Unusual cerebello-pontine angle tumours

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.

Features of postoperative hearing function changes in patients with cerebellopontine angle and intratemporal tumors other than vestibular schwannomas

OBJECTIVE

Tumors around the cerebellopontine angle (CPA) and temporal bone can potentially affect hearing function. In patients with such tumors other than vestibular schwannomas (VSs), auditory tests were investigated before and after surgery to characterize the auditory effect of each tumor and to determine prognostic factors.

METHODS

A total of 378 patients were retrospectively evaluated for hearing functions before and after surgery. These 378 patients included 168 with CPA meningioma, 40 with trigeminal schwannoma (TS), 55 with facial nerve schwannoma (FNS), 64 with jugular foramen schwannoma (JFS), and 51 with CPA epidermoid cyst (EPD).

RESULTS

Preoperative hearing loss was observed in 124 (33%) of the 378 patients. Of these 124 patients, 38 (31%) experienced postoperative hearing improvement. Postoperative hearing deterioration occurred in 67 (18%) of the 378 patients. The prognostic factors for postoperative hearing improvement were younger age and the retrocochlear type of preoperative hearing disturbance. Tumor extension into the internal auditory canal was correlated with preoperative hearing loss and postoperative hearing deterioration. Preoperative hearing loss was observed in patients with FNS (51%), JFS (42%), and MGM (37%), and postoperative hearing improvement was observed in patients with JFS (41%), MGM (31%), and FNS (21%). Postoperative hearing deterioration was observed in patients with FNS (27%), MGM (23%), and EPD (16%).

CONCLUSIONS

According to the results of this study in patients with CPA and intratemporal tumors other than VS, preoperative retrocochlear hearing disturbance was found to be a prognostic factor for hearing improvement after surgery. Among the tumor types, JFS and MGM had a particularly favorable hearing prognosis. The translabyrinthine approach and cochlear nerve section should be avoided for these tumors, regardless of the patient's preoperative hearing level.

The otologic approach in the management of posterior petrous surface meningiomas

PURPOSE

Report our experience in the management of posterior petrous surface meningiomas (PPSMs), and identify features that affect hearing, facial nerve (FN) function, and control of the disease.

METHODS

Retrospective case series of 131 patients surgically managed for PPSMs. FN status, hearing and tumour radicality were assessed and compared between patients with tumours of different locations (Desgeorges classification) and internal auditory canal involvement (IAC).

RESULTS

At the time of surgery 74.8% of patients had a hearing loss. Hearing was mostly unserviceable in tumors attached to the meatus. Pure tone audiometry did not correlate to IAC extension, while speech discrimination scores were statistically worse when the tumor occupied the IAC (unpaired t test, p = 0.0152). Similarly, extrameatal tumors undergoing removal by otic preserving techniques maintained postoperative hearing, whereas hearing worsened significantly in tumors involving the IAC (paired t test, p = 0.048). The FN was affected preoperatively in 11.4% of cases. Postoperative FN palsy was significantly correlated to the IAC involvement (Fisher's exact test, p = 0.0013), while it was not correlated to tumor size. According to the Desgeorges classification, a postoperative FN palsy complicated the majority of anteriorly extending tumors and, two-fifths of meatus centred tumors. 75% of posterior located tumors had a postoperative FN grade I HB.

CONCLUSIONS

Since the involvement of the IAC by the tumor affects both hearing and FN function, the IAC is of primary importance in PPSMs and should be studied and addressed as much as the tumor location in the CPA.

Hearing recovery after surgical resection of non-vestibular schwannoma cerebellopontine angle tumors

PURPOSE

Post-operative outcomes for hearing after resection surgery to remove cerebellopontine angle (CPA) tumors other than vestibular schwannomas (VS) are not well understood. This study presents a series of patients with significant post-operative hearing recovery, trying to define the incidence among all patients operated on for removal of non-VS CPA tumors.

METHODS

This is a retrospective observational case series of 8 patients among 69 operated on for removal of non-VS CPA tumors between 2012 and 2020. All patients had pre- and post-operative hearing measurement with pure-tone average (PTA) and speech discrimination score (SDS), according to the American Academy of Otolaryngology-Head and Neck Surgery recommendations, auditory brainstem response (ABR) measurements and imaging.

RESULTS

Six meningiomas and two lower cranial nerve schwannomas operated on with a retrosigmoid approach were included for analysis. The mean pre-operative PTA and SDS were 58 ± 20.7 dB and 13 ± 17.5%, respectively. All patients had pre-operative class D hearing and asynchronous ABRs. They all showed significant hearing recovery, with an improvement of 36 ± 22.2 dB (p = 0.0025) and 85 ± 16.9% (p = 0.0001) in PTA and SDS, respectively, with mean follow-up of 21 ± 23.5 months. Seven patients recovered to a class A hearing level and one patient to class B. The ABRs became synchronous for three patients. The incidence of auditory recovery was 13% for patients operated on with a conservative approach (n = 60).

CONCLUSION

A significant post-operative improvement in hearing could be a reasonable expectation in non-VS tumors extending into the CPA and a retrosigmoid approach should always be considered regardless of pre-operative hearing status.

