positive predictive value of 33% for detecting a posterior fossa lesion. Clinical features, namely, 1) mid-frequency sudden sensorineural hearing loss (SNHL), 2) bilateral sudden SNHL, and 3) rebound nystagmus may indicate a posterior fossa lesion, representing one, two, and three red flags, respectively.

CONCLUSION

Those with 1) mid-frequency sudden SNHL, 2) bilateral sudden SNHL, and 3) rebound nystagmus trigger one, two, and three red flags, respectively, alerting clinicians the possibility of a posterior fossa lesion, which warrant MR imaging to exclude life-threatening or treatable conditions.

SIGNIFICANCE

Patients with posterior fossa tumors may have potential life-threatening outcome.

Surgical management of large cerebellopontine angle meningiomas: long-term results of a less aggressive resection strategy

OBJECTIVE

Cerebellopontine angle (CPA) meningiomas present many surgical challenges depending on their volume, site of dural attachment, and connection to surrounding neurovascular structures. Assuming that systematic radical resection of large CPA meningiomas carries a high risk of permanent morbidity, the authors adopted an alternative strategy of optimal resection followed by radiosurgery or careful observation of the residual tumor and assessed the efficiency and safety of this approach to meningioma treatment management.

METHODS

This single-center retrospective cohort study included 50 consecutive patients who underwent surgery for meningioma between January 2003 and February 2020.

RESULTS

The most common main dural attachments of the meningiomas were posterior (42%) and superior (26%) to the internal auditory meatus. The suboccipital retrosigmoid route was the most routinely used (92%). At the last follow-up examination, 93% of the patients with normal preoperative facial nerve (FN) function retained good House-Brackmann (HB) grades of I and II, whereas 3 patients (7%) displayed intermediate HB grade III FN function. Hearing preservation was achieved in 86% of the patients who presented with preoperative serviceable hearing, and recovery after surgery was achieved in 19% of the patients experiencing preoperative hearing loss. In order to preserve all cranial nerve function, gross-total resection was obtained in 26% of patients. Of the 35 patients who had undergone subtotal resection, 20 (57%) had been allocated into a wait-and-rescan treatment approach and 15 (43%) underwent upfront Gamma Knife surgery (GKS). The mean postoperative tumor volume was 1.20 cm3 in the upfront GKS group and 0.73 cm3 in the wait-and-rescan group (p = 0.08). Tumor control was achieved in 87% and 55% of cases (p < 0.001), with a mean follow-up of 85 and 69 months in the GKS and wait-and-rescan groups, respectively. The 1-, 5-, and 7-year tumor progression-free survival rates were 100%, 100%, and 89% in the GKS group and 95%, 59%, and 47% in the wait-and-rescan group, respectively (p < 0.001).

CONCLUSIONS

Optimal nonradical resection of large CPA meningiomas provides favorable long-term tumor control and functional preservation. Adjuvant GKS does not carry additional morbidity and appears to be an efficient adjuvant treatment.

Quantitative Chemical Exchange Saturation Transfer Imaging of Amide Proton Transfer Differentiates between Cerebellopontine Angle Schwannoma and Meningioma: Preliminary Results

Vestibular schwannomas are the most common tumor at the common cerebellopontine angle, followed by meningiomas. Differentiation of these tumors is critical because of the different surgical approaches required for treatment. Recent studies have demonstrated the utility of amide proton transfer (APT)-chemical exchange saturation transfer (CEST) imaging in evaluating malignant brain tumors. However, APT imaging has not been applied in benign tumors. Here, we explored the potential of APT in differentiating between schwannomas and meningiomas at the cerebellopontine angle. We retrospectively evaluated nine patients with schwannoma and nine patients with meningioma who underwent APT-CEST MRI from November 2020 to April 2022 pre-operation. All 18 tumors were histologically diagnosed. There was a significant difference in magnetization transfer ratio asymmetry (MTR_asym) values (0.033 ± 0.012 vs. 0.021 ± 0.004; p = 0.007) between the schwannoma and meningioma groups. Receiver operative curve analysis showed that MTR_asym values clearly differentiated between the schwannoma and meningioma groups. At an MTR_asym value threshold of 0.024, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive values for MTR_asym were 88.9%, 77.8%, 80.0%, and 87.5%, respectively. Our results demonstrated the ability of MTR_asym values on APT-CEST imaging to discriminate patients with schwannomas from patients with meningiomas.

Predictors of hearing functional outcome following surgery for cerebellopontine angle meningioma

OBJECTIVE

Cerebellopontine angle (CPA) meningiomas can affect hearing function and require expeditious treatment to prevent permanent hearing loss. The authors sought to determine the factors associated with functional hearing outcome in CPA meningioma patients treated with surgery and/or radiation therapy in the form of either stereotactic radiosurgery or stereotactic radiation therapy.

METHODS

Consecutive patients with CPA meningiomas who had presented at our hospital from 2008 to 2018 were identified through retrospective chart review. Hearing function (as defined by pure tone average (PTA) and speech discrimination score (SDS) on Audiogram) was assessed before and after surgery for CPA meningioma. Audiograms with PTA > 50 dB and SDS < 69% were defined as poor hearing functional outcome. Multivariable Cox Proportional Hazards Regression Model was used to assess the associations between pre-operative hearing functional assessment and post-operative hearing functional outcomes.

RESULTS

The study cohort included 31 patients (80.6% females, with a mean age of 61.3 ± 15.2 years) with a median clinical follow-up of 5 months (range: 1 week-98 months). The mean pre-operative PTA and SDS were 23.8 ± 11.2 dB and 64.4 ± 22.2% respectively. At the last visit, there was significant hearing recovery, with an improvement of 29.7 ± 18.0 dB (p < 0.001) and 87.6 ± 17.8% (p < 0.001) in PTA and SDS respectively. After adjusting for age, gender, tumor volume, location, and tumor classification, Multivariable Cox Proportional Hazards Regression Model was conducted which revealed that patients undergoing surgery through retro sigmoid approach [Hazards Ratio (HR): 32.1, 95% Confidence Interval (CI): 2.11-491.0, p = 0.01] and gross total resection (GTR) (HR: 2.99, 95% CI: 1.09-9.32, p = 0.05) had significantly higher risk of poor hearing functional outcome compared to petrosal approach and near/subtotal resection. Moreover, patients with poor preoperative hearing had 85% higher chance of poor hearing functional outcome postoperatively (HR: 0.15, 95%CI: 0.03-0.59, p = 0.007).

CONCLUSION

Postoperative improvement in hearing is a reasonable expectation following surgery for CPA meningioma. Preoperative hearing, surgical approach and extent of surgical resection are predictive factors of postoperative hearing function outcome and can therefore aid in identification of patients at higher risk of hearing loss.

