Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2002-01-22
2003-12-30
Bockelman, Mark (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
Reexamination Certificate
active
06671559
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to the field of cochlear implants for patients with hearing impairment and/or tinnitus, more particularly to a transcanal, transtympanic cochlear implant system that requires a minimum of surgical intrusion that may be performed at a physician's office under local anesthesia.
BACKGROUND OF THE INVENTION
The present invention relates to a transcanal, transtympanic cochlear implant system ideally suited for those profoundly deaf, where conventional amplifying hearing aids are of limited or no value to those suffering the hearing impairment. That is to say, with maximum gain delivered by the most powerful hearing aids, these profoundly deaf individuals cannot hear sound and hence cannot discriminate and understand speech. In addition, there are an estimated 200-300 million people who have various patterns of severe sensorineural hearing loss, which are imperfectly rehabilitated via hearing aids. An example of such is so called “ski-sloped hearing loss,” where there is near normal hearing in the low to middle frequency range, but the hearing drops out dramatically in the higher frequencies. For these types of hearing loss, amplification is ineffective, because the cochlea cannot perform its transductive function of converting the mechanical energy of sound to the electrical current, which is ultimately perceived as sound by the brain. The inner ear structures responsible for this transductive function are known as hair cells, and the electrical currents, which they produce in response to the mechanical stimulation by sound, are known as cochlear microphonics. When these hair cells are sufficiently damaged in the above mentioned scenarios, no amount of amplification will be effective.
The cochlear implant is, in effect, a bionic ear in that it replaces the lost cochlear microphonic with an electrical current that is the precise analog of sound. Current United States Food and Drug Administration (“FDA”) approved cochlear implant systems are so-called multichannel long electrode devices, which are expensive, highly complex devices surgically introduced via a complicated and (for the average otolaryngologist) risky procedure under general anesthesia known as the facial recess mastoidectomy. The estimated cost of these cochlear implant systems, including surgical, anesthesia, hospital, and programming fees is currently quite high. The hardware necessary to program these devices adds further to these high costs, and the time to program the first map for these devices averages from four to twelve hours depending upon the age of the patient, among other factors. This prohibitive price and impractical complexity is simply not accessible to the vast majority of the global deaf population. Furthermore, the average otologist in the developing countries of the world typically does not have the sophistication, expertise and equipment to confidently undertake the facial recess mastoidectomy in order to introduce the internal component of the multichannel systems.
The most tragic irony of all is that the multichannel long electrode devices can destroy residual hearing when they are inserted into the cochlea. This well acknowledged fact makes these devices difficult to justify in very young infants where the precise degree of hearing loss is often in doubt. Furthermore, they cannot be used for ancillary applications for partial hearing loss aforementioned or for the electrical suppression of tinnitus in serviceable hearing ears. In contrast, the transcanal middle ear cochlear implant system of the present invention is a safe, accessible, and cost effective system in which the internal device can be surgically introduced in an office setting under local anesthesia. As will become apparent hereafter, surgical risk to the facial nerve and inner ear are thus greatly diminished. Postoperative healing and recovery times are greatly lessened, and thus time to hook up and program the external device are significantly shortened. Because the internal device resides in the middle ear and does not significantly damage residual hearing, ancillary uses of the system for applications such as ski sloped hearing loss and the electrical suppression of tinnitus become possible and practical.
The theory behind the use of multiple electrodes is based upon the so-called tonotopic theory for the normally functioning cochlea. That is to say, the normally functioning cochlea mechanically sorts sounds according to their frequency, so that the highest tones vibrate the basilar membrane closer to the round window (lower down in the cochlea) and the lower tones vibrate the basilar membrane closer to the apex of the cochlea. Multiple electrodes thus necessitate a longer electrode to be inserted into the cochlea so that multiple electrodes (sometimes referred to as channels) can deliver specific portions of the frequency spectrum to specific sections of the basilar membrane. Thus, the damaged cochlea is postulated to be analogous to a piano; it does not matter so much how hard we press the keys or at what speed. The critical factor is to press the keys at the right spot on the piano in order to get the proper tone or frequency.
Although presently somewhat controversial, there is ample evidence to discredit the validity of the tonotopic theory for the damaged cochlea. Numerous temporal bone studies of deceased cochlear implant patients have repeatedly shown that few if any of them have any stimuable dendrites remaining in the basilar membrane, i.e., to continue the analogy, the piano keys are missing. In fact, it is now commonly accepted that the more central spiral ganglion nerve cells are the site of stimulation. The facts are that the practice was to initially develop long electrode, multiple channel arrays to conform to a theory, which though accurate and valid for the normally functioning cochlea, is invalid for the damaged cochlea. Nevertheless, these systems work and work well, which is a testament to the remarkable plasticity of the neural pathways and brain. Equally remarkable, a short electrode inserted into the cochlea delivering an exact electrical analog of sound can afford the patient the very same pitch discrimination as multiple channel systems. Several drawbacks to multiple channel systems are: (1) multichannel technology is presently very expensive; (2) multichannel systems are very complex which begets system failures over time; (3) energy requirements for the multichannel systems are high and consequently battery life is lower; and, (4) most important of all, multichannel long electrode arrays can, and often do, damage residual hearing.
Notwithstanding, but, rather because of current orthodoxy, multichannel systems are in current favor. Because multichannel systems necessitate long electrode arrays, the surgical introduction of the internal device requires the more complicated facial recess mastoidectomy in order to technically insert this electrode array properly within the cochlea. A multichannel long electrode could not be inserted via a transcanal approach. Furthermore, the electronics package and receiver coil for such a complex sound-processing scheme would not fit within the middle ear space.
Because these multichannel systems damage residual hearing, they have to date not been useful in combination with hearing aids for selective frequency losses, nor have they been used for the electrical suppression of tinnitus in serviceable hearing ears.
Examples of the prior art, as reflected in the following U.S. Patents, describe several of these multichannel type cochlear implant devices. Such prior art patents are summarized and believed to operate as follows:
a) U.S. Pat. No. 6,289,247, to Faltys et al., relates to a universal strategy selector (USS) for use with a multichannel cochlear prosthesis that includes (a) a processor, or equivalent; (b) a selector; and (c) a display. The multichannel cochlear prosthesis is characterized by multiple stimulation channels through which a specific pattern of electrical stimulation, modulated by acoustic sig
Boylston Byron Lee
Goldsmith Miles Manning
Bernstein Jason A.
Bockelman Mark
Microphonics, Inc.
Powell Goldstein Frazer & Murphy LLP
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