Facial palsy caused by an intrameatal metastatic disease - Reconstruction with an autologous sural nerve graft

Dysfunction of the facial nerve is frequently attributed to inflammation, followed by traumatic injury. Knowledge of the complex anatomical course of the facial nerve is critical to localize the site of pathology and for successful management. The multiplicity of etiologies and its complex anatomy often make facial paralysis a diagnostic challenge. Neoplasms are a fairly rare cause of peripheral facial palsy, and are frequently overlooked in search of the more frequent traumatic or inflammatory etiologies of facial paralysis. Isolated metastatic lesions to the cerebellopontine angle (CPA) and internal auditory canal (IAC) are extremely rare. Their accurate diagnosis is difficult, since they share common clinical and radiological characteristics with vestibular schwannomas. We report a case of a 63-year-old female with a rapidly progressive left-sided hearing loss and complete facial palsy. Magnetic resonance imaging revealed a left intrameatal lesion. A provisional diagnosis of intracanalicular schwannoma or meningioma was made, although the possibility of metastasis due to her rapid neurological deterioration was considered. The patient underwent a translabyrinthine complete removal of the tumor followed by facial nerve reconstruction. The final histopathological findings revealed a metastatic breast adenocarcinoma. To our knowledge only seven prior cases of an isolated metastatic CPA lesion have been reported. In patients without a known malignancy, a rapid progression of hearing loss, disequilibrium, and facial palsy might be the first sign of a metastatic CPA lesion.

Meningiomas of the Internal Auditory Canal

OBJECTIVE

Identify and define specific preoperative and postoperative characteristics of intracanalicular meningiomas (ICMs) in order to improve their diagnosis and management, and to differentiate them from intrameatal vestibular schwannomas (IMVSs).

METHODS

Preoperative symptomatology, magnetic resonance imaging (MRI), and postoperative outcomes of 28 ICMs were analyzed. The results were compared to the literature and IMVSs treated by our group.

RESULTS

Anacusis and progressive hearing loss were more frequent in the present population than the cases reviewed (P = .0064 and P = .0001, respectively). Hearing loss affected more than 90% of the patients, with anacusis in 32.1% of the cases. Facial palsy affected 17.9% of the patients. In comparison to IMVSs, preoperative anacusis was more associated to meningiomas (P = .0037), and the facial nerve was more compromised in ICMs than IMVSs, both preoperatively (P = .0011) and at follow-up (P < .0001). According to a re-evaluation of preoperative MRIs and comparison with IMVSs, linear tumor borders, and linear morphology along the internal auditory canal wall, but not the presence of a dural tail, were significantly more present in ICMs (P = .0035, P = .0004, P = .1963, respectively). These characteristics could have led to a correct preoperative diagnosis in 61% of our cases.

CONCLUSION

Contrariwise to IMVSs, the frequent preoperative anacusis and facial palsy demonstrate the more aggressive nature of ICMs, which also carry a higher risk of postoperative facial palsy and difficulty to preserve hearing. An attentive evaluation of imaging should ease diagnosis, and asymptomatic or stable ICMs should be enrolled in a wait-and-scan protocol.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E413-E419, 2021.

Clinical and Radiological Characteristics of Malignant Tumors Located to the Cerebellopontine Angle and/or Internal Acoustic Meatus

OBJECTIVE

Metastatic lesions to the internal auditory meatus (IAM) and/or the cerebellopontine angle (CPA) are rare and may appear like a vestibular schwannoma (VS). We herein raise the issue of the diagnosis and treatment of nine malignant cases of the CPA and IAM among three referral centers in France and Japan. The aim of this study was 1) to report malignant lesions of the CPA, their diagnosis and treatment, 2) to review the literature, 3) to propose criteria of suspicion for malignant tumors of the CPA.

METHODS

Nine patients who had malignant lesions of the CPA and/or IAM for whom the final diagnosis was made by surgery, lumbar puncture, or PET scan were included. The main outcomes measured were: rapid onset of symptoms, association of cochlea-vestibular symptoms with facial palsy, and MRI analysis.

RESULTS

Among the nine patients with malignant tumor of the CPA, 8 of them (89%) had a facial palsy associated with cochlea-vestibular symptoms. Rapid growth of the tumor was observed in 77% (7/9) of the cases in a mean time interval of 4.6 months. The initial diagnosis evoked was VS in 44% of the cases (4/9). Atypical MRI aspect was seen in 67% of the cases (6/9) with bilateral tumors in 55% of cases (5/9).

CONCLUSION

Although rare, malignant tumors of the CPA and/or IAM should be evoked in case of association of cochleovestibular symptoms and facial palsy, rapid onset and atypical MRI aspect.

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.

Bilateral Internal Auditory Canal Metastasis of Colon Carcinoma Mimicking Neurofibromatosis Type II: A Case Report and Literature Review

BACKGROUND

The vast majority of cerebellopontine angle tumors are benign with a favorable prognosis. Metastatic tumors occurring in the cerebellopontine angle are extremely rare. Herein, we report a case of colon carcinoma metastasis to the bilateral internal auditory canals.

