Field of the Invention

This patent application relates to devices that deliver neural stimulation to the body of an implantee, such as cochlear implants.

Background of the Invention

In many people who are profoundly deaf, the reason for deafness is absence of, or destruction of, the hair cells in the cochlea which transduce acoustic signals into nerve impulses. These people are unable to derive suitable benefit from conventional hearing aid systems, no matter how loud the acoustic stimulus is made, because there is damage to or absence of the mechanism for nerve impulses to be generated from sound in the normal manner.

It is for this purpose that cochlear implant systems have been developed. Such systems bypass the hair cells in the cochlea and directly deliver electrical stimulation to the auditory nerve fibres, thereby allowing the brain to perceive a hearing sensation resembling the natural hearing sensation normally delivered to the auditory nerve:

Cochlear implant systems can consist of essentially two components, an external component commonly referred to as a processor unit and an internal implanted component commonly referred to as a receiver/stimulator unit. Both of these components have cooperated together to provide the sound sensation to a recipient.

The external component has traditionally consisted of a microphone for detecting sounds, such as speech and environmental sounds, a speech processor that converts the detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna coil.

The coded signal output by the speech processor is transmitted transcutaneously to the implanted receiver/stimulator unit situated within a recess of the temporal bone of the recipient. This transcutaneous, transmission occurs via the external transmitter antenna coil which is positioned to communicate with an implanted receiver antenna coil provided with the receiver/stimulator unit. This communication can serve two purposes, firstly to transcutaneously transmit the coded sound signal and secondly to provide power to the implanted receiver/stimulator unit. This link has been in the form of a radio frequency (RF) magnetic induction link.

The implanted receiver/stimulator unit can include a receiver antenna coil that receives the coded signal and power from the external processor component, and a stimulator that processes the coded signal and outputs a stimulation signal to an intracochlear electrode assembly which applies the electrical stimulation directly to the auditory nerve producing a hearing sensation corresponding to the original detected sound.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

Summary of the Invention

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

According to one aspect, the present invention is an implantable component of prosthesis comprising a first stimulation module comprising: a first housing; at least one carrier member extending from the first housing to a leading end and having a plurality of electrodes disposed thereon; and one or more electrically conductive leads extending from the first housing, each lead having an end distal the first housing; wherein the lead comprises an electrically insulating outer layer surrounding one or more insulated electrical conductors extending through the lead from the first housing to the distal end.

5 In one embodiment, the implantable component can comprise one component of an auditory prosthesis. In one embodiment, the auditory prosthesis can comprise a cochlear implant.

In one embodiment, the first housing has a hermetic sealed outer wall. The wall 10 can be formed from a biocompatible material, such as titanium. In one embodiment, the first housing does not contain powered and/or electronic componentry for the implantable component and acts as an anchor member for a pτoximal end of the carrier member. The first housing can have a feedthrough in the wall to provide electrical connection from the carrier member to the interior of the first housing.

^] 5

In a further embodiment, the first housing of the first stimulation module can contain powered and/or electronic componentry. In one embodiment, the first housing can contain a primary stimulator unit that decodes incoming signals and outputs signals suitable for delivery by the carrier member to a neural network of the implantee. In the 0 case of a cochlear implant, the carrier member can be insertable into a cochlea, for example the scala tympani of a cochlea.

In another embodiment, the implantable component can have an antenna mounted thereon or extending therefrom. The antenna can comprise an antenna coil. 5 The antenna coil can comprise one or more windings of a suitable electrically conductive material. The windings can extend from a further feedthrough formed in the outer wall of the first housing. The windings can be formed from a suitable biocompatible material, such as platinum or gold, and/or be contained within an electrically insulating surround. In one embodiment, the surround can be formed of an 0 elastomeric material, such as a silicone. A magnet can be disposed within the antenna coil. The use of the magnet within the antenna coil allows the antenna coil to be appropriately aligned with an external antenna coil to form a transcutaneous radio frequency (RF) magnetic induction link. 5 The first housing of the first stimulation module can contain a primary receiver/stimulator unit that receives signals detected by the antenna and then decodes the signals and outputs signals suitable foτ delivery by the carrier member. The first housing of the first stimulation module can house the necessary receiver circuitry for the antenna. For example, the first stimulation module can house a rectifier and decoding circuitry.

In yet a further embodiment, the implantable component can comprise a totally implantable prosthesis, such as a totally implantable cochlear 'implant. In this case, the implantable component can have a microphone, a speech processor, a power source, a power source controller and/or a power monitor. The power source can comprise a rechargeable battery and so allow the implantable component to operate for a period of time without necessarily the need for an external component. For example, the controller can control when power is delivered and the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power- monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source.

The first stimulation module can be designed to not be removable from the implantee following placement of the carrier member.

In a still further embodiment, the implantable component can comprise at least one second module. The second module can be electrically connected to the first stimulation module by at least one of said at least one leads and an electrical connector. In one embodiment, the second module can be designed to be removable from, the implantee if and when required and/or at least relatively more readily removable than the first stimulation module.

