Publication Date: 2011-Dec-30
The IP.com Prior Art Database
Kurt J. Koester: INVENTOR [+3]
A composite stylet for facilitating insertion of an implantable electrode array into either a left or right cochlea comprises a composite having a glass transition temperature between room temperature and body temperature. While relatively stiff and straight at room temperature, the composite stylet is slidably inserted into a longitudinal lumen of the electrode array. The electrode array is then inserted into the cochlea. As the composite stylet within the electrode array warms to body temperature, it becomes compliant, allowing the electrode array to assume a spiral shape. The proximal end of the composite stylet, which is not inserted into the body, retains its stiffness to aid the implanter in inserting the electrode array.
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 The present invention relates to implantable stimulation devices, e.g., cochlear prostheses used to electrically stimulate the auditory nerve, and more particularly to a stylet for insertion of an electrode array into the cochlea.
Background of Invention
 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 treatable 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 may be unable to derive significant benefits from conventional hearing aid systems alone, no matter how loud the acoustic stimulus is made, because their mechanisms for transducing sound energy into auditory nerve impulses have been damaged.
 To overcome sensorineural deafness, there have been developed numerous cochlear implant systems, or cochlear prostheses, which seek to bypass the hair cells 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 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 a 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.
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Field of Invention
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 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 function of the separating the acoustic signal into a number of parallel channels of information, each representing the intensity of a narrow band of frequencies within the acoustic spectrum. Ideally, each channel of information would be conveyed selectively to the subset of auditory nerve cells that normally transmitted information about that frequency band to the brain. Those nerve cells are arranged in an orderly tonotopic sequence, from high frequencies at the basal...