Small-fenestra cochleostomy for MED-EL electrode

Although the physical characteristics of cochlear implant electrode arrays vary substantially among manufacturers, many otolaryngologists have adopted a surgical cochleostomy technique that is similar for all of them. The objective of this study was to compare the insertion dynamics of the MED-EL Flex electrode using two different sized cochleostomies. Six temporal bones were prepared with either a small fenestra ( approximately 1.0 mm) or a large fenestra ( approximately 1.8 mm) cochleostomy and the electrodes inserted under video fluoroscopy. The resulting video images were analysed for depth of insertion as well as dynamic flexion of the electrode during insertion. The study demonstrated that small-fenestra cochleostomies have a 'pool cue' or 'billiard cue' effect, stabilizing the electrode cable and resulting in easier and deeper insertions. This is achieved by limiting the buckling of the electrode just inside the cochleostomy site.