In a further embodiment, the second module can comprise a second housing containing powered and/or electronic componentry. This second housing of the second module can also be hermetically sealed and be formed from a biocompatible material, such as titanium. The powered componentry of the second module can comprise a secondary receiver/stimulator unit that outputs signals through the electrical connector and said at least one lead to the first stimulation module which in turn delivers the signals to the carrier member. The second module can house a signal encoder, a driver circuit, and impedance matching and isolation circuitry, In a still further embodiment, the second housing of the second module can act as at least one electrode. In a further embodiment, the second module can have an antenna mounted thereon or extending therefrom. This antenna can also comprise an antenna coil. The antenna coil can comprise one or more windings of a suitable electrically conductive S material. The windings can extend from a further feedthrough formed in the outer wall of the housing. The windings can be formed from a suitable biocompatible material, such as platinum or gold, and/or be contained within an electrically insulating surround. In one embodiment, the surround can be formed of an elastomeric material, such as a silicone. A magnet can be disposed within the antenna coil of the second module. The0 use of the magnet within this antenna coil allows the antenna coil to be appropriately aligned with an external antenna coil to form a transcutaneous radio frequency (RF) magnetic induction link. The second module can house the necessary receiver circuitry for the antenna. For example, the second module can house a rectifier and decoding circuitry. 5

In a still further embodiment, the second module can comprise a power source. The power source can comprise a rechargeable battery. The second module can also house a power source controller that controls the operation of the power source and/or a power monitor. For example, the controller can control when power is delivered and0 the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source. 5 In yet another embodiment, the second module can house or support one or more microphone assemblies. Other possible componentry can comprise one or moτe of a temperature sensor, a humidity sensor, an impact or shock sensor, such as an accelerometer, and/or an optical communications or stimulation interface. 0 In one embodiment, the connector can be located at a position between the first stimulation module and the second module. As an example only, the connector can be approximately midway between the modules. Irrespective of its location, a cable can extend from the second housing of the second module to the connector. In another embodiment, the connector can be mounted in the second housing of the second5 module. In one embodiment, the one or moτe leads can be directly electrically connected to the componentry within the first housing. In another embodiment, the one or more leads can be isolated from the componentry within the first housing by one or more galvanically isolated transformers or capacitors.

In a further embodiment, one, some oτ each of the electrical conductors in the lead can comprise a single wire. In another embodiment, one, some or each of the electrical conductors can be comprised of multiple strands. An elongate silicone mesh member can be disposed through some or all of the length of the lead and serve to separate respective conductors within the lead, A plurality of such mesh members can be provided in the lead. In one embodiment, where two or more conductors are present, the conductors can be disposed in a side-by-side arrangement, with mesh members disposed therebetween. Other configurations can be envisaged are included within the scope of the present application.

In a further embodiment, the connector can comprise an electrically conductive joining member. In one embodiment, the connector can comprise an electrically conductive tube member having at least one inner lumen that receives the distal end of said at least one conductor extending through the lead and which is then swaged or otherwise grips the conductor. The tube member can be formed of a biocompatible material, such as platinum.

The connector can further comprise a protective sleeve member. The sleeve member can be slid along the lead and over the tube member. The sleeve member can be tillable with a suitable electrically insulative material, for example a silicone.

In another embodiment, the connectoT can comprise an insulation displacement connection which requires a portion of the electrically insulating outer layer to be stripped from the lead as a connector blade cuts through the outer layer to make contact with the electrical conductor. In another embodiment, connection can be achieved by crimping a connector onto the lead that is suitable for attachment to a receptacle on the housing of the second module. In another embodiment, the connectoT may comprise an integral component of the second module,

As already defined herein, the implantable component can comprise one or more leads in addition to that used to provide electrical connection with the second module. On initial implantation, said one or more leads can also have free distal ends, with the distal ends not necessarily being electrically connected to the second module or another module or implanted component on at least initial implantation of the implantable component. Rather, said one or more additional leads, being insulated can be left in position under the skin. The one or more additional leads are, however, ready to be revealed during a subsequent surgery, trimmed if required and then connected to a component as required. For example, such leads may be required because the second module needs replacing and/or needs to undergo a repair.

Each of these additional leads can have one, some or all of the features of said at least one lead as described above.

In yet another embodiment, the second module itself can have one or more electrically conductive leads extending from the second housing, each lead having an end distal the second housing. The one or more leads of the second module can comprise an electrically insulating outer layer surrounding one or more insulated electrical conductors extending through the lead from the second housing to the distal end. Such leads can be used to allow connection of a third module or higher number of modules to the second module. This connection can be repeated, if necessary, to form a daisy chain of implantable modules. The modules can serve as new modules that bypass and effectively replace the current module or can serve to allow addition of features to the totality of operation of the implantable component, as such features become available or become desired by the implantee.

