Characterizing Insertion Pressure Profiles During Cochlear Implantation: Simultaneous Fluoroscopy and Intracochlear...

Area of Science:

• Otoacoustic Emissions
• Cochlear Implant Technology
• Auditory Neuroscience

Background:

• Combined electrical-acoustical stimulation (EAS) is increasingly used in cochlear implantation for patients with residual hearing.
• Hearing preservation is crucial for cochlear implant outcomes, but some patients experience hearing loss.
• High-amplitude pressure transients, akin to noise exposure, occur during electrode insertion, but their source is unknown.

Purpose of the Study:

• To investigate the source of high-amplitude pressure transients during cochlear implant electrode insertion.
• To analyze intracochlear pressure changes associated with different electrode insertion techniques.
• To correlate pressure transient generation with electrode position within the cochlea.

Main Methods:

• Cadaveric human heads were used with extended facial recess preparation.
• Fiber-optic pressure sensors were placed in the scala vestibuli and scala tympani.
• Two cochlear implant electrode styles (straight and perimodiolar) were inserted while measuring intracochlear pressures and using video fluoroscopy.

Main Results:

• Cochlear implant electrode insertions generated pressure transients up to 160-170 dB pSPL for both electrode styles.
• The specific location within the cochlea where transients occurred varied, especially with contact to the medial or lateral walls.

Conclusions:

• This study elucidates the pressure profiles generated during cochlear implant electrode insertion.
• Findings can inform improved cochlear implant electrode designs.
• Development of "silent-insertion" techniques may enhance hearing preservation.