Preoperative differentiation between meningioma of the cerebellopontine angle and acoustic neuroma using MRI

K, Baral A. Bilateral vestibular schwannoma with a cooccurring meningioma in a child: a case report and review of literature

Introduction

Meningioma and vestibular schwannoma (VS) are the first and second most common benign central nervous system tumors. The coexistence of VS and meningioma presents a rare clinical scenario, particularly in pediatric patients. This report presents a case of bilateral VS with a cooccurring meningioma in a Nepali child and provides an overview of the literature on this condition.

Case report

A 15-year-old male presented with bilateral sensorineural hearing loss, seizures, and neurological deficits and was ultimately diagnosed with concomitant bilateral acoustic neuroma and meningioma. The patient underwent radiosurgery for bilateral VS and nonoperative management of the meningioma. Long-term follow-up revealed symptomatic improvement, emphasizing the importance of a multidisciplinary approach in managing such complex cases. The management of these tumors requires tailored treatment strategies guided by tumor characteristics and associated risks.

Discussion

Meningioma and VS are common tumors of the central nervous system. Their coexistence is possible in neurofibromatosis type 2 but is exceedingly rare in pediatric age group. The tumors, often coexisting, pose diagnostic challenges. Diagnosis relies on clinical and genetic features, with multidisciplinary management involving various specialists. Treatment aims to preserve function and quality of life, utilizing approaches such as bevacizumab and surgical intervention. The role of radiation therapy remains uncertain. Genetic testing and regular monitoring are vital for early detection and intervention.

Conclusion

The cooccurrence of acoustic neuromas and meningiomas is poorly understood, with limited reported cases and unclear pathophysiological mechanisms. Further research into the genetic and molecular mechanisms underlying the coexistence of these tumors is needed to optimize patient outcomes in this rare clinical entity.

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.

Coexistent vestibular schwannoma and meningioma in a patient without neurofibromatosis: A case report and review of literature

BACKGROUND

The simultaneous occurrence of schwannoma and meningioma in the absence of neurofibromatosis (NF) or a previous history of irradiation is exceedingly rare, as only 10 intracranial cases have been reported to date. Herein, we report a case of a coexistent cavernous sinus meningioma and ipsilateral vestibular schwannoma (VS) in a female patient without NF or a history of exposure to irradiation.

CASE SUMMARY

A 63-year-old woman presented with progressive left-side hearing loss and tinnitus over the previous year. In the past 6 mo, she developed facial numbness and intermittent headaches. Magnetic resonance imaging showed two lesions that were located on the left side of the cerebellopontine angle and parasellar region. Both lesions were totally resected via the left retrosigmoid approach. Histopathological examination revealed a VS and a meningioma. The patient did not have a family history or clinical or radiological signs of NF.

CONCLUSION

The coincident occurrence of VS and meningioma within close vicinity is very rare, and the pathogenesis is unclear. A careful whole-body examination needs to be conducted to exclude NF. Surgical treatment with the goal of total tumor resection is the best therapy. Additional studies are needed for a better understanding of the mechanisms that lead to the development of tumor growth in multiple locations.

Rare Diseases of the Middle Ear and Lateral Skull Base

Otalgia, otorrhea and hearing loss are the most common ear-related symptoms that lead to the consultation of an otolaryngologist. Furthermore, balance disorders and affections of the cranial nerve function may play a role in the consultation. In large academic centres, but also in primary care, the identification of rare diseases of the middle ear and the lateral skull base is essential, as these diseases often require interdisciplinary approaches to establish the correct diagnosis and to initiate safe and adequate treatments. This review provides an overview of rare bone, neoplastic, haematological, autoimmunological and infectious disorders as well as malformations that may manifest in the middle ear and the lateral skull base. Knowledge of rare disorders is an essential factor ensuring the quality of patient care, in particular surgical procedures. Notably, in untypical, complicated, and prolonged disease courses, rare differential diagnoses need to be considered.

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.

