Intracochleäre multisite Druckmessung während der Insertion von CI-Elektroden

Background: Physiological hearing is based on an intracochlear pressure travel wave. Intracochlear pressure is assumed to play a central role in the loss of residual hearing during cochlear implantation electrode insertion. Since electrode insertion is a dynamic process, multisite pressure measurement should help to understand the physical background.

This study evaluated intracochlear pressure occurrence at different intracochlear sites during electrode insertion in an artificial cochlear model.

Methods: Two fiberoptic pressure sensors (0,2 mm; FISO, Canada) were introduced in an artificial scala tympani model of the cochlea (length: 30 mm) at 8 mm and 16 mm from the RW and connected to a controller. Cochlear Implant electrodes were inserted, and during the insertion of the CI-electrode, the intracochlear pressure was measured in the setting of 300 low pass filter frequency (Hz) and 75 acquisition rate (Hz). The mean value of the time resolution and time difference between the pressure measurements of two sensors was calculated. The insertional speed was 1.14 ± 0.08 mm/sec.

Results: Alternating pressure measurements showed a time resolution of 5 ± 2.3 msec. The time difference between the pressure measurement sites was 4.4 ± 4.6 msec, indicating a pressure wave speed of 1.82 mm/msec. Control experiments excluded an experimental or technical bias.

Conclusion: Multisite pressure measurement opens a new door for understanding intracochlear damage during electrode insertion and physiological hearing.

This study was supported by Bielefeld University (CSP Program)

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