Translabyrinthine Excision of a Transmodiolar Intralabyrinthine Schwannoma Mimicking Meniere's Disease: A Case Report

Intralabyrinthine schwannomas (ILSs) are rare tumors involving the otic capsule. Notably, they are often misdiagnosed because their symptoms mimic those of other, more common inner ear pathologies. Diagnosis requires high-resolution contrast-enhanced magnetic resonance imaging (MRI), which reveals filling defects (using a T2-weighted MRI sequence) or focal enhancement (using a T1-weighted MRI sequence with gadolinium enhancement) in the inner ear. A 52-year-old male patient with intractable vertigo or single-sided deafness should raise suspicion of this clinical entity as a differential diagnosis. Translabyrinthine excision of the tumor along with auditory rehabilitation using a cochlear implant can provide good outcomes with minimal morbidity in carefully selected cases. Here, we present an interesting case of a transmodiolar ILS mimicking Meniere's disease, wherein surgery using the translabyrinthine approach and an extended cochleostomy yielded favorable outcomes.

Intralabyrinthine schwannoma: Surgical management and cochlear lumen preservation

The present video reports the surgical removal of an intralabyrinthine schwannoma. The video contains patient's medical history, preoperative radiological evaluations and detailed description of surgical steps of the procedure, consisting in labyrinthectomy, cochleostomy and insertion of a dummy electrode in the preserved cochlear lumen within the context of a subtotal petrosectomy.

Intralabyrinthine schwannomas: a two-case series and literature review with a focus on hearing rehabilitation

PURPOSE

Intralabyrinthine schwannomas (ILSs) are an uncommon finding. Diagnosis is challenging and no gold standard treatment exists yet. In this article, we present a two-cases series and review the latest available literature to assess the best diagnostic and therapeutic scheme.

METHODS

We reviewed the latest available literature assessing most frequent and relevant sets of symptoms, clinical features of the disease, diagnostic tests and imaging, possible treatments and after-surgery hearing rehabilitation techniques. We then compared literature data to our own series ones.

RESULTS

ILSs clinical presentation and development may overlap with other, more common otological conditions. Full audiometric battery test, electrophysiological study of VEMPS and MRI with contrast enhancement all appear to be critical to correctly diagnose these tumors. Several treatments exist: radiological follow-up, radiation therapy, full or partial surgical excision. Hearing rehabilitation is mostly accomplished through simultaneous cochlear implantation.

CONCLUSIONS

Our case-series data matches the available literature. ILSs are a rare type of vestibular schwannomas. Diagnosis in challenging and delayed in time as all the diagnostic tests, yet sensitive, are not specific for ILSs. The most suitable treatment seems to be surgical excision of these tumors followed by simultaneous cochlear implantation to restore hearing.

Cochlear Implantation in a Patient with Neurofibromatosis Type 2 and an Intracochlear Schwannoma: A Case Report and Literature Review

A primary intracochlear schwannoma (ICS) is a unique type of vestibular schwannoma (VS); the tumor originates from the terminal branches of the cochlear nerve and is confined to the cochlea. An ICS is the most common subtype of schwannoma in the inner ear. As an ICS is clinically rare, diagnosis and treatment remain challenging. We report a rare case of cochlear implantation (CI) in a patient with neurofibromatosis type 2 and an ICS. The patient exhibited bilateral, profound, sensorineural hearing loss. The tumor on one side was a common VS treated via tumor and acoustic nerve resection and that on the other side an ICS. To ensure auditory rehabilitation via CI, we performed CI while removing part of the ICS via an enlarged round window. Auditory rehabilitation was satisfactory. Thus, ICS patients, especially those who urgently require auditory rehabilitation, can undergo simultaneous CI and (total or partial) tumor removal. However, the long-term results require close observation.

Tight modiolar proximity and feasibility of slim modiolar cochlear implant electrode array insertion in diverse etiologies of hearing loss

PURPOSE

To report on our experience with the slim modiolar electrode (SME) especially focusing on the wide range of etiologies including inner ear anomalies, tumors, ossifications, and even revision surgeries.