Role of diffusion-weighted imaging in differentiation between posterior fossa brain tumors

Background

Diffusion-weighted imaging (DWI) is an imaging modality using multi-section single-shot spin echo planar imaging (EPI) sequence which is extremely sensitive for detection of water motion within intra, extra, and transcellular regions. This character is important to differentiate between brain tumors either low (benign) or highly (malignant) cellular tumors.

Objective

To evaluate the role of DWI and apparent diffusion coefficient (ADC) in evaluation and differentiation between different brain posterior fossa tumors in children and adults.

Patients and methods

The study included 34 patients with different brain posterior fossa tumors for evaluation by conventional MRI (using 1.5 T MRI PHILIPS Achieva 2.1 Best Netherland) and DWI.

Results

Our study showed that mean ADC values were significantly different between the four groups of posterior fossa tumors in children: juvenile pilocytic astrocytoma (JPA), medulloblastoma, ependymoma, and brain stem glioma while mean ADC values were not significantly different between posterior fossa tumors in the adult group. Regions of interest were manually positioned, and all values were automatically calculated and expressed in 10−3 mm2/s.

Conclusion

DWI is an ideal additional imaging technique, which is a rapid, easy, non-invasive imaging modality, with no contrast injection needed. It has been widely applied in the differentiation between posterior fossa brain tumors and in the diagnosis of various intracranial diseases.

Imaging spectrum of meningiomas: a review of uncommon imaging appearances and their histopathological and prognostic significance

Meningiomas are the most common primary non-glial intracranial neoplasms. In most cases, meningiomas have typical imaging appearances and locations, enabling a straightforward radiological diagnosis. However, a myriad of unusual appearances potentially complicate the imaging picture. Furthermore, certain imaging features can also predict the specific histopathological nature and WHO grade of the meningioma. 'Typical' meningiomas include meningothelial, fibrous, and transitional variants and have the characteristic imaging features described for meningiomas. Several 'atypical' variants exist, which, although less common, also generally have a less favourable prognosis and necessitate early diagnosis. In addition, meningiomas can occur in a variety of unusual intracranial and even extra-cranial locations and need to be distinguished from the more common tumours of these regions on imaging. Any associated oedema or haemorrhagic changes may alter the prognosis and have to be carefully assessed and reported. Cystic changes in meningiomas have been divided into five subtypes, and accurate characterisation is essential to predict the prognosis. An extensive review of the several possible variations in imaging appearances of meningiomas including the differential features of common and uncommon variants would facilitate informative radiological reporting of meningiomas. This would be expected to improve pre-operative planning prior to surgical biopsy and thereby improve disease prognosis and patient outcomes.

Non-contrast magnetic resonance imaging for monitoring patients with acoustic neuroma

Objective

To assess the feasibility of non-contrast T2-weighted magnetic resonance imaging as compared to T1-weighted post-contrast magnetic resonance imaging for detecting acoustic neuroma growth.

Methods

Adult patients with acoustic neuroma who underwent at least three magnetic resonance imaging scans of the internal auditory canals with and without contrast in the past nine years were identified. T1- and T2-weighted images were reviewed by three neuroradiologists, and tumour size was measured. Accuracy of the measurements on T2-weighted images was defined as a difference of less than or equal to 2 mm from the measurement on T1-weighted images.

Results

A total of 107 magnetic resonance imaging scans of 26 patients were reviewed. Measurements on T2-weighted magnetic resonance imaging scans were 88 per cent accurate. Measurements on T2-weighted images differed from measurements on T1-weighted images by an average of 1.27 mm, or 10.4 per cent of the total size. The specificity of T2-weighted images was 88.2 per cent and the sensitivity was 77.8 per cent.

Conclusion

The T2-weighted sequences are fairly accurate in measuring acoustic neuroma size and identifying growth if one keeps in mind the caveats associated with the tumour characteristics or location.

