Intralabyrinthine schwannomas

Case report: Concurrent intravestibular schwannoma mimicking Ménière's disease and cochlear hydrops detected via delayed three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging

Objective

To present a case of intralabyrinthine schwannoma (ILS) presenting as Ménière's disease diagnosed via 4-h delayed gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI) and treated successfully using the translabyrinthine approach.

Patient

A patient who was diagnosed with intravestibular ILS.

Interventions

The patient underwent comprehensive preoperative neurological examinations and MRI. The tumor was resected using the translabyrinthine approach and was pathologically confirmed as schwannoma based on the surgical specimen.

Main outcome measures

Preoperative audiogram and vestibular test findings and MRI images.

Results

Preoperatively, pure-tone audiogram showed progressive sensorineural hearing loss only on the affected side. The video head impulse test and vestibular evoked myogenic potential test showed vestibular dysfunction on the affected ear. Immediate gadolinium-enhanced T1-weighted MRI revealed an enhanced region in the vestibule. Meanwhile, magnetic resonance cisternography showed a filling defect. Delayed 3D-FLAIR MRI revealed a signal void in the scala media of the cochlea indicative of cochlear hydrops, and a strong signal in the perilymph at the basal cochlea suggestive of impaired blood–labyrinthine barrier.

Conclusion

Delayed 3D-FLAIR MRI is useful in diagnosing concurrent ILSs and endolymphatic hydrops.

Four-Hour Delayed Gadolinium-Enhanced 3D-FLAIR MR Imaging Highlights Intralabyrinthine Micro-Schwannomas

OBJECTIVE

To demonstrate the clinical significance of 4-hour delayed gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery (delayed 3D-FLAIR) in patients with intralabyrinthine schwannoma (ILS).

PATIENTS

Three patients who were clinically diagnosed with ILS.

INTERVENTIONS

All patients underwent audiological examinations and magnetic resonance imaging (MRI) scans. The MR-protocol included axial MR cisternography, immediate gadolinium-enhanced T1-weighted sequence, and heavily T2-weighted 3D-FLAIR prior to and 4 hours after the intravenous administration of gadolinium contrast medium.

MAIN OUTCOME MEASURES

All MR images were visually inspected.

RESULTS

In all three patients with ILS, delayed 3D-FLAIR MRI demonstrated a strong signal of cochlear fluid surrounding the tumor, which highlighted a tumor region that lacked signals.

CONCLUSIONS

Delayed 3D-FLAIR MRI may serve as a novel diagnostic tool for the early detection of intralabyrinthine micro-schwannoma. The findings also shed light on the pathophysiology of ILS.

Endolymphatic Hydrops in Patients With Intralabyrinthine Schwannomas

Purpose: The presence of endolymphatic hydrops (EH) in patients with intralabyrinthine schwannomas (ILSs) is poorly understood. This study aims to determine whether there is a correlation between endolymphatic hydrops and clinical presentations of ILS.

Methods: Data from nine patients with ILSs were retrospectively reviewed between 2007 and 2020. Temporal bone MRI with intratympanic or intravenous injection of gadolinium was applied to detect ILSs and EH.

Results: 3D real inversion recovery (IR) sequence MRI of the temporal bone confirmed ipsilateral EH in four patients (4/6). All four patients with EH on MRI presented with vertigo similar to Meniere's disease. Among these patients with EH, one patient with EH in the cochlea showed moderate sensorineural hearing loss, while three patients with EH in both the vestibule and cochlea showed profound hearing loss. MRI demonstrated a transmacular tumor (TMA) in one patient, intravestibular (IV) in four patients, and vestibulocochlear (VC) in four patients. Two IV cases showed moderated hearing loss, while the TMA and VC cases showed profound hearing loss. Transotic resection of the tumor was applied in five patients; translabyrinthine resection was applied in one patient; two patients were under observation; and one patient was given intratympanic injection of gentamicin (ITG). During follow-up, all of the treated patients reported relief of vertigo, and postoperative MRI was performed in two patients, which showed no tumor recurrence. The two patients under observation showed no deterioration of hearing loss or vertigo. One patient was lost to follow-up.

Conclusion: EH concurrent with ILSs has been underestimated previously. With the extensive application of temporal bone MRI paradigms, such as 3D-real IR sequence MRI, more cases of potential EH in patients with ILS will be identified. The severity of hearing loss may be associated with the location of the tumor and the degree of EH.