METHODS

All the cochlear implantation cases performed from June 2018 to September 2019 by a single surgeon was prospectively recruited. The molecular/radiological etiology of hearing loss, intraoperative outcomes, and radiographic studies of cases where the SME was implanted was reviewed to evaluate compatibility of SME for the wide range of etiologies. For cases where SME replaced the other electrode as a revision, audiologic assessment was also made.

RESULTS

Among the 99 ears implanted during the study period, the SME was successfully implanted in 86 ears. These SME cases comprised inner ear anomaly/cochear nerve deficiency (n = 21) including cochlear hypoplasia type IV with the modiolus, intracochlear schwannoma (n = 1), far advanced otosclerosis (n = 1) and 7 revision cases. The SME was successfully used in 7 revision surgeries to replace the existing electrode. Shorter spiral diameter and decreased intracochlear position index for SME was found compared with their previous electrodes. Four out of the 6 patients who received revision implantation showed better speech perception after their surgeries.

CONCLUSION

The SME can be implanted in any cases unless the integrity of the modiolus is totally compromised. Due to its slim design and tight modiolar-hugging feature, good functional outcome can also be anticipated. Additionally, it is suitable for revision surgeries possibly allowing better hearing outcomes which may be attributed to its closer proximity to the modiolus.

Intralabyrinthine neurinoma: Management, exeresis and auditory restoration with cochlear implant

BACKGROUND AND OBJECTIVE

Vestibular schwannoma is a benign tumour that originates in the eighth cranial nerve. It is termed intralabyrinthine schwannoma (ILS) when it develops in the inner ear, this being a rare origin. We present our experience in the management of three patients with ILS.

MATERIALS AND METHODS

The results of tumour excision and cochlear implantation were evaluated in three patients with ILS: two intracochlear schwannomas (ICS) and one intravestibular schwannoma (IVS).

RESULTS

Prior to surgery, all patients presented progressive sensorineural hearing loss and tinnitus. Complete tumour resection and cochlear implantation was possible in all patients, with favourable hearing rehabilitation.

CONCLUSIONS

The therapeutic approach will depend on tumour size, growth rate, degree of hearing loss and presence of vestibular symptoms. Cochlear implantation (CI) in patients with ILS is possible when the cochlear nerve is present and functional. CI in patients, whether or not preceded by tumour excision, is an option with good hearing results in selected patients.

Management of vestibular dysfunction and hearing loss in intralabyrinthine schwannomas

PURPOSE

Intralabyrinthine schwannomas (ILS) are rare, benign, slow-growing tumors arising from schwann cells of the cochlear or vestibular nerves within the bony labyrinth. This study provides insight into the management of this rare tumor through a large case series.

MATERIALS AND METHODS

After Institutional Review Board approval, a retrospective chart review was performed of all ILS patients treated at our institution between 2007 and 2019.

RESULTS

20 patients (9 male, 11 female) with ILS were managed at our institution. The right ear was affected in 9 patients (45%) and the left in 11 (55%). Subjective hearing loss was endorsed by all 20 patients. Average pure tone average at presentation was 72 dB nHL. Nine tumors (45%) were intravestibular, 6 (30%) were intracochlear, 4 (20%) were transmodiolar and 1 (5%) was intravestibulocochlear. Hearings aids were used in 3 patients (15%), BiCROS in 2 (10%), CI in 2 (10%), and bone conduction implant in 1 (5%). Vestibular rehabilitation was pursued in 5 patients. Surgical excision was performed for one patient (5%) via translabyrinthine approach due to intractable vertigo. No patients received radiotherapy or intratympanic gentamicin injections.

