Meningiomas of the internal auditory canal

Cerebellopontine Angle Meningiomas: A Multi-Institutional Cohort Study

BACKGROUND AND OBJECTIVES

Cerebellopontine angle (CPA) meningiomas present challenges given their proximity to neurovascular structures. Postoperative complications and persistent symptoms can debilitate patients, and our ability to predict recovery course remains variable. Here, we examine the presentation, management, and outcomes of patients with CPA meningiomas.

METHODS

We retrospectively reviewed CPA meningiomas resected at Mass General Brigham, using descriptive statistics and logistic regression to identify predictors of progression or recurrence.

RESULTS

In total, 95 patients were identified (median age 59.1 years, 82.1% female) who presented most commonly with hearing loss (49.5%), ataxia (42.1%), and headaches (29.5%). The retrosigmoid (78.9%) or transmastoid retrosigmoid (17.9%) approaches were most frequently used for resection, with gross total resection (GTR) achieved in 62.1% of patients: Simpson grade 1 (32.6%), grade 2 (17.9%), and grade 3 (11.6%). Smaller tumor size (t = 3.17, P = .002) is associated with GTR. For tumors with intracanalicular invasion, drilling the internal auditory canal (IAC) was also associated with GTR (χ2 = 21.8, P < .001). Among cases with invasion, GTR was achieved in 88.5% of cases when the IAC was drilled vs 11.8% of cases when the IAC was not drilled. The cranial nerve VII/VIII complex was frequently inferior (45.6%) or superior (19.1%) to the meningioma. Postoperative hearing loss was stable (38.7%) or improved (54.8%) in most of patients at the final clinical follow-up (median: 39.4 months). 25.3% of patients had progression/recurrence, with some difference between World Health Organization grade 1 (median: 3.0 years, IQR: 2.9 years) and World Health Organization grade 2 (median: 1.6 years, IQR: 2.8 years) tumors. After multivariate adjustment, Simpson grade I (P = .02), Simpson grade II (P = .01), or being of older age (P = .003) were associated with lower odds of progression/recurrence.

CONCLUSION

GTR remains critical to achieve optimal symptom control and reduce progression/recurrence rates for CPA meningiomas. Drilling the IAC is an important predictor of GTR in tumors with intracanalicular invasion.

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.

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.

Electrophysiological predictors of hearing deterioration based on AEP monitoring during petroclival meningioma resection

The objective of this study was to calculate the risk of postsurgical hearing deterioration as a function of changes in the amplitude and latency of the most stable components (waves III and V) of the auditory evoked potential (AEP) during petroclival meningioma resection surgery. We retrospectively analyzed intraoperative AEP monitoring results and pre- and postsurgical hearing status in 40 consecutive patients who were surgically treated for petroclival meningiomas. Statistical analyses were conducted to identify the most sensitive and specific way to predict hearing dysfunction after surgery. Patients' mean age was 59 ± 10 years, and 31 (77.5%) were women. Twelve (30%) patients presented with clinically detectable hearing impairment preoperatively. At the first postoperative assessment, four of those 12 patients reported subjective improvement, and eight reported hearing deterioration. Of those eight, four remained stable and four recovered hearing by the last assessment. Wave III latency reached its highest specificity (100%) and sensitivity (71.43%) at x = 143%. Wave V latency, on the other hand, reached its highest sensitivity (71%) and specificity (93%) at x = 124%. Finally, wave V amplitude reached its highest sensitivity (100%) and specificity (79%) at x = 74%. Intraoperative alterations of wave III latency and wave V amplitude seem to be highly sensitive and specific at predicting the risk of auditory dysfunction in patients undergoing petroclival meningioma resection and should be used to determine maximum resection with preservation of function.

Acupuncture for rehabilitation after surgery for cerebellopontine angle meningioma: A case report

RATIONALE

In some cases, surgery of cerebellopontine angle meningioma (CPAM) might result in multiple cranial nerve injury, which could bring serious impact on the patients, especially when it affects the function of facial muscles and eyeballs. This report describes a successful application of acupuncture for rehabilitation in a patient after surgery for CPAM.

