# Patent

## Title
Middle ear fixation structure

## Abstract

An implantable fixation structure includes at least one implantable holding element. The holding element is connected to an implantable cochlear implant element and maintains the cochlear implant element in a desired position relative to the middle ear of a patient user.

## Background
This application claims priority to U.S. Provisional Patent Application 60/825,297, filed Sep. 12, 2006, the contents of which are hereby incorporated by reference.


FIELD OF THE INVENTION
The present invention relates to cochlear implants and, more particularly, to implantable fixation structures which enable the fixation of one or more cochlear implant elements in a desired position in the middle ear of a patient user.
BACKGROUND ART
Cochlear implants are electronic systems designed to provide useful hearing and improved communication ability to individuals who are profoundly hearing impaired and unable to achieve speech understanding with conventional hearing aids. A typical system includes an implantable stimulator containing electronic circuitry, a coil for power and information transfer, and a stimulation electrode array which is inserted into the inner ear (and perhaps a counter electrode).
In addition to such inner ear applications, there are also concomitant applications to detect and/or measure signals from the stapedius muscle/tendon or other middle ear functions that would be beneficial to the patient and improve the adaptation of cochlear implants. U.S. Pat. No. 6,205,360 (hereby incorporated by reference) describes a middle ear electrode for determining stimulation parameters by detecting the activity of the stapedius muscle. No specific fixation structure is described or suggested for attaching the stapedius monitoring electrode to the stapedius muscle. U.S. Pat. No. 6,636,768 (hereby incorporated by reference) describes another application of an implantable middle ear device including a microphone system which is used together with cochlear implant devices, and where the implantable sensor (i.e. implantable microphone) includes a stationary component and a movable component. The stationary component is implanted so that at least a portion resides within the middle ear and does not come in contact with the movable component. In contrast, the movable component is implanted within the middle ear and is attached to one of the moving elements such as malleus, incus, stapes, oval window or tympanic membrane. But again, no detailed description is provided for the fixation and/or mounting of such implantable devices in the middle ear.
SUMMARY OF THE INVENTION
Many cochlear implant systems need a fixation structure adapted for placement in the middle ear cavity to stably fix of one or more cochlear implant elements such as electronic sensors such as for measuring an electrically evoked stapedius reflex threshold (ESRT), additional implantable electrodes, electro-mechanical actuators (e.g. Floating Mass Transducer), implantable microphone or other arbitrary devices without disrupting the cochlear implant electrodes, effecting injuries in the middle ear, or interfering with the middle ear functions.
Embodiments of the present invention include an implantable fixation structure having at least one implantable holding element connected to a cochlear implant element which maintains the cochlear implant element in a desired position relative to the middle ear of a patient user. The cochlear implant element may include at least one of an electronic sensor, an electro-mechanical actuator, an implantable electrode, and an implantable microphone.
Further embodiments include an anchoring element for maintaining the fixation structure in a desired implanted position. For example, a u-shaped fixation clip anchoring element may be fixed to the bony bridge of the middle ear and/or may be attached to an implantable electrode. The anchoring element may use at least one of crimping, clipping, gluing, sticking, and screwing for maintaining the fixation structure in the desired implanted position.
Some embodiments may also include a position adjuster connected to the cochlear implant element for adjusting the positioning of the cochlear implant element relative to the middle ear. For example, the position adjuster may include a positioning bar connected to the cochlear implant element. The position adjuster may include a u-shaped or rolling clip fixation clip for coupling to the cochlear implant element to the positioning bar. The fixation clip may be perpendicular to the positioning bar. The position adjuster may include a coupling hole surrounding at least a portion of the cochlear implant element and/or a coupling platform for coupling the cochlear implant element to the positioning bar.
In some embodiments, the holding element may include a ring-shaped holder; for example, with two, three, or four ring segments. The holding element may be attached to a part of the middle ear, for example, by attachment to the bony bridge of the middle ear. The holding element may include a coupling hole surrounding at least a portion of the cochlear implant element and/or a coupling platform for coupling the cochlear implant element to the fixation structure.
The holding element may include a stent-like tube for insertion into a mastoidectomy of the patient user. The stent-like tube may include flexible biocompatible wire gauze and/or have a diameter larger than a facial recess of the mastoidectomy. There may be a coupling clip on one side of the stent-like tube for coupling to the cochlear implant element. The coupling clip may be u-shaped or a rolling clip. In some embodiments, the holding element may include a flexible tentacle structure for insertion into a mastoidectomy of the patient user.



BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing features of the invention will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings, in which:
FIG. 1 shows an implantable fixation structure including a fixation clip which is attached to the bony bridge;
FIG. 2 shows an implantable fixation structure similar to FIG. 1 with a fixation clip that is attached to a cochlear electrode array;
FIG. 3a shows a front view of an implantable fixation structure with a platform for mounting other devices, and which is attached to a cochlear electrode array;
FIG. 3b shows the fixation structure of FIG. 3a in a side view;
FIG. 4A shows an embodiment of an implantable fixation structure including two fixation clips attached to the bony bridge and the stimulation electrode array, and provided with a platform which is situated in the middle of the bar structure;
FIG. 4B shows an implantable fixation structure similar to the one in FIG. 4a, with a hole in the middle of the bar structure;
FIG. 4C shows an implantable fixation structure similar to the one in FIG. 4a, with a clip in the middle of the bar structure;
FIG. 4D shows an implantable fixation structure similar to the one in FIG. 4a, with a pen-ball clip in the middle of the bar structure;
FIG. 5A shows an implantable fixation structure including a clip and a ring-shaped structure;
FIG. 5B shows an implantable fixation structure including two clips and a ring-shaped holder situated in the middle;
FIG. 6 shows an implantable fixation structure including a wire gauze stent-like tube and a clip on one side; and
FIGS. 7A and 7B show a tentacle structure embodiment of an implantable fixation structure.



DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
One problem with fitting young children (as well as some adults) with cochlear implants is the difficulty measuring a comfortable level of response to the electric stimulation. Such persons may not be able to verbally or otherwise express what is a tolerable level of electric stimulation. With respect to such electrical stimulation, electrical potentials may be developed by a sensor which measures contractions and other movements of the stapedius muscle or tendon in the middle ear, and such signals are related to the comfort level of electric stimulation for that person.
Recording an electrically evoked stapedius reflex threshold (ESRT) may allow the objective fitting of the cochlear implant. Recording the ESRT begins by placing a sensing electrode or other sensor onto the stapedius muscle or tendon. The sensing device should be small and adapted to the size of the muscle or tendon. But, after a stimulating electrode has been inserted into the cochlea, it is difficult to bring a sensing device to the tendon with typical surgical tools. The space is very tight and any movement to approach the tendon or muscle carries a risk of displacing the inserted cochlear stimulating electrode.
Embodiments of the present invention provide an implantable fixation structure to fix and attach one or more cochlear implant elements such as electronic sensors, additional implantable electrodes, electro-mechanical actuators (e.g. Floating Mass Transducer), implantable microphones or other arbitrary devices, and bring them into contact with the stapedius muscle/tendon or other structures in the middle ear, after an electrode array has been inserted into the cochlea. Thus, an implantable fixation structure includes at least one implantable holding element, which is connected to an implantable cochlear implant element and maintains the cochlear implant element in a desired position relative to the middle ear of a patient user.
FIG. 1 shows an embodiment of an implantable fixation structure 101 with only a single holding element. In this case, an anchoring element in the form of a u-shaped fixation clip 102 is attached to the bony bridge 105 of the middle ear to maintain the fixation structure 101 in a desired position relative to the structures of the middle ear. The fixation clip 102 is connected through a positioning bar 103 with a holding element, u-shaped coupling clip 104 that is perpendicular to the fixation clip 102. After the fixation structure 101 is attached to the bony bridge 105, a cochlear implant element 106 such as an electronic sensor or electro-mechanical actuator can be attached to the coupling clip 104. The thin positioning bar 103 acts as a position adjuster which allows for horizontal and vertical movements within a given range until a desired optimal position is found for the cochlear implant element 106. In other specific embodiments, the anchoring element may use crimping, clipping, gluing, sticking, and/or screwing to maintain the fixation structure 101 in the desired implanted position.
FIG. 2 shows another embodiment of an implantable fixation structure 201 similar to that of FIG. 1 with a fixation clip 202 that is attached to a stimulation electrode array 205. A thin positioning bar 203 connects the fixation clip 202 to a coupling clip 204 for mounting of a cochlear implant element 206 that is perpendicular to the fixation clip 202. After the fixation structure 201 is attached to the stimulation electrode array 205, the cochlear implant element 206 is connected to the coupling clip 204.
FIGS. 3A and 3B show an embodiment of a fixation structure 301 for carrying two cochlear implant elements. Two fixation clips 304 and 305 are attached to a stimulation electrode array 302. Coupling platform 303 is connected to the two fixation clips 304 and 305 by a thin positioning bar 306 which allows for horizontal and vertical position adjustments in a given range. The fixation clips 304 and 305 are connected through a thin connecting bar 307. A first sensor device 308 is connected to the top of the coupling platform 303. A sensor cantilever 309 engages the stapedius tendon.
FIG. 4A shows the embodiment of another fixation structure 401 including two fixation clips 402 and 403 which are orientated perpendicular to each other. The first fixation clip 402 is attached to a stimulation electrode array 405 and the other fixation clip 403 is attached to the bony bridge 406. Both fixation clips 402 and 403 are connected together through a positioning bar 404. A part of the bar structure is rolled up as shown in FIG. 4A to afford a coupling platform 407 on which a sensor device 408 is placed. The connection of the coupling platform 407 compared to the positioning bar 404 is thin enough to provide for horizontal and vertical position adjustments in a given range and stiff enough to ensure stabilization.
FIG. 4B shows a fixation structure similar to FIG. 4A which includes a coupling hole 409 in the positioning bar 404 instead of a coupling platform 407. The coupling hole 409 surrounds and attaches at least a portion of the cochlear implant element, sensor 408. Due to the coupling hole 409, the positioning bar 404 may benefit from reinforcement with additional material. Once the cochlear implant element has been placed in an optimal position, the positioning bar 404 is crimped with a small gripper to attach the sensor 408 to the fixation structure.
FIG. 4C shows a fixation structure 411 which is similar to 401 (FIG. 4A) including two fixation clips 402 and 403 with a connecting bar 404 in between. A coupling clip 410 is situated perpendicular to the bar structure 404. After the fixation structure 411 is attached to the bony bridge 406 and the stimulation electrode array 405, a cochlear implant element is plugged into the coupling clip 410.
FIG. 4D shows a fixation structure 413 which is similar to 401 including two fixation clips 402 and 403 and a connecting bar 404 in between. A rolling clip 412 is situated perpendicular to the bar structure 404 for fixing a cochlear implant element. The rolling clip 412 has a wave-like shape which is open on one side to insert the corresponding device. After the fixation structure 413 is attached to the stimulation electrode array 405 and bony bridge 406 or other middle ear structure, the cochlear implant element is plugged laterally into the rolling clip 412.
FIG. 5A shows a fixation structure 501 which has a similar fixation clip 502 like the one shown in FIG. 1. A positioning bar 503 connects the fixation clip 502 with a ring-shaped holder 504 which looks like a spoke wheel. In one embodiment, the fixation clip 502 is orientated perpendicular to the ring-shaped holder 504. The ring-shaped holder 504 is divided into several ring segments 505—for example, two, three or four ring segments—which allow for coupling of one or more sensors, actuators and/or stimulation electrode array 506.
FIG. 5B shows an embodiment of a fixation structure 507 similar to FIG. 5A comprising of a further fixation clip 508 which is attached to the stimulation electrode array 509. The fixation clips 502 and 508 are connected to the ring-shaped holder 504 through a small bar structure 503.
FIG. 6 shows a stent-like tube 601 composed of wire gauze. The stent-like tube 601 has a larger diameter than the average mastoidectomy. A coupling clip 602 fixes in place a cochlear implant element. The coupling clip 602 is attached to and inside the stent-like tube 601.
FIGS. 7A and 7B show a flexible tentacle structure 701 which is insertable into a mastoidectomy. FIG. 7A shows the fixation device from a front view, and FIG. 7B shows the same tentacle structure from above. Due to the flexible tentacles, a fixed anchorage is given in the mastoidectomy. A coupling clip 702 or mounting platform 703 is attached to the tentacle structure to attach a cochlear implant element.
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.

## Claims

1. An implantable fixation structure comprising:
an implantable holding element including a coupling platform connecting parallel c-shaped clips connected to a cochlear implant electrode array element; and
an adjustable positioning bar connected at one end to the holding element and at the other end to an electronic sensor element for maintaining the electronic sensor element in a desired position relative to stapedius tissue in a middle ear of a patient user;
wherein the positioning bar allows horizontal and vertical position adjustments for positioning the electronic sensor element into desired engagement with the stapedius tissue.

2. An implantable fixation structure according to claim 1, wherein the electronic sensor element includes a stapedius reflex sensor.

3. A cochlear implant system having an implantable fixation structure according to claim 1.