Clinical and Instrumental Evaluation of Vestibular Function Before and After Cochlear Implantation in Adults

Vestibular dysfunction is one of the main complications after cochlear implant (CI) surgery, and there are currently no standardized protocols for vestibular assessment in CI candidates. Our objectives were to investigate the incidence of vestibular impairment after CI surgery, anamnestic (age, known systemic pathologies and cause of deafness) and surgical (intraoperative complications, malposition of the CI) risk factors, and the role of vestibular assessment in the selection of the suitable ear for implantation.

We included 68 adult patients (80 ears) affected by moderate-to-profound SNHL undergoing CI. The dizziness handicap inventory (DHI), the video head impulse test (VHIT), the caloric test, and dynamic posturography (DP) were used to study the vestibular function and balance before and one month after CI. The DHI was also administered 24 h after surgery.

Despite significative impairment 24 h after surgery (29.6 ± 30), the mean DHI score returned to preoperative values (17.9 ± 26) after one month. Dizziness persisted in case of age ≥ 65 years old, surgical difficulties, simultaneous bilateral CI, Meniere's disease and otosclerosis, comorbidities ≥ 3, anxiety/depression, and neurological diseases. The VHIT significantly worsened in 25% of ears, while the caloric test SPV nystagmus significantly decreased in 30% of ears. In cases of preoperative unilateral weakness, the implantation of the better ear was significantly related to higher DHI scores. Only 4/68 patients had a significant persistent reduction in the postural composite score after surgery, with an increased risk of falls.

Medical history and vestibular assessment predict the risk of vestibular damage and help to choose the CI's side and to manage vertigo after surgery.