Intralabyrinthine Schwannoma: Distinct Features for Differential Diagnosis

Objectives: The aim of this study was to delineate the clinical and laboratory features suggestive of intralabyrinthine schwannoma (ILS). Methods: We compared the clinical features of 16 patients with ILS, who had been diagnosed at the Seoul National University Bundang Hospital from 2003 to 2018, with those of 18 patients with symptomatic unilateral intracanalicular schwannoma and randomly selected 20 patients with definite or probable unilateral Meniere's disease (MD). Results: Patients with ILS presented with either recurrent spontaneous dizziness/vertigo combined with auditory symptoms (n = 8), isolated auditory symptoms without dizziness/vertigo (n = 7), or recurrent spontaneous dizziness/vertigo without auditory symptoms (n = 1). Most patients reported no improvement (n = 11) or worsening (n = 1) of the symptoms despite medical treatments including intratympanic (n = 5) or intravenous steroids (n = 2). Conventional brain MRIs failed to detect ILS in about a half of the patients (7/16, 44%). However, ILS showed a filling defect on 3-dimensional (3D) heavily T2-weighted MRIs (n = 12), and nodular enhancement on 3D contrast-enhanced T1 (n = 15) or FLAIR MRIs (n = 13) targeted for the inner ear. Compared to MD or intracanalicular schwannoma, ILS showed mostly abnormal head-impulse tests (HITs, p = 0.001). In contrast, the incidence of canal paresis did not differ among the groups (p = 0.513). Conclusion: ILS may mimic MD by presenting recurrent dizziness/vertigo and auditory symptoms. ILS should be suspected in patients with recurrent audiovestibulopathy especially when (1) the duration of the dizziness is not typical for MD, (2) the patients do not respond to medical treatments, or (3) HITs are abnormal.

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: Disease Presentation, Tumor Management, and Hearing Rehabilitation

Intralabyrinthine schwannomas (ILS) are rare tumors that frequently cause sensorineural hearing loss. The development and increased use of magnetic resonance imaging in recent years have facilitated the diagnosis of these tumors that present with otherwise nondiscriminant symptoms such as tinnitus, vertigo, and hearing loss. The following is a review of the presentation, pathophysiology, imaging, and treatment with a focused discussion on auditory rehabilitation options of ILS.

Different clinical presentation of intralabyrinthine schwannomas – a systematic review

Introduction

Intralabyrinthine schwannoma is a rare, benign tumor that affects the most terminal portions of the vestibular and cochlear nerves. This tumor can be classified into 10 subtypes, according to its inner ear location.

Objective

To carry out a comprehensive review of the most frequent auditory manifestations secondary to the intralabyrinthine schwannoma, describing the possible underlying pathophysiological mechanisms.

Methods

Systematic review of the literature until October 2017 using the PubMed, Web of Science and Scopus databases. The inclusion criteria were clinical manifestations of the intralabyrinthine schwannoma. Three researchers independently assessed the articles and extracted relevant information. The description of a case of an intravestibular subtype intralabyrinthine schwannoma with multiple forms of clinical presentations was used as an example.

Results

Twenty-seven studies met our inclusion criteria. The most common intralabyrinthine schwannoma subtype was the intracochlear, followed by the intravestibular type. All the cases demonstrated hearing loss, usually progressive hearing loss.

Conclusion

The diagnosis of intralabyrinthine schwannomas is based on high-resolution magnetic resonance imaging and should be included in the differential diagnosis of patients with vestibulocochlear complaints. Although there are approximately 600 cases in the literature, we still lack a detailed description of the clinical evolution of the patients, correlating it with MRI findings of temporal bones and tumor subtype.

Ocular vestibular evoked myogenic potentials and intravestibular intralabyrinthine schwannomas

Intravestibular intralabyrinthine schwannomas (ILSs) are uncommon benign tumors that arise from the saccular, utricular, and lateral and superior ampullary nerves. According to the literature, there is an average delay of 8 years between the onset of symptoms and diagnosis. The diagnosis is based on an audiovestibular examination and magnetic resonance imaging (MRI). We describe a case of intravestibular ILS in which we included the ocular vestibular evoked myogenic potentials (oVEMPs) test in the diagnostic workup. The oVEMPs test is a relatively new neurophysiologic diagnostic modality that evaluates the superior vestibular pathway and the ascending contralateral pathway through the vestibulo-ocular reflex. In our case, a 65-year-old man presented with progressive right-sided sensorineural hearing loss, dizziness, and tinnitus and fullness in his right ear. Audiovestibular examination and MRI detected an intravestibular ILS on the right. We found that oVEMPs were absent on the contralateral side, which contributed to the diagnostic process. The detection of oVEMPs can provide detailed information on the functionality of the macula of the utricle and the lateral and superior ampullary nerves, with a precise identification of the affected area. Based on our findings, we discuss the role of oVEMPs in the diagnosis of an intravestibular ILS.