Endoscopic retrosigmoid keyhole approach in cerebellopontine angle tumors. A surgical cohort

INTRODUCTION AND OBJECTIVES

To determine the safety and efficacy of endoscopic keyhole surgery in patients with cerebellopontine angle tumours.

MATERIALS AND METHODS

This was a retrospective study of patients with cerebellopontine angled tumours treated by fully endoscopic retrosigmoid keyhole approach in a tertiary centre during a period of four years. Preoperative, transoperative and postoperative variables were analysed.

RESULTS

A number of 40 patients were included. The age average was 49.4 years and male/female proportion was 0.4-1. We found 31 vestibular schwannomas (77.5%), five meningiomas (12.5%), two cholesteatomas (5.0%) and two metastases (5.0%). Vestibular schwannomas Hannover type IIIb, IVa and IVb predominated. The surgical resection was total or near-total 92.5% of patients. Hearing preservation rate was 62.5% and acceptable facial function nerve function rate was 80% after six months. Hospital stay was 7.5 days. The total or near total resection and functionally preservation rate was high. Complications were unusual.

CONCLUSIONS

Endoscopic retrosigmoid keyhole approach represented a safe and efficient procedure in selected patients with cerebellopontine angle tumours.

Clinical Studies and Pre-clinical Animal Models on Facial Nerve Preservation, Reconstruction, and Regeneration Following Cerebellopontine Angle Tumor Surgery-A Systematic Review and Future Perspectives

Background and purpose: Tumorous lesions developing in the cerebellopontine angle (CPA) get into close contact with the 1st (cisternal) and 2nd (meatal) intra-arachnoidal portion of the facial nerve (FN). When surgical damage occurs, commonly known reconstruction strategies are often associated with poor functional recovery. This article aims to provide a systematic overview for translational research by establishing the current evidence on available clinical studies and experimental models reporting on intracranial FN injury.

Methods: A systematic literature search of several databases (PubMed, EMBASE, Medline) was performed prior to July 2020. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guidelines. Included clinical studies were reviewed and categorized according to the pathology and surgical resection strategy, and experimental studies according to the animal. For anatomical study purposes, perfusion-fixed adult New Zealand white rabbits were used for radiological high-resolution imaging and anatomical dissection of the CPA and periotic skull base.

Results: One hundred forty four out of 166 included publications were clinical studies reporting on FN outcomes after CPA-tumor surgery in 19,136 patients. During CPA-tumor surgery, the specific vulnerability of the intracranial FN to stretching and compression more likely leads to neurapraxia or axonotmesis than neurotmesis. Severe FN palsy was reported in 7 to 15 % after vestibular schwannoma surgery, and 6% following the resection of CPA-meningioma. Twenty-two papers reported on experimental studies, out of which only 6 specifically used intracranial FN injury in a rodent (n = 4) or non-rodent model (n = 2). Rats and rabbits offer a feasible model for manipulation of the FN in the CPA, the latter was further confirmed in our study covering the radiological and anatomical analysis of perfusion fixed periotic bones.

Conclusion: The particular anatomical and physiological features of the intracranial FN warrant a distinguishment of experimental models for intracranial FN injuries. New Zealand White rabbits might be a very cost-effective and valuable option to test new experimental approaches for intracranial FN regeneration. Flexible and bioactive biomaterials, commonly used in skull base surgery, endowed with trophic and topographical functions, should address the specific needs of intracranial FN injuries.

Role of the neurotologist in posterior fossa meningioma surgery

Posterior fossa meningiomas that impinge on structures of the temporal bone or clivus may be difficult to access for optimal resection that maximizes tumor control and minimizes short- and long-term morbidities. To address this challenge, the contemporary neurosurgery-neurotology team works collaboratively by managing patients jointly at every stage of care: preoperative evaluation, intraoperative intervention, and postoperative treatment. The neurotologist is important at all stages of posterior fossa meningioma surgery. First, detailed preoperative evaluation of auditory, facial, vestibular, and lower cranial nerve integrity enables assessment of new neurologic deficit risk, prognosis of functional recovery, and pros and cons of candidate surgical approaches. Second, intraoperative partitioning of surgical steps by provider and adopting an overlapping tumor resection philosophy creates an efficient and confident surgical team built on trust. Third, postoperative closure of cerebrospinal fluid leak and treatment of facial weakness, audiovestibular dysfunction, and voicing and swallowing impairments organized by the neurotologist reduces the impact of negative outcomes. The role of the neurotologist in posterior fossa meningioma surgery is to deliver nuanced evaluative metrics, facilitate shared decision making, perform precise bone and soft tissue microsurgery, and mitigate perioperative morbidities.

Comorbidity of cerebellopontine angle meningioma with other primary neoplasms

BACKGROUND

Meningioma is known to be accompanied by other primary neoplasms, yet has been evaluated less than these.

OBJECTIVE

This study investigated comorbidity of cerebellopontine angle (CPA) meningioma with other primary neoplasms.

METHODS

Overall 1,085 meningioma cases including 16 meningiomas at the CPA were enrolled for investigating the presence of other primary neoplasms. Another 16 age-, sex-, and size-matched CPA schwannoma were also included for comparison.

RESULTS

Of a data-base cohort study of overall 1085 meningioma cases, 165 cases (15%) were associated with other primary neoplasms. In contrast, 8 (50%) of 16 CPA meningioma and one (8%) of 16 CPA schwannoma showed other primary neoplasms. Except for one patient who had oral cancer prior to the diagnosis of CPA meningioma by 4 years, the interval from diagnosis of CPA meningioma to that of other primary neoplasm ranged 0-6 (mean, 3.1 ± 2.5) years.

CONCLUSION

Prevalence of comorbidity with other primary neoplasms is significantly higher in CPA meningioma (50%) than overall meningioma (15%) and CPA schwannoma (8%). In addition to follow-up MR imaging to visualize both residual tumor and regional brain environment after treatment of CPA meningioma, long-term systemic screening for other primary neoplasm is also mandatory.

Endoscopic retrosigmoid keyhole approach in cerebellopontine angle tumors. A surgical cohort

INTRODUCTION AND OBJECTIVES

To determine the safety and efficacy of endoscopic keyhole surgery in patients with cerebellopontine angle tumors.

MATERIALS AND METHODS

This was a retrospective study of patients with cerebellopontine angled tumors treated by fully endoscopic retrosigmoid keyhole approach in a tertiary center during a period of four years. Preoperative, transoperative and postoperative variables were analyzed.

