Abstract
Objective. To observe the intracochlear behavior of a cochlear implant electrode insertion technique (called “pullback”) in temporal bones. Study Design. Experimental. Settings. Tertiary referral center. Method. The change of the intracochlear electrode position was investigated under various conditions of an electrode pullback (N = 54) in 9 radiologically, size-estimated temporal bones (TBs). Those TBs were prepared by removal of the cochlear scalar roof to apply digital video capture procedures to monitor the pullback procedures. The digitally captured pictures were analyzed with specific software. Results. An optimal pullback of the electrode varied between 1.37 mm and 2.67 mm. While a limited pullback is without risk, an extended pullback bears the risk of removing the electrode tip out of its initial position or out of the cochlea. A correlation between cochlear size and the amount of pullback was not found. Conclusion. An initial insertion to the first or the second marker on the electrode followed by a limited pullback of about 1.37 mm to 1.5 mm can be recommended to achieve an optimized perimodiolar position. A pullback of up to two marker positions bears the risk of removing the electrode tip out of its initial position.
Highlights
The position of the cochlear implant electrode inside the scalae of the cochlea has been shown to have a significant effect on the electronic compound action potential in guinea pigs [1]
The direct comparison of audiological results of patients with a perimodiolar electrode and perimodiolar ones being pulledback evidenced an increase in frequency discrimination, but not in monosyllabic understanding [8]
Wackym et al [12] demonstrated that an improved proximity of the electrodes to the spiral ganglion cells had a positive impact on the electrical auditory brainstem response in cats and humans for the—at that time—two different, commercially available perimodiolar electrodes
Summary
To observe the intracochlear behavior of a cochlear implant electrode insertion technique (called “pullback”) in temporal bones. The change of the intracochlear electrode position was investigated under various conditions of an electrode pullback (N = 54) in 9 radiologically, size-estimated temporal bones (TBs). Those TBs were prepared by removal of the cochlear scalar roof to apply digital video capture procedures to monitor the pullback procedures. While a limited pullback is without risk, an extended pullback bears the risk of removing the electrode tip out of its initial position or out of the cochlea. An initial insertion to the first or the second marker on the electrode followed by a limited pullback of about 1.37 mm to 1.5 mm can be recommended to achieve an optimized perimodiolar position. A pullback of up to two marker positions bears the risk of removing the electrode tip out of its initial position
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