Article Figures & Data
Figures
- FIG 1.
A, The MVI stimulator comprises 3 fixation magnets, an inductive coil link, electrical current stimulator circuitry, a stimulation electrode array, a stimulation reference electrode, and a recording reference electrode. The electrode array includes a 3-electrode shank for the posterior canal (B, E3–E5), a forked subarray with 2 shanks for the horizontal (C, E6–E8) and anterior (C, E9–E11) canals, and a stimulation reference electrode (D). eCAP indicates electrically evoked compound action potential. Reprinted with permission from Labyrinth Devices, LLC, 2019.
- FIG 2.
Method for generating MSCT (A and B) and FPCT (C and D) MPR. Two planes are generated. The first plane is approximately tangential to the thin segments of the superior and horizontal SCCs at their junctions with their ampullae and includes the 6 electrode contacts of the forked array inserted into the superior and horizontal ampullae. The second plane is in the posterior plane of the SCC and includes the 3 electrode contacts of the linear array implanted in the posterior canal and the tip of braided platinum/iridium wire inserted into the common crus. Section thickness was set to 2 mm to include all electrode contacts on 1 image for both planes. Window width and contrast level were adjusted as needed to optimize the visibility of electrode contacts. A 3D representation of the vestibular lumen and vestibular nerve is added in transparency (E and F) to help visualize the anatomy.
- FIG 3.
Subject: Participant 7. Method for calculating the angle (θ) of the angular insertion depth of the common crus reference electrode. CC indicates common crus of the implanted labyrinth; PE, posterior electrode array; PSCC, posterior semicircular canal; SSCC, superior semicircular canal; RE, reference electrode; Sup, superior; Lat, lateral.
- FIG 4.
MSCT (A–D) and FPCT (E–P) multiplanar reconstructions for all participants. A and B, Participant 1 MSCT. C and D, Participant 2 MSCT. E and F, Participant 3 FPCT. G and H, Participant 4 FPCT. I and J, Participant 5 FPCT. K and L, Participant 6 FPCT, M and N, Participant 7 FPCT. O and P, Participant 8 FPCT. In every panel, the top of the image is superior and the left edge of the image is anteromedial. Sep indicates September; Feb, February; Oct, October; Nov, November; Jan, January.
- FIG 5.
A, Lateral scout view showing electrode arrays visible through the external auditory canals (yellow arrowhead) and cephalic edges of the infraorbital rims (yellow diamond). Those palpable landmarks define the Reid plane (yellow line) and the plane of horizontal canals (red line). The plane of the horizontal semicircular canals, the standard “axial” plane for temporal bone CT reconstructions, is at a ∼20° pitch from the Reid plane.17 By supporting the head on a firm wedge to pitch the head forward from supine (and flexing the neck until the Reid plane is pitched ∼20° nose toward chest from Earth vertical), one can minimize scatter artifacts from the stimulator cannister to the inner ear by keeping them on opposite sides of a separation plane perpendicular to the gantry rotation axis (B).
Tables
Participants Date Implanted Date Imaged Age (yr),a Sex Imaging Protocol Implant Side Reference Location 1 12 Aug 2016 Sep 2016 62, M MSCT Left CC 2 4 Nov 2016 Nov 2016 57, M MSCT Left CC 3 3 Feb 2017 Feb 2017 63, F FPCT, HR mode Left CC 4 15 Dec 2017 Jan 2018 62, F FPCT, FF mode Left CC 5 24 Aug 2018 Sep 2018 51, F FPCT, HR mode Right CC 6 31 Aug 2018 Sep 2018 66, F FPCT, FF mode Right CC 7 14 Jan 2019 Feb 2019 53, F FPCT, HR mode Left CC 8 13 Sep 2019 Oct 2019 55, M FPCT, HR mode Right SP Note:—CC indicates common crus of the implanted labyrinth; SP, in a subperiosteal pocket outside the temporal bone; Aug, August; Jan, January; Sep, September; Dec, December; Feb, February; Nov, November.
↵a Age in years at time of implantation.
- Table 2:
Common crus reference electrode angular depth and insertion length calculations and locations
Participant No. CC Insertion Intended Insertion Depth Angle Insertion Length (mm) Anatomic Location of the Reference Electrode Tip 1 Yes –3° 39 Common crus 2 Yes +26° 66 Superior canal 3 Yes –30° 42 Posterior canal 4 Yes –57° 21 Posterior canal 5 Yes +21° 46 Common crus 6 Yes –2° 41 Posterior canal 7 Yes +45 51 Common crus 8 No NA NA Outside temporal bone Note:—NA indicates not appliable.
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