The invention relates to an implantable actuator for direct stimulation of the patient's cochlea.
One concept of implantable actuators for hearing aids uses a piston-type transducer which is inserted within a frame introduced into an artificial hole penetrating through the cochlear wall for directly acting on the perilymph fluid of the cochlea. An example of such actuator is found in EP 0 891 684 B1, wherein the actuator is located at a position adjacent to the oval window. Another example of such actuator is described in US 2009/0141919 A1, wherein the actuator may be located at a position next to the oval window or in the oval window itself and wherein the actuator comprises a piston-like slidably movable member guided within the frame in such a manner that there is a gap of not more than 0.1 mm extending between the inner wall of the frame and the outer wall of the movable member which may be driven by a motor, by the ear drum or by an ossicle.
EP 1 435 757 A1 relates to an actuator, wherein a frame comprising a membrane at its distal end is inserted into an artificial hole drilled into the cochlear wall in such a manner that the endosteal internal lining of the inner ear is preserved. The location is chosen such that it overlaps the scala vestibuli well above the basilar membrane; another possible location is the oval niche. The membrane may be driven by a piston, a piezo-membrane or a fluid-filled tube. A similar actuator is described in US 2006/0161255 A1, wherein the frame may be positioned in the stapes footplate.
WO 2008/077943 A2 relates to an actuator comprising a frame which attached to an artificially drilled hole in the bony wall accessing the scala vestibuli or to the oval window and a rigid plate which is attached to the inner wall of the frame by a flexible suspension. The plate is driven by a conducting element, such as a fixed rod, an adjustable telescopic slip link or an adjustable hinged link, which is driven by a motor fixed within a frame and which is connected to the plate via a wall joint.
Implantable piston-like actuators also may form part of a Total Ossicular Replacement Prosthesis (TORP) wherein the actuator is driven by the tympanic membrane or of a Partial Ossicular Replacement Prosthesis (PORP) wherein the actuator is driven an ossicle.
Known solutions using a piston or piston-like actuator often encounter significant mechanical losses due to acoustic shortcuts and small efficient piston area (typically less than 0.5 mm2); also, instabilities of actuator position may occur, which requires a surgical intervention and repositioning.
It is an object of the invention to provide for an implantable actuator having only little mechanical losses and having high implantation reliability. It is also an object to provide for a method of implanting such actuator.
According to the invention, these objects are achieved by an implantable actuator as defined in claim 1 and an implanting method as defined in claim 22, respectively.
The invention is beneficial in that, by replacing the stapes footplate by a frame which has a shape conforming to the shape of the oval window and which is fluid-tightly fixed within the patient's oval window, for guiding a rigid vibration element acting on the perilymph fluid, with a elastic holding element being fixed both at the frame and at the vibration element and extending laterally between the frame and the vibration element for allowing axial movement of the vibration element relative to the frame but preventing lateral movement of the vibration element relative to the frame, an actuator having only little mechanical losses and having high implantation reliability can be realized.
The actuatot may form part of an at least partially implantable hearing aid, a TORP or a PORP.
Preferred embodiments of the invention are defined in the dependent claims.
Hereinafter, examples of the invention will be illustrated by reference to the attached drawings, wherein:
An example of a block diagram of the hearing aid of
The external unit 10 also comprises a power supply 54 which may be a replaceable or rechargeable battery, a power transmission unit 56 and a power transmission antenna 58 for transmitting power to the implantable unit 12 via a wireless power link 60. The implantable unit 12 comprises a power receiving antenna 62 and a power receiving unit 64 for powering the implanted electronic components with power received via the power link 60. Preferably, the audio signal antennas 36, 40 are separate from the power antennas 58, 62 in order to optimize both the audio signal link 38 and the power link 60. However, if a particularly simple design is desired, the antennas 36 and 58 and the antennas 40 and 62 could be physically formed by a single antenna, respectively.
The stimulation assembly 21 comprises a driver/motor 70 fixed by a frame 72 within an artificial cavity within the patient's middle ear and the mechanical actuator which comprises a rod 74, a frame 76 and a vibration element 78. The frame 72 may be fixed within the mastoid/temporal bone and may comprise means for adjusting the position of the motor 70, as it is known in the art. One end of the rod 74 is connected to the motor 70, and the other end of the rod 74 is connected to the vibration element 78. The motor 70 may be any electro-mechanical transducer, such as a piezo-electric or electro-magnetic transducer. The motor 70 receives the input signals provided by the driver circuitry 44 via the cable assembly 18 and serves to drive the vibration element 78 via the rod 74 in such a manner that it performs a reciprocating movement within the frame 76. The frame 76 is for guiding the vibration element 78 in order to enable such reciprocating movement caused by the rod 74 and the motor 70. An elastic holding element 80 fixed both at the frame 76 and at the vibration element 78 extends laterally between the frame 76 and the vibration element 78 in a manner to allow axial movement of the vibration element 78 relative to the frame 76 but to prevent lateral movement of the vibration element relative to the frame. Optionally, the holding element 80 and may act to seal the gap between the frame 76 and the vibration element 78 in a fluid-tight manner.
The frame 76, the vibration element 78 and the holding element 80 are designed for replacing the stapes footplate 81. To this end, the frame 76 is of oval shape to fit the natural form of the oval window as close as possible. The frame 76 comprises a distal (inner) portion 82 for passing through the oval window and a proximal (outer) flange portion 84 resting on the edge of the oval window on the side facing away from the perilymph 86, with the flange portion 84 having a broader lateral dimension than the distal portion 82. The frame 76 is made of a biocomapatible material, such as titanium or gold
According the embodiments shown in
The rod 74 preferably is connected to the vibration element 78 via a joint 88 allowing for tilting of the rod 74 relative to the vibration element 78. Preferably, the joint 88 is a ball joint.
In
There are various alternatives for fixing the frame 76 in a fluid-tight manner within the oval window. According to one embodiment, the flange portion 84 of the frame 76 may be cemented to the edge of the oval window (this is indicated at 92 in
Alternatively, flange portion 84 of the frame 76 may comprises bendable legs for engagement with the edge of the oval window
According to a further alternative, the distal portion 82 of the frame 76 may comprise a laterally expandable silicone sealing 94 surrounding the periphery of the distal portion 82. The silicone sealing 94 is compressed when the distal portion 84 of the frame 76 is passed through the oval window and thereafter is allowed to expand laterally for securing the frame 76 within the oval window.
According to the embodiment of
An actuator of the present invention may not only be used with, i.e. driven by, the motor/driver of an implantable hearing aid. Rather, such actuator also may form part of a Total Ossicular Replacement Prosthesis (TORP) wherein the actuator is driven by the tympanic membrane or of a Partial Ossicular Replacement Prosthesis (PORP) wherein the actuator is driven by an ossicle. In such cases, in the embodiments of
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/EP2011/050249 | 1/11/2011 | WO | 00 | 9/5/2013 |