Semiautomatic Cochleostomy Target and Insertion Trajectory Planning for Minimally Invasive Cochlear Implantation

Table 1

Summary of cochleostomy target and drill trajectory planning details.

No.	Distance (mm)					Trajectory alignment (°)
	FN	ChT	EAC	In/Ma	St	𝛿	𝜀	𝜃𝐶
1L	0.44	0.12	0.55	2.60	0.65	8	0	12
1R*	0.37	0.00*	0.90	2.36	0.62	12	0	10
2L*	0.37	<0.00*	0.45	2.64	0.77	11	0	12
2R*	0.32	<0.00*	0.45	3.02	0.68	7	0	12
3L	0.37	0.22	1.60	2.78	0.80	12	0	8
3R	0.43	0.53	1.85	2.95	0.65	15	1	4
4L	0.38	1.17	1.89	2.55	0.74	11	1	12
4R	0.38	1.18	2.34	3.11	0.69	12	0	12
5L	0.39	0.37	0.62	3.01	0.51	10	7	4
5R	0.36	0.33	0.90	2.88	0.58	14	1	4
Avg. ± SD	0.38 ± 0.03	0.49 ± 0.45	1.16 ± 0.70	2.79 ± 0.24	0.67 ± 0.09	11.2 ± 2.4	1.0 ± 2.2	9.4 ± 4.1

FN: facial nerve, ChT: chorda tympani, EAC: posterior wall of the external auditory canal, In: incus, Ma: malleus, St: stapes.
𝛿: out of plane alignment between the trajectory and the basal turn plane, Figure 4(a).
𝜀: in-plane alignment of the trajectory in the basal turn plane, Figure 4(b).
𝜃_𝐶: angular position of the cochleostomy, Figure 2(c).
*Cases with sacrificed chorda tympani because of a small facial recess.