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.     

Cystic versus solid vestibular schwannomas: a series of 80 grade III–IV patients

Cystic acoustic neuromas are less frequent than solid ones and present different clinical and radiological features. Cystic schwannomas are larger, show a shorter clinical history and a different risk of postoperative complications. This study was designed to compare surgical results and complications of solid and cystic vestibular schwannomas of matching size operated upon via either a retrosygmoid or a translabyrinthine approach. The study included 80 patients presenting with grade III and IV acoustic vestibular schwannomas referred to the Neurosurgical and ENT team in the Department of Neuroscience of Torino, Italy. Twenty-six were cystic and 54 were solid tumours. Clinical history, surgical results and complications were compared between the two groups. In cystic tumors, rapid clinical worsening is common, due to sudden expansion of cystic elements. Tighter adherences are found between cystic tumours and nervous elements (particularly brainstem and possibly facial nerve), once compared to solid ones. Operative morbidity appears to be higher in cystic tumours. A wait and see policy should not to be applied to patients with cystic tumours. Careful technique, possibly sharp dissection, to divide the tumour adherences from the nervous tissue must be employed, in order to avoid lesions on brainstem veins and traction on a thin facial nerve. Severe complications may be caused by the excessive efforts to dissect brainstem adherences.     

Intracanalicular and Intratemporal Facial Nerve Schwannomas

Facial nerve schwannomas can mimic acoustic neuromas. We report herein two cases: a purely intracanalicular and an intratemporal facial nerve tumor extending into the internal auditory canal and the cerebellopontine angle. These tumors have to be suspected in patient with small-size tumors presenting with facial paralysis. We advocate translabyrinthine or middle fossa approach to facilitate nerve anastomosis. The establishment of the correct properative diagnosis is difficult, but the patient must be warned about the impossibility of preserving the facial nerve in these tumors.     

Intracanalicular and intratemporal facial nerve schwannomas

Facial nerve schwannomas can mimic acoustic neuromas. We report herein two cases: a purely intracanalicular and an intratemporal facial nerve tumor extending into the internal auditory canal and the cerebellopontine angle. These tumors have to be suspected in patient with small-size tumors presenting with facial paralysis. We advocate translabyrinthine or middle fossa approach to facilitate nerve anastomosis. The establishment of the correct properative diagnosis is difficult, but the patient must be warned about the impossibility of preserving the facial nerve in these tumors.     

Facial Nerve Outcomes in Middle Cranial Fossa vs Translabyrinthine Approaches

OBJECTIVE: To compare the final facial nerve outcomes between middle cranial fossa (MCF) vs translabyrinthine (TL) resection of size-matched vestibular schwannomas. STUDY DESIGN AND SETTING: Retrospective case review at a tertiary care hospital. All patients who underwent resection utilizing either MCF or TL approaches with tumors 18 mm or smaller and complete data were included in the analysis. One hundred twenty-four patients were identified meeting the above criteria, with sixty-three in the translabyrinthine group and sixty-one in the middle fossa group. One-week-postoperative and final facial nerve examinations were compared in the two surgical groups. Patients were separately analyzed in subgroups: tumors smaller than 10 mm and those that were between 10 and 18 mm. RESULTS: The tumor size range for the MCF group was 3-18 mm while it was 4-18 mm for the TL group. No statistically significant difference was found in facial nerve outcomes between the two surgical groups, at the first postoperative visit week and at last follow-up. CONCLUSION: Facial nerve outcomes are similar using TL and MCF approaches for resection of vestibular schwannomas up to 18 mm in size. SIGNIFICANCE: Patients undergoing the MCF approach for hearing preservation can be counseled that there is no increased risk of permanent facial nerve weakness, compared to the TL approach.     

Cavernous angiomas within the internal auditory canal

OBJECT: The aim of this study was to describe the symptomatology, radiological features, and surgical treatment of patients with cavernous angiomas within the internal auditory canal (IAC). METHODS: The authors reviewed the cases of seven patients with cavernous angiomas in the IAC that had been surgically treated in the 22-year period between 1983 and 2005. All the patients had presented with sensorineural hearing loss, and four suffered from tinnitus. Four patients also reported facial symptoms such as hemispasm or progressive palsy; one of these patients had presented with sudden facial paresis due to intrameatal tumor hemorrhage. According to computed tomography (CT) results, the lesions caused enlargement of the IAC. Interestingly, these same angiomas showed variable features on magnetic resonance (MR) imaging, making their differentiation from intrameatal vestibular schwannomas (VSs) sometimes impossible. In all patients the lesions were totally removed via the suboccipital retrosigmoid approach. They could be dissected away from the facial nerve in five cases, whereas in two cases, because of the location of the lesion, the seventh cranial nerve had to be sectioned and repaired with a sural nerve graft. Transient worsening of seventh cranial nerve symptoms occurred in two patients, with postoperative improvement in each of them. The cochlear nerve could not be functionally preserved because of its extreme adherence to the tumor, although its continuity was preserved in four patients. Complete deafness was the only postoperative complication. CONCLUSIONS: Cavernous angiomas of the IAC are very uncommon lesions that can imitate the symptoms of VSs. Although it is the most sensitive study available, MR imaging does not show sufficiently specific findings to differentiate the two lesion types. Thus, the preoperative diagnosis must be based on patient symptoms plus the CT and MR imaging features.     

