Real‐time measurement of electrode impedance during intracochlear electrode insertion

Abstract

Objectives This pilot study details the use of a software tool that uses continuous impedance measurement during electrode insertion, with the eventual potential to assess and optimize electrode position and reduce insertional trauma. Study Design Software development and experimental study with human cadaveric cochleae and two live surgeries. Methods A prototype program to measure intracochlear electrode impedance and display it graphically in real time has been developed. The software was evaluated in human cadaveric temporal bones while simultaneously making real time fluoroscopic recordings, and in two live surgeries during intracochlear electrode insertion. Results Impedance changes were observed with various scalar positions, and values were consistent with those obtained using clinically available software. Using Contour Advance™ electrodes, impedance values increased after stylet removal, particularly when using the monopolar mode. Conclusion Impedance values seem systematically affected by electrode position, with higher values being associated with proximity to the cochlear wall. The new software is capable of acquiring impedance measurements during electrode insertion and this data may be useful to guide surgeons to achieve optimal and atraumatic electrode insertion, to guide robotic electrode insertion, and to provide insights about electrode position in the cochlea.

Facial nerve stimulation associated with cochlear implant use following temporal bone fractures

“…The concept of impedance is important to cochlear implantation in many ways. Once electrode arrays are inserted within the cochlea, impedance can be used to assess not only the integrity of individual electrodes, but array position within the cochlea, as well [10,11]. In most circumstances, the current generated by normal cochlear implant function is insufficient to overcome the impedance of surrounding otic capsule bone, thus preventing systematic FNS with CI use.…”

Long-term electrode impedance changes and failure prevalence in cochlear implants

“…When within the normal range, however, impedance offers engineers and clinicians a view of the power usage of the device. When the cochlear implant is first implanted, electrode impedance is, in general, low, with values affected by the surface area of the electrode pad (Saunders et al, 2002) and electrode position with respect to the cochlear features (Tan et al, 2013). Over the first few weeks in the body, protein adsorption and tissue growth occurs over the array, thereby increasing the impedance (Newbold et al, 2010).…”

Scanning Electrochemical Microscopy as a Novel Proximity Sensor for Atraumatic Cochlear Implant Insertion

“…Amperostatic charging of electrons on the capacitive neural membrane is adequate to control the membrane potentials of neurons, to raise them above the threshold potentials constantly, and to elicit action potentials robustly [48]. However, the current to elicit neural responses (>1 mA) requires the voltage across the electrode-solution interface to be about 10 V because of the resistance between the implanted electrodes (~10 kΩ), which surpasses by far any electrolysis potentials, [47], [49]. Since dc is the sum of any Faradic reactions, Lily et al introduced biphasic charge balanced electrical stimulation to cancel out the net-dc and demonstrated the biocompatibility [50].…”