Patent Application
20120245534
The present invention relates to an implantable electrode for auditory prostheses.
A normal ear transmits sounds as shown in
Hearing is impaired when there are problems in the ability to transduce external sounds into meaningful action potentials along the neural substrate of the cochlea 104. In some cases, hearing impairment can be addressed by an auditory prosthesis system such as a cochlear implant that electrically stimulates auditory nerve tissue with small currents delivered by multiple electrode contacts distributed along an implant electrode.
There are many inner ear disorders which can lead to some degree of hearing loss. Among these are sudden hearing loss, noise induced hearing loss, progressive hearing loss, aminoglycoside induced hearing loss, presbiyacusis etc., autoimmune inner ear disorder, and infections (bacterial, viral, fungal). Many of the diseases that lead to partial or total hearing loss could utilize a therapeutic pharmaceutical treatment to reach some tissue or cells within the inner ear, for example, to arrest or reverse the hearing loss and improve hearing. Examples of therapeutic pharmaceutical molecules include without limitation cortico-steroids, peptides, and other proteins.
But there are relatively few ways to deliver therapeutic drugs to the inner ear. Typical clinical practice involves either oral, veinous, or arterial drug delivery. Topical drug delivery to treat the inner ear is limited to deposition of the drug at the round window and relying on diffusion of the drug through the round window to reach targeted cells. This may be accomplished by flooding the middle ear cavity with the drug in liquid form, or by applying a soaked sponge at or near the round window, for example, through an opening in the tympanic membrane. But a diffusion process through the round window is not particularly predictable or reliable. The permeability of the round window varies greatly between patients and by other criteria such as time of day, physical conditions, application methods, drug used. Thus, the amount of drug that reaches the inner ear through such delivery methods may vary anywhere between zero and toxically too much.
U.S. Patent Publication 20090259267 describes an implantable electrode with an enlarged fluid storage reservoir that stores a treatment volume of therapeutic fluid for an extended therapeutic treatment period. One or more fluid delivery ports connect the fluid storage reservoir to the outer surface of the electrode for delivering the therapeutic fluid from the fluid storage reservoir to the outer surface.
Embodiments of the present invention are directed to an ear implant electrode device. An implantable electrode array has an outer surface with electrode contacts for electrically stimulating adjacent neural tissue. There is a fluid delivery channel within the electrode array for delivering a therapeutic fluid through one or more fluid delivery ports on the outer surface. A temporary fill tube is connected to the fluid delivery channel for providing the therapeutic fluid when the electrode array is partially inserted into patient neural tissue without being functional after the electrode array is fully inserted. At least a portion of the fill tube is adapted for removal after providing the therapeutic fluid to have the fluid delivery channel and any remaining portion of the fill tube completely enclosed within the neural tissue after the electrode array has been fully inserted so as to leave no exposed fluid opening outside the neural tissue.
The fill tube may have a free end that extends into a posterior tympanotomy or even a mastoidectomy when the electrode array is partially inserted. The at least a portion of the fill tube may be adapted for removal by cutting, for example, by cutting the fill tube flush with the outer surface of the electrode array.
Embodiments of the present invention also include a method of delivering a therapeutic fluid with an ear implant electrode. An electrode array is partially inserted into patient neural tissue, which array includes an outer surface including a plurality of electrode contacts for electrically stimulating adjacent neural tissue, a fluid delivery channel within the electrode array for delivering a therapeutic fluid through at least one fluid delivery port on the outer surface, and a temporary fill tube connected to the fluid delivery channel. The therapeutic fluid is provided to the fluid delivery channel via the fill tube to deliver the therapeutic fluid through the at least one fluid delivery port to the outer surface of electrode array. At least a portion of the fill tube is removed and the insertion of the electrode array into the patient neural tissue is completed so that the fluid delivery channel and any remaining portion of the fill tube are completely enclosed within the neural tissue so as to leave no exposed fluid opening outside the neural tissue.
The fill tube may have a free end that extends into a posterior tympanotomy or even a mastoidectomy when the electrode array is partially inserted. And removing the at least a portion of the fill tube may include cutting the fill tube, for example, cutting the fill tube flush with the outer surface of the electrode array.
The ear implant system may include a cochlear implant system, an auditory brainstem implant system, or a vestibular implant system. And embodiments of the present invention also include an ear implant system having an electrode arrangement according to any of the above.
It would be useful to be able to safely deliver therapeutic drugs to the cochlea during implantation of cochlear electrodes. For example, corticosteroid could be useful for the treatment of cochlear inflammation after opening the scala and inserting the electrode. It would also be beneficial to bring other type of therapeutic drugs to the cochlea for acting on the spiral ganglion cells and the cochlear neurites. Some peptides in the form of nerve growth factors also could be useful. With any drug delivery to the inner ear, it is important to bring a precise and controlled dose into the scala at specific locations other that the very base of the cochlea.
In the past, this problem has been addressed by injecting a small amount of drug with a needle at the entrance point of the electrode into the cochlea during implantation. Alternatively, the electrode has been dipped in a drug solution in the hope that a coating of the drug would stay on the electrode during insertion. In another approach, the drug has been placed at the round window of the cochlea before electrode insertion in the hope that some diffusion would occur before, during, or after surgery. Other methods proposed have been a drug delivery reservoir connected to a port and septum for filling or refilling, and to load crystal-form drugs in the silicone carrier material of the electrode and rely on diffusion out of the silicone.
Embodiments of the present invention are directed to an improved ear implant electrode device. This novel approach uses a temporary fill tube that is used after the electrode has been partially inserted to deliver therapeutic drugs to the inner ear. After delivery of the drugs, the fill tube is removed and insertion of the electrode is completed. This ensures that after the implantation surgery all the fluid delivery structures are completely enclosed within the cochlea so as to leave no fluid opening outside the cochlea. This ensures that any future infection in the middle ear does not spread through the implanted electrode into the inner ear, a potentially deadly complication that could otherwise arise.
A temporary fill tube 202 is connected to the fluid delivery channel 203 for providing the therapeutic fluid when the electrode array 201 is partially inserted into a patient cochlea. The free end of the fill tube 202 may extend back into a posterior tympanotomy or even a mastoidectomy when the electrode array 201 is partially inserted during implantation surgery. At least a portion of the fill tube 202 is adapted for removal after providing the therapeutic fluid so that the fluid delivery channel 203 and any remaining portion of the fill tube 202 remain completely enclosed within the cochlea after the electrode array 201 has been fully inserted so as to leave no fluid opening outside the cochlea. For example, a portion of the fill tube 202 may removable by cutting the fill tube 202 flush with the outer surface of the basal end 207 of the electrode array 201.
During surgical implantation, the electrode array 201 is partially inserted into the patient cochlea, step 401 in
Although various exemplary embodiments of the invention have been disclosed, it should be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention without departing from the true scope of the invention.
This application claims priority from U.S. Provisional Patent 61/467,474, filed Mar. 25, 2011, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61467474 | Mar 2011 | US |
