Preservation Of Vestibular Function Research Articles

Vestibular dysfunction after cochlear and auditory brainstem implantation: Madras ENT Research Foundation experience

<p><strong>Background:</strong> Cochlear implantation is an established procedure for patients with bilateral severe to profound sensorineural hearing loss. CI may, in some implantees, have a detrimental impact on vestibular function. Auditory brainstem implantation is a safe and effective procedure in children with bilateral cochlear and cochlear nerve aplasia. The aim of the study was to assess the impact of cochlear implantation and auditory brainstem implantation on the vestibular function.</p><p><strong>Methods:</strong> Three hundred and twenty patients who underwent CI surgery over a four years period from November 2016 to November 2020 were studied for symptoms of vestibular disturbance. Twenty three patients complained of giddiness and underwent vestibular function testing including videooculography, caloric test and vestibular evoked myogenic potentials. 48 patients with cochlear and cochlear nerve aplasia underwent ABI surgery from September 2009 to March 2019. The correlation between the size of the flocculus and the presence of vestibular symptoms was studied.</p><p><strong>Results: </strong>After CI, vestibular disturbances were seen in 23 patients (7.2%) and were transient. In auditory brainstem implantees, vestibular disturbances were seen in eight patients (16.7%) and were found to correlate with the size of the cerebellar flocculus.<strong></strong></p><p><strong>Conclusions: </strong>Vestibular disturbances are rare after cochlear and auditory brainstem implant surgery. During CI, the preservation of vestibular function should be attempted using minimally invasive techniques. ABI surgery requires meticulous dissection, especially of a large cerebellar flocculus to minimize the possibility of vestibular disturbances.<strong></strong></p>

Preservation of Vestibular Function and Residual Hearing After Round Window Cochlear Implantation.

To examine the possible correlation between the loss of short-term residual hearing and vestibular function after cochlear implantation (CI). Retrospective patient review. Academic tertiary referral center. One hundred twenty patients with normal vestibular function (VF) in the caloric testing and residual hearing (RH) at the frequencies 250, 500, and 1000 Hz on the surgery side between 2008 and 2016 were included in the study. Primary CI on the first side via round window with a conventional full-length electrode. Changes of RH and VF 7 weeks after surgery were analyzed. Preservation of RH was defined as measurable postoperative thresholds at the frequencies 250, 500, and 1000 Hz in the pure-tone audiogram. Preservation of the VF after CI was assessed both by an absolute and relative threshold in the caloric testing. Seven weeks after implantation, the preservation of RH was achieved in 52 (43.3 %) patients and the preservation of VF in 95 (79.2 %) patients on the operated side. There was no significant statistical correlation between these two parameters. The loss of RH was more than twice as frequent as the loss of VF. However, no statistical correlation between the failure of the two inner ear functions was found. The exact causes are still unknown, but our data could give an indication that there may be different underlying pathomechanisms.

Intralabyrinthine schwannomas : Surgical management and hearing rehabilitation with cochlear implants.

Intralabyrinthine schwannomas (ILS) are a rare differential diagnosis of sudden hearing loss and vertigo. In an own case series of 12 patients, 6 tumors showed an intracochlear, 3 an intravestibular, 1 a transmodiolar including the cerebellopontine angle (CPA), 1a transotic including the CPA, and 1 a multilocular location. The tumors were removed surgically in 9 patients, whereas 3 patients decided for a “wait-and-test-and-scan” strategy. Of the surgical patients, 3 underwent labyrinthectomy and cochlear implant (CI) surgery in a single-stage procedure; 1 patient had extended cochleostomy with CI surgery; 3 underwent partial or subtotal cochleoectomy, with partial cochlear reconstruction and CI surgery (n = 1) or implantation of electrode dummies for possible later CI after repeated MRI follow-up (n = 2); and in 2 patients, the tumors of the internal auditory canal and cerebellopontine angle exhibiting transmodiolar or transmacular growth were removed by combined translabyrinthine–transotic resection. For the intracochlear tumors, vestibular function could mostly be preserved after surgery. In all cases with CI surgery, hearing rehabilitation was successful, although speech discrimination was limited for the case with subtotal cochleoectomy. Surgical removal of intracochlear schwannomas via partial or subtotal cochleoectomy is, in principle, possible with preservation of vestibular function. In the authors’ opinion, radiotherapy of ILS is only indicated in isolated cases. Cochlear implantation during or after tumor resection (i. e., as synchronous or staged surgeries) is an option for hearing rehabilitation in cartain cases and represents a therapeutic approach in contrast to a “wait-and-test-and-scan” strategy.