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.

Primary Solitary Intralabyrinthine Schwannoma: A Report of 7 Cases and a Review of the Literature

Intralabyrinthine schwannomas (ILSs) are uncommon benign tumors that originate in the Schwann cell sheath of the intralabyrinthine distal branches of the vestibulocochlear nerve. They have no initial involvement in the internal auditory canal although that might develop later. These lesions can arise inside the cochlea, originate in the vestibule or, in rare cases, develop in the semicircular canals. From these sites, spread might take place via the anatomic connections between the perilymphatic spaces in the scala vestibuli and the anterior vestibule. Thus, ILSs centered in the cochlea might involve the vestibule, and those originating in the vestibular end organs would reach the cochlea. Presenting signs and symptoms include a progressive or sudden sensorineural hearing loss (which occurs in more than 95% of patients), as well as tinnitus and vertigo. Magnetic resonance imaging characteristics include sharp circumscription and hypointensity on thin, heavily T2-weighted 3D images and strong enhancement after gadolinium administration on TI-weighted images. We describe a series of 7 cases of primary ILS that were managed at two of our institutions. We also discuss the need for a comprehensive otoneurologic evaluation that encompasses the functional derangement and the tumor location as delineated by MRI, and we describe the treatment options.

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.

Intralabyrinthine schwannomas: a case series with discussion of the diagnosis and management

OBJECTIVE

By extracting cases of intralabyrinthine schwannomas (ILS) from the sum of all vestibular schwannomas, we aim to identify and analyze unique features of its presentation. This allows us to refine the management protocol of this rare condition.

DESIGN

This is a retrospective study of all patients seen in the Department of Otorhinolaryngology-Head and Neck Surgery, Rouen University Hospital, with either ILS or ILS with intracanalicular extension (ILS-IAC) between 2001 and 2011. A literature search was performed and results combined to draw conclusions on management strategies.

METHOD

Three patients with ILS and 6 patients with ILS-IAC were identified. We retrieved data on age, sex, symptoms, audiometry, imaging, and management. Pure tone audiometry and speech discrimination score were assessed and hearing classification recorded. Facial nerve function and vestibular function were documented throughout. The diagnostic and surveillance imaging (MRI with or without CT) were reviewed.

RESULTS

The average age at presentation was 62.8 years and the sex ratio was (male: female) 4:5. An ipsilateral hearing loss was observed in all patients. Eight of 9 patients had tinnitus at presentation, 2 had rotatory vertigo, and 1 patient had a facial palsy and hemifacial spasm. In 2 cases, the labyrinthine extension was initially missed. The patient presenting with a large tumor and facial palsy was operated on without delay. The others underwent MRI surveillance, with 4 requiring surgery at a later stage. No postoperative facial palsies were encountered other than the one that had been present preoperatively.

CONCLUSION

Frequency of ILS is underestimated because of poor diagnostic criteria. These tumors have often been described as having features, which resemble Ménière's disease, which is not found in our series. In the absence of tumor progression or disabling symptoms, their management is surveillance/medical, and when surgery is considered, facial paralysis and recurrence rates seem low. The treatment of IAC-ILS differs from that of ILS.

