Initial Hearing Preservation Is Correlated With Cochlear Duct Length in Fully-inserted Long Flexible Lateral Wall Arrays.

OBJECTIVES

To characterize the relationship between cochlear duct length (CDL) and initial hearing preservation among cochlear implant recipients of a fully inserted 31.5 mm flexible lateral wall electrode array.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary academic referral center.

PATIENTS

Adult cochlear implant recipients who presented preoperatively with unaided hearing detection thresholds of ≤ 65 dB HL at 125 Hz and underwent cochlear implantation with a 31.5 mm flexible lateral wall array.

INTERVENTION

Cochlear implantation with a hearing preservation surgical approach.

MAIN OUTCOME MEASURES

Computed tomography was reviewed to determine CDL. Hearing preservation was characterized by the shift in low-frequency pure-tone average (LFPTA; 125, 250, and 500 Hz), and shift in individual unaided hearing detection thresholds at 125, 250, and 500 Hz.

RESULTS

Nineteen patients met the criteria for inclusion. The mean CDL was 34.2 mm (range: 30.8-36.5 mm). Recipients experienced a mean LFPTA shift of 27.6 dB HL (range: 10-50 dB HL). Significant, negative correlations were observed between CDL and smaller threshold shifts at individual frequencies and LFPTA (p ≤ 0.048).

CONCLUSION

A longer CDL is associated with greater likelihood of preserving low-frequency hearing with long arrays. Low-frequency hearing preservation is feasible with fully inserted long flexible arrays within the initial months after cochlear implantation. Preoperative measurement of CDL may facilitate a more individualized approach in array selection to permit optimal cochlear coverage while enhancing hearing preservation outcomes.