CASE DESCRIPTION

A 59-year-old man presented with a 2-week history of binaural hearing loss. One year before admission, he was diagnosed with colon carcinoma and underwent surgical resection combined with chemotherapy. Physical examination showed complete hearing loss in bilateral ears and bilateral facial palsy. Magnetic resonance imaging of the brain revealed nodules in the bilateral internal auditory canals. Middle-ear computed tomography demonstrated soft-tissue masses extending into the bilateral internal auditory canals. A diagnosis of neurofibromatosis type II was suspected. A unilateral surgical resection of the cerebellopontine angle tumor was performed. Postoperatively, the hearing loss and facial palsy remained unchanged. Pathologic examination showed metastatic, poorly differentiated carcinoma. The patient was diagnosed with metastatic colon carcinoma in the bilateral internal auditory canals. The patient refused radiotherapy and chemotherapy. The tumor progressed rapidly, and the patient developed dysphagia and choking 1 month later. The patient died of respiratory and circulatory failure 2 months after the surgery.

CONCLUSIONS

Clinicians should be aware of metastatic tumors in the internal auditory canals. Comprehensive clinicoradiologic evaluation should be highlighted. A history of malignancy and rapidly progressive hearing loss and facial palsy may suggest the diagnosis of metastasis to the internal auditory canal. The definitive diagnosis still depends on histopathologic examination.

Lesions Mimicking Small Vestibular Schwannomas

Objective  Most tumors of the internal auditory canal and cerebellopontine angle (CPA) are vestibular schwannomas (VSs). Preoperative diagnosis is based on typical clinical symptoms and radiological findings. In rare cases, histopathology can, however, show different results. Design  This is a retrospective chart and database review. Setting  The study was conducted at a tertiary skull base referral center at a university hospital. Participants  A total of 207 consecutive cases of VS surgery via the middle cranial fossa approach performed between December 2005 and January 2015 were reviewed. Main Outcome Measures  The main outcome measures were definitive histologic findings in 198 specimens, analysis of preoperative magnetic resonance imaging (MRI) and computed tomography. Results  Histopathology revealed three meningiomas and two cases of lipochoristomas. Clinical presentation was typical for VS in all five cases. In preoperative MRI, all tumors were suspected to be VSs. Retrospective analysis of the preoperative imaging did not lead to a modification of the diagnosis. Intraoperative findings showed increased adherence of the tumor to the adjacent tissue in two of the five cases. Conclusion  CPA lesions other than VSs are unusual but have to be taken into account. In very small tumors, imaging still remains difficult.

CT- and MRI-based gross target volume comparison in vestibular schwannomas

AIM

This study represents an enumeration and comparison of gross target volumes (GTV) as delineated independently on contrast-enhanced computed tomography (CT) and T1 and T2 weighted magnetic resonance imaging (MRI) in vestibular schwannomas (VS).

BACKGROUND

Multiple imaging in radiotherapy improves target localization.

METHODS AND MATERIALS

42 patients of VS were considered for this prospective study with one patient showing bilateral tumor. The GTV was delineated separately on CT and MRI. Difference in volumes were estimated individually for all the 43 lesions and similarity was studied between CT and T1 and T2 weighted MRI.

RESULTS

The male to female ratio for VS was found to be 1:1.3. The tumor was right sided in 34.9% and left sided in 65.1%. Tumor volumes (TV) on CT image sets were ranging from 0.251 cc to 27.27 cc. The TV for CT, MRI T1 and T2 weighted were 5.15 ± 5.2 cc, 5.8 ± 6.23 cc, and 5.9 ± 6.13 cc, respectively. Compared to MRI, CT underestimated the volumes. The mean dice coefficient between CT versus T1 and CT versus T2 was estimated to be 68.85 ± 18.3 and 66.68 ± 20.3, respectively. The percentage of volume difference between CT and MRI (%VD: mean ± SD for T1; 28.84 ± 15.0, T2; 35.74 ± 16.3) and volume error (%VE: T1; 18.77 ± 10.1, T2; 23.17 ± 13.93) were found to be significant, taking the CT volumes as the baseline.

CONCLUSIONS

MRI with multiple sequences should be incorporated for tumor volume delineation and they provide a clear boundary between the tumor and normal tissue with critical structures nearby.

Internal auditory canal osteoma: Case report and review of the literature

We report a case of internal auditory canal osteoma and discuss this entity's etiology, natural history, and treatment options. The internal auditory canal osteoma is a rare entity with only a few reports published in the medical literature. Its diagnosis is based on two complementary imaging modalities: thin-slice computed tomography and magnetic resonance imaging. No consensus exists regarding the treatment of this entity, and treatment should be tailored to each patient depending on that patient's initial complaints, as well as his or her medical findings.

Cerebellopontine angle primitive neuroectodermal tumor mimicking trigeminal schwannoma

BACKGROUND

Primitive neuroectodermal tumors (PNETs) comprise a group of aggressive, poorly differentiated embryonal tumors occurring in central nervous system as well as in peripheral locations. Primary cerebellopontine angle (CPA) PNET is an extremely rare entity. It is important to have knowledge of this pathology and to be able to differentiate it from other commonly occurring CPA tumors, such as vestibular and trigeminal schwannomas. This distinction is essential because of the difference in the overall treatment plan and prognosis.

CASE DESCRIPTION

This report describes a case of a young male presenting with diplopia and numbness of face; magnetic resonance imaging showed a CPA mass. With a provisional diagnosis of trigeminal schwannoma, the patient underwent surgery. Histopathology provided a diagnosis of PNET.

CONCLUSION

We discuss the importance of recognizing this rare condition and how this entity differs from the commonly occurring tumors.

High rate of bilaterality in internal auditory canal metastases

PURPOSE

Presentation of three cases of metastatic carcinoma to the internal auditory canal bilaterally, as well as a systematic review of the literature regarding the characteristics of these lesions.

