Validation of minimally invasive, image-guided cochlear implantation using Advanced Bionics, Cochlear, and Medel electrodes in a cadaver model

Abstract

Purpose Validation of a novel minimally-invasive, image-guided approach to implant electrodes from three FDA-approved manufacturers—Medel, Cochlear, and Advanced Bionics—in the cochlea via a linear tunnel from the lateral cranium through the facial recess to the cochlea. Methods Custom microstereotactic frames that mount on bone-implanted fiducial markers and constrain the drill along the desired path were utilized on seven cadaver specimens. A linear tunnel was drilled from the lateral skull to the cochlea followed by a marginal, round-window cochleostomy and insertion of the electrode array into the cochlea through the drilled tunnel. Post-insertion CT scan and histological analysis were used to analyze the results. Results All specimens (N=7) were successfully implanted without visible injury to the facial nerve. The Medel electrodes (N=3) had minimal intracochlear trauma with 8, 8, and 10 (out of 12) electrodes intracochlear. The Cochlear lateral wall electrodes (straight research arrays) (N=2) had minimal trauma with 20 and 21 of 22 electrodes intracochlear. The Advanced Bionics electrodes (N=2) were inserted using their insertion tool; one had minimal insertion trauma and 14 of 16 electrodes intracochlear while the other had violation of the basilar membrane just deep to the cochleostomy following which it remained in scala vestibuli with 13 of 16 electrodes intracochlear. Conclusions Minimally invasive, image-guided cochlear implantation is possible using electrodes from the three FDA-approved manufacturers. Lateral wall electrodes were associated with less intracochlear trauma suggesting that they may be better suited for this surgical technique.

High-resolution Imaging of the Human Cochlea through the Round Window by means of Optical Coherence Tomography

“…Furthermore, since the proximal ST follows an approximately straight line 8 , the choice of the correct insertion vector will guarantee atraumatic passage of the electrode until the first cochlear turn. Finally, studies suggest that optimization of the insertion vector can also prevent electrode dislocation near 180° 17,18 . In future research, also the optimal distance between the visualized OSL and the electrode should be determined.…”

“…In patients with residual hearing, this leads to an even more adverse outcome 15,16 . A large portion of insertion trauma occurs within the first 180° of the cochlea 8,17,18 . Atraumatic insertion requires electrode passage in line with the ST trajectory 8,19,20 .…”

Forces and Trauma Associated with Minimally‐Invasive, Image‐Guided Cochlear Implantation

“…The MED-EL custom electrodes were developed in cooperation with the manufacturer by adding 4 nitinol stiffening rods in the silicone surrounding the extracochlear transmitting wire from the internal receiver to the beginning of the electrode array ( Figure 3). Prior experience had shown the standard MED-EL electrode type to be quite flexible, 12 and the stiffening rods were added to assess any change in the depth of insertion by using a more rigid prototype.…”

Effects of object‐to‐detector distance and beam energy on synchrotron radiation phase‐contrast imaging of implanted cochleae

“…Various techniques have been used to localize the CI electrode postoperatively [e.g. (McRackan et al ., ; Reda et al ., ; Bennink et al ., ; Carlson et al ., )]. The intrascalar position of the electrode and the outline of the BM can be delineated in clinical computed tomography (CT) images using state‐of‐the‐art image analysis algorithms (Noble et al ., ).…”