The carrier member can ^' comprise a non-insertable portion and an iπsertable portion. The non-insertable portion can comprise a proximal portion of the carrier member and have no electrodes disposed thereon. The insertable portion can comprise a portion of the carrier member extending back from the leading end of the member and is adapted to be inserted into the cochlea. The insertable portion can have all of the electrodes that are disposed on the carrier member. The carrier member can decrease in diameter over at least a portion of its length towards the leading end. The carrier member can be formed from an elastomeric material, such as a silicone! Each of the electrodes can be formed from a biocompatible material, for example platinum. The electrodes can comprise ring members. In one embodiment, the carrier member can have 22 electrodes. In another embodiment, the carrier can have between about 20 and about 30 electrodes, or 30 or more than 30 electrodes. In another embodiment, the implantable component can have one or more secondary electrode assemblies extending from the housing. The secondary electrode assemblies can have more one or more electrodes. In the case of a cochlear implant, the one or more secondary electrode assemblies can be mounted within the cochlea of an implantee.

In one embodiment, the housing of the implantable component can be positioned subcutaneously. If necessary, it can be positioned within a recess formed in the temporal bone of the implantee.

In another embodiment, the prosthesis can have an external component. The external component can be used to recharge the power source. Still further, it can be used in conjunction with the implantable component to provide a hearing sensation to an implantee. It will be appreciated that a different or the same external component can be used to recharge the power source and work in conjunction with the implantable component to provide the hearing sensation, In one embodiment, the external component can have a microphone for detecting sound, a speech processor that converts the detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna coil. The receiver/stimulator unit of the implantable component and/or the second module (or further modules if used) can receive the coded signal transmitted from the speech processor, process the coded signal and output a stimulation signal. The stimulation signal can be output to an electrode assembly, such as an intracochlear electrode assembly. The electrode " assembly then delivers electrical stimulation to the auditory nerve of the implantee so producing a hearing sensation corresponding to the original detected sound. The implantable component can work to use the input from the external component when it is present but rely on on-board componentry when the external component is not being used. In this latter embodiment, the implantable component can be part of a partially or wholly implantable prosthesis, such as a cochlear implant.

According to a second aspect, the present invention is an implantable component of a prosthesis comprising: a first stimulation module comprising: a first housing; at least one carrier member extending from the first housing to a leading end and having a plurality of electrodes disposed thereon; and one OT moτe electrically conductive leads extending from the first housing, each lead having an end distal the first housing; wherein the lead comprises an electrically insulating outer layer surrounding one or more insulated electrical conductors extending through the lead from the first housing to the distal end; and at least one second module that is electrically cormectahle to the first stimulation module using at least one of said one or more electrically conductive leads.

In this aspect, the implantable component, first stimulation module, second module, carrier member, and/or lead can have one, some or all of the features of the same component as defined herein with respect to other aspects and embodiments.

In this aspect, for example, the second module can have a second housing which itself can have one or more electrically conductive leads extending therefrom, each lead having an end distal the second housing. The one or more leads of the second module can comprise an electrically insulating outer layer surrounding one or more insulated electrical conductors extending through the lead from the second housing to the distal end. Such leads can be used to allow connection of a third module or higher number of modules to the second module. This connection can be repeated, if necessary, to form a daisy chain of implantable modules. The modules can serve as new modules that bypass and effectively replace the current module or can serve to allow addition of features to the totality of operation of the implantable component, as such features become available or become desired by the implantee.

According to a third aspect, the present invention is a method of modifying an implantable component of a tissue-stimulating prosthesis, the component having been implanted in an implantee and having a primary implantable module comprising a primary receiver/stimulator unit and a primary antenna comprising one or more wires, the method comprising: surgically exposing at least the primary antenna; accessing the one or more wires; electrically connecting a secondary implantable module to at least one of said one or more wires. In one embodiment, the tissue-stimulating prosthesis can comprise an auditory prosthesis. The auditory prosthesis can comprise a cochlear implant. The primary receiver/stimulator unit of the implantable component can have a housing having a hermetic sealed outer wall. The wall can be formed from a biocompatible material, such as titanium. In one embodiment, the primary receiver/stimulator unit decodes incoming signals and outputs signals suitable for delivery by an electrode carrier member to a neural network of the implantee. In the case of a cochlear implant, the electrode carrier member can comprise an intracochlear electrode array and be insertable into a cochlea, for example the scala tympani of a cochlea.

The primary antenna can be electrically connected by a feedthrough to the primary τeceiver/stirnulator unit within the housing. In one embodiment, the one or more wires of the antenna can comprise wire coils. The wires or wire coils can be formed from a suitable biocompatible material, such as platinum or gold, and/or be contained within an electrically insulating surround. In one embodiment, the surround can be formed of an elastomeric material, such as a silicone. A magnet can be disposed within the primary antenna. The use of the magnet within the primary antenna allows the primary antenna to be appropriately aligned with an external antenna, for example an external antenna coil, to form a transcutaneous radio frequency (RF) magnetic induction link.

In use and prior to the method as defined herein, the primary receiver/stimulator unit receives signals detected by the primary antenna and then decodes the signals and outputs signals suitable for delivery by the electrode carrier member. The housing of the primary receiver/stimulator unit can also house the necessary receiver circuitry for the primary antenna. For example, the housing can house a rectifier and decoding circuitry.

