Toward steerable electrodes. An overview of concepts and current research.

Abstract

Abstract:Restoration of hearing is a demanding surgical task which requires the insertion of a cochlear implant electrode array into the inner ear while preserving the delicate basilar membrane inside the cochlea for an atraumatic insertion. Already shortly after the first clinical success with early versions of cochlear implants the desire for a controlled insertion of the electrode array arose. Such a steerable electrode should be in its shape adaptable to the individual path of the helical inner ear in order to avoid any contact between the implant and the surrounding tissue. This article provides a short overview of concepts and actuator mechanisms investigated in the past and present with the objective of developing a steerable electrode array for an individualized insertion process. Although none of these concepts has reached clinical implementation, there are promising experimental results indicating that insertion forces can be reduced up to 60% compared to straight and not steerable electrodes. Finally, related research topics are listed which require considerable further improvements until steerable electrodes will reach clinical applicability.

Towards All-Polymeric Cochlear Implant Micro-Electrode Arrays

“…This fact explains why cochlear implant users present reduced music appreciation and difficulties in understanding speech in crowded or noisy places [39]. The main approaches to improve cochlear implants and are focused on enhancing various sections: the electrode array [39]; the implant-tissue interphase [8]; signal processing strategies [40], [41]; the array insertion procedure [24], [42]; or even regenerative medicine treatments to restore hearing [43], [44]. It is worth mentioning that among these limitations, the electrode array presents the most prominent margin of im-2.4.…”

“…The straight and sharp wire of the stylet often damages the cochlear tissue, which also raises the risk of array translocations from the scala tympani to scala vestibuli [36], [66]. Nonetheless, the scientific community is making a strong effort to develop steerable stylets to fully control the cochlear insertions and avoid the contact between the array and cochlear tissue [42]. The strategies to develop such steerable stylets include shape memory alloys [68], tubular manipulators [69], magnetic guidance [70], fluid-mechanic actuators [71], and actuation strands [72].…”

“…The strategies to develop such steerable stylets include shape memory alloys [68], tubular manipulators [69], magnetic guidance [70], fluid-mechanic actuators [71], and actuation strands [72]. The commercialization of steerable stylets might reduce the insertion forces considerably, favoring the achievement of atraumatic cochlear insertions [42]. On the other hand, straight electrode arrays are more flexible and longer [36].…”

Characterization of a measurement setup for the thermomechanical characterization of curved shape memory alloy actuators

“…CIs are used to treat deafness or severe hearing loss by electrically stimulating the auditory nerve within the inner ear (cochlea). The spatial proximity of the electrode array plays an important role and this may be achieved in various ways such as a pre-shaped geometry of the electrode carrier itself [1] or through actuation [2][3][4]. Thus, actuation with the help of a NiTi wire trained to a curved shape is proposed here.…”

Multi-rigid-body modeling and simulation of perimodiolar cochlear electrode arrays

“…During the implantation, the stylet was gradually extracted to restore the spiral state. 2,7 When the doctor was implanting the perimodiolar electrode, the perimodiolar array was pushed into the human cochlea, while the stylet was being extracted. Ingo Todt studies the length of the stylet at each moment when implanting different cochlear specimens.…”