Author(s)
Nicholas J Thompson, MD
Margaret T Dillon, AuD
Emily Buss, PhD
Lisa R. Park, AuD
Harold C Pillsbury III, MD
Brendan P O'Connell, MD
Kevin D Brown, MD, PhD
Affiliation(s)
University of North Carolina
Abstract:
Hypothesis/Objective: Determine variables associated with electrode impedance fluctuations and loss of residualhearing in cochlear implant recipients.Background: Postoperative low-frequency hearing preservation is routinely possible, resulting in improved speechperception with acoustic plus electric stimulation. Recent reports have suggested a relationship between fluctuationsin electrode impedance and loss of residual hearing. Variables affecting this relationship have yet to be determined.Methods: Review of pediatric and adult cochlear implant recipients from 2013-2016 with postoperative hearingpreservation. The correlation between impedance change and change in residual low frequency hearing at 12 monthswas determined. Regression analysis evaluating the effect of array type (lateral wall vs. perimodiolar),manufacturer, age, and pre-operative hearing on impedance was determined.Results: Ninety-four cochlear implant recipients presented with postoperative hearing preservation. An associationbetween change in impedance and loss of residual hearing was observed, however differed between manufacturers(R2=0.30, P = 0.01 vs. R2=0.01, P =0.77). Average absolute impedance changes were higher for a slim electrodeinserted to 20mm vs. a flexible electrode inserted to 24mm; approaching significance (p=0.08). A multivariateregression analysis demonstrated a statistically significant association between preoperative low-frequency puretoneaverage (p=0.048), device manufacturer (p=0.012), and array type (p=0.02) on impedance changes. There wasno effect of patient age.Conclusion: Impedance fluctuations appear to be a marker for delayed loss of residual hearing for some electrodearray types and manufacturers but not others. Specific electrode arrays may affect the cochlear microenvironmentdifferently, resulting in a local reaction with subsequent negative impact on postoperative hearing preservation.Define Professional Practice Gap & Educational Need: Lack of awareness of the association between electrodeimpedance fluctuations and loss of residual hearing in cochlear implantation. 2. Lack of contemporary knowledgeregarding the variables that affect the relationship between electrode impedance and loss of residual hearing incochlear implantation.Learning Objective: To determine variables affecting the relationship between electrode impedance fluctuationsand loss of residual hearing in cochlear implantation.Desired Result: Attendees will better understand the relationship between electrode impedance fluctuations andloss of residual hearing after cochlear implantation and begin to critically think about factors that may influence thisrelationship and long-term hearing outcomes after implantation.Level of Evidence - Level IV - Historical cohort or case-control studiesIndicate IRB or IACUC Approval: Approved