Characterization of mechanical properties of single electrodes and multielectrodes

Over recent years there has been increasing awareness of the potential damage to the fragile structures of the cochlea that could be caused by the insertion of intracochlear electrodes. Temporal bone histologic studies from chronically implanted human patients have shown that intracochlear electrodes can cause significant insertion trauma. This paper describes how the mechanical properties of the electrode array can influence insertion trauma, and compares the properties of solid wire electrodes with those of a tapered electrode array. The maximum force that can be applied by the tip of the solid wire electrode is 25 times what can be applied by the tapered electrode array, whereas the tapered array is ten times more flexible. These differences in mechanical properties suggest that evidence for insertion trauma should be assessed on an electrode-by-electrode basis.