Evaluation of the Relationship between the NRT-Ratio, Cochlear Anatomy, and Insertions Depth of Perimodiolar Cochlear Implant Electrodes

Table 1

Overview of the correlation between the NRT-ratio, the insertion depth angle, and the cochlear size.

Patient	IDA in °	CS in mm	NRT-ratio; original; (16–18/5–7)	NRT-ratio; mod. 1; (16–18/3–5)	NRT-ratio; mod. 2; (16–18/4–6)	NRT-ratio; mod. 3; (16–18/2–4)	NRT-ratio; mod. 4; (18–20/2–4)	NRT-ratio; mod. 5; (18–20/3–5)	NRT-ratio; mod. 6; (18–20/4–6)	NRT-ratio; mod. 7; (18–20/5–7)
1	328	7.6								1.05
2	333	8.2								0.83
3	343	7.8								0.88
4	373	8								1.1
5	326	8								0.91
6	332	8.3								0.87
7	392	7.9								0.99
8	367	7.3								0.95
9	400	8								0.93
10	353	7.2								0.86
11	392	7.8								0.79
12	373	7.2								0.84
13	368	7.6								0.85
14	332	7.6								1
15	370	8.8								0.83
16	333	9.0								0.95
17	381	7.4								0.82
18	356	8.4								0.66
19	356	8.4								1.01
20	358	8.2								0.91
21	332	7.8								0.83
22	320	8.7								0.88
23	380	7.4								0.99
24	388	7.5								0.87
25	382	7								0.85
26	351	7.4								0.97
(IDA versus NRT)	—	—
value	—	—	>0.05	> 0.05	>0.05	>0.05	>0.05	>0.05	>0.05	>0.05
(CS versus NRT)	—	—
value	—	—	>0.05	>0.05	>0.05	>0.05	>0.05	>0.05	>0.05	>0.05

IDA: insertion depth angle; CS: cochlear size; NRT: neural response telemetry.
values were calculated using Pearson’s product-moment correlation.