Vestibular Screening Before Cochlear Implantation: Clinical Implications and Challenges in 409 Cochlear Implant Recipients.

Abstract

Cochlear implantation (CI) carries a risk of loss of vestibular function following surgery. Thus, vestibular assessment presurgery is used to identify vestibulopathy that may contraindicate implantation and guide in selecting the candidate ear. The aim of this study was to evaluate the clinical implications of preoperative vestibular assessment, and to identify challenges in performing vestibular testing in patients with profound hearing loss, i.e., CI candidates. Retrospective study of all CI recipients implanted since the introduction of a vestibular screening program. Tertiary referral center in 2013. CI candidates routinely underwent testing with the video head impulse test (VHIT) and the cervical vestibular evoked myogenic potential (cVEMP) test as a part of the CI work up. Three hundred thirty-five individuals were screened before the first CI and 74 individuals before the second CI. In 301 cases (73.6%), the vestibular function was considered normal and consequently carried no contraindications for surgery or implications for choice of ear to be implanted. Bilateral vestibular loss was found in 43 cases (10.5%) and unilateral vestibular loss was found in 62 cases (15.2%). In the latter cases, evaluation of multiple variables was indicated to select candidate ear. In nine implanted patients (2.2%), a relative contraindication to operate based on an "only balancing" ear was overruled by other factors. Vestibular testing was challenged by various factors (e.g., neck immobility, eye tracking issues, communication, and other patient issues), limiting the vestibular data output. This resulted in omittance, testing failure, or interpretation uncertainty 24 times (5.9%) for VHIT and 65 times (15.9%) for cVEMP. Vestibular screening is an important part of the clinical workup with respect to selection of candidate ear for cochlear implantation, as 15.2% of CI candidates present with unilateral vestibulopathy. Challenges in performing the vestibular tests are not uncommon, as test failure occurred in 15.9% of cases for the cVEMP and 5.9% for the VHIT. The most common reasons for test failure were neck immobility, communication issues, and problems of pupil tracking.