MATERIALS AND METHODS

Using a MEDLINE Ovid search (1946-2015), we identified and reviewed 102 cases of metastatic carcinoma to the internal auditory canal. Metrics recorded include: patient age, sex, tumor type, laterality, past oncologic history, co-occurring metastatic sites, clinical findings, radiographic findings, therapy received, and outcome. Cases of unilateral versus bilateral IAC were compared.

RESULTS

Remarkably, 52.9% reported cases of internal auditory canal metastases have bilateral occurrence. The most common primary tumor sites for internal auditory canal metastases were lung (21.2%), skin (18.6%), and breast (16.7%), with lung and skin cancers having the highest rates of bilateral metastasis. Meningeal metastasis occurred at a much higher rate in bilateral cases (47.2%) versus unilateral cases (8.5%). Brain parenchymal metastasis also occurred at a higher rate in bilateral cases (38.2%) versus unilateral cases (19.2%). Outcomes for cases of internal auditory canal metastases are generally poor, with 56.3% of unilateral cases and 86.1% of bilateral cases reporting patient death within 5 years from diagnosis.

CONCLUSIONS

In cases of internal auditory canal metastasis, clinicians should carefully assess for not only contralateral disease but also additional metastatic disease of the central nervous system. Rapid-onset hearing loss, tinnitus, vertigo, or facial palsy should raise suspicion for internal auditory canal metastasis, particularly in patients with a known oncologic history.

Hearing disorders in brainstem lesions

Auditory processing can be disrupted by brainstem lesions. It is estimated that approximately 57% of brainstem lesions are associated with auditory disorders. However diseases of the brainstem usually involve many structures, producing a plethora of other neurologic deficits, often relegating "auditory symptoms in the background." Lesions below or within the cochlear nuclei result in ipsilateral auditory-processing abnormalities detected in routine testing; disorders rostral to the cochlear nuclei may result in bilateral abnormalities or may be silent. Lesions in the superior olivary complex and trapezoid body show a mixture of ipsilateral, contralateral, and bilateral abnormalities, whereas lesions of the lateral lemniscus, inferior colliculus, and medial geniculate body do not affect peripheral auditory processing and result in predominantly subtle contralateral abnormalities that may be missed by routine auditory testing. In these cases psychophysical methods developed for the evaluation of central auditory function should be employed (e.g., dichotic listening, interaural time perception, sound localization). The extensive connections of the auditory brainstem nuclei not only are responsible for binaural interaction but also assure redundancy in the system. This redundancy may explain why small brainstem lesions are sometimes clinically silent. Any disorder of the brainstem (e.g., neoplasms, vascular disorders, infections, trauma, demyelinating disorders, neurodegenerative diseases, malformations) that involves the auditory pathways and/or centers may produce hearing abnormalities.

Vestibular schwannoma or tanycytic ependymoma: Immunohistologic staining reveals

Background:

The cerebellopontine angle (CPA) is a common location for primary tumors, most often vestibular schwannomas, and also meningiomas, dermoids, and a host of other neoplasms. Our case report illustrates how radiologic and histopathologic presentations of an unusual variant of ependymal neoplasm can be diagnostically challenging and how accurate diagnosis can affect treatment protocols.

Case History:

Our patient had a CPA mass that was a variant of ependymoma known as tanycytic ependymoma that mimicked vestibular schwannoma radiologically and during intraoperative pathologic examination. Diagnosis as a World Health Organization (WHO) grade II tanycytic ependymoma was supported by its appearance on evaluation of the permanent sections, its diffuse immunoreactivity for glial fibrillary acidic protein (GFAP), and the perinuclear dot-and-ring-like staining for epithelial membrane antigen (EMA).

Conclusions:

Our patient's CPA mass initially believed to be a vestibular schwannoma on preoperative evaluation, surgical appearance, and intraoperative pathologic consultation was then correctly diagnosed as a WHO grade II tanycytic ependymoma on permanent histologic sections with the assistance of immunohistochemical stains, including EMA. After this definitive diagnosis, our patient's adjuvant treatment was adjusted. Earlier diagnosis could have provided guidance for goals of resection and prompt initiation of adjuvant treatment.

Bilateral Internal Auditory Canal Metastasis of Non-small Cell Lung Cancer

We report on a patient with brain metastasis involving bilateral internal auditory canal from non-small cell lung cancer (NSCLC). A 49-year-old woman who had been diagnosed with NSCLC (T2aN1M0) complained of persistent vertigo and bilateral tinnitus for three months. The patient had refused all treatments, including surgery and chemotherapy; however, she sought alternative medicine. The patient’s hearing loss showed rapid progression bilaterally, and rotatory vertigo with peripheral-type nystagmus developed. Magnetic resonance imaging of the brain showed irregular nodular enhancement within both internal auditory canals with leptomeningeal enhancement and multiple intracranial metastasis. The patient was treated with epidermal growth factor receptor-tyrosine kinase inhibitor, and the tumor showed partial response. This was a rare case of multiple brain metastases involving bilateral internal auditory canal from known NSCLC presenting with vertigo and hearing loss.

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.