RESULTS

A number of 40 patients were included. The age average was 49.4 years and male/female proportion was 0.4-1. We found 31 vestibular schwannomas (77.5%), five meningiomas (12,5%), two cholesteatomas (5,0%) and two metastases (5.0%). Vestibular schwannomas Hannover type IIIb, IVa and IVb predominated. The surgical resection was total or near-total 92.5% of patients. Hearing preservation rate was 62.5% and acceptable facial function nerve function rate was 80% after six months. Hospital stay was 7.5 days. The total or near total resection and functionally preservation rate was high. Complications were unusual.

CONCLUSIONS

Endoscopic retrosigmoid keyhole approach represented a safe and efficient procedure in selected patients with cerebellopontine angle tumors.

Additional diagnostic role of MRI spectroscopy, diffusion and susceptibility imaging in differentiation of CPA masses: our experience with emphasis on schwannomas and meningiomas

Background

CPA masses are uncommon lesions and usually have quite distinctive imaging features. Still, diagnosis can be challenging in some cases, carrying a significant impact on the choice of treatment and surgical approach. The purpose of this study was to validate the usefulness of MRI spectroscopy, diffusion, and susceptibility in the characterization of CPA masses with the emphasis on the two commonest lesions: schwannomas and meningiomas.

Results

The study included a total of 27 cases: schwannomas (n = 12), meningiomas (n = 7), epidermoid cysts (n = 2), two chondrosarcomas (n = 2), arachnoid cyst (n = 1), glomus tumor (n = 1), a meningeal metastasis (n = 1), and an endolymphatic sac tumor (n = 1). DWI revealed: eight lesions showed low ADC (<1 × 10−3 mm2/s), 15 lesions with intermediate ADC values (1–1.8 × 10−3 mm2/s), and 4 lesions had high ADC (>1.8 × 10−3 mm2/s.) Meningiomas showed low to intermediate ADC values while schwannomas showed intermediate to high ADC values. A cut-off ADC value of (1 × 10−3 mm2/s) is statistically significant in the differentiation of meningioma from schwannoma. A myoinositol peak was in all 12 schwannomas and single meningioma while 6 meningiomas displayed alanine peak, with a very good statistical significance. Remaining lesions revealed non-specific spectra. SWI made in 18 lesions revealed signal voids in three schwannomas and glomus.

Conclusions

Though MRI features of CPA masses are distinctive in most clinical settings; MRI spectroscopy, diffusion, and susceptibility can provide highly informative additional data in problematic cases. An intermediate to high ADC value plus myoinositol peak and signal voids of micro-bleeds are highly suggestive of schwannomas. This is in contrary to meningiomas displaying low to intermediate ADC and an alanine peak with no micro-bleeds. The less common lesions revealed non-specific data.

Current decision-making in meningiomas

The incidence of meningiomas is rising and the number of incidental cases is increasing steadily. The efficiency and the safety of each treatment strategy are also improving over time. Therefore the indications to treat meningiomas are constantly changing. The aim of meningioma treatment is keeping the patient fully functional while achieving long-term relief or prevention from problems related to intracranial tumor growth. This chapter reviews the natural history and treatment results and aims to put together the information for the most objective decision-making in treating meningiomas. Factors acting on the treatment decision such as anatomical localization, symptomatology, variations in tumor biology, recurrence status, age and co-morbidities, operative gains, and patient preference are individually discussed.

Natural history of intracranial meningiomas

We know that the extent of resection is the greatest predictor of long-term survival. However, the potential tradeoff for gross total resection in difficult locations is diminished quality of life. Benign subtotally resected or small incidentally discovered meningiomas may be followed clinically especially in the elderly. In addition, radiosurgery plays a role in the treatment of meningiomas as a primary treatment modality, or as a salvage therapy. Decisions regarding management should be made with an understanding of the natural history and rate of growth. In this chapter we review the known meningioma epidemiology as well as the growth patterns of meningiomas based upon location.

Petrous face meningiomas

Cerebellopontine angle (CPA) meningiomas arise from the petrous face of the temporal bone, which forms the lateral boundary of the CPA. They can be categorized into anterior, middle, and posterior, based on their attachment in relation to the internal acoustic meatus. Each of them presents with their own characteristic clinical syndromes. Because of their close proximity to neurovascular structures, they pose a challenge during surgery. Microsurgery remains the primary treatment modality for large and symptomatic meningiomas. The retrosigmoid approach provides an ideal access for most of the tumors in this location. Radiosurgery is the primary modality of adjuvant therapy for residual, recurrent, and small lesions. Fully fractionated external beam radiotherapy can be used for larger, broader-based residual/recurrent tumors. Management of these complex lesions should include patient preferences and a team approach, including a skull base neurosurgeon, neurotologist, and radiation oncologist.

Gamma Knife stereotactic radiosurgery for cerebellopontine angle meningioma

OBJECTIVE

Meningiomas comprise 6-15 % of cerebellopontine angle (CPA) tumors. Surgical treatment is a real challenge because this area is occupied by several critical neurovascular elements. Currently, surgery is the first choice of treatment, however several factors may be present that necessitate choosing the alternative treatments such as Gamma Knife Stereotactic Radiosurgery (GKS).

PATIENTS AND METHODS

Ninety-three patients with CPA meningioma who were treated by GKS for a period of 8 years, were retrospectively reviewed. Factors affecting clinical and radiological improvement were analyzed.

RESULTS

The median tumor volume was 6 cm³. The mean values for maximal and marginal dose were 20.2 and 13.6 Gy, respectively. The mean follow-up time was 31.5 months. Tumor control (lack of progression) was achieved in 96.8% of the patients and 55.9% of the patients showed tumor regression on follow-up MRI. The actuarial 3-year progression-free survival (PFS) rate was 96%. Clinical improvement was seen in 49.5% of the patients while 11.8% experienced worsening or new-onset symptoms. Adverse radiation effects were seen in 4.3% of the patients. A worse symptomatic outcome, male sex, a lower tumor coverage, and marginal doses <13.5 Gy were associated with worse radiologic outcomes. Worse radiologic outcomes and higher tumor volumes, especially tumor volumes ≥8.5 cc, were associated with worse symptomatic outcomes. The male sex was associated with a lower PFS.

CONCLUSION

Gamma Knife radiosurgery, either primarily or post- operatively, offers a decent long-term tumor control in CPA meningioma, and is associated with an acceptable complication profile, especially in tumors with lower volumes.

Posterior fossa meningioma with invasion of the internal acoustic canal

BACKGROUND

To evaluate the significance for outcome of meningioma invasion into the internal auditory canal (IAC) in posterior fossa meningiomas.