PATIENT CONCERNS

A 27-year-old patient presented with limitation of left eye abduction, accompanied with frontal and facial sensory disturbance on the left after resection of the pontocerebellar angle tumor. The patient also suffered from significant anxiety and depression as concomitant symptoms.

DIAGNOSES

Based on medical history, clinical symptoms, and magnetic resonance imaging results, the patient was diagnosed with the fourth, fifth, sixth, and seventh cranial nerve injury after surgery for CPAM.

INTERVENTIONS

Acupuncture treatment was applied for this patient. One acupuncture session was given every 2 days in 35 days, and the needles were retained for 30 minutes per session.

OUTCOMES

After acupuncture treatment, the limitation of left eye abduction had totally recovered. The superficial sensory disturbance in the frontal and facial region was significantly relived. Besides, the scores of Hamilton Anxiety and Depression Scale showed a significant reduction. However, the superficial sensory of the alar and nasolabial groove on the left side still decreased mildly when compared with the right side.

CONCLUSION

Acupuncture might be an option for rehabilitation after surgery for CPAM.

Hearing preservation after Gamma Knife radiosurgery for cerebellopontine angle meningiomas

OBJECTIVE

The objective of this study was to assess hearing function after Gamma Knife treatment of cerebellopontine angle (CPA) meningiomas and assess factors affecting hearing outcome. Additionally, the authors opted to compare these results with those after Gamma Knife treatment of vestibular schwannomas (VSs), because most of the information on hearing outcome after stereotactic radiosurgery (SRS) comes from reports on VS treatment. Hearing preservation, to the best of the authors’ knowledge, has never been separately addressed in studies involving Gamma Knife radiosurgery (GKRS) for CPA meningiomas.

METHODS

This study included all patients who underwent a single session of GKRS between 2002 and 2014. The patients were divided into two groups. Group A included 66 patients with CPA meningiomas with serviceable hearing and tumor extension into the region centered on the internal auditory meatus. Group B included 144 patients with VSs with serviceable hearing. All patients had serviceable hearing before treatment (Gardner-Robertson [GR] Grades I and II). The median prescription dose was 12 Gy (range 10–12 Gy) in both groups. The median follow-up of groups A and B was 42 months (range 6–149 months) and 49 months (range 6–149 months), respectively.

RESULTS

At the last follow-up, the tumor control rate was 97% and 94% in groups A and B, respectively. Hearing preservation was defined as maintained serviceable hearing according to GR hearing score. The hearing preservation rate was 98% and 66% and the 7-year actuarial serviceable hearing preservation rate was 75% and 56%, respectively, between both groups. In group A, the median maximum cochlear dose in the patients with stable and worsened hearing grade was 6.3 Gy and 5.5 Gy, respectively. In group B, factors affecting hearing preservation were cochlear dose ≤ 7 Gy, follow-up duration, and tumor control. The only determinant of hearing preservation between both groups was tumor type.

CONCLUSIONS

GKRS for CPA meningiomas provides excellent hearing preservation in addition to high tumor control rate. Hearing outcome is better with CPA meningiomas than with VSs. Further long-term prospective studies on determinants of hearing outcome after GKRS for CPA meningiomas should be conducted.

Efficacy and outcomes of facial nerve-sparing treatment approach to cerebellopontine angle meningiomas