Surgical approaches and complications in the removal of vestibular schwannomas. 2007

Vestibular schwannomas are benign tumors that usually originate from the balance portion of cranial nerve VIII. The treatment options currently available for vestibular schwannomas include observation with serial imaging, stereotactic radiation, and microsurgical removal. Although the ultimate goal in treatment of vestibular schwannomas is preservation of life, the best option for each patient depends on symptoms, tumor size, tumor location, and the patient's general health and age. Surgical exposure of the cerebellopontine angle for removal of vestibular schwannomas can be performed safely via a translabyrinthine, retrosigmoid, and middle fossa approach. Each approach has its advantages and disadvantages. The goal of surgery is complete eradication of tumor with preservation of hearing and facial nerve function when possible.     

VIIIth nerve cavernous hemangioma mimicking a stage 1 acoustic schwannoma

ObjectiveTo report a case of VIIIth nerve cavernous hemangioma, a very rare differential diagnosis among the various pathologies presenting as small enhancing entities into the internal auditory canal. It is one of the most challenging when imaging is not able to differentiate it from an intrameatal vestibular schwannoma.Methods and resultsWe report a cavernous hemangioma extruding from the internal auditory canal, diagnosed after a left translabyrinthine resection in a 45-year-old man complaining of profound sensorineural hearing loss, with no facial paresis or dizziness. The preoperative differential diagnosis of a vestibular schwannoma was impossible, due to the absence of calcifications that usually characterize temporal bone hemangiomas. Clinical presentation, radiological features and treatment considerations are discussed along with up-to-date review of pertinent literature.ConclusionsWhen considering an apparent small intra-auditory canal schwannoma, otoneurologists should be aware of the rare possibility of a cavernous hemangioma. Early diagnosis and surgical treatment may improve the functional outcome, possibly preserving neural integrity.     

Hamartomas of the internal auditory canal: report of two cases

OBJECTIVE AND IMPORTANCE: To highlight the clinical, radiological, and surgical findings and therapeutic options for this rare entity, which may mimic a purely intrameatal vestibular schwannoma, and to define the particular aspects of preoperative differential diagnosis and surgical management. CLINICAL PRESENTATION: Two patients presented with clinical findings typical of vestibular schwannomas, i.e., tinnitus, hearing loss of 30 dB, and an intrameatal contrast-enhancing lesion on magnetic resonance imaging studies. TECHNIQUE: The lesions were exposed via a suboccipital transmeatal approach, and tumor infiltration of the cochlear and/or facial cranial nerves was identified. In view of the unclear intraoperative histology, surgical management was based on criteria of cranial nerve function. In Patient 1, after nerve decompression by subtotal tumor removal, preserved auditory brainstem responses and facial nerve electromyography indicated functional nerve preservation and facilitated the decision for partial resection. In Patient 2, minimal tumor dissection resulted in complete loss of auditory brainstem response without reversibility. Therefore, a radical tumor removal was performed that sacrificed the cochlear but preserved the facial nerve. CONCLUSION: Symptoms and signs of internal auditory canal hamartomas are congruent with other typical pathological lesions of the internal auditory canal and cerebellopontine angle. Accurate preoperative diagnosis by radiological means is not possible, but careful evaluation of the different signal intensities on magnetic resonance imaging studies may indicate this rare pathological condition. Intraoperative surgical findings of tumor infiltration of the faciocochlear cranial nerve complex may support simple observation. In view of the nonneoplastic characteristic of these lesions, a more conservative approach is justified. The decision should be based on the functional status of the cranial nerves, for which reliable electrophysiological monitoring is indispensable.     

Meningiomas Intrinsic to the Geniculate Ganglion

Geniculate ganglion meningiomas are extremely rare lesions-only 14 cases have been reported in the literature. Two new cases of these tumors are described. On computed tomography and magnetic resonance imaging, both lesions appeared centered on the area of the geniculate ganglion, extending to the tympanic cleft and eroding the middle cranial fossa floor. The first case was treated through a middle cranial fossa approach. Because the tumor was so large in the second case, a subtotal petrosectomy was used. The authors review the literature to clarify the clinical and radiological characteristics of these tumors and their surgical treatment.     

