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Publication Date: 2004-Aug-19
Document File: 11 page(s) / 2M

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The Prior Art Database


An insertion tool is used to insert an electrode array and positioner into a human cochlea at the same time. The insertion tool includes two stylet wires, two expelling tubes, and a compression spring attached to one of the expelling tubes to reduce, if any, high compressive forces between the insertion tool and the positioner. Once inserted into the cochlea, the positioner and the electrode array are located within the scala tympani and the electrode contacts are positioned against the inner wall of the modiolus of the cochlea, wherein the electrode contacts provide direct electrical stimulation to the auditory nerve cells of a patient with sensorineural hearing loss.

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            The present invention relates to implantable stimulation devices, e.g., cochlear prosthesis used to electrically stimulate the auditory nerve, and more particularly to an insertion tool used to aid in the insertion process of an electrode array for use with a cochlear stimulator that is designed to hug the modiolus so as to place electrode contacts of the electrode array in close proximity to the ganglion cells and thereby to the auditory nerve fibers.

            Hearing loss, which may be due to many different causes, is generally of two types: conductive and sensorineural.  Of these, conductive hearing loss occurs where the normal mechanical pathways for sound to reach the hair cells in the cochlea are impeded, for example, by damage to the ossicles.  Conductive hearing loss may often be helped by use of conventional hearing aids, which amplify sound so that acoustic information does reach the cochlea and the hair cells.  Some types of conductive hearing loss are also amenable to alleviation by surgical procedures.

            In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss.  This type of hearing loss is due to the absence or the destruction of the hair cells in the cochlea which are needed to transduce acoustic signals into auditory nerve impulses.  These people are unable to derive any benefit from conventional hearing aid systems, no matter how loud the acoustic stimulus is made, because their mechanisms for transducing sound energy into auditory nerve impulses have been damaged.  Thus, in the absence of properly functioning hair cells, there is no way auditory nerve impulses can be generated directly from sounds.

            To overcome sensorineural deafness, there have been developed numerous cochlear implant systems --or cochlear prosthesis-- which seek to bypass the hair cells in the cochlear (the hair cells are located in the vicinity of the radially outer wall of the cochlea) by presenting electrical stimulation to the auditory nerve fibers directly, leading to the perception of sound in the brain and an at least partial restoration of hearing function.  The common denominator in most of these cochlear prosthesis systems has been the implantation into the cochlea of electrodes which are responsive to suitable external source of electrical stimuli and which are intended to transmit those stimuli to the ganglion cells and thereby to the auditory nerve fibers.

            A cochlear prosthesis operates by direct electrical stimulation of the auditory nerve cells, bypassing the defective cochlear hair cells that normally transduce acoustic energy into electrical activity in such nerve cells.  In addition to stimulating the nerve cells, the electronic circuitry and the electrode array of the cochlear prosthesis performs the...