Navigable implantable electrodes and collapsible lubricant reservoirs

Abstract

An implantable electrode device for a cochlear implant system includes an elongated electrode array for insertion into a patient's cochlea. A fluid delivery channel is located within the electrode array, parallel to a central longitudinal axis and has at least one fluid delivery port for delivering a lubricant fluid from the fluid delivery channel to an outer surface of the electrode array. The fluid delivery port and the lubricant fluid are configured to create a lubricated area near an outer surface of the electrode array adjacent to the fluid delivery port during insertion of the electrode array into the patient's cochlea to reduce insertion resistance at an adjacent segment of a side wall of the patient's cochlea.

Description

[0001] This application claims priority to U.S. Provisional Patent Application No. 62 / 584,166, filed on November 10, 2017, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates to medical implants and, more particularly, to implantable electrode devices for cochlear implant systems. Background Art

[0003] Normal ears Figure 1 As shown, the sound is transmitted to the eardrum 102 through the outer ear 101, and the eardrum 102 causes the bones of the middle ear 103 to move, thereby vibrating the oval window and the circular window opening of the cochlea 104. The cochlea 104 is a narrow tube that is spirally wound about its axis for about two and a half turns. The cochlea 104 includes an upper channel called the vestibular scala and a lower channel called the scala tympani, which are connected by the cochlear duct. The cochlea 104 forms an upright spiral cone with a center called the modiolus, and the spiral ganglion cells of the auditory nerve 113 are located on the modiolus. In response to the received sound transmitted by the middle ear 103, the fluid-filled cochlea 104 acts as a transducer to generate electrical pulses, which are transmitted to the cochlear nerve 113 and finally transmitted to the brain.

[0004] Hearing is impaired when there is a problem with the ability of the neural matrix along the cochlea 104 to convert external sounds into meaningful action potentials. In order to improve impaired hearing, hearing prostheses have been developed. For example, when the damage is related to the functioning of the middle ear 103, conventional hearing aids can be used to provide acoustic-mechanical stimulation to the auditory system in the form of amplified sound. Or when the damage is related to the cochlea 104, a cochlear implant with an implanted electrode can electrically stimulate the auditory nerve tissue with a small current delivered by a plurality of electrode contacts distributed along the electrode.

[0005] Figure 1 Also shown are some components of a typical cochlear implant system, where an external microphone provides an audio signal input to an external signal processor 111 that is capable of performing various signal processing schemes. The processed signal is then converted to a digital data format for transmission by an external transmitter coil 107 to the implant 108. In addition to receiving the processed audio information, the implant 108 also performs other signal processing, such as error correction, pulse forming, etc., and (based on the extracted sound information) generates a stimulation pattern that is transmitted to an implanted electrode array 110 via electrode leads 109. Typically, such an electrode array 110 includes a plurality of stimulation contacts 112 on its surface that provide selective stimulation of the cochlea 104.

[0006] The electrode array 110 includes a plurality of electrode wires embedded in a soft silicone body called an electrode carrier. The electrode array 110 needs to be mechanically strong, yet flexible and of small size for insertion into the cochlea 104. In order to minimize trauma to the neural structures of the cochlea 104, the material of the electrode array 110 needs to be soft and flexible. However, an electrode array 110 that is too floppy tends to buckle too easily, making it impossible for the electrode array 110 to be inserted into the cochlea 104 to the desired insertion depth. A trade-off needs to be made between a certain hardness of the electrode array 110 that allows insertion into the cochlea 104 to the desired insertion depth without buckling of the array, and a certain flexibility of the electrode array 110 that keeps the mechanical forces acting on the scala tympani structure of the cochlea 104 sufficiently low.

[0007] Injury and trauma cause bleeding, inflammation, perforation of soft tissue, tears and holes in membranes, and fracture of thin bone structures. For example, damage to the inner ear can cause loss of viable hair cells, retrograde degeneration of dendrites innervating the organ of Corti, and in the worst case, death of spiral ganglion cells in Rosenthal's canals. Cell death means quantitatively less neural tissue available for stimulation, and qualitatively, fewer frequency-tuned fibers available to represent frequency information.

[0008] Cochlear implant electrode array design and surgical techniques attempt to minimize the trauma of the implantation procedure so that the electrode array can be inserted into the cochlea as smoothly and without resistance as possible, either at the tip of the electrode array or elsewhere on the outer surface of the electrode array. In some cases, there may be resistance during electrode insertion. For example, Figure 2 A cross-sectional view of the cochlea 104 is shown during insertion of the electrode array 110 through the electrode opening 201, wherein the tip 202 contacts the outer side wall 203 at the first turn. When this happens, the surgeon either stops insertion so that only a portion of the length of the electrode array 110 is within the cochlea 104, or the surgeon increases the insertion force to push the electrode array 110 beyond the resistance point, causing trauma within the cochlea 104.