CONCLUSION

ILS presents a diagnostic and management challenge given the similarity of symptoms with other disorders and limited treatment options. Hearing loss may be managed on a case-by-case basis according to patient symptoms while vestibular loss may be mitigated with vestibular therapy. Surgical excision may be considered in patients with intractable vertigo, severe hearing loss with concurrent CI placement, or in other case-by-case situations.

Histopathologic Evaluation of Intralabyrinthine Schwannoma

OBJECTIVES

The aim of this study is to perform a histopathologic analysis of temporal bones with an intralabyrinthine schwannoma (ILS) in order to characterize its extension.

METHODS

Archival temporal bones with a diagnosis of sporadic schwannoma were identified. Both symptomatic and occult nonoperated ILS were included for further analysis.

RESULTS

A total of 6 ILS were identified, with 4 intracochlear and 2 intravestibular schwannomas. All intracochlear schwannomas involved the osseous spiral lamina, with 2 extending into the modiolus. The intravestibular schwannomas were limited to the vestibule, but growth into the bone next to the crista of the lateral semicircular canal was observed in 1 patient.

CONCLUSIONS

Complete removal of an ILS may require partial removal of the modiolus or bone surrounding the crista ampullaris as an ILS may extend into these structures, risking damage of the neuronal structures. Due to the slow growth of the ILS, it remains unclear if a complete resection is required with the risk of destroying neural structures hindering hearing rehabilitation with a cochlear implant.

Diagnostic assessment of magnetic resonance imaging for patients with intralabyrinthine schwannoma: A systematic review

OBJECTIVES

Recent advancements in high-resolution imaging have improved the diagnostic assessment of magnetic resonance imaging (MRI) for intralabyrinthine schwannoma (ILS). This systematic review aimed to evaluate the diagnostic performance of MRI for patients with ILS.

METHODS

Ovid-MEDLINE and EMBASE databases were searched for related studies on the diagnostic performance of MRI for patients with ILS published up to February 10, 2020. The primary endpoint was the diagnostic performance of MRI for ILS. The quality of the enrolled studies was assessed using tailored questionnaires and the Quality Assessment of Diagnostic Accuracy Studies-2 criteria.

RESULTS

Overall, 6 retrospective studies that included 122 patients with ILS from a parent population of 364 were included. The sample size, parent population and its composition, reference standard, detailed parameters of MRI, and even the diagnostic methods varied between the studies. The studies had moderate quality. The sensitivity of combination of T2WI and CE-T1WI was over 90%. Relative sensitivity of T2WI comparative to CE-T1WI ranged from 62% to 100%, and the specificity were 100%.

CONCLUSIONS

MRI has acceptable diagnostic performance for ILS. There is a need for well-organized research to reduce the factors causing heterogeneity.

[Bilateral intracochlear schwannomas in a patient with no genetic or clinical features of neurofibromatosis type 2. German version]

Schwannomas of the eighth cranial nerve are benign tumours commonly found in the internal auditory meatus or in the cerebellopontine angle. In most cases, they arise from the inferior or vestibular portion of the vestibular nerve. Rarely, these tumours present in the inner ear and are then called intralabyrinthine schwannomas. Bilateral schwannomas are known in neurofibromatosis type 2 (NF2). Bilateral and ipsilateral, multilocular sporadic schwannomas of the eighth cranial nerve have been described as extremely rare findings. This report describes the first case of bilateral sporadic intracochlear schwannomas in a patient with no genetic or clinical features of NF2.

Combined surgical approach to intralabyrinthine schwannoma

INTRODUCTION

Intralabyrinthine schwannoma (ILS) is a tumor originating from the Schwann cells in the inner ear. Various surgical approaches can be used for the resection of ILS. The aim of this report is to describe a case involving a 60-year-old man who was treated successfully with a combined surgical approach.

CASE REPORT

The patient underwent a combined microscopic (transmastoid labyrinthectomy) and endoscopic procedure for surgical excision of ILS involving the vestibule and the lower half of the cochlear basal turn. The combined surgical technique enabled a complete removal of the ILS without removal of the unaffected cochlea as well as the external auditory canal. Besides additional exclusion of the middle ear, blind-sac closure of the external auditory canal and cavity obliteration were avoided. No postoperative complications were observed.