In yet a further embodiment, the implantable component can comprise a partially or totally implantable prosthesis, such as a partially or totally implantable cochlear implant. For example, the primary implantable module can also comprise a power source and a power source controller. Still further, the primary implantable module can have a microphone, a speech processor, a power source, a power source controller and/or a power monitor. The power source can comprise a rechargeable battery and so allow the primary implantable module to operate for a period of time without necessarily the need for an external component. For example, the power source controller can control when power is delivered and the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source.

In one embodiment of the method according to the first aspect, the step of exposing the primary antenna cat comprise using a scalpel or other surgical tool to form an incision before peeling back as necessary the skin and body tissue, if present, that overlies the location of the primary antenna. The step of accessing the wires can comprise slicing the elastomeric surround surrounding the wire, removing the magnet, if present, and then removing the wire from the surround. In a further embodiment, and once accessed, the wires if in the form of coils can be straightened and trimmed, if required. Surgical scissors may be used to remove the elastomeric surround or alternatively a surgical punch may be used.

The step of connecting the secondary implantable module can comprise forming an electrical connection between the wire or wires and the secondary implantable module. The electrical connection can be provided by electrically contacting the wire or wires to an electrical contact on the secondary implantable module. In a further embodiment, a connector can be used to connect the wire or wires to the secondary implantable module. In one embodiment, .one or more leads can extend from the secondary implantable module and be connectable to said connector. In another embodiment, a suitable connector can be mounted in a housing of the secondary implantable module.

The secondary implantable module can be designed to be removable from the implantee if and when required and/or at least relatively more readily removable than the housing of the primary implantable module of the implantable component.

Once implanted, the secondary implantable module can be designed to work in conjunction with and/or supplement the operation of the primary receiver/stimulator unit of the primary implantable module. In another embodiment, the secondary implantable module can be designed to replace the function of the primary receiver/stimulator unit, particularly if the unit has failed or is no longer suitable for the implantee. In a further embodiment, the secondary implantable module can also comprise a housing containing powered and/or electronic componentry. This housing can also be hermetically sealed and be formed from a biocompatible material, such as titanium. The powered componentry of the secondary implantable module can comprise a secondary receiver/stimulator unit that outputs signals through the electrical connector and the wiring that used to comprise the primary antenna and into the housing of the primary receiver/stimulator unit which in turn delivers the signals to the electrode carrier member. The secondary implantable module can house a signal encoder, a driver circuit, and/or impedance matching and isolation circuitry.

In a further embodiment, the secondary implantable module can have a secondary antenna mounted thereon or extending therefrom. The secondary antenna can replace the function of the primary antenna of the primary implantable module that is modified by the method of the present invention. The secondary antenna of the secondary implantable module can also comprise an antenna coil. This antenna coil can comprise one or more windings of a suitable electrically conductive material. The windings can extend from a further feedthrough formed in the outer wall of the housing of the secondary implantable module. The windings can be formed from a suitable biocompatible material, such as platinum or gold, and/or be contained within an electrically insulating surround. In one embodiment, the surround can be formed of an elastomeric material, such as a silicone. A magnet can be disposed within the secondary antenna coil. The use of the magnet within the secondary antenna coil allows the antenna coil to be appropriately aligned with an external antenna coil to form a transcutaneous radio frequency (RF) magnetic induction link. The implantable module can house the necessary receiver circuitry for the secondary antenna. For example, the secondary implantable module can house a rectifier and decoding circuitry.

In a still further embodiment, the secondary implantable module can comprise a power source. The power source can comprise a rechargeable battery. The secondary implantable module can also house a power source controller that controls the operation of the power source and/or a power monitor. For example, the controller can control when power is delivered and the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source.

In yet another embodiment, the secondary implantable module can house or S support one or more microphone assemblies. Other possible componentry can comprise one or more of a temperature sensor, a humidity sensor, an impact or shock . sensor, such as an accelerometer, and/or an optical communications or stimulation interface. 0 In one embodiment, the connector can be located at a position between the housing of the primary receiver/stimulator unit and the housing of the secondary implantable module. As an example only, the connector can be approximately midway between the primary receiver/stimulator unit and the secondary implantable module. In another embodiment, the connector can be mounted in the housing of the secondary 5 implantable module.

In a further embodiment, the connector can comprise an electrically conductive joining member. In one embodiment, the connector can comprise an electrically conductive tube member having at least one inner lumen that receives the distal end of0 at least one conductor that extends through the lead and which is then swaged or otherwise grips the conductor. The tube member can be formed of a biocompatible material, such as platinum.

The connector can further comprise a protective sleeve member. The sleeve5 member can be slid along the lead and over the tube member. The sleeve member can be fillable with a, suitable electrically insulative material, for example a silicone.