METHODS

From April 2005 to September 2015, 174 posterior fossa meningiomas have been surgically treated in our Institution. Careful analysis of preoperative MRI depicted in 63 cases (36%) meningioma invasion into the IAC. A retrospective analysis was done of clinical and radiological presentation, surgical findings, outcome, and relevant prognostic factors in order to stratify the risk of complication and evaluate the surgical outcome.

RESULTS

Gross total resection was achieved in 67% of patients. There was no mortality. CSF leak occurred in 5%. Postoperative moderately severe (HB 4) and severe dysfunction (HB 5) of the facial nerve was observed in 5% of patients. In 17 patients (27%), IAC was opened. Deterioration of facial function occurred in 24% of patients, hearing loss in 12%, and CSF leak in 6%. In 46 patients (73%), IAC was not opened. Deterioration of facial function occurred in 43% of patients, hearing loss in 13%, and CSF leak in 4%. Opening the IAC, a GTR was achieved in 82% while, without opening, in 61% of patients.

CONCLUSIONS

Meningiomas of the posterior fossa may in one-third of the cases invade the IAC. Opening of the IAC in these cases was a crucial step for increasing the GTR. Despite the minimal increased risk of transient CSF leak, IAC opening was not associated with an increased risk of facial palsy or hearing loss in comparison to non-opening the IAC.

Cochlear Dysfunction is not Common in Human Meningioma of the Internal Auditory Canal

HYPOTHESIS

Cochlear dysfunction is not common in human meningioma of the internal auditory canal.

BACKGROUND

Meningiomas arising from the cerebellopontine angle and internal auditory canal typically cause hearing loss. Cochlear dysfunction is known to contribute to sensorineural hearing loss induced by vestibular schwannoma, the most common tumor of the internal auditory canal. Detailed cochlear histopathology in meningioma has not been reported.

METHODS

Retrospective analysis of cochlear histopathology in five unoperated and five operated meningiomas of the internal auditory canal identified after screening human temporal bone collections from three academic medical centers.

RESULTS

While some dysfunction of all analyzed cochlear cell types was identified, a predominant or exclusive loss of hair cells was not observed in any meningioma. Only 14.3% of temporal bones showed significantly more hair cell damage on the side of the tumor when compared with the contralateral ear; cochlear neuronal damage was more prevalent in meningiomas. The incidence of hydrops, perilymphatic precipitate, or endolymphatic precipitate was low.

CONCLUSIONS

Substantial cochlear damage in human meningioma of the internal auditory canal is not common. This may explain the anecdotal hearing improvement observed after surgical resection of meningioma. Our findings underline the importance of developing therapeutic strategies to prevent cochlear neuronal degeneration due to tumors of the internal auditory canal.

Petrous Face Meningiomas: Classification, Clinical Syndromes, and Surgical Outcomes

BACKGROUND

Petrous face meningiomas (PFMs) are challenging tumors because of their proximity to the cranial nerves, brainstem, and critical vasculature. The objective of this study is to present surgical outcomes and support an anatomic classification for PFM based on clinical presentation.

METHODS

A retrospective chart review was performed, and 51 PFMs were identified. Tumors were classified by location along the petrous face into anterior, middle, and posterior. Presentation and outcomes were analyzed with logistic regression.

RESULTS

The median follow-up was 31.6 months. Tumors were World Health Organization grade I (n = 50), with 1 World Health Organization grade II tumor. Location was anterior (22%), middle (14%), posterior (53%), and overlapping (12%). Median tumor diameter was 3.0 cm (range, 0.8-6.2 cm). Anterior location was associated with facial pain/numbness on presentation (P < 0.0001), middle location with hearing loss/vestibular dysfunction (P = 0.0035), and posterior with hydrocephalus (P = 0.0190), headache (P = 0.0039), and vertigo (P = 0.0265). Extent of resection was gross total (63%), near total (14%), and subtotal (25%). The observed radiographic recurrence rate was 15%. Mean progression-free survival after diagnosis was 9.1 years with 2-year, 5-year, and 10-year progression-free survival of 91.8%, 78.6%, and 62.9%, respectively. The complication rate was 27%. Age, location, and approach were not associated with complications.

CONCLUSIONS

PFMs present with distinct clinical syndromes based on their location along the petrous face: anterior with trigeminal symptoms, middle with auditory/vestibular symptoms, and posterior with symptoms of mass effect/hydrocephalous. Surgical resection is associated with excellent long-term survival and a low rate of recurrence, which can be managed with radiotherapy.

Differentiation of vestibular schwannomas from meningiomas of the internal auditory canal using perilymphatic signal evaluation on T2-weighted gradient-echo fast imaging employing steady state acquisition at 3T

BACKGROUND

Our aim was to confirm the usefulness of the perilymphatic signal changes on T2-weighted (T2W) gradient-echo sequence to differentiate vestibular schwannomas from internal auditory canal (IAC) meningiomas, through a compartmental analysis of inner ear fluids signal intensity.

METHODS

A total of 203 patients with all criteria for typical vestibular schwannoma on T1-weighted contrast-enhanced sequences were retrospectively enrolled (190 schwannomas and 13 meningiomas). All patients underwent a T2W gradient-echo steady state free precession (SSFP) acquisition at 3T. Two radiologists analysed the signal intensity of the perilymph (cistern and cochlea) and endolymph (saccule and utricle) using a region of interest-based method for obtaining ratios between the analysed structures and the cerebrospinal fluid (CSF).

RESULTS

Obstructive vestibular schwannomas showed a markedly decreased perilymphatic signal in both cistern and cochlea; the cistern/CSF ratio (Ci/CSF) was 0.62. The decrease was more moderate in IAC meningiomas (Ci/CSF = 0.81). For Ci/CSF > 0.70, the tumour was more likely a meningioma, with a 92% sensitivity and 83% specificity. No endolymphatic signal changes were observed.

CONCLUSION

The pronounced decrease in perilymphatic signal on a T2W SSFP sequence in obstructive vestibular schwannoma provides a new tool to differentiate schwannomas from IAC meningiomas, which may be useful to overcome the insufficiencies of morphological analysis.

Combined Transtemporal Access for Large (>3 cm) Meningiomas of the Cerebellopontine Angle

OBJECTIVES: Large meningiomas of the cerebellopontine angle present a formidable surgical challenge due to tumor vascularity, neural attachment, and brain stem compression. The purpose of this paper is to present our use of the combined transtemporal approach in the surgical treatment of 29 large meningiomas.

STUDY DESIGN AND SETTING: Twenty-nine patients with large meningiomas of the CPA were surgically treated through a combined retrosigmoid-transpetrosal-transcochlear approach at our tertiary care academic medical center from July 1995 through July 2004. Data was collected from a retrospective medical records review.

