Cochlear implants can successfully provide auditory information for bilaterally profoundly deaf patients by electrically stimulating auditory nerve fibres via an electrode array, which is surgically implanted into the...Cochlear implants can successfully provide auditory information for bilaterally profoundly deaf patients by electrically stimulating auditory nerve fibres via an electrode array, which is surgically implanted into the scala tympani of the cochlea. It is therefore important that the electrode array does not cause damage to the fine intracochlear structures during the process of insertion, as this can result in the loss of spiral ganglion cells, which are necessary for the implant to evoke auditory percepts. There is strong evidence that trauma and damage during insertion of electrode arrays into the human cochlea are related to the stiffness of the electrode array. Previous studies were conducted to experimentally determine the stiffness properties of electrode arrays using three-point flexural bending and buckling tests.In this paper, the design of nucleus straight electrode array is modified to give a greater flexibility to further reduce the risk of trauma to delicate structures of the cochlea during surgical insertion of the electrode array. This is achieved by reducing the cross-sectional area of the electrode array at selected positions over its length. Improvements in the flexibility of the new straight electrode array and the bending behavior at its tip have been demonstrated using finite element analysis. Loads applied to the tip of the electrode array at different angles with respect to the longitudinal axis of the electrode array showed that the modified design caused the tip to be more flexible and therefore better able to curl around the inner spiral of the scala tympani and thus less likely to penetrate the basilar membrane during insertion. Loads applied at other positions along the electrode array showed that bending occurred more readily using the modified design thereby reducing the friction and shear stresses at the contact interface between the electrode array and the delicate cochlea structures.展开更多
文摘Cochlear implants can successfully provide auditory information for bilaterally profoundly deaf patients by electrically stimulating auditory nerve fibres via an electrode array, which is surgically implanted into the scala tympani of the cochlea. It is therefore important that the electrode array does not cause damage to the fine intracochlear structures during the process of insertion, as this can result in the loss of spiral ganglion cells, which are necessary for the implant to evoke auditory percepts. There is strong evidence that trauma and damage during insertion of electrode arrays into the human cochlea are related to the stiffness of the electrode array. Previous studies were conducted to experimentally determine the stiffness properties of electrode arrays using three-point flexural bending and buckling tests.In this paper, the design of nucleus straight electrode array is modified to give a greater flexibility to further reduce the risk of trauma to delicate structures of the cochlea during surgical insertion of the electrode array. This is achieved by reducing the cross-sectional area of the electrode array at selected positions over its length. Improvements in the flexibility of the new straight electrode array and the bending behavior at its tip have been demonstrated using finite element analysis. Loads applied to the tip of the electrode array at different angles with respect to the longitudinal axis of the electrode array showed that the modified design caused the tip to be more flexible and therefore better able to curl around the inner spiral of the scala tympani and thus less likely to penetrate the basilar membrane during insertion. Loads applied at other positions along the electrode array showed that bending occurred more readily using the modified design thereby reducing the friction and shear stresses at the contact interface between the electrode array and the delicate cochlea structures.