In another embodiment, the connector can comprise an insulation displacement connection which requires a portion of an electrically insulating outer layer of the lead0 to be stripped from the lead as a connector blade cuts through the outer layer to make contact with the electrical conductor. In another embodiment, connection can be achieved by crimping a connector onto the lead that is suitable for attachment to a receptacle on the housing of the secondary implantable module. In another embodiment, the connector may comprise an integral component of the secondary5 implantable module. The electrode carrier member can comprise a non-insertable portion and an insertable portion. The non-insertable portion can comprise a proximal portion of the carrier member and have no electrodes disposed thereon. The insertable portion can comprise a portion of the carrier member extending back from the leading end of the member and is adapted to be inserted into the cochlea. The insertable portion can have all of the electrodes that are disposed on the carrier member. The carrier member can decrease in diameter over at least a portion of its length towards the leading end. The carrier member can be formed from an elastomeric material, such as a silicone. Each of the electrodes can be formed from a- biocompatible material, for example platinum. The electrodes can comprise ring members. In one embodiment, the carrier member can have 22 electrodes. In another embodiment, the caiτieτ can have between about 20 and about 30 electrodes, or 30 or more than 30 electrodes.

In another embodiment, the primary receiver/stimulator unit can have one or multiple secondary electrode assemblies extending from the housing. The secondary electrode assemblies can each have more one or more electrodes. In the case of a cochlear implant, the secondary electrode assembly can be mounted external the cochlea of an implantee.

In one embodiment, the housing of the primary receiver/stimulator unit can be positioned subcutaneously. If necessary, it can be positioned within a recess formed in the temporal bone of the implantee.

In another embodiment, the prosthesis can have an external component. The external component can be used to recharge the power source that is part of the primary implantable module and/or the secondary implantable module, if present. Still further, it can be used in conjunction with the primary implantable module and/or the secondary implantable module, once implanted, to provide a hearing sensation to an implantee. It will be appreciated that a different or the same external component can be used to recharge the power source and work in conjunction with the primary implantable module and/or the secondary implantable module to provide the hearing sensation. In one embodiment, the external component can have a microphone for detecting sound, a speech processor that converts the detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna coil. The primary receiver/stimulator unit of the primary implantable module or the secondary implantable module can receive the coded signal transmitted from the speech processor of the external component, process the coded signal and output a stimulation signal. The stimulation signal can be output to the carrier member. The carrier member then delivers electrical stimulation to the auditory nerve of the implantee so producing a hearing sensation corresponding to the original detected sound. The primary implantable module and/or the secondary implantable module can work to use the input from the external component when it is present but rely on on-board componentry when the external component is not being used. In this latter embodiment, the primary and secondary implantable modules can work together to form a partially or fully implantable prosthesis, such as a cochlear implant system,

In the method according to the third aspect, once electrical connection has been made between the housing of the primary receiver/stimulator unit and the housing of the secondary implantable module, the incision site is surgically closed. Closure can be made using stitches, staples and/or adhesive.

In the third aspect, it will be appreciated that the step of electrically connecting an implantable module can be repeated, for example, by electrically connecting a tertiary implantable module to the wires constituting, for example, an antenna of the secondary implantable module. This can be repeated as required with still further implantable modules. In another embodiment, the secondary implantable module can be removed or explanted and replaced with a tertiary implantable module. Again, this can be repeated as required.

In another aspect, the present invention is an implantable component of a tissue- stimulating prosthesis as modified using the method as defined herein.

The third aspect as defined herein provides a technique for modifying the implantable component of a tissue-stimulating prosthesis. The modification technique can be performed when it is desired to upgrade or otherwise modify the performance of the implantable component of the prosthesis. It can also be used if the implantable component has failed in some way. The advantage of the present invention is that it provides a technique for modifying or restoring operation without the need of removing the electrode carrier member. This is considered important in the case of cochlear implants where it is at least desirable to not have to τemove the intracochlear electrode array from its position within the cochlea once in place. The present technique can also be used for children. For children under three years of age, it is currently considered preferable to not implant a totally or fully implantable cochlear implant as the head undergoes rapid growth during this period. As early implantation is also critical to ensure an infant is capable of processing sounds, the present invention provides the option of firstly implanting one type of implantable component for the first few years of life. At the appropriate time, the method of the present invention can be performed to place the secondary implantable module in position within the implantee. This secondary implantable module allows the implantee to potentially have the benefit of a totally or fully implantable prosthesis or a prosthesis with improved capability without the risk of having to harm the relatively delicate structures of the cochlea of the implantee.

Brief Description of the Drawings

By way of example only,' embodiments are now described with reference to the accompanying drawings, in which:

Fig. 1 is one embodiment of an implantable component of a cochlear implant according to the present invention; • -

Fig. 2 is another embodiment of an implantable component of a cochlear implant according to the present invention

Fig. 3 is a cross-sectional view of one embodiment of a lead according to the present invention;

Figs. 4A to 4D depict examples of various conductor configurations for the lead;

Figs. 5A to 5C depict an embodiment of a connector for use in the present invention;

Fig. 6 depicts an implantable component of a cochlear implant system that is implantable in an implantee and comprising a primary implantable module having a primary receiver/stimulator unit and a primary antenna comprising one or more wire coils; and Fig. 7 depicts an implantable component that has undergone modification using the method according to the present invention.