RESULTS: Total tumor removal was achieved in 19 of 29 (67%) of the patients and the facial nerve was anatomically preserved in 26 of 29 (89%) of the cases. Cerebrospinal fluid leakage was seen in 3.5% of the patients and additional transient cranial nerve deficits were noted in 14% of the cases, but no significant neurologic sequelae occurred. Of the 10 patients with residual tumor, 6 have been stable without growth, 2 were treated with reoperation for regrowth of disease, and 2 were controlled with localized radiotherapy.

CONCLUSIONS: This combined lateral transtemporal approach provided wide exposure to the cerebellopontine angle and optimized the surgical extirpation of 29 large meningiomas presented in this series.

Non-schwannomatosis lesions of the internal acoustic meatus-a diagnostic challenge and management: a series report of nine cases

Vestibular schwannomas (VS) are the most common lesions of cerebellopontine angle (CPA) corresponding to 76-91 % of the cases. Usually, these lesions present typical CT and MRI findings. Non-schwannomatous tumors restricted to the internal auditory meatus (IAM) are rare and their preoperative radiological diagnosis may be difficult. This article describes nine surgically treated intrameatal non-schwannomatous lesions (NSL) and reviews the literature. In the last 16 years, a total of 471 patients with diagnosis of VS were operated on in our department. Preoperatively, 42 patients had diagnosis of intrameatal schwannomas, but surgery revealed in nine cases NSL (3 meningiomas, 3 arachnoiditis/neuritis, 1 cavernoma, 1 vascular loop, and 1 arachnoid cyst). Most frequent symptoms presented by patients with NSL were hearing loss 89 % (8/9) of patients, tinnitus 78 % (7/9), and vertigo 33 % (3/9). Almost all lesions (8/9) presented MRI findings of isointense signal in T1W with contrast enhancement. The only exception was the arachnoid cyst with intracystic bleeding, which was hyperintense in T1W that is not enhanced with contrast. This series shows an occurrence of 21.4 % of non-schwannomatous tumors in 42 cases of lesions restricted to the IAM. Whenever a solely intrameatal enhanced tumor is detected, it is necessary to think about other diagnostic possibilities rather than VS. Therapeutic management may be changed, specially if radiosurgical treatment is considered.

Meningiomas of the cerebellopontine angle: radiological differences in tumors with internal auditory canal involvement and their influence on surgical outcome

This study explored the clinical, radiological, and pathological characteristics of cerebellopontine angle (CPA) meningiomas with internal auditory canal (IAC) involvement. The pre- and postoperative MR images of 193 consecutive patients with pathologically diagnosed meningioma centered around the IAC were analyzed, focusing on changes in the IAC, maximal axial tumor volume, peritumoral brain edema, and postoperative residual tumor. Patient age, sex, tumor volume, postoperative residual tumor, and pathological subtype were compared in patients with and without IAC involvement by the tumor and among the different types of IAC involvement. The results showed that the 71 patients (36.8%) with IAC involvement had a higher ratio of peritumoral edema (χ²=5.922, P=0.015), postoperative residual tumor (χ²=22.183, P< 0.001), and a predominance of the meningothelial subtype (χ²=5.89, P=0 .015). Peritumoral edema was a risk factor for IAC involvement (P=0.016, OR=2.186). Radiologically, IAC involvement could be distinguished as intruding (31%, 22/71), filled (29.6%, 21/71), and dilated (39.4%, 28/71). Patients with intruding IAC were significantly older (54.5±9.54 years, P=0.021) and had the lowest postoperative residual tumor values (42%, χ²=7.865, P= 0.005), while those with filled IAC were more likely to be female (95%, χ²=9.404, P=0.009).Our observations provide the basis for a morphological classification of IAC involvement by CPA meningiomas and further insight into the clinical features of these tumors.

Cerebellopontine angle meningiomas: postoperative outcomes in a modern cohort

OBJECT

Tumors of the cerebellopontine angle (CPA) have always proven difficult for neurosurgeons to optimally manage. Studies investigating the natural history and treatment of vestibular schwannomas have dominated the literature in this regard. Distinguishing meningiomas from schwannomas in this location carries particular importance as each tumor type has certain prognostic and surgical considerations. In this study, the authors have characterized the outcomes of 34 patients surgically treated for CPA meningiomas and have investigated various factors that may affect postoperative neurological function.

METHODS

The medical records of patients with CPA meningiomas who underwent surgery from 2005 to 2013 at the Duke University Health System were reviewed. Various patient, clinical, and tumor data were gathered from the medical records including patient demographics, pre- and postoperative neurological examinations, duration of symptoms, procedural details, tumor pathology and size, and treatment characteristics. Differences in continuous variables were then analyzed using the Student t-test while categorical variables were evaluated using the chi-square test.

RESULTS

A total of 34 patients underwent surgical treatment for CPA meningiomas during the 8-year period. Jugular foramen invasion was seen in 17.6% of tumors, with nearly half (41.2%) extending into the internal acoustic canal. The most common presenting symptom was hearing loss (58.8%), followed by headache (52.9%) and facial numbness/pain (50.0%). The most common cranial nerve (CN) affected was CN X (11.8%), followed by CNs VI and VII (5.9%). Postoperatively, no patients experienced a decrease in hearing, with only 5.9% of patients experiencing facial nerve palsies. Patients with tumors larger than 3 cm had a significantly higher incidence of permanent CN deficits than those with smaller tumors (45.5% vs 5.9%, respectively; p = 0.011). Also, tumor extension into the jugular foramen was associated with the occurrence of lower CN deficits, none of which occurred in tumors without jugular foramen invasion. Internal acoustic canal tumor extension was not seen to be associated with postoperative complications or CN deficits.

CONCLUSIONS

Meningiomas of the CPA are challenging lesions to treat surgically. However, the risk of facial palsy and hearing loss is significantly lower when compared with vestibular schwannomas. Novel methods for preoperative differentiation are needed to appropriately counsel patients on surgical risks. Also, due to the significant potential for neurological deficits, further studies are needed to investigate the utility of radiotherapy for these lesions.

Gamma Knife Radiosurgery for Cerebellopontine Angle Meningiomas

BACKGROUND:

Resection of cerebellopontine angle (CPA) meningiomas may result in significant neurological morbidity. Radiosurgery offers a minimally invasive alternative to surgery.

OBJECTIVE:

To evaluate, in a multicenter cohort study, the outcomes of patients harboring CPA meningiomas who underwent Gamma Knife radiosurgery (GKRS).

