Influence of the multichannel cochlear implant on vestibular function

Area of Science:

• Otorhinolaryngology
• Neuroscience
• Audiology

Background:

• Vestibular function is crucial for balance and spatial orientation.
• Cochlear implantation is a common treatment for severe to profound hearing loss.
• Potential effects of cochlear implants on the vestibular system require thorough investigation.

Purpose of the Study:

• To assess pre- and post-operative vestibular function in patients undergoing cochlear implant surgery.
• To characterize the incidence and types of dizziness experienced by these patients.
• To explore the relationship between cochlear implant use and subjective dizziness.

Main Methods:

• Evaluated vestibular function using optokinetic nystagmus and eye-tracking tests pre-surgery.
• Administered caloric stimulation tests before and approximately one month after surgery.
• Collected subjective reports of dizziness, categorizing by onset and duration.
• Assessed dizziness related to cochlear implant device usage.

Main Results:

• Pre-surgery, 85% had normal optokinetic nystagmus and 82% normal eye-tracking.
• Pre-surgery caloric testing revealed hypofunction or anfunction in 67% of patients.
• Post-surgery, 38% showed deterioration in caloric stimulation test results.
• 47% of patients reported subjective dizziness after surgery, with early, prolonged, and delayed types observed.
• 18% of patients linked dizziness to implant device use, suggesting potential electrical current spread to the vestibular nerve.

Conclusions:

• Cochlear implantation is associated with a significant incidence of post-operative dizziness.
• Dizziness following cochlear implantation can manifest in various patterns.
• A subset of patients may experience dizziness due to electrical stimulation of the vestibular nerve by the implant.