WO2016168245A1

WO2016168245A1 - Cochlear implant stabilization in the mastoid bone

Info

Publication number: WO2016168245A1
Application number: PCT/US2016/027208
Authority: WO
Inventors: Abdulrahman Abdullah HAGR; Claude Jolly; Anandhan Dhanasingh
Original assignee: Med-El Elektromedizinische Geraete Gmbh
Priority date: 2015-04-14
Filing date: 2016-04-13
Publication date: 2016-10-20
Also published as: EP3284270A4; AU2016102345A4; EP3284270A1

Abstract

A cochlear implant system is described which includes an implant housing that includes an inward planar surface fits against an outer temporal bone surface of the implant patient, an outward planar surface is parallel to the inward planar surface and fits against overlying skin of the implant patient, and an outer perimeter around each of the planar surfaces forms a connecting surface between the planar surfaces. An implant stabilizer fits over a portion of the connecting surface at the radial outer perimeter and extends into a mastoid bowl opening in the temporal bone of the implant patient. At least one stabilizer attachment element connects to the implant stabilizer parallel to the planar surfaces and project towards the temporal bone at the mastoid bowl opening to fixedly secure the implant housing against the outer temporal bone surface.

Description

Cochlear Implant Stabilization in the Mastoid Bone

[0001] This application claims priority from U. S. Provisional Application 62/147,025, filed April 14, 2015, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to hearing implant systems such as cochlear implant systems, and specifically to arrangements to securely stabilize an implantable housing for such a system against the mastoid/temporal bone.

BACKGROUND ART

[0003] A normal ear transmits sounds as shown in Figure 1 through the outer ear 101 to the tympanic membrane (eardrum) 102, which moves the bones of the middle ear 103, which in turn vibrate the oval window and round window openings of the cochlea 104. The cochlea 104 is a long narrow duct wound spirally about its axis for approximately two and a half turns. The cochlea 104 includes an upper channel known as the scala vestibuli and a lower channel known as the scala tympani, which are connected by the cochlear duct. The scala tympani forms an upright spiraling cone with a center called the modiolar where the spiral ganglion cells of the acoustic nerve 113 reside. In response to received sounds transmitted by the middle ear 103, the fluid filled cochlea 104 functions as a transducer to generate electric pulses that are transmitted to the cochlear nerve 113, and ultimately to the brain. 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.

[0004] In some cases, hearing impairment can be addressed by a cochlear implant (CI) that electrically stimulates auditory nerve tissue with small currents delivered by multiple electrode contacts distributed along an implant electrode. Figure 1 shows some components of a typical cochlear implant system where an external microphone provides an audio signal input to an external signal processing stage 111 which implements one of various known signal processing schemes. The processed signal is converted by the external signal processing stage 111 into a digital data format, such as a sequence of data frames, for transmission via external coil 107 into a receiver processor in an implant housing 108. Besides extracting the audio information, the receiver processor in the implant housing 108 may perform additional signal processing such as error correction, pulse formation, etc., and produces a stimulation pattern (based on the extracted audio information) that is sent through wires in an electrode lead 109 to an implanted electrode array 110. Typically, the electrode array 110 includes multiple electrodes on its surface that provide selective stimulation of the cochlea 104.

[0005] Conventionally, the implant housing is placed in a bony bed or flattened area drilled on the skull bone. This is done for various reasons including improved stability and protection when external forces act on the implant housing. Recessing the implant housing in the skull bone also reduces the amount by which the implant housing protrudes out from the bone surface towards the skin and makes the implant bump on the skin less obvious when seen from the outside. Adults have comparatively thick skull bones which generally allow the drilling of deep implant beds and consequently a good fixation of the device. But the skull bones in children are much thinner and it may be difficult to sufficiently recess the implant housing without drilling all the way through the skull bone down to the outer layer of the cerebral membrane, the dura mater. In many young patients, the implanting surgeon decides to remove all underlying bone in order to obtain an appropriately recessed implant housing, which undesirably exposes the dura mater.

