A Coated Electrode Carrier for Cochlear Implantation Reduces Insertion Forces

Objectives/Hypothesis: To assess the insertion forces and feasibility of insertion of a prototype electrode carrier coated with a flexible and biodegradable coating developed for lubrication and drug delivery. Study Design: Experimental study. Methods: Eight coated and eight uncoated electrode carriers were inserted into a scala tympani model by means of an insertion device, and forces produced during insertion were determined in near real time. The maximum insertion depths and insertion angle were determined. To test the handling and operability, five coated electrode carriers were implanted into human temporal bones. Additionally, the bones were processed undecalcified and the distribution of the coating material within the cochlea evaluated. Results: Insertion forces were markedly reduced in the group of coated electrode carriers for insertion depths above 15 mm. The insertions were less fitful and led to a higher maximum insertion angle. The insertion of the coated electrode carrier was feasible, and the coating material was evident up to the apical parts of the cochlea postimplantation. Conclusions: Coating of a cochlear implant electrode carrier may reduce insertion forces responsible for the surgical trauma. Loaded with active substances, the coating may help to deliver drugs to the apical parts of the cochlear where hair cells reside in patients with residual hearing.