Management of intralabyrinthine schwannomas

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: 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.

Gamma Knife radiosurgery for intravestibular and intracochlear schwannomas

BACKGROUND

Schwannomas of the VIIIth cranial nerve are benign tumours, with vast majority occurring in vestibular division. Rarely, they can also arise from distal branches of cochlear, superior or inferior vestibular. We review our experience with Gamma Knife radiosurgery (GKR), as first intention treatment for intracochlear (ICS) and intravestibular (IVS) schwannomas.

METHODS

A total number of five patients were analysed, treated over 8 years, between June 2010 and September 2018, with Leksell Gamma Knife Perfexion or Icon (Elekta Instruments, AB, Sweden). The marginal dose prescribed was 12 Gy at a mean prescription isodose line of 61.4% (range 50-70). Clinical evaluation included auditory and facial function.

RESULTS

The mean age was 49.9 (range 34-63). The mean follow-up period was 52.8 months (range 12-84). The mean target volume (TV) was 0.087 ml (range 0.014-0.281). The mean maximal dose received by the cochlea was 11.2 Gy (range 2.6-20.3). The mean marginal dose received by the vestibule (e.g. utricula) was 14.2 Gy (range 3.8-17.5). No patient experienced an acute or subacute clinical adverse radiation effect after GKR. Four cases had overall symptom stability. In one patient (1/5), the vertigo, which was the main clinical complain, disappeared 1 year after GKR. However, it reappeared 3 years later, with same pretherapeutic characteristics and is currently fluctuating. One patient experienced hearing decrease after GKR, during the first 12 months. This case received 11.2 Gy to the cochlea. Follow-up MRI course showed a decrease in size in four patients, and stability in one.

CONCLUSIONS

Gamma Knife radiosurgery is a valuable first intention treatment for ICS or IVS, in selected cases. Special attention should be paid for the dose delivered to the cochlea and the vestibular apparatus. Acute and subacute clinical effects are exceptional, while tumour control was achieved in all cases in our small series.

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.

The Feasibility of a Modified Exclusive Endoscopic Transcanal Transpromontorial Approach for Vestibular Schwannomas

Objective  We evaluated the feasibility of an exclusive endoscopic transcanal transpromontorial approach (EETTA) for the treatment of small vestibular schwannomas (VSs) limited to the internal auditory canal (IAC), and introduced a modification without external auditory canal closure.

Methods  Between June 2016 and June 2017, seven patients with VS underwent surgery using a modified EETTA. Treatment outcomes, including efficacy of tumor resection, preservation of function, operation time, and quality of life (QOL), were evaluated.

Results  The patients preoperatively exhibited Koos Grade I/II tumors and severe-to-profound hearing loss. Gross total resection was accomplished in all cases. There were no major complications, and all patients exhibited normal facial nerve function immediately after surgery. The mean follow-up period was 12.9 months. The operation time (average 196.3 ± 64.9 minutes) and hospitalization period (average 7.4 ± 1.0 days) were favorable. Short Form-36 scores for QOL showed unremarkable results compared with previous reports.

Conclusions  The modified EETTA was effective in the removal of VSs in the IAC. It can be an alternative surgical option for small VSs.

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.

Clinical presentation of intralabyrinthine schwannomas: a multicenter study of 110 cases

OBJECTIVE

To describe the presentation of intralabyrinthine schwannomas (ILSs).

STUDY DESIGN AND SETTING

Retrospective multicenter study involving 12 European skull base surgery tertiary referral centers.

PATIENTS

One hundred ten patients with the diagnosis of ILS, either labyrinth confined or extending into the internal auditory meatus for less than 50% of their volume.

MAIN OUTCOME MEASURES

Data collected were age, sex, nature and timing of presenting symptoms, hearing (according to the AAO-HNS grading system), results of vestibular tests (caloric tests and cervical vestibular-evoked myogenic potentials [c-VEMPs]), and tumor localization. Presenting symptoms and laboratory test results were studied according to the extension of the lesion into the cochlea (C) and vestibule (V), on one hand, and according to unifocal (L1) or plurifocal (L2) extension into the labyrinth, on the other.

RESULTS

Intracochlear type was more common (50%) than vestibular (19.1%) and more diffuse forms (30.9%). The mean delay for diagnosis was long (72.5 mo; SD, 76.6). Mean age was 53.9 years (SD, 13.2). Deafness was the most common symptom (77.8 dB HL [SD, 33.6], with only 24.6% of patients keeping viable hearing. Caloric tests (65.5% of patients) were abnormal in 77.8% of cases. c-VEMPs were abnormal in 65.7% of the 36 cases analyzed. In V forms, hearing was significantly better (class A + B in 21.1% in C and 45.8% in V forms) (p = 0.03), and vestibular function was more altered (C: 57%, V: 100%, p = 0.0009*). L2 forms were diagnosed later (L1: 59.1 mo, L2: 104.5 mo; p = 0.004*) and were associated more frequently with a dead ear (L1: 13.1%, L2: 41.2%, p = 0.002*) than L1 forms.

CONCLUSIONS

This series, which is the largest in the literature, demonstrates that even very small and localized ILSs heavily compromise labyrinthine functions.

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.

A purely intracanalicular cochlear schwannoma presenting with progressive hearing loss

Schwannomas arising from the cochlear nerve and confined to the internal auditory canal are rare. Clinically, a cochlear schwannoma can cause a progressive hearing loss. We report the case of a 56-year-old woman with a cochlear schwannoma that manifested as a slowly progressive hearing loss. The lesion was diagnosed by gadolinium-enhanced 3-Tesla magnetic resonance imaging.

[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.

Intracochlear schwannoma presenting as diffuse cochlear enhancement: diagnostic challenges of a rare cause of deafness

Intracochlear schwannoma is a rare, treatable, cause of unilateral hearing loss. Due to the small size, position, and variable clinical and imaging features, diagnosis presents a significant challenge and is often delayed. We present a case of a patient with an intracochlear schwannoma presenting as a diffuse enhancement of the cochlea, mimicking an infectious or inflammatory process. The absence of focal nodularity in this lesion on multiple high-resolution MRI examinations led to a delay of over 3 years from the patient's initial presentation to surgical diagnosis. Clinical history and examination, imaging features, pathologic findings, and surgical management options are described.

A cochlear schwannoma presenting with sudden hearing loss

A cochlear schwannoma is a rare tumor that arises from the cochlear nerve. Clinically, a cochlear schwannoma mimics the clinical features of sudden deafness or Meniere's disease. We report a case of cochlear schwannoma that presented with sudden hearing loss, which was diagnosed with gadolinium-enhanced magnetic resonance imaging and removed using a transotic approach.