[Intralabyrinthine schwannoma extending into the round window niche and internal auditory canal]

Intralabyrinthine schwannomas (ILSs) are rare benign neoplasms arising from distal branches of the cochlear, superior vestibular, or inferior vestibular nerves. We report on a case of ILS with extensions to the round window niche and internal auditory canal (IAC) in a 47-year-old male. The patient noticed sudden hearing loss and tinnitus in his left ear at the age of 36, received steroid therapies, but was left with complete deafness. He had suffered from repetitive vertigo attacks for 6 months at 41. At 46 when he presented with deterioration of his left tinnitus, he was finally diagnosed as having ILS on enhanced MRI and constructive interference in steady-state analysis. The tumor was located in all turns of cochlea, vestibule, and the fundus of the IAC. Because follow-up MRI suggested growth of the IAC tumor, we performed total removal of the tumor via the translabyrinthine and transcanal approaches. The tumor had invaded only the cochlear nerve in the IAC and appeared in the round window niche in the middle ear. Pathological examination showed an Antoni A type schwannoma with fibrous changes of the semicircular canals. We should remember this inner

Histopathologic markers of hearing loss in intralabyrinthine schwannomas: implications for management

OBJECTIVE

This study aimed to review the clinical history and management of patients with intralabyrinthine schwannomas and evaluate the histopathologic features of these tumors.

STUDY DESIGN

A retrospective case review of 24 patients and 7 temporal bone specimens.

SETTING

An otologic tertiary referral private practice.

PATIENTS

Patients with magnetic resonance imaging-confirmed intralabyrinthine schwannoma diagnosed after 1995 and non-Neurofibromatosis type 2 temporal bone specimens with schwannomas confined to the bony labyrinth.

MAIN OUTCOME MEASURES

Clinical data including history, imaging and audiometry were evaluated. The histopathologic features of temporal bone specimens including tumor location and degenerative changes were analyzed.

RESULTS

The intralabyrinthine location of the tumor does not predict the degree or time to progression of hearing loss. Both sensorineural and conductive hearing loss can occur. Mechanisms of hearing loss include hair cell, spiral ganglion, and stria vascularis degeneration in addition to mechanical obstruction.

CONCLUSION

Hearing loss is the most common symptom with intralabyrinthine schwannomas. Histopathology reveals that multiple mechanisms of degeneration may occur within the labyrinth to induce hearing loss. Observation provides the most reliable hearing preservation strategy.

Intralabyrinthine schwannomas: imaging diagnosis and classification

BACKGROUND AND PURPOSE

ILS is a rare lesion that has a different management from the more common "acoustic" schwannoma. To date, only 137 cases have been reported. We present a classification scheme based on labyrinthine anatomy to describe and localize these lesions. Treatment and prognosis hinge on the appropriate localization of these tumors; thus, a concise terminology that can be used by both the otolaryngologist and radiology communities is desirable.

MATERIALS AND METHODS

After approval of the institutional review board, a retrospective study of all patients with the diagnosis of ILS imaged between 1996 and 2010 was performed. Clinical and imaging data were collected. Patients were imaged with thin-section high-resolution T2 and contrast-enhanced MR imaging.

RESULTS

There were 45 patients with a diagnosis of ILS. Forty-three had complete histories. There were 18 male and 25 female patients with an age range of 21-78 years with a mean age of 53 years. The most common presenting symptom was progressive sensorineural hearing loss. Lesions were characterized on the basis of their location. Intracochlear was most common (14/45) followed by transmodiolar (13/45), intravestibular (7/45), vestibulocochlear (5/45), transmacular (4/45), and transotic (2/45). Sixteen patients underwent surgical resection. The remaining patients were followed clinically and by serial MR imaging.

CONCLUSIONS

ILS is an uncommon but under-reported tumor. We characterized the MR imaging appearance of these tumors by using high-resolution techniques. In addition, an anatomically based classification system is presented that will help the radiologist accurately describe ILS within the inner ear and help the surgeon determine which tumors are potential surgical candidates.

[Intralabyrinthine schwannomas]

Schwannomas are benign neurogenic tumors arising from Schwann cells that usually form the myelin sheath of peripheral nerves. The typical localization of vestibular schwannomas is the internal auditory canal or the cerebellopontine angle. Intralabyrinthine lesions are extremely rare. Here we describe a series of four consecutive cases of intralabyrinthine schwannomas that were treated in the Department of Otorhinolaryngology, Head and Neck Surgery, Klinikum Bielefeld in Bielefeld, Germany. Therapeutic options are discussed and the literature is reviewed.

Imaging of intralabyrinthine schwannomas: a retrospective study of 52 cases with emphasis on lesion growth

BACKGROUND AND PURPOSE

Only a few case reports and small series of intralabyrinthine schwannomas (ILSs) have been reported. The purpose of this study was to assess prevalence, MR characteristics, location, clinical management, and growth potential/patterns of ILSs in the largest series reported.