DISCUSSION

A combined microscopic and endoscopic approach to surgery enables removal of the ILS involving the vestibule and the lower half of the cochlear basal turn while helping to reduce surgical radicality.

Intralabyrinthine schwannomas: a new surgical treatment

OBJECTIVE

To define a new surgical option, with lower morbidity, for the treatment of intralabyrinthine schwannomas.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral centers.

PATIENTS

Eight patients affected by an intralabyrinthine schwannoma, with or without extension to the internal auditory canal, that underwent surgery with a transcanal transpromontorial approach, were included in the study. The average age at presentation was 47 years. Patients' characteristics, symptoms, tumor features, and surgical results were analyzed.

INTERVENTIONS

All patients were diagnosed and evaluated pre-operatively with high-resolution, gadolinium-enhanced MRI and CT scan of the temporal bone, and underwent surgery via either transcanal transpromontorial endoscopic approach (TTEA) or enlarged transcanal transpromontorial endoscopic approach (ETTA).

MAIN OUTCOME MEASURES

Hearing function was evaluated with the Hearing Classification System according to the Committee on Hearing and Equilibrium Guidelines. Facial nerve function was evaluated using the House-Brackmann grading system (HB).

RESULTS

In six patients out of eight, a TTEA was performed, whereas, due to the extension of the pathology to the cerebellopontine angle, two patients underwent an ETTA. The mean follow-up period was 15.5 months (range 1-69). No intra-operative and post-operative major complications were observed. Post-operative facial nerve function was normal in seven out of eight patients (grade I HB). One patient presented a grade II HB.

CONCLUSION

The endoscopic approach to cochlear schwannoma represents a good treatment option for patients and should be preferred to other more invasive surgical techniques when indicated, to reduce complications, hospitalization, and offer to patients the chance to eradicate the disease, thus avoiding the stress of a long-life radiological follow-up.

LEVEL OF EVIDENCE

4.

MRI screening of the internal auditory canal: Is gadolinium necessary to detect intralabyrinthine schwannomas?

OBJECTIVE

Non-contrast MRI of the internal auditory canal (IAC) using high-resolution T2WI (T2 weighted image) has been proposed as the primary screening study in patients with sudden or asymmetric sensorineural hearing loss (ASNHL). However, there are concerns that non-contrast MRI may not detect labyrinthine pathology, specifically intralabyrinthine schwannomas (ILSs). The purpose of this study was to determine if non-contrast high-resolution T2WI alone are adequate to exclude these uncommon intralabyrinthine tumors.

METHODS

31 patients with ILSs and 36 patients without inner ear pathology that had dedicated MRI of the IAC performed with both non-contrast T2WI and post-contrast T1WI (T1 weighted image) were identified. Three board-certified neuroradiologists reviewed only the T2WI from these 67 cases. When an ILS was identified, its location and size were recorded. Sensitivity, specificity, and accuracy were calculated using the post-contrast T1WI as the "gold standard." A consensus review of cases with discordant results was conducted.

RESULTS

The sensitivity, specificity, and accuracy were 1.0, 1.0, and 1.0 for Observer 1; 0.84, 1.0, and 0.96 for Observer 2; 0.90, 1.0, and 0.98 for Observer 3. The 5 ILSs with discordant results were correctly identified upon consensus review. The median size of the ILSs was 4.4mm (±2.9mm) and most (18/31) were intracochlear in location.

CONCLUSION

Non-contrast high-resolution T2WI alone can detect ILSs with 84-100% sensitivity, suggesting that gadolinium may be unnecessary to exclude ILSs on screening MRI. These findings have implications for reducing cost, time, and adverse events associated with gadolinium administration in patients presenting with sudden or ASNHL.

LEVEL OF EVIDENCE

4.

