Audiovestibular Function Deficits in Vestibular Schwannoma

Abstract

Introduction. Vestibular schwannomas (VS) are benign tumours of the vestibular nerve and can lead to hearing loss, tinnitus, vertigo, facial palsy, and brainstem compression. Audiovestibular diagnostic tests are essential for detection and treatment planning. Methods. Medline was used to perform a systematic literature review with regard to how audiovestibular test parameters correlate with symptoms, tumour size, and tumour location. Results. The auditory brainstem response can be used to diagnose retrocochlear lesions caused by VS. Since hearing loss correlates poorly with tumour size, a retrocochlear lesion is probably not the only cause for hearing loss. Also cochlear mechanisms seem to play a role. This can be revealed by abnormal otoacoustic emissions, despite normal ABR and new MRI techniques which have demonstrated endolymphatic hydrops of the inner ear. Caloric and head impulse tests show frequency specific dynamics and vestibular evoked myogenic potentials may help to identify the location of the tumour regarding the involved nerve parts. Conclusion. In order to preserve audiovestibular function in VS, it is important to stop the growth of the tumour and to avoid degenerative changes in the inner ear. A detailed neurotological workup helps to diagnose VS of all sizes and can also provide useful prognostic information.

Unusual discovery of a vestibular schwannoma following eradication therapy forMycobacterium abscessus

“…Progressive hearing loss is the most common symptom of vestibular schwannoma,13 and they cause sensorineural hearing loss in up to 95% of patients 14. It has been shown vestibular schwannomas cause significant degeneration of labyrinthine structures in the ear15; however, the mechanism of hearing loss is poorly understood. Various proposals such as microvascular changes, conduction block of the cochlear nerve and endolymphatic hydrops have been put forward.…”

Volume quantification of endolymphatic hydrops in patients with vestibular schwannoma

“…The inner ear image was acquired 24 h after intratympanic Gd-DTPA injection. The T2-weighted turbo spin-echo (T2 TSE) sequence was used to acquire inner ear images that emphasized the fluid-filled compartments: echo time (TE), 78 ms; repetition time (TR), 3,000 ms; matrix, 269 × 384; 190 contiguous 1 mm thick slices; and acquisition time of 53 s. 3D-FLAIR was used to image the Gd-DTPA in the inner ear: TE, 181 ms; TR, 5,000 ms; flip angle, TSE with 180° refocusing flip angle; echo train length, 23; matrix size, 384 × 384; 12 axial 0.8 mm thick slices; and scan time of 14 min 50 s. Based on the radiologic evaluation, patients were classified according to the Koos classification scale for VS: grade I, purely intracanalicular tumor; grade II, small tumor with protrusion into the CPA without brainstem contact; grade III, tumor filling the CPA cistern with no brain stem displacement; and grade IV, large tumor with brain stem compression ( Fujiwara et al, 2019 , Koos et al, 1998 , von Kirschbaum and Gürkov, 2016 ).…”

“…Common symptoms of VS are unilateral hearing loss, tinnitus, poor speech discrimination, and vestibular symptoms. These symptoms are attributed to a combination of compressional/neurotoxic effects on vestibular nerve afferents and/or a compromised vascular supply to the inner ear ( Eliezer et al, 2019 , Fujiwara et al, 2019 , Myrseth et al, 2006 , Taylor et al, 2015 , Tsutsumi et al, 2000 , Ushio et al, 2009 , von Kirschbaum and Gürkov, 2016 ). In general, the slow progressive reduction of vestibular function results it the gradual implementation of central adaptive mechanisms, which minimize VS-related symptoms and clinical signs ( Curthoys, 2000 , Fujiwara et al, 2019 ).…”

“…In general, the slow progressive reduction of vestibular function results it the gradual implementation of central adaptive mechanisms, which minimize VS-related symptoms and clinical signs ( Curthoys, 2000 , Fujiwara et al, 2019 ). Despite this, vestibular symptoms are still the most painful clinical symptoms for patients with VS ( von Kirschbaum and Gürkov, 2016 ). Previous studies have also shown that 30% to 75% of patients with VS report at least one vestibular symptom when diagnosed, ranging from dizziness, disequilibrium, directional pulsion, positional to severe spontaneous vertigo, and vestibular crisis events ( Andersen et al, 2015 , Carlson et al, 2015 , Hızlı et al, 2016 , Taylor et al, 2013 ).…”

MRI based volumetric measurements of vestibular schwannomas in patients with neurofibromatosis type 2: comparison of three different software tools

“…Hallmarks of NF2 are bilateral vestibular schwannomas (VS), peripheral schwannomas, cranial or spinal meningiomas and ependymomas 2 . VS are benign in nature but can cause severe neurological deficits and deafness as a result of local tumor growth 3 . In 2009 bevacizumab—given off-label for compassionate use—showed tumor reduction and hearing improvement in patients with NF2 4 .…”