Susceptibility weighted imaging - a problem-solving tool in differentiation of cerebellopontine angle schwannomas and meningiomas

Background and purpose Vestibular schwannomas and meningiomas of the cerebellopontine angle can be differentiated by the presence of foci of blooming on susceptibility weighted imaging. Materials and methods In this retrospective study, magnetic resonance imaging with susceptibility weighted imaging sequence in addition to other routine sequences was done in 73 patients. All the cases were studied for the presence of foci of blooming within the tumor on susceptibility weighted imaging. Histopathological examination confirmed the diagnosis in all cases. Results There were 59 patients in the vestibular schwannoma group and 14 in the meningioma group. Susceptibility weighted imaging showed presence of blooming (due to microhemorrhages) in all the cases of cerebellopontine angle schwannomas. In the meningioma group, 13 cases showed no blooming within the lesion; one case showed blooming which was confirmed to be due to calcification on computed tomography study. For the detection of foci of blooming and predicting histopathologic diagnosis of schwannoma pre-operatively, susceptibility weighted imaging showed a sensitivity of 100%, specificity of 92%, positive predictive value of 98.3%, and negative predictive value of 100%. The Fisher exact test showed a statistically significant difference in the differentiation of vestibular schwannoma from meningioma on the basis of detection of blooming on susceptibility weighted imaging ( p < 0.0001). Conclusion Susceptibility weighted imaging is a problem-solving tool in making accurate pre-operative differentiation of vestibular schwannoma from meningioma.

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.

Decreased vestibular signal intensity on 3D-FIESTA in vestibular schwannomas differentiating from meningiomas

INTRODUCTION

With reported characteristic MR features, it is difficult to differentiate vestibular schwannomas (VSs) from cerebellopontine angle (CPA) meningiomas (CPAMs) in some cases. This study aimed to evaluate vestibular signal intensity changes in patients with VS and those with CPAM on three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA), and to test the effectiveness of the signal intensity change to differentiate these two common CPA tumors.

METHODS

We retrospectively reviewed 21 patients with unilateral VS, six patients with unilateral CPAM, and 25 control subjects. Setting regions of interest in the bilateral vestibules and cerebellar white matter on 3D-FIESTA, we compared the ratio of the signal intensity (SIR) of the vestibule to that of the cerebellar white matter (SIRv) among the VS, CPAM, and control subject groups. We also compared the ratio of SIRv on the affected side (a-SIRv) to that on the unaffected side (AURv) between the VS and CPAM.

RESULTS

The a-SIRv in the VS group was significantly lower than the overall SIRv in the control subjects (pre-contrast, P < 0.001; post-contrast, P < 0.001) and the a-SIRv in the CPAM group (pre-contrast, P = 0.001; post-contrast, P = 0.001). The AURv in the VS group was significantly lower than that in the CPAM groups (pre-contrast, P < 0.001; post-contrast, P < 0.001).

CONCLUSION

Decreased vestibular signal intensity on the affected side on 3D-FIESTA was observed in patients with VS, but not in those with CPAM or in normal subjects. The signal intensity change has the potential to be used in differentiating VS from CPAM.

Concurrent vestibular schwannoma and meningioma mimicking a single cerebellopontine angle tumor

Vestibular schwannomas account for ~;80% of cerebellopontine angle (CPA) tumors, with meningiomas being the second most common tumor of the CPA. The occurrence of both a schwannoma and a meningioma in the cerebellopontine angle is rare. After obtaining Institutional Review Board approval, we present a case of a concurrent vestibular schwannoma and meningioma in the CPA mimicking a single tumor.

Concurrent spinal nerve root schwannoma and meningioma mimicking single-component schwannoma