MATERIALS AND METHODS

Lesion localization, MR characteristics, lesion growth, and clinical management were reviewed in 52 patients diagnosed with an ILS between February 1991 and August 2007 in 2 referral centers. The number of ILSs and vestibulocochlear schwannomas in the cerebellopontine angle/internal auditory canal was compared to assess the prevalence.

RESULTS

ILSs most frequently originate intracochlearly, are hyperintense on unenhanced T1-weighted images, enhance strongly after gadolinium administration, and are sharply circumscribed and hypointense on thin heavily T2-weighted 3D images. The scala tympani is more frequently or more extensively involved than the scala vestibuli. Follow-up MR imaging, available in 27 patients, showed growth in 59% of subjects. Growth was seen from the scala tympani into the scala vestibuli and from the scala vestibuli to the saccule and vice versa. Twelve lesions were resected, and the diagnosis of ILS histopathologically confirmed.

CONCLUSION

ILSs can account for up to 10% of all vestibulocochlear schwannomas in centers specializing in temporal bone imaging, grow in more than 50%, and are most frequently found intracochlearly, often anteriorly between the basal and second turn. Cochlear ILSs most often originate in the scala tympani and only later grow into the scala vestibuli. Growth can occur from the cochlea into the vestibule or vice versa through the anatomic open connection between the perilymphatic spaces in the scala vestibuli and around the saccule.

Intralabyrinthine schwannomas: Symptoms and managements

OBJECTIVE

To describe the characteristic presentations, radiologic findings and managements of the intralabyrinthine schwannomas.

METHOD

Retrospective review of patient records, their managements, and review of the literature.

RESULT

Four patients with a variety of otologic symptoms including hearing loss, vertigo, and tinnitus were found to have a schwannomas involving the labyrinth. In all cases, the inner ear lesions were preoperatively identified on magnetic resonance imaging, and the surgical removals were performed in all patients without serviceable hearing. The patients experienced improvement in their vertigo and tinnitus after surgery. Two patients were implanted the Bone-Anchored Hearing Aid (BAHA) to reconstruct the pseudo-stereophonic hearing.

CONCLUSION

Intralabyrinthine schwannomas are the rare tumours in the otology. The tumour can be removed by surgical approach, but we do not propose surgical excision for the patients with serviceable hearing. BAHA can give patients a post-operative monaural pseudo-stereophonic hearing.

Management of intralabyrinthine schwannomas

OBJECTIVES

Our protocol to manage the intralabyrinthine schwannoma (ILS).

METHODS

Retrospective chart review of 7 consecutive patients managed for ILS.

RESULTS

Five patients underwent surgical removal of the lesions and none experienced significant complications or recurrent disease. One patient refused surgical treatment and was closely followed by serial MRI scans with no signs of tumor growth. One patient is presently managed conservatively due to a good hearing.

CONCLUSIONS

Diagnosis of ILS is based on high resolution MRI scans and should be included in the differential diagnosis of patients investigated for cochleovestibular symptoms. Treatment modality of ILS is controversial and depends patients' age, severity of vertigo and hearing loss. In the authors' experience surgery is indicated in all cases with invalidating vertigo and in the young patients with severe hearing loss. Conservative strategy is advised in older patients and in cases with preserved good hearing and no invalidating vertigo. These patients must be followed up using high resolution MRI because of the risk of tumor growth into the internal auditory canal. While tumors with exclusive involvement of the inner ear may be removed by means of a completely extradural approach, tumor growth with involvement of the internal auditory canal dictates the necessity of opening the dura exposing the patients to the potential risks associated with the procedure.

Diagnosis and Management of Intracochlear Schwannomas

OBJECTIVE

To describe and analyze a series of intracochlear schwannomas.

METHODS

From 1987 to 2005, 19 patients with schwannomas involving the cochlea were included in this series. Clinical, audiovestibular, and imaging data concerning initial and follow-up visits were collected.

