Influence of the Electrode Array Design on Incidence of Vertigo Symptoms and Vestibular Function After Cochlear Implantation.

Purpose: To evaluate if a specific type of cochlear implant (CI) electrode array (EA) reveals higher rates/prevalence of vestibular symptoms and to characterize their respective relationship to intracochlear position and objective vestibular function.

Methods: This retrospective study included 71 cochlear implantations in patients older than 18 years. The electrode position within the cochlea, electrode insertion angle, and cochlear coverage were determined from postoperative multiplanar reconstructed cone-beam computed tomography scans. All device manufacturers were represented. Data related to preoperative and postoperative PTA as well as vestibular symptoms in the preoperative and postoperative stages were collected from the patient's records.

Results: Twelve of the 71 (16.9%) CI patients experienced vertigo symptoms in the early postoperative period. In 5 (7.0%) patients, the vertigo complaints lasted until the time of the first activation (5-6 weeks postoperative). Postoperative onset of vestibular symptoms was more often seen in patients receiving lateral wall (LW)/straight EAs (19%) compared to perimodiolar/precurved EAs (7%), but this was only a trend and no statistical significance was observed. Moreover, preoperative pathologic caloric responses (CRs) better predicted the postoperative onset of vestibular symptoms.

Conclusion: The preoperative consideration of a complicated CI-induced vertigo is important in the counseling particularly of elderly patients. We identified some risk factors for post-CI vertigo that should be considered in the patient's counseling: preoperative pathologic CRs, the extent of surgical trauma, and possibly the use of an LW EA, regardless of the length.