We present a first case of concurrent tumors consisting of schwannoma and meningioma arising at the same spinal level in a patient without neurofibromatosis. A 49-year-old man without clinical evidence of neurofibromatosis presented with a 5-month history of right neck pain. MRI demonstrated an extradural tumor involving the right-sided C2 nerve root with a small intradural component. T1- and T2-weighted and contrast-enhanced MRI could not differentiate the intradural tumor as different from the extradural tumor. Total removal of the tumors was performed. No contiguity of the extradural tumor with the intradural tumor was seen. The intradural tumor attached strongly to the dura mater around the C2 nerve root exits. Intraoperative pathological diagnosis confirmed the extradural tumor as schwannoma and the intradural tumor as meningioma. We therefore thoroughly coagulated the dura mater adjacent to the intradural tumor and resected the dura mater around the nerve root exits together with the tumor. Pathological examination revealed that the resection edge of the extradural component consisted of a spinal nerve with thickened epineurium and was free of neoplastic cells. No schwannoma component was evident in the intradural tumor. No obvious transition thus existed between the extra- and intradural tumors. Distinguishing these tumors prior to surgery is critical for determining an optimal surgical plan, as schwannoma and meningioma require different surgical procedures. We therefore recommend a careful review of preoperative imaging with the possibility of concurrent tumors in mind.

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.

Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma

BACKGROUND AND PURPOSE

Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas.

MATERIALS AND METHODS

In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining.

RESULTS

There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01).

CONCLUSION

Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.

Meningiomas involving the internal auditory canal: a diagnostic and surgical challenge

Meningiomas are the second most common lesion encountered within the cerebello-pontine angle (CPA) and rarely project into or originate from the internal auditory meatus (IAM). It is important to distinguish between meningiomas and acoustic neuromas preoperatively as the choice of surgical approach may differ depending on the tumour type. Fortunately, most lesions can be accurately diagnosed with gadolinium-enhanced magnetic resonunce imaging (MRI). We report six cases of meningioma involving the IAM, often leading to an incorrect preoperative MRI diagnosis. We highlight the challenges these tumors present to radiologists and surgeons.

MRI Evaluation of Neurofibromatosis 2 Patients: A Standardized Approach for Accuracy in Interpretation

OBJECTIVE

To determine the level of agreement between local radiologists' and an experienced neuroradiologist's measurements of vestibular schwannomas.

STUDY DESIGN

Prospective study with uniform magnetic resonance acquisition protocol parameters and reporting instructions across 30 magnetic resonance imaging facilities worldwide.

SETTING

Multicenter natural history study of neurofibromatosis Type 2.

SUBJECTS

One hundred fifteen magnetic resonance imaging examinations of 57 neurofibromatosis Type 2 patients older than 5 years of age.

INTERVENTIONS

Thin-slice, postcontrast cranial magnetic resonance imaging.

MAIN OUTCOME MEASURES

Spearman's rho interobserver association coefficient of vestibular schwannoma linear measurements.

RESULTS

The local and experienced radiologist measurements and identification of tumors agreement was fair (kappa = 0.77). Discordant interpretations were adjudicated by another experienced neuroradiologist.

CONCLUSION

The least interobserver variability was found in measurements of thin-slice postcontrast magnetic resonance imaging scans obtained at neurofibromatosis Type 2 centers in patients without previous operations and moderately sized tumors. If the schwannoma was difficult to assess, because of magnetic resonance imaging acquisition protocol, postoperative changes, or tumors smaller than 5 mm in greatest diameter, the neuroradiologist provided a more thorough assessment. The authors suggest uniform reporting criteria for vestibular schwannoma assessments to ensure clinically relevant information is communicated regarding vestibular schwannoma size.

Imaging of the temporal bone

Classical descriptions of the temporal bone are based on its five embryologically distinct osseous components: the petrous, tympanic, mastoid, squamous, and styloid portions.

Meningiomas of the internal auditory canal

OBJECTIVE

Meningiomas arising primarily within the internal auditory canal (IAC) are notably rare. By far the most common tumors that are encountered in this region are neuromas. We report a series of eight patients with meningiomas of the IAC, analyzing the clinical presentations, surgical management strategies, and clinical outcomes.

METHODS

The charts of the patients, including histories and audiograms, imaging studies, surgical records, discharge letters, histological records, and follow-up records, were reviewed.