RESULTS

The mean age was 54 years (range, 25-71 yr). The series comprised 10 women and 9 men, 18 solitary tumors and 1 neurofibromatosis Type 2 patient. The mean diagnosis delay was 11 years (range, 1-31 yr). At diagnosis, a total or profound hearing loss (Class D of American Academy of Otolaryngology-Head and Neck Surgery classification) was noted in 17 patients (89%), and a severe loss (Class C) was reported in 2 patients (11%). Facial paresis was reported in 2 patients (11%; Grades 2 and 4 of House and Brackmann classification). Magnetic resonance imaging showed an involvement of the posterior labyrinth in 8 patients (37%), an extension of the schwannoma to the internal auditory meatus in 8 patients (37%), and a cerebellopontine angle extension in 7 patients (32%). In 11 patients (58%), the schwannoma was removed through a transotic route. In the 8 remaining patients, a watch-and-rescan policy was decided. The postoperative course was uneventful. Postoperative follow-up period was 27 months (range, 6-88 mo). Postoperative facial function was assessed as Grade 1 in 7 patients, as Grade 2 in 4, and as Grade 4 in 1 patient.

CONCLUSION

The diagnosis of intracochlear schwannomas can be difficult on magnetic resonance imaging. The diagnosis should be considered in all unilateral hearing losses.

Intrakochleäres Schwannom als Ursache für eine Surditas

Inner ear extension caused by schwannomas, which can cause hearing loss, tinnitus and vertigo, is an extremely rare finding. We report a male patient who presented with progressive hearing loss as well as tinnitus in the right ear. Despite rheologic infusion therapy with glucocorticosteroids at another hospital, the patient showed an explicit hearing loss and vertigo related to the right ear. In the pure tone audiogram, we found complete deafness of the right ear, the equilibriometry with caloric testing showed complete loss of the labyrinth. In the HR-MRI, a structure appeared in ranges of the basal and middle cochlea with enhancement of the contrast medium. From the MRI aspect, this appeared to be a small intracochlear schwannoma. As a differential diagnosis, a chronic granulation is also possible. In agreement with the patient, we decided to control the structure clinically every 6 months using MRI; no further growth of the structure appeared. A precise imaging via HR-MRI is required to detect intracochlear schwannomas. Observation is an appropriate option for patients who have serviceable hearing. Surgical exploration can be recommended in cases of progressive diseases and growth into the inner ear with recurrent vertigo attacks. The option of radiotherapy for the treatment of intrameatal acoustic neurinomas should be considered.

Intralabyrinthine Schwannomas: Diagnosis, Management, and a New Classification System

OBJECTIVE

To outline the diagnosis and management of intralabyrinthine schwannomas and to propose a new classification system to further define them.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center at a university hospital.

PATIENTS

Twenty-eight patients seen at the institution with intralabyrinthine schwannomas between 1996 and 2002 were included in the study.

INTERVENTIONS

Diagnosis was made with magnetic resonance imaging in all but one case. Our ability to detect these tumors has been greatly enhanced by the introduction of high-resolution T2-weighted magnetic resonance imaging. Treatment options were observation with serial magnetic resonance imaging versus complete surgical removal via a translabyrinthine or transotic approach. Surgery was indicated for dizziness caused by the tumor or extralabyrinthine growth.

MAIN OUTCOME MEASURES

Clinical features, audiology, radiology, and management outcomes were evaluated.

RESULTS

Eight patients have undergone successful surgery with removal of their tumors and resolution of symptoms. One patient chose to have stereotactic radiotherapy. Of the 20 patients who were managed with observation and serial magnetic resonance imaging, only 1 has shown significant growth requiring surgical removal.

CONCLUSION

Intralabyrinthine schwannomas are uncommon tumors that mimic the clinical features of many other neurotologic conditions. A high index of suspicion and precise imaging are often required to detect these tumors. Surgical treatment is indicated for specific indications and will be needed in the minority of patients with this disorder. The classification system that we propose is helpful in both the diagnosis and the management of these tumors.

Inner ear extension of vestibular schwannomas

OBJECTIVE

Inner ear extension of vestibular schwannomas (VSs) is a rare finding but has important clinical implications. This report reviews the treatment options and presents the experience of the Gruppo Otologico, Piacenza, Italy, in this field.

STUDY DESIGN

Case report and literature review.

METHODS

Five cases of VSs with inner ear extension were surgically removed. In all of them, the cochlea was partially or completely invaded by the lesion.

RESULTS

In 4 cases, the inner ear extension was preoperatively identified on magnetic resonance imaging, and the surgical removal was planned through a transotic approach. In the last case, the cochlear invasion was not detected preoperatively, and the lesion was removed during a second surgery performed to seal a cerebrospinal fluid fistula.

