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 therapeutic issues relating to these tumors.     

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.     

Facial nerve paralysis and meningioma of the internal auditory canal

Pathological lesions confined to the internal auditory canal (IAC) commonly present with cochleovestibular symptoms; sensorineural hearing loss, tinnitus and balance disturbance. The commonest lesion of the IAC is vestibular schwannoma. Other lesions include meningioma, facial neuroma, cavernous haemangioma, lipoma and arachnoid cyst. Presentation with facial palsy and an intracanalicular lesion is suggestive of pathology other than acoustic neuroma. Magnetic resonance imaging (MRI) cannot reliably distinguish intracanalicular vestibular schwannomas from meningiomas. Particular care is required for surgery of these lesions: the facial nerve typically does not lie in a protected anterior position within the IAC.     

Ectopic extra-cranial meningioma presenting as an aural polyp

Ectopic meningiomas located within the external auditory canal without any intracranial connection are an extremely rare finding. A report is made of a 38-year-old woman presenting with a conductive hearing loss due to an aural polyp, which was subsequently diagnosed as a meningioma. Computer-aided tomography (CT) and magnetic resonance imaging (MRI) showed the tumour to be entirely extracranial. Complete tumour excision was achieved using a modified radical mastoidectomy approach.     

Evaluating the role of magnetic resonance imaging scans in the surgical management of acoustic neuromas

OBJECTIVE: To assess the reliability of magnetic resonance imaging (MRI) in predicting the size and position of an acoustic neuroma, with particular reference to the intracanalicular portion. STUDY DESIGN: Prospective study comparing the position of the tumor in the internal auditory canal on fast spin-echo MRI with the actual position measured intraoperatively. METHODS: The study was performed in a tertiary referral neurotology center, encompassing both the public and private health care systems. Fifteen consecutive patients admitted for acoustic neuroma removal via the translabyrinthine approach were studied. The main outcome measure was tumor position in the internal auditory canal expressed in millimeters, accurate to the nearest 0.5 mm. RESULTS: The fast spin-echo MRI was accurate within an error of 1 mm in predicting the lateral extent of the tumor in the internal auditory canal. CONCLUSION: Fast spin-echo MRI can accurately predict the lateral extent of an acoustic neuroma and allow accurate planning of the surgical approach.     

Current concepts in neuroradiological diagnosis of acoustic neuromas

Two hundred twenty-one cases with clinical suspicion of a cerebellopontine angle (CPA) and/or internal auditory canal (IAC) lesions were evaluated in our hospital in the last 21/2 years by various radiological modalities. Fifty-two tumors were diagnosed and surgically removed; 48 were acoustic neuromas (33 large tumors and 15 intracanalicular small tumors) and 4 meningiomas. Polytomography detected 10 lesions out of 15 (66.7%) with 5 false-negative (33.3%) and 4 false-positive (26.7%) studies. Routine CT scan visualized large and enhancing lesions (37 out of 52), but missed the small intracanalicular tumors (15 tumors) which were only visualized by CT scan combined with cisternography or magnetic resonance imaging (MRI). MRI diagnosed 23 lesions out of 23 (100%) with no false-positive or negative studies, including 8 intracanalicular small tumors missed on the routine CT scans. MRI is far more reliable in the radiological diagnosis of CPA and IAC lesions.     

HIV-associated cerebral lymphocyte infiltration mimicking vestibular schwannoma

The association of unilateral, rapidly progressive hearing loss, tinnitus and vestibular dysfunction in combination with a contrast-enhancing mass within the internal auditory canal on MRI is suggestive of a vestibular schwannoma (VS). We report the rare finding of a HIV-associated cerebral lymphocyte infiltration, most probably malignant lymphoma, which was presumed initially to be a VS. A 36-year-old male presented with progressive unilateral hearing loss accompanied by acute, ipsilateral tinnitus. Interpreted first as sudden sensorineural hearing loss, his symptoms were treated with rheologic therapy. Ipsilateral facial palsy appeared. MRI with gadolininium disclosed a contrast-enhancing mass within the internal auditory meatus of the left side. Within five weeks an extended leptomeningeal lymphocyte infiltration evolved and the diagnosis of an underlying HIV infection was made. Unilateral, rapidly progressive hearing loss and a fast growing cerebello-pontine mass is atypical for VS and highly suspicious of malignant disease. To our knowledge we report the first case of an HIV-associated cerebral lymphocyte infiltration, mimicking a VS. In such cases the diagnostic work-up should include a HIV test.     