METHODS:

From 7 institutions participating in the North American Gamma Knife Consortium, 177 patients with benign CPA meningiomas treated with GKRS and at least 6 months radiologic follow-up were included for analysis. The mean age was 59 years and 84% were female. Dizziness or imbalance (48%) and cranial nerve (CN) VIII dysfunction (45%) were the most common presenting symptoms. The median tumor volume and prescription dose were 3.6 cc and 13 Gy, respectively. The mean radiologic and clinical follow-up durations were 47 and 46 months, respectively. Multivariate regression analyses were performed to identify the predictors of tumor progression and neurological deterioration.

RESULTS:

The actuarial rates of progression-free survival at 5 and 10 years were 93% and 77%, respectively. Male sex (P = .014), prior fractionated radiation therapy (P = .010), and ataxia at presentation (P = .002) were independent predictors of tumor progression. Symptomatic adverse radiation effects and permanent neurological deterioration were observed in 1.1% and 9% of patients, respectively. Facial spasms at presentation (P = .007) and lower maximal dose (P = .011) were independently associated with neurological deterioration.

CONCLUSION:

GKRS is an effective therapy for CPA meningiomas. Depending on the patient and tumor characteristics, radiosurgery can be an adjuvant treatment to initial surgical resection or a standalone procedure that obviates the need for resection in most patients.

[Typical tumors of the petrous bone]

In the region of the petrous bone, inner acoustic canal and cerebellopontine angle, a variety of different tissues can be found, such as bony, epithelial, neural and vascular structures. Tumorous or tumor-like lesions, vascular or bony malformations or other pathologies can therefore be found in all of these areas. We discuss various frequently occurring tumorous or tumor-like pathologies including congential lesions, such as mucoceles, inflammatory disorders including osteomyelitis, pseudotumors and Wegener's granulomatosis. Benign non-neoplastic lesions, such as cholesteatoma, cholesterol granuloma, epidermoid and benign neoplastic tumors, such as the most commonly found vestibular schwannoma, meningeoma, paraganglioma, vascular pathologies and finally malignant lesions, such as metastasis, chordoma or chondrosarcoma and endolymphatic sac tumor (ELST) are also discussed. The emphasis of this article is on the appearance of these entities in computed tomography (CT) and more so magnetic resonance imaging (MRI), it provides key facts and typical images and discusses possibilities how to distinguish these pathologies.

Stereotactic radiosurgery for cerebellopontine angle meningiomas

Object

To assess the long-term outcomes of stereotactic radiosurgery (SRS) for cerebellopontine angle (CPA) meningiomas, the authors retrospectively reviewed data from a 20-year experience. They evaluated progression-free survival as well as improvement, stabilization, or deterioration in clinical symptoms.

Methods

Seventy-four patients with CPA meningiomas underwent SRS involving various Gamma Knife technologies between 1990 and 2010. The most common presenting symptoms were dizziness or disequilibrium, hearing loss, facial sensory dysfunction, and headache. The median tumor volume was 3.0 cm3 (range 0.3–17.1 cm3), and the median radiation dose to the tumor margin was 13 Gy (range 11–16 Gy). The median follow-up period was 40 months (range 4–147 months).

Results

At last imaging follow-up, the tumor volume had decreased in 46 patients (62%), remained stable in 26 patients (35%), and increased in 2 patients (3%). The progression-free survival after SRS was 98% at 1 year, 98% at 3 years, and 95% at 5 years. At the last clinical follow-up, 23 patients (31%) showed neurological improvement, 43 patients (58%) showed no change in symptoms or signs, and 8 patients (11%) had worsening symptoms or signs. The neurological improvement rate after SRS was 16% at 1 year, 31% at 3 years, and 40% at 5 years. The post-SRS deterioration rate was 5% at 1 year, 10% at 3 years, and 16% at 5 years. A multivariate analysis demonstrated that trigeminal neuralgia was the symptom most likely to worsen after SRS (HR 0.08, 95% CI 0.02–0.31; p = 0.001). Asymptomatic peritumoral edema occurred in 4 patients (5%) after SRS, and symptomatic adverse radiation effects developed in 7 patients (9%).

Conclusions

Stereotactic radiosurgery for CPA meningiomas provided a high tumor control rate and relatively low risk of ARE. Tumor compression of the trigeminal nerve by a CPA meningioma resulted in an increased rate of facial pain worsening in this patient experience.

Surgical management of posterior petrous meningiomas

BACKGROUND AND PURPOSE

The aim of the study is to present our experience in the surgical treatment of posterior petrous meningiomas in regard to clinical presentation, surgical anatomy, complications and long-term functional postoperative results.

MATERIAL AND METHODS

A series of 48 consecutive patients operated on for posterior petrous meningiomas at the authors' institution between 2002 and 2011 is reported. The main symptom on first admission was hypoacusis, impairment of the fifth cranial nerve and cerebellar ataxia. The tumour was found to be attached to the premeatal dura in 46%, the inframeatal dura in 29% and the postmeatal dura in 25% of cases. Tumour resection was categorized as grade I in 16 patients, grade II in 29 patients, grade III in 1 patient and grade IV in 2 patients, according to the Simpson classification system. The petrosal approach and retrosigmoid approach were suitable for posterior petrous meningiomas.

RESULTS

Postoperative facial nerve dysfunction appeared in 8 and further deteriorated in 2 patients. Hearing function deteriorated after surgery in 8 and improved in 2 cases. Perioperative death occurred in two patients. Tumour recurrence was observed in two patients, and both underwent a second operation and postoperative stereotactic radiotherapy.

CONCLUSIONS

Surgical treatment of posterior petrous meningiomas has become increasingly safe but these tumours still remain a surgical challenge because of the relatively high incidence of permanent complications associated with their removal. The site of displacement of the cranial nerves depending on the dural origin of the tumour has the most influence on the related difficulties in its removal.

Facial nerve damage following surgery for cerebellopontine angle tumours. Prevention and comprehensive treatment

Facial nerve (CN VII) palsy or even its transient paresis causes physical disability but is also a psychosocial problem. Immediately after vestibular schwannoma removal, different degrees of CN VII paresis occur in 20-70% of patients. Facial nerve paresis is observed in 10-40% after surgery of cerebellopontine angle meningiomas. Postoperative facial nerve weakness significantly reduces or completely withdraws with time in the majority of cases. However, even if prognosis for CN VII regeneration is good, proper management is needed because of the potential for serious ophthalmic complications. In this paper, the authors raise the issue of perioperative prophylaxis and comprehensive treatment of postoperative paresis of CN VII. Prophylaxis and treatment of ophthalmic complications are discussed. Current trends in the treatment of intraoperative loss of facial nerve continuity, management of facial paresis with good prognosis and dealing with facial palsy with no spontaneous recovery are also described in the paper.

