Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Ear or nose prosthesis
Reexamination Certificate
1999-11-29
2002-03-19
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Ear or nose prosthesis
C607S057000, C600S025000
Reexamination Certificate
active
06358281
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to human hearing, and more specifically to the design and surgical insertion and positioning of a totally implantable cochlear prosthesis.
BACKGROUND OF THE INVENTION
Human deafness results from numerous sources including trauma, ear infections, congenital factors, ototoxic effects of some antibiotics, and from diseases such as meningitis. Sensorineural damage (damage to the hair cells in the cochlea) is the largest single form of hearing loss. In a healthy ear these hair cells convert acoustic signals in the inner ear to electrical signals that can be interpreted by the brain as sound. It is estimated that over 7% of the U.S. population is affected by sensorineural deafness, and one in a thousand infants is born totally deaf. Extrapolating these percentage figures, it is estimated that there are more than
30
million people in the world who are profoundly deaf.
Currently available cochlear prostheses generally use an internal part containing an electrode array for insertion into the cochlea, and at least some electronics in a sealed subcutaneous package. Information is inductively transmitted through the skin via a head-mounted (magnetically held) device to the subcutaneous package, which package is designed to receive and process coded information for further transmission to the electrode array. The battery and a major part of the acoustic signal-processing electronics are housed in an externally worn device. These designs are not aesthetically pleasing, nor practical for sleeping or for other activities such as diving, swimming or other physical activities. Besides the inconvenience of said designs, there is a social stigma, especially for children, in wearing a head-mounted device, connected to an externally visible apparatus. Additionally, the length of surgery and the surgical complexity of implanting current commercial cochlear prostheses is significant, especially for very young and for very old persons. Said implant procedure involves exposure of the mastoid cortex and external auditory canal of the implanted ear via elevation of a postauricular skin flap, generally requiring 2-4 hours where the patient is totally anesthetized, with the inherent medical risks of total anesthetic. Finally, the cost of said cochlear prostheses is high, limiting the availability of this technology mostly to the wealthy industrialized countries.
In spite of the surgical risks, complexity and device costs, currently available cochlear prostheses do provide a major improvement over the alternative—total deafness. However, there are still great differences in hearing percepts amongst implanted patients. Some patients after implantation are able to use the telephone, while others can only perceive environmental sounds.
Such cochlear prostheses are commercially available from a number of companies worldwide, for example, from Cochlear Limited, Sydney, Australia; Advanced Bionics Corporation, Sylmar, Calif., U.S.A.; Med-El Medical Electronics, Innsbruck, Austria; PHILIPS-Antwerp Bionic Systems N.V./S.A., Edegem, Belgium; and MXM Medical Technologies, Vallauris, France. A comprehensive introduction to the development of cochlear implants is given in, for example, “Cochlear Prostheses,” edited by G. M. Clark, Y. C. Tong and J. F. Patrick, distributed in the U.S.A. by Churchill Livingstone Inc., New York, N.Y. (ISBN 0-443-03582-2), and in “The Cochlear Implant,” (ISSN 0030-6665) by T. J. Balkany, editor of The Otolaryngologic Clinics of North America, Vol. 19, No. 2, May, 1986. Some of the early cochlear implant work is also described in, for example, U.S. Pat. 4,357,497; 4,419,995 and 4,532,930.
Although a commercial totally implanted cochlear prosthesis does not yet exist, A. J. Maniglia in U.S. Pat. 5,906,635 and A. J. Maniglia, et. al. in “The Middle Ear Bioelectronic Microphone for a Totally Implantable Cochlear Hearing Device for Profound and Total Hearing Loss”, in The American J. of Otology, 20:602-611, 1999, describe a possible design for a totally implanted device. Their proposed device uses a permanent magnet attached to the malleus which movement is detected by a nearby coil so as to detect vibrations of the ear drum. Said design uses a relatively complex arrangement of hermetically sealed packages, rods and brackets. A separate external RF linked unit is used to control the volume and on/off functions. The Maniglia prior art has a number of shortcomings namely: (a) said design is not MRI compatible, (b) a large excavation is required in the mastoid cavity to anchor and position said device, (c) mounting a magnet directly onto the ossicular chain can reduce the blood supply, creating the danger of future necrosis of the bone, (d) the device is not suitable for use in newborns, (e) there is no manual panic safety off switch, and (f) there is no allowance for future head growth between the various permanently anchored mounting brackets.
A totally implantable cochlear prosthesis of the present invention is designed to address the limitations of the prior art and to: (a) significantly improve the aesthetics and practical problems of coping with the relatively bulky external components of conventional cochlear prostheses, (b) allow the user to hear more naturally via the auditory canal (ear canal) and (c) enable versatile speech processing algorithms to be used to stimulate the auditory nerve cells for improved speech perception. Additionally, the implant is designed to reduce the surgical complexity and time needed by the surgeon for device implantation.
SUMMARY OF THE INVENTION
In one of its aspects, the invention comprises two parts, namely:
1. An implanted part, and
2. An external part
The implanted part itself embodies further aspects of the invention. The implanted part comprises four principal components:
(a) a housing
(b) a coil
(c) a microphone, and
(d) an electrode array
1. The Implanted Part
The implanted part is a stand-alone fully functional cochlear prosthesis, such functionality only limited by the capacity of the battery, or other storage device, contained within the implant housing. Said implanted part is comprised of a housing, coil, microphone and electrode array, where all components in contact with body tissues are biocompatible, and all non-biocompatible materials are substantially hermetically sealed with biocompatible materials. Such hermetic sealing is required to prevent ingress of biological fluids into the enclosure, creating device malfunction, and/or to prevent leakage of non-compatible material into the surrounding biological tissues. Medical devices such as conventional cochlear prostheses or pacemakers commonly use titanium enclosures (or ceramic enclosures with metal sputtered bonding surfaces) which are hermetically sealed using laser welding. For a brief review of sealing concepts, see for example, S. J. Rebscher's article in Chapter 4 (Cochlear Implant Design and Construction), published in Cochlear Implants, ed. Roger F. Gray, Croon Helm Ltd., London, 1985.
The preferred embodiment is to position the housing and coil substantially against the skull, posterior to the pinna, with the electrode array entering the middle ear via a mastoid cavity and facial recess approach, using either a modified version of a cochleostomy in conjunction with a transcanal approach. Such surgical cavity also allows for convenient positioning of the microphone underneath the skin in the posterior wall of the external auditory canal.
The connections from the microphone and electrode array to the housing are comprised of, preferably, platinum and/or gold wires formed lithographically, said wires encapsulated in a bioinert polymer, such as the fluorocarbon polymer FEP. Said connections are “corrugated” to enable the connections to expand with minimum stress during surgical handling, skull growth, and any post surgical movement of the implanted components.
(a) The Housing
The housing, which contains the wiring interconnections, electronics, battery, means for setting volume and safety “off/on”, and, in an alternate emb
Berrang Peter G.
Bluger Henry V.
Jarvin Stacey D.
Lupin Alan J.
Epic Biosonics Inc.
Jackson Suzette J.
Smith Paul R.
Willse David H.
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