CONCLUSIONS

VSs with inner ear extension should be distinguished from pure intralabyrinthine schwannomas because of differences in clinical significance. Cochlear involvement is more frequent than vestibular involvement and is often accompanied by a dead ear. Dead ear caused by small VSs should alert the surgeon to the possibility of a cochlear extension. The presence of an intracochlear involvement requires the adoption of an approach that allows control of the cochlear turns, and we found the transotic approach to be the most suitable. Undetected cochlear extensions that are left in place may grow with time.

Intralabyrinthine schwannomas

OBJECTIVE

To describe the patient presentation, radiographic findings, and treatment results in a series of eight patients with a diagnosis of intralabyrinthine schwannoma, and to review the presentation of other cases of intralabyrinthine schwannoma in the English otolaryngologic literature.

METHODS

Retrospective review of patient records, operative reports, and radiologic studies, and review of the literature.

RESULTS

Eight patients with a variety of otologic symptoms including progressive hearing loss, episodic vertigo, and tinnitus were found to have a schwannoma involving the vestibule or cochlea. Surgery was performed to remove the tumors from four patients with nonserviceable hearing. The patients experienced significant improvement in their vertigo and tinnitus after surgery. Observation and serial magnetic resonance imaging were adequate treatment of the four patients with serviceable hearing. In the literature review, 447 cases of intralabyrinthine schwannoma were identified, and the presentations were similar to those in the cases described here.

CONCLUSION

Intralabyrinthine schwannomas are rare tumors that arise from the distal portion of either the vestibular nerve or the cochlear nerve. Consequently, the cochlea, the semicircular canals, the vestibule, or a combination of these structures may become involved with these lesions. Transmastoid labyrinthectomy or a transotic approach can be used to remove intralabyrinthine tumors from patients with nonserviceable hearing and severe vertigo or tinnitus. In addition, these surgical approaches should be used if the tumor grows to involve the internal auditory canal. Observation is an appropriate option for patients who have serviceable hearing.

MR findings in intralabyrinthine schwannomas

AIM

Intralabyrinthine schwannomas (ILS) are rare benign tumours. They are not always recognized on routine magnetic resonance imaging (MRI). We aimed to study the clinical presentation and MRI findings in our patients with ILS.

MATERIALS AND METHODS

Retrospective analysis of patients with vestibular schwannomas treated at this center.

RESULTS

Of 144 vestibular schwannomas studied at this centre, three patients had an ILS. The most common presenting symptoms were unilateral hearing loss, tinnitus and vertigo. Two patients demonstrated a progressive sensorineural hearing loss (SNHL). The third patient had a severe SNHL at presentation. MRI enhanced with contrast medium was positive in the two patients with progressive SNHL and negative in the patient with the severe SNHL.

CONCLUSION

This series demonstrates the ability of MRI to identify schwannomas filling the labyrinth, and also its inability to identify extremely small ILS. It underlines the importance of sending the cristae of patients undergoing labyrinthectomy for presumed Ménière's disease for histological examination.

A comprehensive classification system of vestibular schwannomas

Because traditional classifications of vestibular schwannomas (according to relative size) cannot comprehensively describe lesions that grow in different patterns after arising in regions as diverse as the cerebellopontine (CP) angle, the internal auditory canal, and the region lateral to the fundus of the internal auditory canal (labyrinth), we developed a new system to classify vestibular schwannomas, a system that describes the anatomical structures involved by the tumour, rather than size alone. The vestibular schwannoma is classified first by location and then by extent. Our system provides surgeons information helpful in choosing the surgical approach, in estimating the difficulty of tumour excision, and in determining whether hearing might be preserved. Our system also avoids confusion and misunderstanding in discussions of treatment results because it reflects the diverse biological characteristics of vestibular schwannomas.

Invisible culprit: intralabyrinthine schwannomas that do not appear on enhanced magnetic resonance imaging

Intralabyrinthine schwannoma (ILS) is an infrequent tumor that arises in isolation within the periphery of the temporal bone. Only 32 cases have been reported to date in the literature, of which 12 were discovered at autopsy. Prior to the advent of gadolinium-enhanced magnetic resonance imaging (Gd-MRI), only 1 ILS had been diagnosed preoperatively. However, after Gd-MRI became a common modality, 5 ILSs were imaged. Two additional cases are reported that were discovered during labyrinth-destructive surgery despite normal Gd-MRI findings. Possible explanations for and potential ramifications of nonenhancing ILS are discussed.