FLEXIBLE POSITIONER WITH SPINE ELECTRODE FOR USE WITH COCHLEAR ELECTRODE ARRAY
Publication Date: 2003-Mar-19
The IP.com Prior Art Database
An electrode system includes an electrode array and a positioner. The electrode system is adapted to be used with a cochlear stimulation system, or other neural stimulation system. When used with a cochlear stimulation system, the electrode system is inserted into the scala tympani of the cochlea. Electrode contacts on the electrode array are positioned and held in close proximity to the ganglion cells in the modiolus by the positioner at the same time that an elongate spine electrode, on a back side of the positioner, is located near a back wall of the scala tympani. During use, such electrode positioning guides steer stimulation current flowing between the electrode contacts of the array and the spine electrode of the positioner so that more effective stimulation of the target ganglion cells is realized. In one embodiment, the electrode array has spaced-apart electrode contacts exposed only along a medial side thereof; and the positioner has an elongate spine electrode located along the full length (or at least a substantial portion of the full length) of its back side.
Background and Summary
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, numerous cochlear implant systems --or cochlear prosthesis-- have been developed. Such systems 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 of electrodes into the cochlea 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 thus 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 frequenc...