Preferred Mode of Carrying out the Invention

The depicted embodiments of the present invention are shown as part of a cochlear implant system. . It is to be understood that the present invention has application to other implantable prostheses including but not limited to auditory prostheses, such as cochlear implants.

One example of an implantable component of a cochlear implant system according to the present invention is depicted generally as 10 in Fig. 1. The component 10 has a fiτst stimulation module 9 which comprises a hermetically sealed and biocompatible titanium first housing 11. Extending from the first housing 11 is a cable 13 that extends to a carrier member 20 which has a plurality of electrodes 21 disposed thereon.

While there can be just one or more than two, the embodiment of the implantable component in Fig. 1 also has two electrically conductive leads 31a,31b extending from the first housing 11, with each lead 31a,31b having an end 32 distal the first housing 11. In one embodiment, the leads 31a,31b can be directly electrically connected to the componentry within the first housing 11. In another embodiment, the one or more leads can be isolated from the componentry within the first housing 11 by one or more galvanically isolated transformers or capacitors.

In one embodiment, the first housing 11 can be provided without powered and/or electronic componentry of the implantable component 10 and serves to act as an anchor member for a proximal end of the carrier member 20. The first housing 11 can have a feedthrough in the wall to provide electrical connection from the carrier member 20 to the interior of the first housing 11.

In a further embodiment that is depicted in Fig. 1, the first housing 11 can contain powered and/or electronic componentry. In the depicted embodiment, the first housing 11 contains a primary receiver/stimulator unit that receives signals detected by the antenna coil 12 and then decodes the signals and outputs signals suitable for delivery by the carrier member 20. The first housing 11 of the first stimulation module 9 can also house the necessary receiver circuitry for the antenna 12. For example, the first housing 11 can house a rectifier and decoding circuitry.

The first housing 11 could instead just contain a stimulation unit that decodes incoming signals received from a second module 40 (as described below) or other module and outputs signals suitable for delivery by the carrier member 20 to a neural network of the implantee. In the case of a cochlear implant, the carrier member 20 can be insertable into a cochlea, for example the scala tympani of a cochlea. In this case, the antenna 12 on module 9 could be missing and instead be mounted on the second module 40 or other module.

The antenna coil 12, wherever it is positioned, can comprise one or more windings of a suitable electrically conductive material. The windings can extend from a further feedthrough formed in the outer wall of the housing of the module to which it is mounted. The windings can be formed from a suitable biocompatible material, such as platinum or gold, and/or be contained within an electrically insulating surround. In one embodiment, the surround can be formed of an elastomeric material, such as a silicone. A magnet can be disposed within the antenna coil. The use of the magnet within the antenna coil allows the antenna coil to be appropriately aligned with an external antenna coil to form a transcutaneous radio frequency (RF) magnetic induction link.

In yet a further embodiment, the first stimulation module 9 and carrier member 20 could comprise at least part of a totally implantable prosthesis, such as a totally implantable cochlear implant. In this case, the implantable component 10 could be provided with some or all of the features necessary to allow the prosthesis to operate, for at least a period of time, in a stand-alone fashion. Foτ example, the component 10 could include a microphone, a speech processor, a power source, a power source controller and/or a power monitor. In this case, the power source can comprise a rechargeable battery and so allow the implantable component to operate for a period of time without necessarily the need for an external component. For example, the controller can control when power is delivered and the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source. The depicted first stimulation module 9 is designed to not be removed from the implantee following placement of the carrier member 20.

As depicted, the implantable component comprises at least one second module

40. The second module 40 is electrically connected to the first stimulation module 9 by lead 31, an electrical connector 41 and a cable 42. In this embodiment, the second module 40 is designed to be removable from the implantee if and when required and/or at least relatively more readily removable than the first stimulation module 9.

The second module 40 has a second housing 43 containing powered and/or electronic componentry. This second housing 43 can also be hermetically sealed and be formed from a biocompatible material, such as titanium. The powered componentry of the second module 40 can comprise a secondary receiver/stimulator unit that outputs signals via the cable 42, electrical connector 41, and lead 31a to the first stimulation module 9 which in turn delivers the signals to the carrier member 20. The second module 40 can house a signal encoder, a driver circuit, and impedance matching and isolation circuitry. The housing 43 can also act as at least one electrode.

While not depicted, the second module 40 can have an antenna mounted thereon or extending therefrom. This antenna can also comprise an antenna coil and can have one, some or all of the features of the antenna coil as described herein. The second module 40 can house the necessary receiver circuitry for the antenna. For example, the second module can house a rectifier and decoding circuitry.

The second module 40 can also house a power source. The power source can comprise a rechargeable battery. The second module 40 can also house a power source controller that controls the operation of the power source and/or a power monitor. For example, the controller can control when power is delivered and the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source.

The second module 40 can also house or support one or more microphone assemblies. Other possible componentry provided by the second module for the component 10 can comprise one or more of a temperature sensor, a humidity sensor, an impact or shock sensor, such as an accelerometer, and/or an optical communications or stimulation interface.

