Partial deafness cochlear implantation at the University of Kansas: techniques and outcomes

One of the most significant recent advances in cochlear implantation is the implantation of patients with residual hearing. These patients have a downsloping sensorineural hearing loss with poor speech discrimination and perform poorly with standard amplification. Studies using a variety of different electrode designs have demonstrated that it is possible to implant an inner ear and preserve residual hearing. Initial studies have demonstrated that a combination of residual acoustic hearing in the low frequencies with electrical stimulation in the mid- to high frequencies resulted in superior hearing performance in background noise.

The objective of this study was to determine the effect of electrode insertion depth on hearing preservation.

Eighteen patients with mild to severe hearing loss in the low frequencies combined with poor word recognition were recruited for the study.

Cochlear implantation.

Pre- and postoperative hearing test, Hearing in Noise Test, and consonant-nucleus-consonant testing. Data analysis was performed with Kruskal Wallis and Mann-Whitney testing.

In our study of 18 patients implanted with a Med-El PulsarCI100 we demonstrated the ability to preserve residual hearing with implant insertion depths ranging from 20 to 28 mm, giving us the possibility of near complete cochlear frequency coverage with an implant array while preserving residual hearing. These patients performed well both in quiet and in 10 dB signal-to-noise ratio conditions.

Hearing preservation was achievable even with deep implant insertion. Patients performed well in combined acoustic and electric conditions.