Resection of large vestibular schwannomas: facial nerve preservation in the context of surgical approach and patient-assessed outcome

OBJECT: Vestibular schwannoma surgery has evolved as new therapeutic options have emerged, patients' expectations have risen, and the psychological effect of facial nerve paralysis has been studied. For large vestibular schwannomas for which extirpation is the primary therapy, the goals remain complete tumor resection and maintenance of normal neurological function. Improved microsurgical techniques and intraoperative facial nerve monitoring have decreased the complication rate and increased the likelihood of normal to near-normal postoperative facial function. Nevertheless, the impairment most frequently reported by patients as an adverse effect of surgery continues to be facial nerve paralysis. In addition, patient assessment has provided a different, less optimistic view of outcome. The authors evaluated the extent of facial function, timing of facial nerve recovery, patients' perceptions of this recovery and function, and the prognostic value of intraoperative facial nerve monitoring following resection of large vestibular schwannomas; they then analyzed these results with respect to different surgical approaches. METHODS: The authors retrospectively reviewed a database of 67 patients with 71 vestibular schwannomas measuring 3 cm or larger in diameter. The patients had undergone surgery via translabyrinthine, retrosigmoid, or combined approaches. Clinical outcomes were analyzed with respect to intraoperative facial nerve activity, responses to intraoperative stimulation, and time course of recovery. Eighty percent of patients obtained normal to near-normal facial function (House-Brackmann Grades I and II). Patients' perceptions of facial nerve function and recovery correlated well with the clinical observations. CONCLUSIONS: Trends in the data lead the authors to suggest that a retrosigmoid exposure, alone or in combination with a translabyrinthine approach, offers the best chance of facial nerve preservation in patients with large vestibular schwannomas.     

Cranial nerve preservation in contemporary vestibular schwannoma (acoustic neuroma) treatment

Vestibular schwannomas (acoustic neuromas) have long been considered one of the most difficult tumors to remove without causing neurologic dysfunction. In recent years, with marked improvements in neurophysiologic monitoring, microsurgical techniques, and neuroimaging, the focus of treatment has shifted from prolongation of life to preservation of cranial nerve function. Contemporary treatment of vestibular schwannoma includes serial evaluation with magnetic resonance imaging, conventional microsurgical resection, and stereotactic radiosurgery. Microsurgical removal may be subdivided by approach: retrosigmoid, translabyrinthine, or middle fossa depending on the patient’s preoperative neurologic status and the experience of the surgeon. Furthermore, radiosurgery may involve gamma knife radiation, linear accelerator, or heavy particle radiation. Despite great advances in the treatment of these complex tumors, there is still debate as to what constitutes optimal management. This is particularly true when one considers cranial nerve preservation. In this review, we analyze several recent articles that deal with strategies for preserving cranial nerve function before, during, and after treatment. We present a variety of perspectives, and in doing so, we hope to shed light on some of the ongoing controversies surrounding the contemporary treatment of vestibular schwannomas.     

Extended middle cranial fossa approach for acoustic neuroma surgery

The enlarged middle cranial fossa approach was used for removal of acoustic neuromas in 209 cases. Complete tumor removal was accomplished in 96% of cases. Hearing was preserved in 51% of cases, with better results in smaller tumors. Our experience with the enlarged middle fossa approach has led us to discard the translabyrinthine approach for removal of acoustic neuromas.     

Extended Middle Cranial Fossa Approach for Acoustic Neuroma Surgery

The enlarged middle cranial fossa approach was used for removal of acoustic neuromas in 209 cases. Complete tumor removal was accomplished in 96% of cases. Hearing was preserved in 51% of cases, with better results in smaller tumors. Our experience with the enlarged middle fossa approach has led us to discard the translabyrinthine approach for removal of acoustic neuromas.     

Simultaneous presentation of meningiomas with other intracranial tumours

Fifteen patients with simultaneous presentation of meningiomas with other intracranial tumours are reviewed. The associated tumours included a brain metastasis in six cases, glioma in three, pituitary adenoma in two, craniopharyngioma in one,acoustic schwannoma in two and brain lymphoma in one. A correct preoperative radiological diagnosis was made in 12 patients; in three others the associated tumour was discovered at operation and by histological studies. A one-stage removal of both tumours through the same approach was performed in nine patients, whereas six others underwent two-stage operations with an interval of 1 - 13 months. The literature relating to meningiomas associated with other intracranial tumours is reviewed and the possible pathogenetic correlations are discussed. A diagnostic pitfall may occur for metastasis into a meningioma, glioma surrounding a meningioma and different suprasellar lesions. The surgical indication and management of meningiomas may be significantly influenced by the presence of another different intracranial tumour.     