5 One or both leads 31 a,3 Ib can have the construction of the lead depicted in Figs.

3 to 4D. Fig. 3 depicts a portion of the lead at or adjacent its distal end 32. As depicted in Fig. 3, the lead 31a,31b can comprise an electrically insulating outer layer 51 surrounding two insulated electrical conductors 52 that extend through the lead from the housing 11 to the distal end 32.

10

The electrical conductor 52 can comprise a single wire, or be comprised of multiple strands. An elongate silicone mesh member 53 is disposed through the length of the lead and serves to separate the respective conductors 52 within the lead. As depicted in Figs. 4A to 4D, a plurality of conductors 52 and mesh members 53 can be

15 provided in various configurations, such as side-by-side and triangular configurations, in the lead. Other configurations can be envisaged are included within the scope of the present application.

If desired, the lead can be cut or trimmed and then stripped to reveal the

20 electrical conductors) 52. As depicted in Figs. 5A to 5C, the electrically insulating outer layer can be firstly removed from the lead. The exposed conductor 52 can then be inserted into an electrically conductive joining member 54. In the depicted embodiment, the joining member comprises an electrically conductive and biocompatible tube member having at least one inner lumen that receives the distal end

25 32 of said at least one conductor 52. As depicted in Fig. 5B ₃ the joining member 54 is then swaged or otherwise grips the conductor 52. In the depicted embodiment, the member 54 is formed of platinum but other suitable materials can be envisaged.

As depicted in Fig. 5C, the connector 41 can further comprise a protective 30 sleeve member 55. The sleeve member 55 can be slid along the lead 3 Ia, 3 Ib or cable 42 and over the joining member 54. The sleeve member 55 is fillable with a suitable electrically insulative material, for example a silicone, using a blunt needle 56.

As depicted in Fig. 1, the connector 41 can be located at a position between the

35 first stimulation module 9 and the second module 40. As an example only, the connector can be approximately midway between the modules 9, 40. Irrespective of its location, the cable 42 can extend from the housing of the second module 40 to the connector 41.

As depicted in Fig. 2, the connector 42 can be mounted in the second housing of the second module 40.

In other embodiments, the connector can comprise an insulation displacement connection which requires a portion of the electrically insulating outer layer to be stripped from the lead as a connector blade cuts through the outer layer to make contact with the electrical conductor. Connection can also be achieved by crimping a connector onto the lead that is suitable for attachment to a receptacle on the second housing of the second module. In another embodiment, the connector may comprise an integral component of the second module.

As already defined herein, the implantable component can comprise one or more leads 31b in addition to that (i.e. lead 31a) used to provide electrical connection with the second module 40. On initial implantation, said one or more leads can also have free distal ends 32, with the distal ends not necessarily being electrically connected to the second module or another module or implanted component on at least initial implantation of the implantable component 10. Rather, said one or more additional leads, being insulated can be left in position under the skin. The one or more additional leads are, however, ready to be revealed during a subsequent surgery, trimmed if required and then connected to a component as required. For example, such leads may be required because the second module 40 needs replacing and/or needs to undergo a repair.

Each of these additional leads 31b can have one, some or all of the features of said at least one lead 31a as described above.

As depicted in Figs. 1 and 2, the second module 40 itself can have one or more electrically conductive leads 44 extending from the housing, each lead 44 having an end 45 distal the housing of the second module 40. The one or more leads 44 of the second module 40 can have one, some or all of the features of the leads 31a, 31b. The lead 44 can be used to allow connection of a third module or higher number of modules to the second module 40, This connection can be repeated, if necessary, to form a daisy chain of implantable modules. The modules can serve as new modules that bypass and effectively replace the current module or can serve to allow addition of features to the totality of operation of the implantable component, as such features become available or become desired by the implantee.

The carrier member 20 can comprise a non-insertable portion and an insertable portion. The non-insertable portion can comprise a proximal portion of the carrier member (e.g. cable 13) and have no electrodes disposed thereon. The insertable portion can comprise a portion of the carrier member extending back from the leading end of the member. The insertable portion can have all of the electrodes 21 that are disposed on the carrier member. The carrier member 20 can decrease in diameter over at least a portion of its length towards the leading end. The carrier member 20 can be formed from an elastomeric material, such as a silicone. Each of the electrodes 21 can be formed from a biocompatible material, for example platinum. The electrodes 21 can comprise ring members. In one embodiment, the carrier member 20 can have 22 electrodes. In another embodiment, the carrier can have between about 20 and about 30 electrodes, or 30 or more than 30 electrodes. Extending from the first housing 11 via a feedthrough is a cable 13 that extends to an implantable tissue stimulating intracochlear electrode array 20. It will be noted that a series of wires 14 extend through the cable 13 to the plurality of electrodes 21. Not all of the wires 14 are depicted for reasons of clarity.

