Individual Optimization of the Insertion of a Preformed Cochlear Implant Electrode Array

Table 1

Trauma risk: rating scale for evaluation of trauma risk, ranging from grade 0 to grade IV. Verbal description of the different criteria used for rating each step of electrode insertion.

	Grade of “trauma risk”	Description and representation in the simulation
	IV	(i) Extensive contour damage, secondary contact areas^† due to electrode deformation and restraint^† of the electrode array leading to high contact forces; (ii) Electrode array is visualized far outside the cochlear contour
	III	(i) Softip intersects with the cochlear contour by more than its total size; (ii) Large-scale penetration of the silicone body by more than its total cross section; (iii) Pronounced deformation^† of the electrode array resulting in secondary contact areas^†; (iv) Involves additional contour damage^†, possibly including restraint^† of the electrode array between inner and outer walls
	II	(i) Softip intersects with the cochlear contour by more than half its size; (ii) Orientation of the Softip contraindicates its yielding with low contact forces; (iii) Large-scale penetration of the silicone body by more than a quarter of its cross section
	I	(i) Slight contact between the Softip and the inner or outer contour; (ii) Slight penetration of the silicone body up to 0.25 of the total cross section; (iii) Intersection to such a small extent that it is assumed that the flexible Softip or the elastic electrode array results in; (iv) no secondary contact owing to elastic deformations of the implant
	0	(i) No contact between electrode array and cochlea.

Not directly visualized but taken into consideration by the mechanically experienced user.