Sublocalization and volumetric growth pattern of intracanalicular vestibular schwannomas

OBJECTIVE: None of several previous reports on the growth pattern of vestibular schwannomas (VS) have dealt with the sublocalization and volumetric growth pattern of intracanalicular tumors. This paper reports such data from 196 patients. STUDY DESIGN: All VS patients have been registered prospectively at one center in Denmark since 1975. Data on intracanalicular tumors were drawn from the database, yielding 196 patients with a diagnostic and at least one control magnetic resonance imaging scan. All images were retrieved and the tumor sublocalization, size, and growth rate determined. RESULTS: The majority (50%) of the tumors was located centrally in the internal auditory canal (IAC), whereas 31% were porus-near and 19% fundus-near. Of the 196 tumors, 88 (45%) displayed growth, 20 (10%) shrinkage, and 88 (45%) remained unchanged. Thirty-eight (19%) tumors grew to extrameatal extension. Growth occurred only within 5 years after diagnosis. In the 88 growing tumors, the mean absolute growth rate was 111mm/year and the relative rate 114%/volume/year. The occurrence of IAC expansion at diagnosis was higher for tumors displaying subsequent shrinkage. Growth occurrence and rate, IAC expansion, and progression to extrameatal extension were not related to tumor sublocalization. CONCLUSION: Most intracanalicular VS are located centrally in a nonexpanded IAC at diagnosis. Growth occurs within 5 years after diagnosis in up to 45% of the tumors, although only 19% extend into the cerebellopontine angle. IAC expansion, growth occurrence, and rate are not related to tumor sublocalization. These findings justify primary observation of all purely intracanalicular tumors, unless realistic hearing preservation is intended.     

Preservation of the auditory nerve function after translabyrinthine removal of vestibular schwannoma

OBJECTIVE: To evaluate the function of the postoperative auditory nerve preserved after translabyrinthine (TL) vestibular schwannoma (VS) removal. METHODS: Fifteen patients, who underwent unilateral VS resection via a TL approach, were preserved auditory nerve anatomically. The size and location of VS were measured on MRI preoperatively. After surgery, the electrical stimulation test (EST) or electrically evoked auditory brainstem response (EABR) was performed. RESULTS: Four cases (27%) out of fifteen patients were retained the functional integrity of the auditory nerve after surgery. The maximum tumor size in the group with a positive response to EST or EABR was significantly smaller than that in the group with a negative response to EST. It seems to be difficult to preserve auditory nerve function in cases where a tumor extends to the fundus of internal auditory canal. CONCLUSION: These results suggest that size of tumor and/or extension of tumor to the fundus might be important factors in preserving the auditory nerve function even if using a TL approach.     

Intracanalicular meningioma: clinical features, radiologic findings, and surgical management.

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.     

Facial canal bifurcation with inner ear anomalies in a case of Klippel–Feil syndrome: A case report

We present a case of Klippel–Feil syndrome in a 2-year-old Chinese girl who presented with global developmental delay and bilateral profound hearing loss. High resolution computed tomography (HRCT) of temporal bones showed bilateral common cavity malformations with hypoplastic internal auditory canals and anomalous labyrinthine segments of both facial canals. The labyrinthine segment of the right facial canal was duplicated. Her brain magnetic resonance imaging (MRI) showed aplasia of both vestibulocochlear nerves, while the cisternal and intracanalicular segments of both facial nerves were of normal caliber. These congenital anomalies, coupled with global developmental delay, precluded her candidacy for cochlear implantation. This case report is aimed at highlighting the association of inner ear malformations and in particular facial canal anomalies in Klippel–Feil syndrome.     

Hearing loss in vestibular schwannomas: analysis of cochlear function by means of distortion-product otoacoustic emissions

Objective

We investigated cochlear function in a group of patients affected by vestibular schwannoma (VS), by means of recording distortion-product otoacoustic emissions (DPOAEs).

Methods

Between January 1996 and January 2007, we observed 183 patients affected by unilateral VS. DPOAEs, compared to the corresponding hearing thresholds, were subjectively classified into three categories: “compatible” with hearing function, “cochlear” and “retro-cochlear”. We also related the responses to some clinical variables (tumor size, intracanalicular tumor and radiologic appearance of the internal auditory canal). Statistical analysis was performed.

Results

In 137 cases (74.9%), DPOAEs were as expected based on audiometry responses, while in 11 patients (6%) a “cochlear” DP-gram was recorded and in 35 patients (19.1%) DPOAEs evidenced a “retro-cochlear” pattern. In eight cases we detected acoustic responses despite a profound hearing loss. No statistically significant data merged from the comparison between “cochlear” and “retro-cochlear” responses and the clinical variables.

Conclusion

Our results confirm that sensorineural hearing loss due to VS can be of sensory and/or neural origin. DPOAEs still remain just a complementary auditory test; nevertheless, in case of severe or profound unilateral hearing loss, recorded acoustic responses may be suspicious for the presence of a vestibular schwannoma.     