Retrosigmoid approach for meningiomas of the cerebellopontine angle: results of surgery and place of additional treatments

BACKGROUND

Meningiomas of the cerebellopontine angle (CPA), although homogenous in terms of location, present different surgical challenges depending on their site of dural origin and extension. Complete tumor resection sometimes leads to high morbidity. The objective of this work is to evaluate the results of surgery and the place of additional treatments.

METHODS

In a series of 115 patients with CPA meningiomas, we retrospectively studied 69 patients operated on between 1994 and 2007 using a retrosigmoid approach. Clinical presentation, operative findings and functional outcome were reviewed for a mean follow-up time of 36 months.

RESULTS

Usual presentation was hearing loss associated with gait disturbance (50%) and vertigo (35%). Preoperative cochlear evaluation was abnormal in 40% of the cases. Most tumors (90%) originated on the posterior face of the petrous part of the temporal bone. In one-third of the cases, the meningioma had invaded the internal acoustic meatus. Total or subtotal tumor removal was achieved in 91% of patients without perioperative mortality. Fourteen patients received additional treatment with radiotherapy or radiosurgery for a small residual tumor, often deliberately left in place to reduce operative morbidity. At long-term follow-up, facial nerve function was preserved in 91% of the cases. Hearing worsened in 17% of patients. The tumor recurred in only one case.

CONCLUSION

The retrosigmoid approach is a safe surgical procedure. The modern management of CPA meningiomas should achieve as complete a resection as possible within reasonable limits, considering that a small residual tumor can be controlled fairly easily with radiosurgery for a relatively long time.

Contemporary surgical outcome for skull base meningiomas

Although surgical excision of meningioma and its dural base is the most common primary management, skull base meningiomas are quite different, and contemporary management usually consists of multimodal treatment with the aim of achieving the best possible functional outcome and quality of life (QOL) for these patients. As surgery plays an important role in the treatment of skull base meningiomas, it is crucial for neurosurgeons to appreciate the surgical outcome and QOL after meningioma surgery. Outcome is usually measured for meningiomas in terms of morbidity, mortality, time to recurrence, and QOL. The extent of resection, tumor grade, proliferative markers, and tumor location are significant factors in predicting the surgical outcome. Therefore, we address each of these factors in detail in this review. Advances in recent decades in microsurgical techniques, neuroimaging modalities, neuroanesthesia, and perioperative intensive care have substantially improved the surgical outcome; therefore, most surgical outcomes discussed in this review are cited from contemporary literature (2000 to the present) in order to depict the surgical outcome of contemporary microsurgery.

Outcome after microsurgery for meningiomas involving the internal auditory canal

BACKGROUND

The subset of patients suffering from meningiomas truly originating in or extending into the internal auditory canal is not well described in the literature.

OBJECTIVE

To evaluate postoperative facial motor and hearing outcomes in patients undergoing resection of meningiomas originating in or extending into the internal auditory canal.

METHODS

Chart reviews were done of 19 consecutive patients undergoing surgery for meningiomas originating in or extending into the internal auditory canal at the Mayo Clinic, Rochester, with emphasis on clinical exam and audiometry.

RESULTS

Median follow-up for the entire group was 29 months. Seventy-four percent of patients had stable facial nerve function. One patient experienced improvement. Postoperative cochlear nerve function was unchanged in 74% of patients and worsened in 21% of patients. One patient with a sudden preoperative hearing loss improved to full hearing at 3 months.

CONCLUSION

Every attempt should be made to preserve hearing and facial motor function in surgical removal of posterior fossa meningiomas that originate in or extend into the internal auditory canal. Normal or nearly normal facial nerve function can be preserved in 88% of patients presenting with normal facial nerve function; serviceable hearing can be preserved in 92% of patients who present with normal hearing. A standard retrosigmoid craniotomy with drilling of the posterior canal wall of the internal auditory canal worked well in the majority of cases.

The classification of posterior petrous meningiomas and its clinical significance

This retrospective analysis of the clinical records of 42 patients was used to study the clinical significance of a classification system for posterior petrous meningiomas. According to clinical manifestations and radiological images, posterior petrous meningiomas were classified into three types: type I (cerebella type; 12 patients), tumours involved and compressed the cerebellum; type II (cranial nerve type; 16 patients), tumours involved the cranial nerves; and type III (combined type; 14 patients), tumours involved more than one structure such as the cerebellum, cranial nerves and the brain stem. All patients underwent microneurosurgery and the total resection rate was 90%. It was more difficult totally to resect type II and III tumours than type I tumours and the post-operative functional outcomes were worse. Microneurosurgical techniques and skills are critical to increase the total resection rate of posterior petrous meningiomas in order to decrease the mortality and disability rates.

Comparison of vestibular function between large cerebellopontine angle meningioma and schwannoma

CONCLUSION

Abnormal caloric and vestibular evoked myogenic potential (VEMP) responses are frequently encountered with a large cerebellopontine angle (CPA) schwannoma, while normal caloric responses and abnormal VEMPs are noted with a large CPA meningioma. This difference may possibly exist because schwannoma causes vestibular deficits via parenchymal involvement, while vestibular deficits in the meningioma are mostly due to compression neuropathy.

OBJECTIVES

This study aimed to compare the tumor characteristics in relation to vestibular function, i.e. caloric and VEMP responses, between large-sized (>2.5 cm) meningioma and schwannoma in the CPA.

PATIENTS AND METHODS

Five patients with large CPA meningioma and nine patients with large CPA schwannoma were enrolled in this study. Each patient underwent a battery of tests including audiometry, caloric test, VEMP test, and MRI study.

RESULTS

The meningioma group showed 20% caloric abnormality and 75% VEMP abnormality, while the schwannoma group revealed 100% caloric and 100% VEMP abnormalities. A significant difference existed in relation to caloric abnormality between the two groups, but not in relation to VEMP abnormality.

Transpetrosal approaches for meningiomas of the posterior aspect of the petrous bone

OBJECTIVE

To assess outcome following excision of meningiomas of the posterior aspect of the petrous bone through transpetrosal approaches.

MATERIAL AND METHOD

We carried out a retrospective case-series study in a multidisciplinary tertiary care center on all patients who underwent meningiomas removal from January 1989 to September 2005. Surgical approaches were transpetrosal: widened retrolabyrinthine, translabyrinthine, transotic and transcochlear, occasionally combined with a subtemporal transtentorial approach. Epidemiology, symptoms, preoperative evaluation, surgery, postoperative complications and facial and auditory results were analyzed using standardized grading systems. The Desgeorges and Sterkers classification was used to assess tumor size and location.

