Scala Tympani Volume Influences Initial 6‐Month Hearing Preservation With Lateral Wall Electrode Arrays
Michael W. Canfarotta, Margaret T. Dillon, A. Morgan Selleck, Kevin D. BrownObjectives
To examine the effects of scala tympani (ST) volume, cochlear duct length (CDL), and angular insertion depth (AID) on low‐frequency hearing preservation for cochlear implant (CI) recipients of lateral wall electrode arrays.
Methods
A retrospective review identified 45 adult CI recipients of 24‐, 28‐, or 31.5‐mm lateral wall electrode arrays with preoperative unaided hearing thresholds ≤45 decibel hearing level (dB HL) at 250 Hz. All patients underwent preoperative and postoperative computed tomography to evaluate cochlear morphology and electrode array position. A linear mixed effects model evaluated effects of ST volume, CDL, AID, preoperative low‐frequency pure‐tone average (LFPTA; 125, 250, and 500 Hz), age at surgery, and biological sex on the postoperative change in LFPTA at activation and 6 months post‐activation.
Results
There were significant main effects of ST volume (p = 0.044), age (p = 0.028), and biological sex (p = 0.003), indicating better low‐frequency hearing preservation for CI recipients with larger ST volumes, younger age at surgery, and female biological sex. Although CDL positively correlated with ST volume (r = 0.74, p < 0.001), there was no significant main effect of CDL (p = 0.367). A broad range in AID of the most apical electrode contact was observed (301.4°–681.8°); however, there was no significant main effect of AID on low‐frequency hearing preservation (p = 0.700).
Conclusions
During the initial 6 months following implantation, intrinsic factors such as cochlear morphology may have a greater impact on low‐frequency hearing preservation than apical positioning of a flexible lateral wall electrode array when using soft surgical techniques.
Level of Evidence
3 Laryngoscope, 2024