[0009] The size and mechanical properties of the electrode array are key parameters for optimal patient benefit. Some electrode array designs are pre-bent, but the disadvantage of this approach is that a special electrode insertion tool is required to keep the electrode array straight until the insertion point. As described in the literature of Erixon et al., Variational Anatomy of the Human Cochlea: Implications for Cochlear Implantation, Otology & Neurotology, 2008 (incorporated herein as a reference), the size, shape and curvature of the cochlea vary greatly between individuals, which means that the cochlear implant electrode array must be matched with a variety of scala tympani (ST) geometries. In addition, a recent study published by Verbist et al., Anatomical Considerations of Cochlear Morphology and Its Implications for Insertion Trauma in Cochlear Implant Surgery, Otology & Neurotology, 2009 (incorporated herein as a reference) shows that the human ST is not inclined toward the cochlear opening at a constant slope, but has several sections of slope changes along the ST, sometimes even becoming a negative slope (i.e., downward). The location and magnitude of these slope changes have also been found to vary between individuals. Therefore, CI electrode arrays should be highly flexible in all directions to accommodate individual variations in the curvature and slope changes of the ST for minimally invasive implantation.

[0010] It is known to provide fluid delivery channels within the electrode array to deliver therapeutic drugs and / or insertion lubricants to the outer surface of the electrode array. For example, one such device is described in U.S. Patent Publication 2017 / 0028182 (incorporated herein by reference in its entirety). Summary of the invention

[0011] Embodiments of the present invention relate to an implantable electrode device for a cochlear implant system. An elongated electrode array is configured for insertion into a patient's cochlea. The electrode array has a central longitudinal axis and an outer surface having a plurality of stimulation contacts for transmitting electrical stimulation signals to adjacent cochlear nerve tissue. A fluid delivery channel is located within the electrode array, the fluid delivery channel being parallel to the central longitudinal axis and having at least one fluid delivery port for delivering a lubricant fluid from the fluid delivery channel to the outer surface of the electrode array. The fluid delivery port and the lubricant fluid are configured to create a lubricated area near the outer surface of the electrode array adjacent to the fluid delivery port to reduce insertion resistance at an adjacent segment of a side wall of the patient's cochlea.

[0012] In further specific embodiments, the lubricant fluid is characterized in that when the lubricant fluid contacts the perilymph in the patient's cochlea, a solid lubrication area is formed between the electrode array and the sidewall. The electrode array may include a top end that accommodates at least one fluid delivery port. The outer surface of the electrode array may have an outer side that accommodates at least one fluid delivery port. The at least one fluid delivery port may be a plurality of fluid delivery ports or a single fluid delivery port.

[0013] There can be at least one fluid reservoir connected to the fluid delivery channel and containing lubricant fluid, the at least one fluid reservoir being configured to collapse irreversibly under compressive pressure to deliver the lubricant fluid through the at least one fluid delivery port without forming a suck back into the fluid delivery channel. The at least one fluid reservoir includes a metal layer configured to collapse irreversibly. The at least one fluid reservoir can be a plurality of fluid reservoirs or a single fluid reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Shown are various structures in a human ear with a cochlear implant.

[0015] Figure 2 A cross-sectional view of the insertion of an electrode into the cochlea of ​​a patient is shown.

[0016] FIG. 3A to FIG. 3C A cross-sectional view of a cochlear implant electrode with a fluid delivery device according to an embodiment of the present invention is shown.

[0017] FIG. 4A to FIG. 4B A cross-sectional view of a cochlear implant electrode having a fluid delivery device according to another embodiment of the present invention is shown inserted.

[0018] FIG. 5A to FIG. 5B A cross-sectional view of a cochlear implant electrode with a fluid delivery device according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0019] Embodiments of the present invention relate to an implantable electrode device for a cochlear implant system having an electrode array including a fluid delivery channel and one or more fluid delivery ports. The fluid delivery ports and lubricant fluid are configured to create a lubricated area on an outer surface of the electrode array adjacent to the fluid delivery port during insertion of the electrode array into a patient's cochlea to reduce insertion resistance at adjacent sections of a side wall of the patient's cochlea. The electrode can also be prevented from contacting delicate structures of the side wall during insertion.