[0006] Removing the bone volume in the implant bed by layer by layer drilling is a time consuming task, and minimizing the implant surgery time is gradually becoming more important, not only to minimizes the costs of surgery, but also to reduce the time that the implant patient is under general anesthetic. Even if surgeon spent time for a practicable bone bed it may turn out that the remaining bone is has become too thin to safely fix the implant with conventional screws perpendicularly screwed into skull bone.

[0007] Other tasks that can take considerable amounts of time during implantation surgery include fixation of the implant housing in the bony recess. While specific implant fixation (e.g. tying down with sutures) is strongly recommended by cochlear implant manufacturers, some surgeons prioritize a shorter surgery time over the benefits of direct implant fixation and do not specifically fixate the device. Commonly practiced indirect fixations are achieved by tightly closing the periosteum over the implant housing and suturing the surgical opening in the skin over the implantation site.

[0008] U. S. Patent Publication 2010/0049318 and Patent Cooperation Treaty

Application WO 2014/138149 each describe various ways to fix the implant housing to the bone underneath the device. But if there is no or little bone under the implant housing, then some of the described fixation methods are inappropriate. Similar concepts are described in U. S. Patent Publication 2006/01 16743 where one or more flanges extend outward from the implant housing for fixation to the tissue. U. S. Patent Publication 2009/0209806 describes a bone conductor transducer that is connected to the skull bone to transmit vibrations using static force methods.

SUMMARY

[0009] Embodiments of the present invention are directed to cochlear implant arrangements that include an implant housing containing a stimulation processor for processing communications signals to generate electrical stimulation signals for the cochlea of an implant patient. The implant housing has an inward planar surface configured to fit against an outer temporal bone surface of the implant patient, an outward planar surface parallel to the inward planar surface and configured to fit against overlying skin of the implant patient, and an outer perimeter around each of the planar surfaces forming a connecting surface between the planar surfaces. An implant stabilizer is configured to fit over a portion of the connecting surface at the radial outer perimeter and extend into a mastoid bowl opening in the temporal bone of the implant patient. And there is at least one stabilizer attachment element that is configured to connect to the implant stabilizer parallel to the planar surfaces and project towards the temporal bone at the mastoid bowl opening to fixedly secure the implant housing against the outer temporal bone surface.

[0010] In further specific embodiments, the at least one stabilizer attachment element may specifically be a bone screw configured to penetrate through the implant stabilizer to attach to the temporal bone, or a clamping member configured to press the implant stabilizer against the temporal bone. The portion of the implant stabilizer configured to extend into the mastoid bowl opening may be malleable to be deformed to fit over the temporal bone as the mastoid bowl opening, or pre-shaped to fit over the temporal bone at the mastoid bowl opening. The portion of the implant stabilizer configured to extend into the mastoid bowl opening may also be electrically connected to the stimulation processor and configured to act as ground electrode for the stimulation processor. And the implant stabilizer may be a structurally integrated component of the implant housing, or it may be a structurally separate element from the implant housing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 shows various anatomical structures of the human ear and components of a typical cochlear implant system in relation thereto.

[0012] Figure 2 shows an ear with a cochlear implant system having an implant stabilizer arrangement according to one embodiment of the present invention.

[0013] Figure 3 shows an ear with a cochlear implant system having an implant stabilizer arrangement according to another embodiment of the present invention.

DETAILED DESCRIPTION

[0014] Embodiments of the present invention are directed to cochlear implant systems having an implant stabilizer that fixes the implant housing to the temporal bone at the mastoid bowl opening. The attachment force is arranged to be parallel to the skull surface rather than perpendicular, which thereby avoids contacting the underlying dura mater. Such arrangements completely avoid exposure of the dura matter and are applicable for both adults and pediatric patients. The attachment structure also provides some impact protection to the electrode lead where it connects to the implant housing.

[0015] Figure 2 shows one embodiment of the present invention. An implant housing 202 contains a stimulation processor for processing communications signals received by a receiver coil 201 from the external transmitter coil 107 and generates electrical stimulation signals that are delivered via the electrode lead 109 and implanted electrode array 110 to the cochlea 104 of an implant patient. The implant housing has an inward planar surface 206 that is configured to fit against an outer temporal bone surface 207 of the implant patient, and an outward planar surface 208 that is parallel to the inward planar surface 207 and which is configured to fit against overlying skin 209 of the implant patient. The implant housing 202 also has an outer perimeter 210 around each of the planar surfaces 206/208 forming a connecting surface between the planar surfaces.

