Impact of the Insertion Speed of Cochlear Implant Electrodes on the Insertion Forces

• DOI: 10.1097/mao.0b013e318219f6ac
• Publication Date: 2011-04-07T21:05:09Z
• Authors: Georgios Kontorinis; Thomas Lenarz; Timo Stöver; Gerrit Paasche
• Keywords: Models, Anatomic; 03 medical and health sciences; Cochlear Implants; 0302 clinical medicine; Humans; Scala Tympani; Cochlear Implantation

Objective of the present experimental research study was to examine the hypothesis that cochlear implant insertion speed can significantly affect the insertion forces.Cochlear implant electrode insertion forces can influence the insertion trauma and the preservation of residual hearing. The effect of the electrode insertion speed on the insertion forces still remains unknown.Force measurements were performed while inserting human electrodes in an artificial scala tympani model at different speeds. For these measurements, an Instron 5542 Force Measurement System with a 10 N load cell and Nucleus 24 Contour Advance electrodes were used. Additionally, the insertion speed was measured through videos of 116 human implantations; these videos were recorded in our theaters and involved different surgeons and electrode types.Progressive increase in insertion speed from 10 to 200 mm/min resulted in significant, proportional increase in the average insertion forces from 0.09 to 0.185 N and in the maximum forces from 0.18 to 0.42 N, respectively. The average insertion speed used in the theaters during human cochlear implantations was 96.5 mm/min (range, 42-165.2 mm/min) and depended on the electrode type and the surgeon.High insertion speeds cause significant increase of the forces. Cochlear implant surgeons should use low and stable speeds during the insertion. Insertion speed close to the average value used in the theaters should be applied on experimental models, to approximate human implantation conditions.