[0020] FIG. 3A to FIG. 3CA cross-sectional view of an elongated cochlear implant electrode array 301 for insertion into a patient's cochlea 104 is shown according to an embodiment of the present invention. A fluid delivery channel 302 is located within the electrode array 301 and has a fluid delivery port 303 on the outside of the top end 304 of the electrode array 301 for delivering a lubricant fluid 306 from the fluid delivery channel 302 to the outer surface of the electrode array 301. This creates a lubricated area 307 near the outer surface of the electrode array 301 adjacent to the fluid delivery port 303 during insertion of the electrode array 301 into the patient's cochlea 104 to reduce insertion resistance at adjacent sections of the side wall 305 of the patient's cochlea 104. The lubricant fluid 306 can be a biocompatible lubricant selected from hyaluronic acid or a biocompatible polyethylene glycol-based lubricant with special end groups that readily react with the perilymph to form a solidified hydrogel that is resorbable over time. Figure 3C In the embodiment shown in , the fluid delivery port 303 on the top 304 of the electrode array 301 is adapted to release lubricant in such a way that when the lubricant contacts the perilymph in the patient's cochlea 104, a solid chute lubrication area 307 is formed between the electrode array 301 and the sidewall 305. In this configuration, the fluid delivery port 303 may include two or more openings for fluid delivery that are laterally separated on the outer surface of the electrode array 301. The openings may have a cross-section that varies relative to each other to control fluid flow resistance and fluid delivery between the openings. During insertion, the electrode array 301 may slide on the solid chute and thereby support the electrode array 301 to be held on the solid lubricant area 307 so as to "curl" or "navigate" the electrode during insertion into the scala tympani and avoid touching delicate structures, such as at the sidewall 305.

[0021] exist Figure 3BIn the illustrated embodiment, the tip 304 of the electrode array 301 is formed to support electrode curling during insertion. The tip 304 has a tapered design toward the tip of the electrode array. The tapering can be linear evenly around the lateral outer surface of the electrode array 301 (not shown) and / or along the longitudinal direction of the electrode array 301. In another embodiment, the tapering can be non-linear along the longitudinal direction of the electrode array 301 and more significantly offset from the tip of the electrode array and at the fluid delivery port 303 or slightly behind the fluid delivery port 303. The significant tapering can be located only at the lateral position of the electrode array 301 where the fluid delivery port 303 is arranged. With this electrode design, while the lubricant fluid is released through the fluid delivery port 303, a lubricant area 307 will be formed partially in front of the electrode array 301 (as seen in the insertion direction). During the subsequent insertion into the scala tympani, the electrode array 301 slides on the solidified lubricant. Due to the conical taper design of the tip 304 and the lubricant area 307 in front of the electrode array 301, this allows the electrode array 301 to be bent or curled away from a straight insertion direction. This avoids contact with delicate structures, such as the sidewalls 305. The fluid delivery port 303 can be similar to the previously described Figure 3B The adaptation is performed in the same manner as described.

[0022] Those skilled in the art will appreciate that any fluid delivery system can be used to implement the electrode device of the present invention as described above. In a preferred exemplary embodiment, the fluid reservoir 308 is connected to the fluid delivery channel 302 and contains a certain amount of lubricant fluid 306. During the surgical insertion of the electrode array 301 into the patient's cochlea 104, if insertion resistance is generated, the surgeon can provide squeezing of the fluid reservoir 308 to generate a compression pressure, which pushes the lubricant fluid 306 through the fluid delivery channel 302 and flows out of the open fluid delivery port 303 to form a lubricating area 307 that lubricates the outer surface of the electrode array 301, thereby overcoming the resistance. The fluid reservoir 308 collapses irreversibly under the compression pressure without returning to its original shape. For example, the fluid reservoir 308 can have a metal layer so that it collapses under the compression pressure without returning to its original shape. This prevents the occurrence of back suction, which tends to undesirably suck the fluid / perilymph mixture back into the fluid delivery channel 302. In addition to lubricants, the reservoir / channel / port arrangement may also provide therapeutic drug fluids to the outer surface of the electrode array 301 .

[0023] FIG. 4A to FIG. 4BA cross-sectional view of a cochlear implant electrode having a fluid delivery device having multiple fluid delivery ports and multiple fluid reservoirs according to another embodiment of the present invention is shown. An elongated electrode array 401 is configured for insertion into a patient's cochlea 104. The electrode array 401 has a central longitudinal axis 410 and an outer surface 409 having multiple stimulation contacts 412 for transmitting electrical stimulation signals to adjacent cochlear nerve tissue.

[0024] A plurality of fluid reservoirs 408 are connected in series to the fluid delivery channel 402 and contain lubricant fluid 405. The terminal fluid reservoir 413 has a relatively thick silicone septum 411 that can be pierced by a syringe needle to fill the fluid reservoirs 408 and the fluid delivery channel 402 with lubricant fluid.