[0016] An implant stabilizer 203 is configured to fit over a portion of the connecting surface at the outer perimeter 210 and extends into a mastoid bowl opening in the temporal bone 205. A stabilizer attachment element 204 is configured to connect to the implant stabilizer 203 parallel to the planar surfaces 206/208 and projects towards the temporal bone 205 at the mastoid bowl opening to fixedly secure the implant housing 205 against the outer temporal bone surface 207. In the specific embodiment shown in Figure 2, the stabilizer attachment element 204 specifically is a bone screw that is configured to penetrate through the implant stabilizer 203 to attach to the temporal bone 205. Figure 3 shows a different embodiment where the stabilizer attachment element specifically is a clamping member 301 that is configured to press the implant stabilizer 203 against the temporal bone 205 at the mastoid bowl opening.

[0017] In specific embodiments, the implant stabilizer 203 may be a structurally integrated component of the implant housing 202, or it may be a structurally separate element from the implant housing 202. In the latter case, the implant stabilizer 203 can be fixed to the temporal bone 205 first, after which, the implant housing 202 can then be attached to the implant stabilizer 203.

[0018] And the portion of the implant stabilizer 203 that extends into the mastoid bowl opening may be malleable to be deformed to fit over the temporal bone 205 as the mastoid bowl opening, or it may be pre-shaped to fit over the temporal bone 205 at the mastoid bowl opening. The extension portion of the implant stabilizer 203 may be made of metallic material or a polymer material such as the silicon material that typically is used to cover the implant housing 202. [0019] The extension portion of the implant stabilizer 203 also may be electrically connected to the stimulation processor within the implant housing 202 and configured to act as ground electrode for the stimulation processor. The electrode lead 109 also gets additional impact protection from the implant stabilizer 203 where the electrode lead 109 connects to the implant housing 203. This additional protection promotes maintaining the desired shape and angle of that connection— i.e., maintaining the electrode lead 109 straight or maintaining it at a 90° angle at the connection point with the implant housing 203

[0020] 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

CLAIMS What is claimed is:

1. A cochlear implant arrangement comprising:

an implant housing containing a stimulation processor for processing

communications signals to generate electrical stimulation signals for the cochlea of an implant patient, the implant housing having: a. an inward planar surface configured to fit against an outer temporal bone surface of the implant patient,

b. an outward planar surface parallel to the inward planar surface and configured to fit against overlying skin of the implant patient, and c. an outer perimeter around each of the planar surfaces forming a connecting surface between the planar surfaces;

an implant stabilizer configured to fit over a portion of the connecting surface at the radial outer perimeter and extend into a mastoid bowl opening in the temporal bone of the implant patient; and

at least one stabilizer attachment element configured to connect to the implant stabilizer parallel to the planar surfaces and project towards the temporal bone at the mastoid bowl opening to fixedly secure the implant housing against the outer temporal bone surface.

2. The arrangement according to claim 1, wherein the at least one stabilizer attachment element is a bone screw configured to penetrate through the implant stabilizer to attach to the temporal bone.

3. The arrangement according to claim 1, wherein the at least one stabilizer attachment element is a clamping member configured to press the implant stabilizer against the temporal bone.

4. The arrangement according to claim 1, wherein the portion of the implant stabilizer configured to extend into the mastoid bowl opening is malleable to be deformed to fit over the temporal bone as the mastoid bowl opening.

5. The arrangement according to claim 1, wherein the portion of the implant stabilizer configured to extend into the mastoid bowl opening is pre-shaped to fit over the temporal bone at the mastoid bowl opening.

6. The arrangement according to claim 1, wherein the portion of the implant stabilizer configured to extend into the mastoid bowl opening is electrically connected to the stimulation processor and configured to act as ground electrode for the stimulation processor.

7. The arrangement according to claim 1, wherein the implant stabilizer is a structurally integrated component of the implant housing.

8. The arrangement according to claim 1, wherein the implant stabilizer is a structurally separate element from the implant housing.