Pig as a large animal model for posterior fossa surgery in oto-neurosurgery: A cadaveric study - Fig 6

<p><b>Comparison between CPA microscopic view and acoustic-facial bundle in (A) human (courtesy of Dr Y. Nguyen) and (B) pigs</b>.</p

Pre-implantation hearing (dB) according to the electrode array.

<p>Preoperative measurement according to the animal group: 0.4R (black squares) (n = 7), 0.4 (dark grey circles) (n = 7), and 0.3 (light grey triangles) (n = 6). Before implantation, the animals in the three groups had similar hearing thresholds (dB).</p

Maximal peak force measured during insertion of the three electrode array types.

<p>Electrode array geometry influences the maximal peak of the insertion force. Values are means± SEM. One-way Anova, *p<0.05.</p

Array force insertions in mN (millinewtons) as function of insertion duration in a guinea pig model with three different array design.

<p>Insertion forces remained low in the first half on the insertion and then slowly rose and reached a maximum with the three array design at the end of the insertion. In this example, a higher peak force with the 0.4R arrays (red) can be observed compared 0.4(blue) and 0.3 (green) array design.</p

Electrode array placement in the cochlea.

<p>(A) Diagram of a cochlea section passing through the three scala (SV, scala vestibuli; SM, scala media; ST, scala tympani) with a classification according to the placement of electrodes. From A (close to the basilar membrane) to E in a vertical orientation, and from 1 (close to the modiolus) to 5 (close to the lateral wall) in a horizontal orientation. Black circles correspond to electrode placement without hearing loss at D30, black triangles correspond to electrode placement with hearing threshold shift >40 dB at D30 without fibrosis, and light grey triangles correspond to fibrosis. (B) Macroscopic anatomy section of an electrode array in A placement, in contact with a fracture of the osseous spiral lamina (blue circle in A). (C) Macroscopic anatomy section of an electrode array in 4C placement surrounded by reaction fibrosis * (green circle in A). (D) Macroscopic anatomy section of an electrode array in 2C placement away from basilar membrane and osseous spiral lamina (red circle in A).</p

Hearing loss (dB) between D7 and D30 according to the electrode arrays.

<p>Hearing threshold shift between D7 and D30 measurement according to the animal group: 0.4R (black squares) (n = 7), 0.4 (dark grey circles) (n = 7), and 0.3 (light grey triangles) (n = 6). At D30, hearing loss was unchanged compared to that at D7, and this applied to each group.</p

Electrode array prototypes inserted in guinea pig cochleae in vivo.

<p>Electrode array prototypes inserted in guinea pig cochleae in vivo.</p

Hearing loss (dB) at 8000 and 16000 Hz, between D7 and D0, between D30 and D0, and between D30 and D7, in the 6 guinea pigs studied for macroscopic anatomy and with poor hearing (hearing loss > 40 dB).

<p>Hearing loss (dB) at 8000 and 16000 Hz, between D7 and D0, between D30 and D0, and between D30 and D7, in the 6 guinea pigs studied for macroscopic anatomy and with poor hearing (hearing loss > 40 dB).</p

Correlation between hearing loss (dB) at 16000 Hz on D7 and maximal peak force measured during insertion of the three types of electrode array.

<p>0.4R (black squares) (n = 7), 0.4 (dark grey circles) (n = 7), and 0.3 (light grey triangles) (n = 6) electrode arrays. Linear regression, respectively: Y = 0.31X + 17.2, Y (mN), X (dB), n = 20, R = 0.13, slope not different from 0, p = 0.12.</p

Influence of electrode array geometry on hearing loss.

<p>A: D7. B: D30. Hearing threshold shift measurement according to 0.4R (black squares) (n = 7), 0.4 (dark grey circles) (n = 7), and 0.3 (light grey triangles) (n = 6) electrode arrays, inserted at 0.25 mm/s. Values are means ± SEM. Statistical analysis was with two-way Anova (p<0.001 at D7, and p<0.05 at D30), comparison between 0.3 and 0.4R (*p<0.05, **p<0.01, ***p<0.001), comparison between 0.4 and 0.4R (^$p<0.05).</p