RESULTS

One thousand eight hundred meningiomas were operated on between 1978 and 2002 at the Neurosurgical Department of Nordstadt Hospital. Among them, there were 421 cerebellopontine angle meningiomas; 7 of these (1.7% of cerebellopontine angle meningiomas) were limited to the IAC. One additional patient underwent surgery at the Neurosurgical Department of the International Neuroscience Institute, where a total of 21 cerebellopontine angle meningiomas were treated surgically from 2001 to 2003. As a comparison, the incidence of intrameatal vestibular schwannomas during the same period, 1978 to 2002, was 168 of 2400 (7%). There were five women and three men, and the mean age was 49.3 years (range, 27-59 yr). Most patients had signs and symptoms of vestibulocochlear nerve disturbance at presentation. One patient had sought treatment previously for total hearing loss before surgery. No patient had a facial paresis at presentation. The neuroradiological workup revealed a homogeneously contrast-enhancing tumor on magnetic resonance imaging in all patients with hypointense or isointense signal intensity on T1- and T2-weighted images. Some intrameatal meningiomas showed broad attachment, and some showed a dural tail at the porus. In all patients, the tumor was removed through the lateral suboccipital retrosigmoid approach with drilling of the posterior wall of the IAC. Total removal was achieved in all cases. Severe infiltration of the facial and vestibulocochlear nerve was encountered in two patients. There was no operative mortality. Hearing was preserved in five of seven patients; one patient was deaf before surgery. Postoperative facial weakness was encountered temporarily in one patient.

CONCLUSION

Although intrameatal meningiomas are quite rare, they must be considered in the differential diagnosis of intrameatal mass lesions. The clinical symptoms are very similar to those of vestibular schwannomas. A radiological differentiation from vestibular schwannomas is not always possible. Surgical removal of intrameatal meningiomas should aim at wide excision, including involved dura and bone, to prevent recurrences. The variation in the anatomy of the faciocochlear nerve bundle in relation to the tumor has to be kept in mind, and preservation of these structures should be the goal in every case.

Meningioma of the internal auditory vanal: case report

Meningiomas limited to the internal auditory canal (IAC) are rare. Acoustic neuroma is usually the diagnosis made when a tumor is found in this location because of its higher frequency. We report on a 58 year-old woman with a meningioma arising from the IAC and the difficulty to establish the pre-surgical diagnosis, based on clinical and radiological features. The perioperative suspicion and confirmation are very important to deal with the dura and bone infiltration in order to reduce tumor recurrence.

Imaging of the temporal bone

Classical descriptions of the temporal bone are based on its five embryologically distinct osseous components: the petrous, tympanic, mastoid, squamous, and styloid portions.

Cerebellopontine angle meningioma with a high jugular bulb

A cerebellopontine angle meningioma originating from the skull base over a high jugular bulb is quite rare. We report a case of a 68-year-old woman who had a right cerebellopontine angle meningioma with a prominent high jugular bulb. CT and MRI revealed a round tumour which attached to a bony prominence over the high jugular bulb. The apex of the jugular bulb was 3 mm higher than the floor of the internal auditory canal. The tumour was removed via a suboccipital retrosigmoid approach. The bony projection was drilled off carefully using a diamond drill; the jugular bulb became visible through the thinned bone. When a meningioma of this type is removed including bony changes, special attention is needed to avoid injury to the jugular bulb.

Imaging evaluation of sensorineural hearing loss

The imaging evaluation of patients with sensorineural hearing loss (SNHL) focuses on the acoustic pathways from the cochlea to the auditory cortex. Magnetic resonance imaging (MRI) is the modality of choice for most patients with SNHL, though computed tomography (CT) also plays an important role in the evaluation of bony changes and in patients for whom MRI is contraindicated. Conventional enhanced MRI is the most commonly used technique in this clinical setting. High-resolution fast spin-echo T2 MRI is an adjunctive technique that provides exquisite evaluation of the cerebellopontine angle (CPA), internal auditory canal (IAC), cranial nerves, and membranous labyrinth, and plays a significant role in the diagnosis and surgical evaluation of SNHL. Categories of lesions that cause SNHL include brain lesions involving central auditory pathways; neoplasms of the CPA and IAC, the most common being schwannoma; other neoplastic, congenital, and cystic masses of the CPA and IAC; congenital anomalies of the inner ear; intrinsic cochlear nerve defects, inflammatory processes of the inner ear; and temporal bone trauma.

