Ipsilateral acoustic electric pitch matching: a case study of cochlear implantation in an up-sloping hearing loss with preserved hearing across multiple frequencies.

OBJECTIVES

Determine ipsilateral acoustic electric pitch place match in a patient with preserved residual hearing across a broad frequency range.

METHODS

Case report. Patient with up-sloping sensorineural hearing loss underwent implantation with a 680° insertion angle with preserved residual hearing. Pitch matching with variance of pulse rate was carried out.

RESULTS

Electrical pitch percepts closely approximated the Greenwood map when compared to the acoustical pitch percepts and electrode position as determined by post-operative computed tomographic scan. The pitch matching results achieved from the deeply inserted electrodes, in the apical portion of the cochlea, suggest that the electrical stimulation may activate the dendritic extensions from the ganglion cell bodies that radiate from the terminal bulb. Stimulation rate influenced pitch perception in the apical turn but not in the mid- and basilar regions.

DISCUSSION

Frequency to pitch allocation can potentially be improved by cochlear implants that access the apical third of the spiral ganglion. The ultimate goal of stimulating the apical third of the cochlea is to provide the maximum amount of spectral information to the user. We had the unique opportunity to work with a patient who presented with a severe sensorineural hearing loss rising to within normal limits and poor speech discrimination scores. Data from this study may aid our ability to give patients a broader spectrum of sound perception.