OBJECTIVE Advanced microsurgical techniques contribute to reduced morbidity and improved surgical management of meningiomas arising within the cerebellopontine angle (CPA). However, the goal of surgery has evolved to preserve the quality of the patient's life, even if it means leaving residual tumor. Concurrently, Gamma Knife radiosurgery (GKRS) has become an acceptable and effective treatment modality for newly diagnosed, recurrent, or progressive meningiomas of the CPA. The authors review their institutional experience with CPA meningiomas treated with GKRS, surgery, or a combination of surgery and GKRS. They specifically focus on rates of facial nerve preservation and characterize specific anatomical features of tumor location with respect to the internal auditory canal (IAC). METHODS Medical records of 76 patients with radiographic evidence or a postoperative diagnosis of CPA meningioma, treated by a single surgeon between 1992 and 2016, were retrospectively reviewed. Patients with CPA meningiomas smaller than 2.5 cm in greatest dimension were treated with GKRS, while patients with tumors 2.5 cm or larger underwent facial nerve-sparing microsurgical resection where appropriate. Various patient, clinical, and tumor data were gathered. Anatomical features of the tumor origin as seen on preoperative imaging confirmed by intraoperative investigation were evaluated for prognostic significance. Facial nerve preservation rates were evaluated. RESULTS According to our treatment paradigm, 51 (67.1%) patients underwent microsurgical resection and 25 (32.9%) patients underwent GKRS. Gross-total resection (GTR) was achieved in 34 (66.7%) patients, and subtotal resection (STR) in 17 (33.3%) patients. Tumors recurred in 12 (23.5%) patients initially treated surgically, requiring additional surgery and/or GKRS. Facial nerve function was unchanged or improved in 68 (89.5%) patients. Worsening facial nerve function occurred in 8 (10.5%) patients, all of whom had undergone microsurgical resection. Upfront treatment with GKRS for CPA meningiomas smaller than 2.5 cm was associated with preservation of facial nerve function in all patients over a median follow-up of 46 months, regardless of IAC invasion and tumor origin. Anatomical origin was associated with extent of resection but did not correlate with postoperative facial nerve function. Tumor size, extent of resection, and the presence of an arachnoid plane separating the tumor and the contents of the IAC were associated with postoperative facial nerve outcomes. CONCLUSIONS CPA meningiomas remain challenging lesions to treat, given their proximity to critical neurovascular structures. GKRS is a safe and effective option for managing CPA meningiomas smaller than 2.5 cm without associated mass effect or acute neurological symptoms. Maximal safe resection with preservation of neurological function can be performed for tumors 2.5 cm or larger without significant risk of facial nerve dysfunction, and, when combined with GKRS for recurrence and/or progression, provides excellent disease control. Anatomical features of the tumor origin offer critical insights for optimizing facial nerve preservation in this cohort.

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.

Dural metastasis of nasopharyngeal carcinoma: rare, but worth considering

Metastasis of nasopharyngeal carcinoma (NPC) to the dura, an extremely rare condition, can be symptomatically silent and mistaken for a benign entity radiographically. Missed diagnosis can lead to serious consequences or prove immediately fatal. We report a woman with dural metastasis of NPC that mimicked a meningioma on radiography. Craniectomy with tumour resection was performed due to rapid progression from the onset of symptoms to disability. The patient was still alive two years after surgery. This case emphasises the need to keep in mind the possibility of dural metastasis of NPC in patients with abnormal imaging features. This would not only avoid wrong and optimistic diagnosis, but also allow for appropriate treatment in a timely manner. To our knowledge, this is the first report of metastasis of NPC to the dura. We provide detailed information on the neoplastic lesion, which masqueraded as a benign entity and caused potentially fatal consequences.

[Typical tumors of the petrous bone]

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

Contemporary surgical outcome for skull base meningiomas

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

Intracanalicular epidermoid cyst. A case report

We describe the presentation and management of a rare case of an epidermoid cyst located within canal of the left internal acoustic meatus, lying entirely within the petrous part of the temporal bone. The patient underwent surgery by an extended middle fossa approach and a total excision of a cyst containing cheesy, pearly white, avascular material was achieved. Neuroradiology provides a diagnosis with reasonable accuracy and an appropriate surgical approach can be planned for the excision of the tumour.

Outcome after microsurgery for meningiomas involving the internal auditory canal

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

OBJECTIVE

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

MATERIAL AND METHOD

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

RESULTS

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

DISCUSSION

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

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.

Morbidity in 201 patients with small sized meningioma treated by microsurgery

BACKGROUND

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

METHODS

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

FINDINGS

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

CONCLUSIONS

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

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.