Germinoma in the internal auditory canal mimicking a vestibular schwannoma

The appearance of a primary germinoma in the central nervous system but not on or near the midline or within the brain is exceptional. It may occur at any age; however, it is rare in patients over 50 years old. Only a handful of cases of germinomas located in the cerebellopontine angle were presented, but to our knowledge, there has been no description of an isolated germinoma in the internal auditory canal. We report a case of germinoma in the internal auditory canal in a 51-year-old man simulating the clinical and radiological characteristics of a vestibular schwannoma.

Facial nerve schwannomas of the cerebellopontine angle: the mayo clinic experience

Background There is often controversy regarding the optimal management for patients with facial nerve schwannomas (FNSs) of the cerebellopontine angle (CPA). Methods The clinical and radiological outcomes in 14 patients with CPA FNS were retrospectively reviewed. Results Patients underwent resection with anatomic nerve preservation (n = 3), facial-hypoglossal nerve anastomosis (n = 4), gamma knife radiosurgery (GKS) (n = 6), or observation (n = 1). A total of 83% of tumors that underwent GKS were stable or decreased in size. No patient who underwent resection showed evidence of tumor recurrence; the tumor under observation remained unchanged with normal facial function at the time of the last follow-up. Facial function was decreased in 57%, stable in 14%, and improved in 29% of those who underwent microsurgery. A total of 67% of patients who underwent GKS had stable facial function. Serviceable hearing was maintained in 50% of patients in the GKS group and 67% of the tumor resection group. Mean and median follow-up was 48 and 43 months, respectively (range, 12 to 95 months). Conclusion Observation should be the primary management when encountered with FNS of the CPA in those with good neurologic function. Microsurgery or radiosurgery may be used in those with poor facial function or tumor progression.

Meningiomas of the internal auditory canal: two case reports

Meningiomas represent 3 to 12% of the tumors that involve the cerebellopontine angle and internal auditory canal (IAC). Intracanalicular meningiomas, however, are rare. Only 10 well-documented cases have been reported in the English literature. The differential diagnosis includes acoustic neuromas, facial nerve neuromas, hemangiomas, lipomas, and meningiomas. We report two new cases of intracanalicular meningioma. Both patients had unilateral tinnitus. In case 1, the patient also experienced sensorineural hearing loss with unilateral tinnitus. In case 1, the lesion appeared hyperintense on T1-weighted and hypointense on T2-weighted magnetic resonance images. In case 2, the patient had an enhancing lesion in the right IAC. The tumors were moderately cellular, and meningeal whorls and meningothelial inclusions were present. Immunohistochemical staining revealed the tumors to be positive for epithelial membrane antigen (EMA) and negative for S-100 protein. The radiologic findings that help distinguish a meningioma from other lesions are reviewed.

Fast-growing vestibular schwannoma

A case of a Jehovah's witness affected by an intracanalicular vestibular schwannoma with an extremely fast growth rate is presented. Nine months after presentation, the tumor reached 23 mm in the cerebellopontine angle. A partial removal through a retrosigmoid approach was planned. Because of the presence of a dominant high jugular bulb masquering the internal auditory canal, the intracanalicular portion of the tumor was left in place. The residual tumor grew 12 mm in 2 months. Even after a gross total removal through a middle cranial fossa approach, the tumor recurred, reaching the size of 30 mm in 17 months. A modified transcochlear approach was then performed, and the patient was free of disease at the last radiologic follow-up, 8 months after the surgery. We illustrate our strategy in treating this aggressive benign lesion with unusual behavior.

Solitary metastasis of bronchogenic adenocarcinoma to the internal auditory canal: a case report

We report a patient with an isolated metastasis to the internal auditory canal (IAC) of bronchogenic adenocarcinoma. A 58-yr-old man who had received 6-cycle of chemotherapy under diagnosis of non-small cell lung carcinoma (T4N2M0) two years ago was referred to our department with vertigo, right-sided facial paralysis and right-sided hearing loss. A provisional diagnosis of vestibular schwannoma or meningioma involving right IAC was made from magnetic resonance imaging. The patient underwent a translabyrinthine removal of the tumor. Histopathological study of the resected lesion showed a poorly differentiated adenocarcinoma compatible with bronchogenic origin. The patient died 9 months after surgery from extensive brain metastasis despite postoperative radiation therapy. In patients with a previous history of treatment of malignancy elsewhere in the body, the possibility of IAC metastasis must be considered when an IAC lesion is detected.

Metastatic tumours mimicking vestibular schwannoma

In this review of the literature we discuss the rare occurrence of metastatic tumours mimicking bilateral vestibular schwannoma and present an own case with pancreatic signet-ring cell carcinoma as primary tumour.

Bilateral osteomas arising from the internal auditory canal: case report

OBJECTIVE

Osteomas arising from the internal auditory canal and developing in the cerebellopontine angle have rarely been reported. We present the first case of bilateral osteomas in this region and describe our management strategy.

CLINICAL PRESENTATION

A 30-year-old woman presented with strong vertigo, tinnitus, and hypacusis on the left side. Brain magnetic resonance imaging and computed tomographic scans displayed bilateral cerebellopontine angle osteomas arising from the internal auditory canal. The larger tumor on the left side was found to be compressing the vestibulocochlear nerve.

INTERVENTION

Surgery was performed on the symptomatic side via the retrosigmoid approach, and the tumor was removed completely. The vertigo resolved completely after surgery, and the patient had no further tinnitus attacks. An audiogram showed slightly improved hearing with a mean of 20 dB in the main speech area.

