Abstract
Background: The importance of intracochlear pressure during cochlear electrode insertion for the preservation of residual hearing has been widely discussed. Various aspects of pre-insertional, intra-insertional, and post-insertional relevant conditions affect intracochlear pressure. The fluid situation at the round window during electrode insertion has been shown to be an influential factor.Aims/Objectives: The aim of the study was to compare various insertion techniques in terms of the fluid situation at the round window.Material and Methods: We performed insertion of cochlear implant electrodes in a curled artificial cochlear model. We placed and fixed the pressure sensor at the tip of the cochlea. In parallel to the insertions, we evaluated the maximum amplitude of intracochlear pressure under four different fluid conditions at the round window: (1) hyaluronic acid; (2) moisturized electrode, dry middle ear; (3) middle ear filled with fluid (underwater); and (4) moisturized electrode, wet middle ear, indirectly inserted.Results: We observed that the insertional intracochlear pressure is dependent on the fluid situation in front of the round window. The lowest amplitude changes were observed for the moisturized electrode indirectly inserted in a wet middle ear (0.13 mmHg ± 0.07), and the highest values were observed for insertion through hyaluronic acid in front of the round window (0.64 mmHg ± 0.31).Conclusions: The fluid state in front of the round window influences the intracochlear pressure value during cochlear implant electrode insertion in our model. Indirect insertion of a moisturized electrode through a wet middle ear experimentally generated the lowest pressure values. Hyaluronic acid in front of the round window leads to high intracochlear pressure in our non-validated artificial model.
Highlights
The aim of modern cochlear implantation is intracochlear structural and functional preservation
The extended round window and cochleostomy approach have been shown to allow hearing preservation, most clinics use a round window approach related to a higher risk of labyrinthine damage by the two other approaches [3]
Different studies have evaluated in an artificial cochlea model insertional factors that could influence residual hearing, like force [8] and pressure, in terms of speed [9], moisturized insertion [4], manual tremor and automated insertion [10], and positioning of the cochlear array [11]
Summary
The aim of modern cochlear implantation is intracochlear structural and functional preservation. The extended round window and cochleostomy approach have been shown to allow hearing preservation, most clinics use a round window approach related to a higher risk of labyrinthine damage by the two other approaches [3]. Different studies have evaluated in an artificial cochlea model insertional factors that could influence residual hearing, like force [8] and pressure, in terms of speed [9], moisturized insertion [4], manual tremor and automated insertion [10], and positioning of the cochlear array [11]. The importance of intracochlear pressure during cochlear electrode insertion for the preservation of residual hearing has been widely discussed. The fluid situation at the round window during electrode insertion has been shown to be an influential factor
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