Intralabyrinthine schwannomas: Symptoms and managements

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.

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.

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.

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.

Transcanal surgical excision of an intracochlear schwannoma

An intracochlear schwannoma is a rare cause of sensorineural hearing loss, which is little discussed in the literature. This case report details the presentation of a patient with a sensorineural hearing loss due to an intracochlear schwannoma. The patient was initially managed conservatively; however, as her symptoms and serial imaging indicated progression, the lesion was surgically resected via a transcanal/transotic approach. Diagnosis and management of this unusual schwannoma are reviewed.

What is the site of origin of cochleovestibular schwannomas?

The belief that cochleovestibular schwannomas arise from the glial-Schwann cell junction has repeatedly been quoted in the literature, although there is no published evidence that supports this statement. A systematic evaluation of the nerve of origin and the precise location of cochleovestibular schwannomas using our respective archival temporal bone collections was conducted. Forty tumors were within the internal auditory canal (IAC), while 10 were intralabyrinthine neoplasms. Of the 40 IAC schwannomas, 4 arose from the cochlear nerve, and 36 from the vestibular nerve. Twenty-one tumors clearly arose lateral to the glial-Schwann cell junction, while 16 tumors filled at least two thirds of the IAC, with the epicenter of the neoplasm located in the mid part or the lateral part of the IAC. Only 3 schwannomas were located in the medial one third of the IAC in the area of the glial-Schwann cell junction. We concluded that cochleovestibular schwannomas may arise anywhere along the course of the axons of the eighth cranial nerve from the glial-Schwann sheath junction up until their terminations within the auditory and vestibular end organs.

[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.

[Tinnitus treatment: neurosurgical management]

Tinnitus is a very frequent symptom affecting 10% of the general population. It corresponds to the perception of an internal noise that can severely impair the quality of life. Tinnitus management requires a multidisciplinary approach in which neuromodulation and neurosurgery tend to play major roles. Classification of tinnitus separates objective tinnitus (i.e., tinnitus that can be heard or recorded) from the more frequent subjective tinnitus (i.e., tinnitus only perceived by the patient). Objective tinnitus is either pulsatile synchronous with heartbeat or asynchronous. In the former, appropriate radiological testing should search for a vascular abnormality as well as other neurological diseases (intracranial hypertension, Arnold-Chiari malformation, vascular loops, etc.). Asynchronous objective tinnitus generally corresponds to muscular contractions that require specific management. The pathophysiology of subjective tinnitus is more complex, showing strong analogies with postamputation pain syndromes. After peripheral middle ear or inner ear damage, auditory deafferentation could result in hyperactivity and/or functional reorganization within central auditory and nonauditory structures. This could explain the persistence of tinnitus after total hearing amputation (e.g., translabyrinthine approach for vestibular schwannoma) and associated symptoms such as hyperacusis or anxiety and depression. This central model finds strong support in animal experiments and in functional neuroimagery (PET, fMRI, MEG). Since no etiologically based therapies are currently available, severe subjective tinnitus management only targets tinnitus tolerance with sound enrichment or cognitive behavior therapy. However, in the near future better knowledge of tinnitus pathophysiology and innovative therapeutic tools could emerge from neuromodulation techniques such as repeated transcranial magnetic or epidural electric stimulation.