CONCLUSION

Osteomas should be considered in patients with bilateral cerebellopontine angle tumors. Surgical removal might provide resolution of symptoms.

Steroid responsive fluctuating sensorineural hearing loss due to juvenile pilocytic astrocytoma involving the cerebellopontine angle

Tumors of the cerebellopontine angle (CPA) are common and represent up to 10% of all intracranial tumors. Rarely, intrinsic brainstem tumors can involve the CPA and present with auditory symptoms typical of CPA tumors such as hearing loss, vertigo and tinnitus. We report on a rare case of an intrinsic brainstem neoplasm presenting with steroid responsive fluctuating sensorineural hearing loss in a child. The patient initially presented with an acute worsening of an unilateral sensorineural hearing loss, without additional symptoms, that responded to oral steroids. Otoacoustic emission testing demonstrated normal outer hair cell function suggesting retrocochlear pathology. Magnetic resonance imaging with contrast enhancement revealed an intrinsic neoplasm of the middle cerebellar peduncle impinging on the 7th/8th neurovascular bundle within the CPA. The patient underwent gross total resection of the juvenile pilocytic astrocytoma via retrosigmoid craniotomy and remains disease free at 2 years postoperatively. This case highlights that suspicion of central nervous system pathology should be heightened in the presence of steroid responsive, fluctuating sensorineural hearing loss with normal outer hair cell function.

Normal pressure hydrocephalus after gamma knife radiosurgery for cerebellopontine angle meningioma

There are no reports of hydrocephalus following radiosurgery for a meningioma. We report on a case where gamma knife therapy for a 4 cm diameter right cerebellopontine meningioma accelerated hydrocephalus three months post treatment. Examination of the cerebrospinal fluid (CSF) revealed a high protein level and thus, CSF malabsorption and CSF obstruction might have occurred after the radio surgery. It is important to consider this pathology, and the need for long term follow up.

CPA Melanoma

OBJECTIVE

Melanoma rarely invades the cerebellopontine angle (CPA) and can evade accurate diagnosis, which may alter management decisions. Diagnosis may be facilitated via careful history, magnetic resonance imaging (MRI) findings, and cerebrospinal fluid (CSF) analysis.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Thirteen internal auditory canal/CPA lesions in eight patients who presented with CPA syndrome and who had a pathological diagnosis consistent with malignant melanoma. There were four bilateral and four unilateral lesions. Six of eight patients had a history of melanoma. One was apparently primary CPA lesion, whereas all others were metastatic.

INTERVENTION(S)

T1- and T2-weighted precontrast and postcontrast gadolinium-enhanced MRI were obtained, including fat suppression and fluid-attenuated inversion recovery sequence images in two patients; lumbar puncture with CSF centrifugation and cytological analysis confirmed the diagnosis in two patients. Translabyrinthine craniotomy was performed for tumor extirpation in five patients.

MAIN OUTCOME MEASURE(S)

Symptoms at presentation, MRI findings, presence of malignant cells in CSF, tumor progression, intraoperative findings, response to treatment, time interval from initial diagnosis of melanoma elsewhere, and survival.

RESULTS

Seven of eight patients had history and/or MRI findings suggestive of malignancy in the internal auditory canal and/or CPA, and diagnosis was confirmed via CSF analysis in two patients. In one patient, diagnosis was made at surgery.

CONCLUSION

Internal auditory canal melanoma portends a grim prognosis, can occur up to 17 years after initial melanoma diagnosis/treatment, and can be detected with appropriate MRI sequences, especially enhanced fluid-attenuated inversion recovery images. In disseminated cases, diagnosis can be confirmed with lumbar puncture demonstrating malignant cells. Management includes tumor resection when melanoma seems to be solitary and malignant cells are not present in CSF. Intrathecal chemotherapy and radiation are recommended for dissemination, although the survival rate is still poor.

Intracanalicular Meningioma

OBJECTIVE

Intracanalicular meningiomas are extremely rare, and only 36 cases have been reported to date. The aim of this study is to describe the clinical, radiologic, and histopathologic features of 13 intracanalicular meningiomas highlighting important aspects of tumor diagnosis and treatment.

STUDY DESIGN

Retrospective study.

SETTING

Quaternary referral otology and cranial base private center.

PATIENTS

Thirteen consecutive patients with pathologically confirmed intracanalicular meningioma surgically treated between December 1988 and July 2006. The follow-up of the series ranged from 13 to 60 months.

INTERVENTIONS

Nine patients with unserviceable hearing were operated on through the translabyrinthine approach. Four patients underwent enlarged middle cranial fossa approach with the intention of preserving their hearing.

RESULTS

Total tumor removal was achieved in all cases. The postoperative facial nerve function was either excellent or good (House-Brackmann Grade I or II) in 10 cases (77%) and acceptable (Grade III) in one case. Two patients with preoperative facial paresis showed no improvement in their facial nerve function. In patients who underwent surgery via the enlarged middle cranial fossa, hearing was preserved at the preoperative level in two cases, but serviceable hearing was lost in the remaining two.

CONCLUSION

Primary meningiomas of the internal auditory canal are extremely rare. On account of a lack of specific symptoms and the limited diagnostic findings, preoperative diagnosis of intracanalicular meningioma still represents a diagnostic challenge. Intraoperative findings may help in differentiating meningiomas from other intracanalicular lesions.

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.