RESULTS

Forty women and three men underwent surgery (mean age: 56.7). Medium-sized tumors stages 2 and 3 (84%) and AM and P localization (34% and 20.4%) predominated. In 65% of cases, the tumor extended beyond the CPA. Main presenting symptoms were balance disorders (72%) and sensorineural hearing loss (53.5%). Mortality was nil. A preoperative facial nerve paresis was present in 14% of patients. Tumor removal was complete in 79.1% of cases. At 1-year post-op, 73% of patients had a normal or subnormal facial function and 55% had serviceable hearing. A cerebrospinal fluid leakage occurred in 6.9%.

DISCUSSION

Posteriorly attached meningiomas are less symptomatic and of better prognosis than medially inserted ones. Transpetrosal approaches are reliable for the removal for all types and sizes of such tumors, and can be easily combined in the same procedure with a subtemporal transtentorial approach to remove extensions to the clivus and tentorium. They offer low morbidity and a high proportion of facial nerve and hearing preservation.

Imaging of cerebellopontine angle lesions: an update. Part 1: enhancing extra-axial lesions

Computed tomography (CT) and magnetic resonance (MR) imaging reliably demonstrate typical features of vestibular schwannomas or meningiomas in the vast majority of mass lesions in the cerebellopontine angle (CPA). However, a large variety of unusual lesions can also be encountered in the CPA. Covering the entire spectrum of lesions potentially found in the CPA, these articles explain the pertinent neuroimaging features that radiologists need to know to make clinically relevant diagnoses in these cases, including data from diffusion and perfusion-weighted imaging or MR spectroscopy, when available. A diagnostic algorithm based on the lesion's site of origin, shape and margins, density, signal intensity and contrast material uptake is also proposed. Part 1 describes the different enhancing extra-axial CPA masses primarily arising from the cerebellopontine cistern and its contents, including vestibular and non-vestibular schwannomas, meningioma, metastasis, aneurysm, tuberculosis and other miscellaneous meningeal lesions.

Cerebellopontine angle lesions in children

BACKGROUND

Cerebellopontine angle (CPA) lesions are more commonly found in adults in which they account for 5-10% of all intracranial tumors. However, they are uncommon in children, with an incidence of only 1%.

MATERIALS AND METHODS

This is a review of the management of CPA lesions in children admitted to the Hospital Nacional de Pediatría "Profesor Doctor Juan P. Garrahan" (Argentine National Pediatrics Hospital "Professor Juan P. Garrahan") between January 1988 and December 2003.

RESULTS

The series included 30 children with 33 CPA lesions, 20 arising from the subarachnoid space of the CPA and 13 from the vicinity and growing mainly into the CPA. Twenty-seven tumors were located in the left CPA (82%) and six (12%), on the right. Ten of the 30 patients developed hydrocephalus, but only three of these required treatment. All patients underwent retrosigmoid suboccipital craniotomy and microsurgical resection. Gross total removal was achieved in 12 cases, subtotal in 18, and fenestration of the cyst wall in the three arachnoid cysts. Ten patients have no sequelae, ten have mild deficit, three have severe deficits, and seven have died.

CONCLUSION

The CPA is a rare location for lesions in children, with clear predominance on the left side. Benign lesions are more frequent. Even though schwannoma is the most frequently found lesion, the histology varies widely.

Morbidity in 201 patients with small sized meningioma treated by microsurgery

BACKGROUND

The management of patients with small, often asymptomatic meningiomas is controversial and includes observation, microsurgery (MS) and stereotactic radiosurgery (SRS). The purpose of this retrospective study was to analyze the morbidity and the extent of removal after MS for small (< or =3 cm) intracranial meningiomas and compare these results to those of SRS reported in the literature.

METHODS

All patients with an intracranial meningioma with a maximum diameter up to 3 cm operated on in our institution over a 10 year period (1992-2002) were included in the study and retrospectively analyzed. Patients were grouped into asymptomatic and symptomatic and according to tumor location as: group I (cranial vault, parasagittal, lateral sphenoid), group II (falx, frontobasal, medial sphenoid, parasellar and tentorial), group III (cavernous sinus, petroclival, petrosal, CPA and foramen magnum).

FINDINGS

There were a total of 201 patients, of whom 102 were asymptomatic and 99 were symptomatic. The overall risk of permanent neurological morbidity was 4.9% in asymptomatic and 23.2% in symptomatic patients. The combined risk in asymptomatic and symptomatic patients was 5.4% in group I, 11.5% in group II, and 39.9% in group III lesions. Radical removal was achieved in all patients in group I, in 93.7% of group II, and 80% of group III lesions. There was no disease related mortality.

CONCLUSIONS

MS provides excellent efficacy and morbidity results in groups I and II meningiomas, especially in asymptomatic patients and might therefore be considered the first choice of treatment for these patients. The results of MS in group III were worse than those of SRS reported in the literature.

Serous otitis media revealing temporal en plaque meningioma

OBJECTIVES

To present a series of temporal en plaque meningiomas involving the middle ear or mastoid, whose main symptoms suggested a serous otitis media.

STUDY DESIGN AND SETTINGS

Multicentric retrospective study reviewing clinical records originating from eight tertiary referral centers.

MATERIALS AND METHODS

The clinical records of 10 patients presenting with signs and symptoms suggesting serous otitis media and whose neuroimaging studies revealed a temporal en plaque meningioma involving the middle ear or mastoid are reported.

RESULTS

All the patients were women, ranging from 49 to 71 years old. The delay between the onset of symptoms and the diagnosis of meningioma varied from 1 to 10 years. All the patients underwent various procedures usually applied for the treatment of serous otitis media, which failed in all the cases, particularly ventilating tube placement, which was followed by severe episodes of discharge. In all cases, the computed tomographic scans showed three imaging signs: soft tissue mass filling the middle ear or mastoid, hyperostosis of the petrous bone, and hairy aspect of the intracranial margins of the affected bone. This imaging triad must alert the otologist of the possibility of intracranial meningioma. Magnetic resonance imaging was the method of choice to assess the diagnosis of intracranial meningioma involving the middle ear or mastoid. When analyzing management options, it appeared that conventional middle ear procedures were inefficient.

CONCLUSION

Temporal en plaque meningioma involving the middle ear or mastoid can mimic a serous otitis media. A computed tomographic scan is recommended for cases of atypical or prolonged unilateral serous otitis media to investigate indirect signs of a meningioma, which has to be confirmed with magnetic resonance imaging.