Clinical features of delayed endolymphatic hydrops and intralabyrinthine schwannoma : An imaging-confirmed comparative case series. English version

BACKGROUND

The aim of this study was to compare the clinical history and audiovestibular function test results of patients suffering from intralabyrinthine schwannoma or delayed endolymphatic hydrops (DEH).

PATIENTS AND METHODS

Five patients diagnosed with intralabyrinthine schwannoma by magnetic resonance imaging (MRI) and five patients diagnosed with DEH by locally enhanced inner ear MRI (LEIM) were retrospectively studied.

RESULTS

All patients with intralabyrinthine schwannoma or DEH initially presented with hearing loss. Vertigo occurred in two patients with intralabyrinthine schwannoma and in all patients with DEH. While audiometry achieved poorer results for patients with intralabyrinthine schwannomas, vestibular function tests revealed normal results in about half of the patients in both groups.

CONCLUSION

Patients with intralabyrinthine schwannomas may present with clinical symptoms similar to patients suffering from other inner ear disorders such as delayed endolymphatic hydrops and they may obtain similar findings in audiovestibular function tests. High-resolution magnetic resonance imaging with locally applied contrast agent may provide evidence of both underlying pathologies.

Meta-analysis on the clinical outcomes in patients with intralabyrinthine schwannomas: conservative management vs. microsurgery

The objective of this review is to compare the symptomatological evolution following conservative management (CM) or microsurgery (MS) in patients with intralabyrinthine schwannomas (ILS). A thorough systematic review of the English and French literature from 1948 to February 2014 was performed using Ovid Medline. An ancestor search was also completed. The major inclusion criterion consisted of a diagnosis of ILS with magnetic resonance imaging. Patients with a classic vestibular schwannoma, cases of incidentaloma during surgery or an autopsy were the main exclusion criteria. Thirty-one studies met our selective criteria. Descriptive data were collected from the articles. Clinical outcomes regarding the hearing loss, tinnitus, vertigo, dizziness and aural fullness were stated as improved, unchanged or worse at the last follow-up. All data were then separated into two different groups according to the management option: CM and MS. The data were analyzed using a Pearson χ (2) test and Fisher's exact test. This meta-analysis suggests that MS has a statistically significant favorable outcome regarding symptom relief compared to CM in patients with ILS suffering from tinnitus, vertigo and dizziness. Hearing level was not compared between treatment groups, as MS leads to anacusis. An indicative bias was the main limitation of this study, as patients suffering from intractable vertigo with moderate-to-severe hearing loss were referred to MS. Therefore, in the presence of a serviceable hearing, we suggest that CM should be the treatment of choice.

Recovery of hearing after surgical removal of intralabyrinthine schwannoma

Intralabyrinthine schwannomas (ILSs) are rare benign tumors arising from the distal part of the cochleovestibular nerve confined within the labyrinth. Patients with ILSs complain of hearing loss, vertigo, tinnitus, and ear fullness. Surgical treatment of ILS is performed in special cases such as in cases of patients with nonserviceable hearing, progressive hearing loss, intractable vertigo, or tumor extension. We present an unusual case of a patient with intralabyrinthine schwannoma who underwent surgery to treat progressive hearing loss and recovered his hearing after surgery.

Intracochlear schwannoma

Intralabyrinthine schwannomas are benign, slow-growing tumors that originate from Schwann cells lining the terminal ends of the cochlear and vestibular nerves. Magnetic resonance imaging (MRI) with gadolinium is considered the best diagnostic tool for this disease. Kennedy et al proposed a classification system, based upon the MRI observations, that identifies seven different classes according to the site of the tumor: intravestibular, intracochlear, intravestibulocochlear, transmodiolar, transmacular, transotic, and tympanolabyrinthine. A case of a patient undergoing a 2-year follow-up with serial MRI and managed with a wait-and-see strategy is described. The rationale of the diagnosis and the different treatments of choice are discussed.