Cerebrospinal fluid cytology to aid the diagnosis of cerebellopontine angle tumors

OBJECTIVE

To determine if cerebrospinal fluid (CSF) cytology can be useful in the workup of patients with internal auditory canal/cerebellopontine angle (IAC/CPA) tumors and facial paralysis to diagnose metastatic disease before surgical intervention.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

Patients who presented with or developed facial paralysis and IAC/CPA tumors.

OUTCOME MEASURE

Lumbar puncture and CSF cytological analysis.

RESULTS

Seven patients presented with or developed high-grade facial paralysis (greater than House-Brackmann Grade II). In the first patient, excision of the tumor revealed adenocarcinoma. All subsequent patients were evaluated with CSF cytological analysis. In five of these patients, cytological CSF analysis revealed malignant cells, suggesting a diagnosis of a metastatic lesion rather than acoustic neuroma. Primary neoplasms were identified in all but one of these patients. A sixth patient had metastatic breast cancer, but negative CSF cytology and a stable CPA tumor after radiation treatment. Two patients who were being conservatively followed up for their IAC/CPA tumor developed a nonprogressive but persistent mild Grade II facial weakness and underwent CSF analysis which tested negative. One patient had surgical resection with pathologic findings consistent with a typical acoustic schwannoma, and the other patient has been conservatively followed up without change.

CONCLUSION

Our experience suggests that patients presenting with IAC/CPA tumors and progressive facial paralysis of House-Brackmann Grade III or greater should have a CSF cytological examination before surgical intervention to evaluate for a malignant process.

Atypical haemangioma of the internal auditory meatus: a case report

Haemangiomas involving the internal auditory meatus (IAM) are rare and can mimic other frequent lesions of the IAM such as schwannomas by their clinical and imaging aspects. The case of a patient with an atypical IAM haemangioma fluctuating in size is reported to highlight this diagnostic possibility. A 36-year-old female presented with a sudden and recurrent left sensorineural hearing loss (SNHL). Three consecutive MRIs were performed in a 10-month period of preoperative observation. They showed a fluctuation of the tumour signal and size. The surgical removal was performed via a translabyrinthine approach. Pathological findings were consistent with the diagnosis of a heamangioma. MRI and CT findings suggested the diagnosis of IAM heamangioma, but the rapid variation in size and signal was misleading. This phenomenon may be due to haemorrhage or oedema, and can be accompanied by a deterioration of the hearing function. Early surgical resection is the treatment of choice and allows to confirm the diagnosis.

Solitary metastasis of lung carcinoma to the internal auditory canal

We report a case of solitary metastasis of lung carcinoma into the internal auditory canal. On admission, the 60-year-old patient was complaining about a rapidly developing hearing loss with ipsilateral facial nerve paralysis. Magnetic resonance imaging revealed an intracanalicular tumor, which was interpreted as vestibular schwannoma. After tumor resection, the histopathologic examination revealed a metastasis of a squamous cell carcinoma. Computed tomographic scan and bronchoscopy identified an asymptomatic primary pulmonary neoplasm.

Facial and Cochlear Nerve Function after Surgery of Cerebellopontine Angle Meningiomas

OBJECTIVE:

Meningiomas of the cerebellopontine angle (CPA) share a common location, but their site of dural origin and their relationship to surrounding neurovascular structures of the CPA are variable. The clinical presentation and outcome after surgical resection are different because of the diversity of this tumor entity. We report on a series of 421 patients with CPA meningiomas, with special emphasis on the analysis of the preoperative and postoperative facial and cochlear nerve function in relation to the site of dural attachment and main tumor location in the CPA cistern.

METHODS:

Among 421 patients, the charts of 347 patients with complete clinical data, including the history and audiograms, imaging studies, surgical records, discharge letters, histological records, and follow-up records, were reviewed retrospectively. Data about preoperative and postoperative facial nerve function were available in 334 patients, and audiometric analysis was conducted in 333 patients. Patients with neurofibromatosis Type 2 were excluded from the study.

RESULTS:

There were 270 women and 77 men, with a mean age of 53.4 years (range, 17.6–84 yr). Among these patients, 32.9% of the tumors originated at the petrous ridge anterior to the inner auditory canal (IAC) (Group 1), 22.2% showed involvement of the IAC (Group 2), 20.2% were located superior to the IAC (Group 3), 11.8% were inferior to the IAC (Group 4), and 12.9% were posterior to the IAC, originating between the IAC and the sigmoid sinus (Group 5). Patients presented with disturbance of Cranial Nerves V–VIII, the lower cranial nerves, and ataxia, depending on the main tumor location. Tumor resection was performed through a suboccipital-retrosigmoidal approach in the semisitting position in 95% of the patients. A combined supratentorial-infratentorial presigmoidal approach was performed in 5%. Total tumor removal (Simpson Grade 1 and 2) was achieved in 85.9% and subtotal removal in 14.1%. The best initial postoperative facial and auditory nerve function was observed in tumors belonging to Groups 3 and 5. Recovery from preoperative deafness was observed in 1.8% of patients. On long-term follow-up, good facial nerve function (House-Brackmann Grade 1 or 2) was observed in 88.9% of patients. Hearing preservation among patients with preoperative functional hearing was documented in 90.8% on long-term follow-up.

