Vestibular dysfunction in cochlear implant candidates: Prevalence and outcomes

Abstract

Purpose: Cochlear implantation (CI) has been shown to reduce vestibular function postoperatively in the implanted ear. The objective of this study was to identify the prevalence of preoperative vestibular weakness in CI candidates and identify any risk factors for postoperative dizziness.

Study design: Retrospective cohort study.

Materials and methods: Patients who underwent CI and had preoperative videonystagmography (VNG) at the Silverstein Institute from January 1, 2017 to May 31, 2020 were evaluated. The primary endpoint was dizziness lasting more than one month postoperatively.

Results: One hundred and forty nine patients were evaluated. Preoperative VNG revealed that 46 (30.9%) had reduced vestibular response (RVR) on one side and 32 (21.5%) had bilateral vestibular hypofunction (BVH). Postoperative dizziness occurred in 14 (9.4%) patients. Patients with postoperative dizziness were more likely to have abnormal preoperative VNG (RVR or BVH), compared to patients without postoperative dizziness (78.6% versus 49.6%, p = 0.0497). In cases of RVR, implantation of the weaker or stronger vestibular ear did not affect the postoperative dizziness (16.1% versus 6.7%, p = 0.38). Postoperative VNG in patients with dizziness showed decreased caloric responses in the implanted ear (28.4 to 6.4 degrees/s, p = 0.02).

Conclusion: Preoperative caloric weakness is prevalent in CI candidates and abnormal preoperative vestibular testing may be a predictor of postoperative dizziness. CI has the potential to cause vestibular injury and preoperative testing may aid in both counseling and decision-making.

Keywords: Caloric testing; Cochlear implantation; Postoperative dizziness; Vestibular; Videonystagmography.