[0025] The fluid delivery channel 402 is located within the electrode array 401, parallel to the central longitudinal axis 410, and has a plurality of fluid delivery ports 403 on the outer side of the outer surface 409 for delivering the lubricant fluid 405 from the fluid delivery channel 402 to the outer surface of the electrode array 401. The fluid delivery ports 403 and the lubricant fluid 405 are configured to create a lubricated area on the outer surface 409 of the electrode array 401 adjacent to the fluid delivery ports 403 during the insertion of the electrode array 401 into the patient's cochlea 104, so as to reduce the insertion resistance at the adjacent section of the side wall of the patient's cochlea 104; for example, near the top 404 of the electrode array 401.

[0026] FIG. 5A to FIG. 5B A cross-sectional view of a cochlear implant electrode array 501 with a fluid delivery device according to another embodiment of the present invention is shown, which uses a fluid reservoir 508 and multiple fluid delivery ports 503. The insertion of the electrode array 501 can be controlled during robotic surgery, where the insertion depth is continuously measured and the controller of the surgical robot injects lubricant fluid 506 in appropriate amounts and times to lubricate the electrode array 501 where it contacts the side wall 505 of the cochlea 104.

[0027] Although the present invention has been described in conjunction with specific embodiments of the present invention, it will be appreciated that the present invention is capable of further modifications. This application is intended to cover any modification, use or modification of the present invention, and includes deviations from the present disclosure within the known or customary practice in the field to which the present invention belongs.

Claims

1. An implantable electrode device for a cochlear implant system, comprising: an elongated electrode array configured for insertion into a patient's cochlea, the electrode array having a central longitudinal axis and an outer surface having a plurality of stimulation contacts configured to deliver electrical stimulation signals to adjacent cochlear nerve tissue; as well as a fluid delivery channel within the electrode array, parallel to the central longitudinal axis and having at least one fluid delivery port, the fluid delivery port configured to deliver lubricant fluid from the fluid delivery channel to an outer surface of the electrode array; wherein the fluid delivery port and the lubricant fluid are configured to create a lubricated area near an outer surface of the electrode array adjacent to the fluid delivery port during insertion of the electrode array into the patient's cochlea to reduce insertion resistance at an adjacent segment of a lateral wall of the patient's cochlea, and The lubricant fluid is characterized in that, when the lubricant fluid contacts the perilymph in the patient's cochlea, a solid lubrication area is formed between the electrode array and the side wall.

2. The implantable electrode device according to claim 1, wherein: The electrode array includes a top end that houses the at least one fluid delivery port.

3. The implantable electrode device according to claim 1, wherein: The outer surface of the electrode array has an outer side that accommodates the at least one fluid delivery port.

4. The implantable electrode device according to claim 1, wherein: The at least one fluid delivery port is a plurality of fluid delivery ports.

5. The implantable electrode device according to claim 1, wherein: The at least one fluid delivery port is a single fluid delivery port.

6. The implantable electrode device according to claim 1, further comprising: and at least one fluid reservoir connected to the fluid delivery passage and containing the lubricant fluid, wherein the at least one fluid reservoir is configured to irreversibly collapse under a compressive pressure to deliver the lubricant fluid through the at least one fluid delivery port without causing a suck back into the fluid delivery passage.

7. The implantable electrode device according to claim 6, wherein: The at least one fluid reservoir comprises a metal layer configured for irreversible collapse.

8. The implantable electrode device according to claim 6, wherein: The at least one fluid reservoir is a plurality of fluid reservoirs.

9. The implantable electrode device according to claim 6, wherein: The at least one fluid reservoir is a single fluid reservoir.

10. The implantable electrode device according to claim 1, wherein: The elongated electrode array further comprises a top end having a tapered design toward the tip of the electrode array, wherein one of the fluid delivery ports is located at an outboard position of a tip of the electrode array, such that the one fluid delivery port and the lubricant fluid are configured to create a lubricated area proximate an outer surface of the electrode array adjacent the fluid delivery port during insertion of the electrode array into the patient's cochlea, and Wherein, the lubricant fluid is configured to react with perilymph fluid within the patient's cochlea to form a solidified hydrogel between the electrode array and the side wall during insertion.

11. The implantable electrode device according to claim 10, wherein: The taper of the top end is linear along the longitudinal direction of the electrode array.

12. The implantable electrode device according to claim 10, wherein: The taper of the top end is non-linear along the longitudinal direction of the electrode array.

13. The implantable electrode device according to claim 12, wherein: The taper is more significantly offset in the longitudinal direction from the electrode array tip and at the fluid delivery port.

14. The implantable electrode device according to claim 12, wherein: The taper is more significantly offset in the longitudinal direction from the electrode array tip and slightly behind the fluid delivery port.

15. The implantable electrode device according to claim 13 or 14, wherein: The significant taper is only located at the lateral locations on the electrode array where the fluid delivery ports are arranged.

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