Endolymphatic Hydrops in Patients With Intralabyrinthine Schwannomas

A Case Report Demonstrating Preservation of Vestibular Receptor Function after Transcochlear Removal of an Intracochlear Schwannoma with Extension to the Fundus of the Internal Auditory Canal

Preservation of function is an important goal during surgical management of cochleovestibular schwannomas. We here demonstrate the relief of vertigo and the preservation of function of all five vestibular receptors after removal of an intracochlear schwannoma with extension to the fundus of the internal auditory canal. A 61-year-old male with a five-year history of left-sided deafness, tinnitus, vertigo attacks, and an MRI consistent with an intracochlear schwannoma with limited extension through the modiolus to the fundus of the internal auditory canal (IAC) underwent transcanal, transcochlear total tumor removal and-due to a cerebrospinal fluid leak from the fundus of the IAC-revision surgery with lateral petrosectomy and blind sac closure of the external auditory canal. Despite complete removal of the cochlear partition of the inner ear (total cochlectomy), the patient's vestibular receptors remained functional, and the vertigo symptoms disappeared. These results show that vestibular labyrinthine function may not only be preserved after partial or subtotal cochlectomy but also after complete cochlear removal. This further confirms the vestibular labyrinth's robustness and encourages surgical management of transmodiolar schwannomas with limited extension to the fundus of the IAC.

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.

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.

Pathological significance and classification of endolymphatic hydrops in otological disorders

We summarize the presence of endolymphatic hydrops (EH) in otological disorders evaluated with magnetic resonance imaging (MRI) of temporal bones, and propose a classification of EH based on its pathological significance. A search of the literature published in English-language journals was performed using electronic databases, especially focusing on EH-related otological disorders. Clinical articles that contained the terms EH and contrast-MRI published from 2007 to the present, with relevant human temporal bone studies, were included. The following three main points are discussed based on the results in the relevant articles: i) otological disorders that present EH, ii) current grading for evaluation of EH on MRI, and iii) a proposed classification of EH based on its pathological significance. MRI evaluation revealed that EH exists extensively not only in ears with typical Meniere's disease (MD), but also in those with various other otological disorders. The etiological classification of EH helps to summarize ideas for determining the pathophysiology of otological disorders, while a therapeutic classification provides clues to their management. MRI evaluations of EH have led to breakthroughs in investigations of EH in otological disorders. Precise grading for evaluation and clarification of EH on MRI based on its pathological significance could provide keys to elucidating the pathophysiology of EH-related otological disorders.