One-stage removal of residual intracanalicular acoustic neuroma and hemihypoglossal-intratemporal facial nerve anastomosis: technical note

OBJECTIVE AND IMPORTANCE: Incomplete removal of residual intracanalicular tumor and injury to the facial nerve are the main problems associated with surgery of large acoustic neuromas via the retromastoid suboccipital approach. In patients with residual or recurrent intracanalicular neuromas, the translabyrinthine approach is the preferred surgical route, allowing complete tumor removal; it may eventually also be used for exposure of the intratemporal portion of the facial nerve for a hemihypoglossal-facial nerve anastomosis when a postoperative facial palsy exists This one-stage procedure has not been described previously. CLINICAL PRESENTATION: Three patients with postoperative facial palsy and residual intracanalicular tumor after surgical removal of a large acoustic neuroma via the retromastoid suboccipital approach underwent reoperation via the translabyrinthine approach and one-stage removal of the residual tumor and hemihypoglossal-facial nerve anastomosis. All three patients had a complete facial palsy of House-Brackmann Grade VI and a residual tumor of 8 to 12 mm. TECHNIQUE: A classic translabyrinthine approach was used to open the internal auditory canal and remove the residual intracanalicular tumor. The facial nerve was exposed in its mastoid and tympanic parts, mobilized, and transected; then, the long nerve stump was transposed into the neck and used for an end-to-side anastomosis into the hypoglossal nerve. The operation resulted in variable improvement of the facial muscle function up to Grade III (one patient) and Grade IV (two patients). CONCLUSION: Reoperation via the translabyrinthine approach is indicated for removal of residual intracanalicular acoustic neuroma and realization of a hypoglossal-facial nerve anastomosis in a single procedure. It is suggested that this type of anastomosis may also be used during the initial operation for acoustic neuroma removal when the facial nerve is inadvertently sectioned.     

Acoustic neuroma

Acoustic neuromas are benign schwannomas that arise from the vestibular portion of the eighth cranial nerve. Small tumors confined to the internal auditory canal may be removed via an extradural subtemporal approach. Tumors that involve the cerebellopontine angle require posterior fossa craniotomy utilizing either the suboccipital or translabyrinthine technique. The choice of surgical approach depends primarily on the size of the tumor, its location, and the status of hearing in the involved ear. Operative mortality is very low. The most common sources of morbidity are hearing loss and facial nerve dysfunction.     

Intrapetrous neurinoma of the facial nerve. Removal by the oto-neurologic route

A case of a 33 year-old woman presenting an intrapetrous facial nerve neurinoma is reported. The neurological finding was a quickly progressive facial nerve palsy without hearing loss which the initial diagnosis was a Bell's palsy. The radiological findings showing an petrous bone erosion located at the third portion of the facial nerve gave the diagnosis. It was confirmed by CT scan and arteriography that allows a pre-operative embolisation. A one stage operation performed by a triple retromastoid, transpetrous and retroparotid approach, allowed a complete removal. The post-operative course was uneventful and a reconstructive facial surgery was performed to restore a facial symmetry six months later. The authors review the literature about this tumor which remains rare and point out two facts: --A non regressive or recurrent or atypical facial nerve palsy had to be checked up by neuroradiology and even by surgical exploration. --The triple retromastoid, transpetrous and retroparotid approach is very interesting, allowing a one stage complete removal of the tumor and a check up of the facial nerve repair possibilities.     

Surgical treatment of trigeminal schwannomas

Schwannomas that arise from the trigeminal nerve are rare, but this nerve is the second most frequent intracranial site of schwannoma occurrence next to the vestibular nerve. The advent of microsurgical techniques and skull-base approaches has greatly enhanced the surgical management of these tumors, and outcomes have improved markedly. This report documents 18 cases of histologically verified schwannomas that arose from the trigeminal nerve and were treated surgically in our clinic between January 1992 and July 2005. The patients were ten women and eight men of age 39.7 years (range, 22–62 years). The tumor was located in the middle fossa (type A) in five cases, in the middle and posterior fossae (type C) in nine cases, in the posterior fossa (type B) in two cases, and in the branches of the trigeminal nerve (type D) in two cases. Total excision was achieved in 17 cases, and there was no mortality in the series. Our results indicate that trigeminal schwannomas, regardless of type, can be removed via skull-base approaches. We present an algorithm for surgical management of trigeminal schwannomas based on our experience and information from the literature.     

Temporal bone meningiomas

Meningiomas should be considered in the differential diagnosis of space-occupying lesions of the temporal bone. Five cases of meningiomas of the temporal bone are described and the literature reviewed. These tumours may stimulate Schwannomas and glomus tumours in their presentation and radiological findings. The tumours were managed by combining standard neurosurgical approaches with temporal bone and skull base techniques.