Meningiomas of the cerebellopontine angle

BACKGROUND

Meningiomas of the cerebellopontine angle (CPA), although uniform in location, are diverse with regard to the site of dural origin and displacement of neurovascular structures. A study of patients with CPA meningiomas was undertaken to gain more information regarding the relationship between site of dural attachment, clinical presentation, operative approach, and outcome.

METHODS

In this report, we retrospectively review 40 patients with CPA meningiomas managed surgically.

RESULTS

Common clinical presentations were hearing loss, unsteadiness, and dysequilibrium. Findings upon physical examination included hearing loss (73%), cerebellar signs (32%), trigeminal neuropathy (16%), and facial nerve dysfunction (16%). The most common site of dural origin was the petrous ridge (anterior to the IAC [26%], posterior [21%], superior [18%], and inferior [16%]). Less common sites of dural origin included the tentorium (31%), the clivus (15%), the IAC (10%), and the jugular foramen (8%). Site of dural origin determined the direction of displacement of the facial/vestibulocochlear nerve bundle. The most common microsurgical complication was facial nerve dysfunction (30%). Gross total resection was achieved in 82% of cases, whereas 18% underwent subtotal resection. Two patients died. Follow-up ranged from three months to 13 years with three recurrences.

CONCLUSIONS

CPA meningiomas displace the seventh and eighth cranial nerves in various directions depending on the site of dural origin. Total surgical excision can be accomplished in the majority of cases with acceptable morbidity.

Meningioma of the internal auditory canal with extension into the vestibule

Meningiomas account for approximately 18 to 19 per cent of all brain tumours. Although they can arise in numerous locations, meningiomas of the internal auditory canal (IAC) are rare. Most tumours that originate in the IAC are schwannomas of the VIIIth cranial nerve (acoustic neuromas). We report a case of a meningioma which appears to originate from the IAC and extends into the vestibule. The clinical findings and the radiographical features of meningiomas of the IAC are similar to those of acoustic neuromas. Pre-operative differentiation between acoustic neuromas and meningiomas of the IAC may be difficult.

Clinical features and outcomes in patients with non-acoustic cerebellopontine angle tumours

OBJECTIVES

Non-acoustic tumours of the cerebellopontine angle differ from vestibular schwannomas in their prevalence, clinical features, operative management, and surgical outcome. These features were studied in patients presenting to the regional neuro-otological unit.

METHODS

A retrospective analysis of clinical notes identified 42 patients with non-acoustic tumours of the cerebellopontine angle. Data were extracted regarding presenting clinical features, histopathological data after surgical resection, surgical morbidity and mortality, and clinical outcome (mean 32 months follow up).

RESULTS

The study group comprised 25 meningiomas (60%), 12 epidermoid cysts/cholesteatomata (28%), and five other tumours. In patients with meningiomas, symptoms differed considerably from patients presenting with vestibular schwannomas. Cerebellar signs were present in 52% and hearing loss in only 68%. Twenty per cent of patients had hydrocephalus at the time of diagnosis. After surgical resection, normal facial nerve function was preserved in 75% of cases. In the epidermoid group, fifth, seventh, and eighth nerve deficits were present in 42%, 33%, and 66% respectively. There were no new postoperative facial palsies. There were two recurrences (17%) requiring reoperation. Overall, there were two perioperative deaths from pneumonia and meningitis.

CONCLUSIONS

Patients with non-acoustic lesions of the cerebellopontine angle often present with different symptoms and signs from those found in patients with schwannomas. Hearing loss is less prevalent and cerebellar signs and facial paresis are more common as presenting features. Hydrocephalus is often present in patients presenting with cerebellopontine angle meningiomas. Non-acoustic tumours can usually be resected with facial nerve preservation.