双内听道的影像学特征

目的 总结双内听道(duplication of internal auditory canal,DIAC)的多层螺旋CT和MRI影像学特点,提高对该病的认识.方法 结合文献回顾性分析4例(5耳)DIAC患者的影像学资料,4例均行多层螺旋CT检查,其中2例同时行MRI检查.结果 多层螺旋CT显示5耳内听道被骨性间隔分为双管状,上部骨管与面神经管相连,下部骨管与前庭和耳蜗相连,其中2耳骨性间隔不完整.5耳上下两管径之和均超过2 mm.3耳可显示蜗神经管狭窄.5耳均合并前庭扩大及外半规管发育不良,2例(2耳)同时合并小耳廓畸形,1耳合并小耳廓畸形、外耳道闭锁及听小骨发育不良.多平面重建(multiplanar reconstruction)、容积再现(volume rendering)图像可全面立体显示骨性间隔及双管结构.MRI显示1耳前庭和蜗神经发育不良、面神经完好,另1耳前庭、蜗神经和面神经均发育不良.结论 多层螺旋CT能清晰显示内听道被骨性间隔分为双管状及伴发畸形,可作为确诊DIAC的依据.MRI能表示其神经发育异常,为电子耳蜗植入对象的选择提供一定帮助.     

Sudden sensorineural hearing loss as a revealing symptom of vestibular schwannoma

CONCLUSIONS: Sudden sensorineural hearing loss (SSHL) is a frequent symptom of vestibular schwannoma (VS), often reveals small VSs and does not exhibit specific features. Therefore, every case of SSHL should be evaluated using systematic MRI to rule out VS in order to improve hearing and preservation facial nerve function. OBJECTIVE: SSHL leads to the discovery of a VS in a small proportion of cases (2%). However, SSHL appears to be a more frequent occurrence in the history of patients with VS (3-23% in the literature), suggesting a large disparity in the evaluation of SSHL. MATERIAL AND METHODS: A total of 139 consecutive unilateral VSs operated on between 2000 and 2002 were reviewed and analyzed regarding the prevalence, clinical and audiological features of SSHL and their relation to the size of the tumor. RESULTS: SSHL was observed in 20% of cases at some point in their VS history. The characteristics of SSHL were: (i) lack of a specific audiometric pattern, except that low-tone loss was rare; and (ii) a high rate of hearing recovery (50%). Tumor size was significantly smaller in SSHL-associated VSs compared to other VSs. In the former cases, 96% involved the internal auditory canal.     

122例听神经瘤患者听力受损相关因素分析

目的分析听神经瘤患者听力受损相关因素。方法回顾性分析122例单侧听神经瘤患者MRI,颞骨CT及听力学检查结果(纯音听阈及言语识别率),根据术前纯音听阈≤50dB、言语识别率≥50%的标准将患者分为实用听力组和无实用听力组,比较两组患者肿瘤大小、肿瘤囊变、脑干受压移位、瘤周有无水肿、内听道宽度、内听道长度、内听道底有无脑脊液等因素。结果内听道扩大程度与听力受损明显相关(P<0.001),肿瘤大小(P=0.25)、脑干受压移位(P=0.38)、瘤周有无水肿(P=0.91)、内听道长度(P=0.75)、内听道底有无脑脊液与听力受损无明显相关(P=0.18);肿瘤囊变可能有相关,但两组患者无统计学意义(P=0.08)。结论内听道扩大的程度与听神经瘤患者听力受损明显相关,其在一定程度上反应了内听道内耳蜗神经长时间受压情况。     

Extended middle fossa surgery for meningiomas within or at the internal auditory canal

OBJECTIVE: To show the clinical outcome in patients with meningioma within or at the internal auditory canal (IAC) operated on by the extended middle cranial fossa approach. STUDY DESIGN: Retrospective case review. SETTING: A tertiary referral center. PATIENTS: Twelve patients, 9 women and 3 men, whose ages ranged from 37 to 70 years (mean 57 years). One tumor was entirely intracanalicular, 5 had an intra-extracanalicular growth, 3 were centered at the posterior porus lip, and 3 tumors were localized in the midpetrosal region with spread into the IAC. INTERVENTION: Extended middle cranial fossa approach. MAIN OUTCOME MEASURES: Magnetic resonance imaging and computed tomography were used for follow-up and reevaluation of the operative sites. Facial nerve function and hearing were examined. RESULTS: Complete resection was achieved in 10 (83%) of 12 patients. The retrosigmoid approach was necessary to complete tumor resection in one patient, and in another, partial resection was done because of the en plaque type of tumor growth. There was one unexpected recurrence. All patients retained normal or near-normal facial nerve function postoperatively. Three patients were deaf before surgery, and preoperative hearing level was preserved in 42%. CONCLUSIONS: Attempted hearing preservation surgery is justified in patients with small tumors and preserved hearing, because tumor exposure and safety of resection are comparable with that of hearing-destructive procedures. Lateral extension of the tumor to the fundus does not prevent complete resection with preservation of function, and elective bone resections beyond the visible tumor margins seem not to substantially influence the tumor recurrence rates.     

