Cochlear Implant Electrode Effect on Sound Energy Transfer Within the Cochlea During Acoustic Stimulation. Issue 9 (October 2015)

• Record Type: Journal Article
• Authors: Greene, Nathaniel T.; Mattingly, Jameson K.; Jenkins, Herman A.; Tollin, Daniel J.; Easter, James R.; Cass, Stephen P.
• Is Part Of: Otology & neurotology. Volume 36:Issue 9(2015)
• Publication Date: 2015-10
• Subjects: Otology -- Periodicals; Ear -- Diseases -- Periodicals; Skull base -- Surgery -- Periodicals; 617.8005
• DOI: 10.1097/MAO.0000000000000838
• Languages: English
• ISSNs: 1531-7129

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Hypothesis:</title> <p>Cochlear implants (CIs) designed for hearing preservation will not alter mechanical properties of the middle and inner ears as measured by intracochlear pressure (P<sub>IC</sub>) and stapes velocity (V<sub>stap</sub>).</p> </sec> <sec> <title>Background:</title> <p>CIs designed to provide combined electroacoustic stimulation are now available. To maintain functional acoustic hearing, it is important to know if a CI electrode can alter middle or inner ear mechanics because any alteration could contribute to elevated low-frequency thresholds in electroacoustic stimulation patients.</p> </sec> <sec> <title>Methods:</title> <p>Seven human cadaveric temporal bones were prepared, and pure-tone stimuli from 120 Hz to 10 kHz were presented at a range of intensities up to 110 dB sound pressure level. <italic>P</italic><sub>IC</sub> in the scala vestibuli (<italic>P</italic><sub>SV</sub>) and tympani (<italic>P</italic><sub>ST</sub>) were measured with fiber-optic pressure sensors concurrently with <italic>V</italic><sub>Stap</sub> using laser Doppler vibrometry. Five CI electrodes from two different manufacturers with varying dimensions were inserted via a round window approach at six different depths (16–25 mm).</p> </sec> <sec> <title>Results:</title> <p>The responses of <italic>P</italic><sub>IC</sub> and <italic>V</italic><sub>Stap</sub> to acoustic stimulation were assessed as a function of stimulus frequency, normalized to sound pressure level in the external auditory canal, at baseline and electrode-inserted conditions. Responses measured with electrodes inserted were generally within approximately 5 dB of baseline, indicating little effect of CI electrode insertion on <italic>P</italic><sub>IC</sub> and <italic>V</italic><sub>Stap</sub>. Overall, mean differences across conditions were small for all responses, and no substantial differences were consistently visible across electrode types.</p> </sec> <sec> <title>Conclusion:</title> <p>Results suggest that the influence of a CI electrode on middle and inner ear mechanics is minimal despite variation in electrode lengths and configurations.</p> </sec> </abstract>