Longitudinal Acoustic Threshold and Concurrent Electrode Impedance Changes After Cochlear Implantation With Lateral...

Area of Science:

• Otolaryngology
• Biomedical Engineering
• Neuroscience

Background:

• Cochlear implantation (CI) is a vital treatment for severe to profound hearing loss.
• Understanding post-implantation hearing changes, including delayed onset hearing loss (doHL), is crucial for patient management.
• Variations in electrode array design may influence hearing outcomes and device performance.

Purpose of the Study:

• To investigate hearing sensitivity changes following cochlear implantation using MED-EL and Advanced Bionics (AB) lateral wall electrode arrays.
• To characterize the incidence, degree, and timing of delayed onset hearing loss (doHL).
• To examine concurrent electrode impedance changes in patients experiencing doHL.

Main Methods:

• Retrospective review of 96 adult CI recipients (101 ears).
• Assessment of hearing sensitivity using low-frequency pure tone average (LFPTA).
• Analysis of immediate and delayed hearing decrements, doHL characteristics, and electrode impedances.

Main Results:

• Median immediate hearing loss was 19 dB; 73% had functional hearing at activation.
• Overall incidence of doHL was 27% (median 24 dB loss at 76 weeks), with most cases being gradual.
• doHL incidence increased with longer follow-up (31% at 1 year, 44% at 2 years); no MED-EL recipients with doHL showed impedance changes, unlike 3 AB recipients.

Conclusions:

• Delayed onset hearing loss (doHL) occurs gradually and later than previously reported, with precipitous loss being less common.
• Most cochlear implant recipients maintain functional hearing post-implantation.
• The lack of impedance changes in MED-EL array recipients with doHL aligns with prior findings.