CONCLUSION:

Although the outcome of facial and cochlear nerve function is different in CPA meningiomas, depending on the topographic classification of these tumors, preservation of the cochlear nerve is possible in every tumor group and should be attempted in every patient with CPA meningioma. It has to be kept in mind that recovery of hearing was also observed in patients with preoperative profound hearing deficits.

Intraoperative auditory brainstem responses in patients with cerebellopontine angle meningiomas involving the inner auditory canal: analysis of the predictive value of the responses

Object. Meningiomas of the cerebellopontine angle (CPA) can either arise from or secondarily grow into the inner auditory canal (IAC). This location may have a great impact on hearing function following surgery to remove these lesions. The aim of this retrospective study was to investigate the reliability and predictive importance of auditory brainstem responses (ABRs) for the determination of postoperative auditory function in patients with CPA meningiomas in comparison with results obtained in patients who undergo surgery for vestibular schwannomas.

Methods. In a consecutive series of 1800 meningiomas surgically treated between 1978 and 2002, 421 lesions were located in the CPA. In 38 patients with CPA meningiomas involving the IAC, the findings of intraoperative ABR monitoring and the hearing status of each patient before and after surgery were retrospectively analyzed.

On analysis, ABR monitoring demonstrated stable findings in 24 patients throughout tumor resection and fluctuating signals in 10 patients. Among the 24 patients with stable ABRs, postoperative hearing function improved in three patients, remained the same in 15, and worsened in six patients, including one patient who displayed postoperative deafness. There was even one patient recovering from preoperative deafness. Among the 10 patients with unstable ABRs, intermittent decreases in amplitude and deformations of variable duration in the ABR wave were noted. The risk of deafness was considerably higher in patients with prolonged phases of intermittent ABR deterioration.

Conclusions. The presence and absence of ABRs during surgery for CPA meningiomas reliably predicted the presence and absence of postoperative auditory function. Intermittent deterioration of ABRs may result in postoperative deafness, depending on the duration of these events during surgery. Improvements in hearing are only seen when the ABRs are stable for amplitudes and latencies throughout surgery.

Meningioma of the internal auditory canal

A comprehensive literature search identified only 14 well-documented cases of intracanalicular meningioma. A case is presented of meningioma confined to the internal auditory canal which was excised using a sub-occipital retrosigmoid approach. Preoperative MRI and CT scans were suggestive of intracanalicular vestibular schwannoma. Only the intraoperative findings, which were confirmed by the histological data, revealed that the tumor was a meningioma. We review the literature and discuss the diagnostic and therapeuticissues relating to these tumors.

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.

Medulloblastoma of the cerebellopontine angle--case report

A 21-year-old male patient presented with a rare cerebellopontine angle medulloblastoma manifesting as cerebellar and long tract involvement signs and symptoms. The clinical and radiological characteristics of the lesion were similar to extraaxial lesions of cerebellopontine angle. The histological diagnosis of the lesion was medulloblastoma. Surgery achieved partial removal and was followed by radiotherapy and chemotherapy. The patient remained well after 18 months. Medulloblastoma of the cerebellopontine angle is a relatively rare clinical entity and may occur as a dural-based extraaxial mass.

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.

Cerebellopontine angle paraganglioma

BACKGROUND

Acoustic neuroma account for 80% of cerebellopontine angle tumors. Paraganglioma is a rare tumor in this region.

OBJECTIVE

The authors report a case of cerebellopontine angle paraganglioma arising from the anterior inferior cerebellar artery.

RESULTS

The clinical and radiologic features were indistinguishable from those of a neuroma, and only the intraoperative view showed a vascular tumor. Definitive diagnosis was made by histopathologic methods.

CONCLUSIONS

This unique paraganglioma location may be explained by existing embryologic data. The minimal retrosigmoid approach, assisted by endoscopy, allows safe and complete removal of the tumor.

Fascicle preservation surgery for facial nerve neuromas involving the posterior cranial fossa

OBJECTIVE

To assess facial nerve function after fascicle preservation surgery in cases of facial nerve neuroma involving the cerebellopontine angle.

STUDY DESIGN

Retrospective case series and literature review.

SETTING

Tertiary referral center.

PATIENTS

Seven patients with facial nerve neuroma involving the posterior cranial fossa were reviewed from a single neurotologist's practice and combined with a review of 648 cases reported in the literature.

INTERVENTIONS

Translabyrinthine resection was used in all patients for complete tumor removal. Nerve reconstruction was accomplished with fascicle preservation (three cases), cable nerve interposition grafting (three cases, one of which involved using cranial nerve VIII as the graft), or direct anastomosis (one case).

MAIN OUTCOME MEASURE

Facial nerve function as measured by the House-Brackmann grading system. RESULTS A postoperative facial nerve (House-Brackmann) grade of II/VI was obtained in two of our three patients who underwent fascicle preservation reconstruction and in two of eight cases reported by other authors. One case reported elsewhere resulted in grade I/VI, and four other cases reported elsewhere achieved grade III/VI; only two cases were grade V/VI. There were no tumor recurrences at 5 to 19 years of follow-up.

CONCLUSION

Most cases of facial nerve neuroma require facial nerve resection. In rare cases, these tumors can be dissected away from the nerve fascicles, allowing the surgeon to preserve the facial nerve. This method resulted in better long-term postoperative facial nerve function (House-Brackmann grade II/VI vs. grade III/VI) compared with other techniques for patients in this small series, and no tumor recurrence.