Meningioma of the internal auditory canal

Meningiomas are the second most common tumor to involve the cerebellopontine angle (CPA), but controversy exists as to whether they can arise within the internal auditory canal (IAC) or whether involvement of the IAC occurs secondarily by extension from the CPA. This paper reports on a patient with an enhancing IAC meningioma that then grew and on subsequent scans was found to involve the CPA. This case demonstrates that these tumors can arise within the IAC and can grow out to involve the CPA. These findings are discussed within the context of meningioma tumor genetics and the histologic evidence for precursor cells in the IAC. The radiologic findings useful in distinguishing an acoustic neuroma from a meningioma are reviewed in the light of this case. While an enhancing mass projecting into the IAC is most often an acoustic neuroma, this radiologic findings is not pathognomonic.

Extracranial meningioma presenting as a tumour of the external auditory meatus: a case report

A rare case of extracranial meningioma presenting as a tumour of the external auditory meatus is reported. Biopsy indicated a diagnosis of meningioma, but the radiological appearance was unusual. For example, computed tomography (CT) scans showed an unenhanced tumour mainly located in the squamous part of the temporal bone which expanded into the external meatus destroying the temporal bone. Magnetic resonance imaging (MRI) revealed that the tumour did not extend into the intradural space. This meningioma, had an obvious tendency for extracranial development. According to the operative findings, the tumour arose from the middle cranial fossa dura and extended through the air cells of the temporal bone into the external meatus, instead of growing intracranially. Secondary extracranial meningiomas of the temporal bone usually have a large intracranial component and cause neurological symptoms. However, this was a very rare case of a small meningioma causing no symptoms except for conductive hearing loss.

Tc-99m MIBI brain SPECT of cerebellopontine angle tumors

To prospectively evaluate the imaging feasibility of Tc-99m sestamibi brain SPECT of cerebellopontine angle (CPA) tumors, seven patients with CPA lesions seen on CT or MRI and five normal control subjects underwent brain SPECT using a triple-headed camera. Five of these patients had acoustic neuromas, one had a meningloma, and the other had a vascular loop. Subsequently, four patients underwent surgery. In normal control subjects and patients with CPA lesions, there was Tc-99m sestamibi activity in the pituitary gland, choroid plexi, and extraocular muscles. The uptake in these structures, especially the choroid plexi could not be blocked by the oral administration of potassium perchlorate in two normal subjects. Four of seven patients with CPA lesions larger than 1.0 cm in diameter showed tumor uptake (3 acoustic schwannomas, 1 meningloma). Two small ( > 1.0 cm in diameter) intracanalicular type acoustic neuromas failed to show uptake, despite additional attenuation correction for the petrous bone. There was no abnormal uptake in the patient with a vascular loop in the CPA. Preliminary data suggest that, with the exception of small intracanalicular neuromas, CPA tumors can be imaged using Tc-99m sestamibi brain SPECT.

Hearing improvement after conservative approach for large posterior fossa meningioma

Hearing preservation during the posterior fossa surgery depends on many factors, including tumor size and site of origin. In many cases, regardless of the presumed tumor origin, the severity of the pure-tone loss or decline in speech discrimination on preoperative testing prompts the surgeon to choose a surgical approach (translabyrinthine or transcochlear) that negates the chance for postoperative functional hearing in the involved ear. We describe a 41-year-old woman with unilateral severe sensorineural hearing loss who experienced a remarkable recovery of hearing after combined retrolabyrinthine and retrosigmoid removal of a 4 cm petrous ridge meningioma using intraoperative cochlear monitoring. Despite the tumor size, early intraoperative loss of wave I and proximity of the tumor to the porus, complete tumor removal was accomplished with preservation of the cochleovestibular bundle. Three weeks postoperatively, the patient noted marked subjective improvement and speech audiometry demonstrated an improvement in word recognition, from 0% to 86%. This improvement has remained 1 year postoperatively, with no evidence of persistent tumor on repeat MRI scan. The case report illustrates the possibility of not just hearing preservation but improvement after removal of even large posterior fossa meningiomas that do not directly invade the cochlear nerve itself.