Force Application During Cochlear Implant Insertion: An Analysis for Improvement of Surgeon Technique

Abstract

Highly invasive surgical procedures, such as the implantation of a prosthetic device, require correct force delivery to achieve desirable outcomes and minimize trauma induced during the operation. Improvement in surgeon technique can reduce the chances of excessive force application and lead to optimal placement of the electrode array. The fundamental factors that affect the degree of success for cochlear implant recipients are identified through empirical methods. Insertion studies are performed to assess force administration and electrode trajectories during implantations of the Nucleus reg 24 Contourtrade and Nucleus reg 24 Contour Advancetrade electrodes into a synthetic model of the human Scala Tympani, using associated methods. Results confirm that the advance off-stylet insertion of the soft-tipped contour advance electrode gives an overall reduction in insertion force. Analysis of force delivery and electrode positioning during cochlear implantation can help identify and control key factors for improvement of insertion method. Based on the findings, suggestions are made to enhance surgeon technique. Disciplines Physical Sciences and Mathematics Publication DetailsThis article was originally published as Todd, C Naghdy,

The Effects of Insertion Speed on Inner Ear Function during Cochlear Implantation: A Comparison Study

“…A possible explanation is, especially when considering previous findings, that the slow electrode insertion reduces intracochlear pressure peaks and facilitates pressure equalisation by allowing time for perilymph egress while the electrode enters the confined fluid-filled intracochlear space [Roland et al, 2005;Todd et al, 2007]. This would result in a net reduction of intracochlear volume displacement with potentially less mechanical effects and trauma on the basilar membrane and the organ of Corti [Todd et al, 2007].…”

“…As the electrodes are inserted into a progressively smaller scala tympani, with a progressively small cross section towards the apex, lesser and lesser space is left for the perilymph to escape, thereby increasing pressure on the intracochlear structures. It is therefore logical to assume that shorter electrodes give the perilymph more space to decompress as opposed to electrodes covering the entire length of the cochlea [Todd et al, 2007]. Considering this, it would be unlikely to preserve hearing with a complete cochlear coverage electrode; however, the experience of various groups including ours has shown that this can be achieved using a slow insertion speed and atraumatic surgical techniques via the round window [Usami et al, 2011].…”

Automated insertion of preformed cochlear implant electrodes: evaluation of curling behaviour and insertion forces on an artificial cochlear model

“…Todd et al [40] published a study dealing with the assessment of insertion forces and electrode trajectory of Contour and Contour Advance electrodes. They also used a calibrated Instron 5543 force measurement device with a 10 N load cell to insert the electrode into a two dimensional artificial model of the human scala tympani.…”

Path Planning and Workspace Determination for Robot-Assisted Insertion of Steerable Electrode Arrays for Cochlear Implant Surgery

“…The negative forces happen in Fig. 12 (a) and (b) because the steerable electrode hugs the inner wall of the scala tympani [11]. These results suggest the effectiveness of adjusting the angle of approach of the steerable electrode array with respect to the scala tympani in reducing the insertion forces.…”