How does cochlear implantation affect five vestibular end-organ functions and dizziness?

Area of Science:

• Otolaryngology
• Neuroscience
• Audiology

Background:

• Cochlear implantation (CI) is a common treatment for severe to profound hearing loss.
• Vestibular function assessment is crucial for understanding the impact of CI.
• The Dizziness Handicap Inventory (DHI) quantifies subjective vertigo symptoms.

Purpose of the Study:

• To evaluate all five vestibular end-organ functions (lateral, anterior, and posterior semicircular canals, utricle, and saccule) after CI.
• To investigate the relationship between DHI scores and objective vestibular function tests.
• To assess vestibular function at specific postoperative time points (day 3 and month 3).

Main Methods:

• Prospective descriptive study of 42 patients undergoing unilateral CI.
• Utilized video head impulse test (vHIT) for semicircular canal (SSC) function.
• Employed ocular vestibular-evoked myogenic potential (oVEMP) for utricle and cervical vestibular-evoked myogenic potential (cVEMP) for saccule function.
• Administered DHI for subjective vertigo assessment preoperatively and postoperatively.

Main Results:

• Significant vestibular function impairment occurred in 28.5% of patients on the implantation side.
• 16.6% showed SSC dysfunction, 19% saccule dysfunction, and 11.9% utricle dysfunction 3 days post-CI.
• Posterior SSC function was more affected than lateral SSC function.
• A significant correlation (r=0.795) was found between DHI scores and objective vestibular tests.
• Vestibular dysfunction and elevated DHI persisted in a subset of patients at 3 months post-CI.

Conclusions:

• CI can lead to damage in both semicircular canal and otolith functions, especially early postoperatively.
• Posterior SSC function appears more vulnerable than lateral SSC function after CI.
• A comprehensive vestibular test battery evaluating all five end-organs is essential for accurate preoperative and postoperative assessments in CI and other otologic surgeries.