MRI of endolymphatic hydrops in patients with vestibular schwannomas: a case-controlled study using non-enhanced T2-weighted images at 3 Teslas

European Archives of Oto-Rhino-Laryngology - Vestibular schwannomas (VS) may present with similar symptoms endolymphatic hydrops. Association between hydrops and internal auditory canal VS has been...     

Lesions of the internal auditory canal and cerebellopontine angle in an only hearing ear: is surgery ever advisable?

OBJECTIVE: To define the indications for surgery in lesions of the internal auditory canal (IAC) and cerebellopontine angle (CPA) in an only hearing ear. STUDY DESIGN: Retrospective case series. SETTING: Tertiary referral center. PATIENTS: Seven patients with lesions of the IAC and CPA who were deaf on the side opposite the lesion. Five patients had vestibular schwannoma (VS), and one each had meningioma and progressive osseous stenosis of the IAC, respectively. The opposite ear was deaf from three different causes: VS (neurofibromatosis type 2 [NF2]), sudden sensorineural hearing loss, idiopathic IAC stenosis. INTERVENTION(S): Middle fossa removal of VS in five, retrosigmoid resection of meningioma in one, and middle fossa IAC osseous decompression in one. MAIN OUTCOME MEASURE: Hearing as measured on pure-tone and speech audiometry. RESULTS: Preoperative hearing was class A in four patients, class B in two, and class C in one. Postoperative hearing was class A in three patients, class B in one, class C in two, and class D in one. CONCLUSIONS: Although the vast majority of neurotologic lesions in an only hearing ear are best managed nonoperatively, in highly selected cases surgical intervention is warranted. Surgical intervention should be considered when one or more of the following circumstances is present: (1) predicted natural history of the disease is relatively rapid loss of the remaining hearing, (2) substantial brainstem compression has evolved (e.g., large acoustic neuroma), and/or (3) operative intervention may result in improvement of hearing or carries relatively low risk of hearing loss (e.g., CPA meningioma).     

Retrosigmoid approach for acoustic tumor removal.

The retrosigmoid technique has evolved from the traditional suboccipital operation and, when combined with removal of the posterior wall of the internal auditory canal, affords a wide exposure of the cerebellopontine angle. This approach may be used for acoustic neuromas of all sizes, from intracanalicular to more than 4 cm from the porus acusticus. Hearing preservation may be attempted and is generally successful in a substantial minority of cases. The facial nerve is readily visualized at the lateral end of the internal auditory canal and is at no greater risk than in the translabyrinthine operation. We use this approach for all hearing preservation surgery as well as for tumors of more than 3 cm, regardless of hearing.     

Postoperative magnetic resonance imaging findings after transtemporal and translabyrinthine vestibular schwannoma resection

OBJECTIVES/HYPOTHESIS: Magnetic resonance imaging (MRI) has become the investigation of choice to follow up patients after vestibular schwannoma resection. STUDY DESIGN: Retrospective. METHODS: Postoperative MRI findings of 70 patients after vestibular schwannoma resection through a transtemporal (n = 48) and a translabyrinthine (n = 22) approach were reviewed. Time-dependent changes in intensity, size, and shape of enhancement in the internal auditory canal before and after contrast administration, postoperative temporal lobe gliosis, and changes of fat grafts were evaluated. RESULTS: After vestibular schwannoma resection, all patients showed signal enhancements in the internal auditory canal ranging from a faint to high signal intensity in the first postoperative MRI, 3 to 6 months after surgery. In the next MRI at 12 to 24 months after surgery, 30 patients (43%) showed a decreased signal, 35 patients (50%) a stable enhancement, and 5 patients (7%) an increased enhancement in the internal auditory canal depicted as an intense nodular or mass-like pattern. In patients with decreased or stable enhancement, a residual tumor could be excluded in the following MRI scans, whereas in all patients with increased enhancements after 12 to 24 months, signal enhancement further increased and residual tumors were detected. Different degrees of temporal lobe gliosis were found in 15 of 48 cases (31%) after transtemporal tumor removal. Enhancement of fat grafts used in 22 cases decreased to different degrees in 14 cases (64%). CONCLUSIONS: Differentiation of residual tumor from scar tissue in the internal auditory canal after vestibular schwannoma resection requires close, long-term follow-up. Nodular and progressive enhancements in the internal auditory canal indicate residual tumor. Linear enhancement in the internal auditory canal has been found to be a common finding after vestibular schwannoma resection not associated with residual tumor.