As depicted, the implantable component 10 can ^' have at least one secondary electrode assembly 15 extending from the first housing 11. The secondary electrode assembly 15 can have more one or more electrodes. In the case of a cochlear implant, the electrode assembly 15 can be mounted external the cochlea of an implantee.

In one embodiment, the first housing 11 of the implantable component 10 can be positioned subcutaneously. If necessary, it can be positioned within a recess formed in the temporal bone of the implantee.

The implantable component 10 can work in conjunction with an external component. The external component can be used to recharge the power source, where present, in either the first module 9 or second module 40. Still further, it can be used in conjunction with the implantable component 10 to provide a hearing sensation to an implantee. It will be appreciated that a different or the same external component can be used to recharge the power source and work in conjunction with the implantable component 10 to provide the hearing sensation. In one embodiment, the external component can have a microphone for detecting sound, a speech processor that converts the detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna coil. The receiver/stimulator unit of the implantable component 10 and/or the second module 40 (or further modules if used) can receive the coded signal transmitted from the speech processor, process the coded signal and output a stimulation signal. The stimulation signal can be output to the carrier member 20. The carrier member 20 then delivers electrical stimulation to the auditory nerve of the implantee so producing a hearing sensation corresponding to the original detected sound. The implantable component 10 can work to use the input from the external component when it is present but rely on on-board componentry when the external component is not being used. In the latter embodiment, the implantable component 10 can be part of a partially or wholly implantable prosthesis.

In one embodiment, the present invention also comprises a method of modifying an implantable component of a prosthesis. Fig. 6 depicts generally as 100 one example of such an implantable component, In this embodiment, the component 100 comprises a primary implantable module and has a primary receiver/stimulator unit 90 which comprises a hermetically sealed and biocompatible titanium housing 110. Extending from the housing 110 via a feedthrough is a cable 130 that extends to a carrier member 200 which has a plurality of electrodes 210 disposed thereon. The depicted carrier member 200 is insertable into a cochlea, for example the scala tympani of a cochlea.

In normal operation, the primary receiver/stimulator unit 90 receives signals detected by a primary antenna 120 and then decodes the signals and outputs signals suitable for delivery by the carrier member 200. The housing 110 of the primary receiver/stimulator unit 90 can also house the necessary receiver circuitry for the primary antenna 120. For example, the housing 110 can house a rectifier and decoding circuitry.

The primary antenna 120 comprises one or more windings of a suitable electrically conductive material. The windings can extend from a further feedthrough formed in the outer wall of the housing 110 to which it is mounted. The windings can be formed from a suitable biocompatible material, such as platinum or gold, and/or are contained within an electrically insulating surround. In one embodiment, the surround can be formed of an elastomeric material, such as a silicone. A magnet can be disposed within, the primary antenna 120. The use of the magnet within the primary antenna 120 allows the antenna to be appropriately aligned with an external antenna coil to form a transcutaneous radio frequency (RF) magnetic induction link.

In one embodiment, the housing 110 of the implantable component 100 can be positioned subcutaneously. If necessary, it can be positioned within a recess formed in the temporal bone of the implantee. The primary receiver/stimulator unit 90 as depicted is designed to not be removed from the implantee following placement of the carrier member 200.

To modify the implantable component 100, the method can firstly comprise a step of surgically exposing at least the piimaτy antenna 120. The step of exposing the primary antenna 120 can comprise using a scalpel or other surgical tool to form an incision before peeling back as necessary the skin and body tissue, if present, that overlies the location of the primary antenna 120.

Once exposed, the wire coils that make up the primary antenna 120 can be accessed by the suτgeon. The step of accessing the wire coils can comprise slicing the elastomeric support, for example along line A in Fig. 6, that surrounds the wire coils. Prior to or during this step, the magnet, if present, can also be removed.

Once accessed, the wires that used to constitute the coils can be straightened and trimmed, if required, to form the connecting wires 210 depicted in Fig. 7. Surgical scissors may be used to remove the elastomeric support from the wires or alternatively • a surgical punch may be used.

Various techniques can be employed to electrically connect the wires 210 to a further or secondary implantable module which is depicted generally as 300 in Fig. 7. The step of connecting the secondary implantable module can comprise forming an electrical connection between the wire or wires 210 that used to form the coils and the secondary implantable module 300. The electrical connection can be provided by electrically contacting the wires 210 to an electrical contact on the secondary implantable module 300. In the depicted embodiment, a connector 400 can be used to connect the wires 210 to the secondary implantable module 300. As depicted, leads 310 can also extend from the secondary implantable module 300 and be connectable to the connector 400. In another embodiment, a suitable connector could be mounted in the housing 320 of the secondary implantable module 300.

The connector 400 can be formed using the technique as depicted in Figs 5 A to 5C and described above.

In ^" other embodiments, the connector 400 can comprise an insulation displacement connection which requires a portion of the electrically insulating outer layer to be stripped from the lead as a connector blade cuts through the outer layer to make contact with the electrical conductor. Connection can also be achieved by crimping a connector onto the lead that is suitable for attachment to a receptacle on the housing of the secondary implantable module. In another embodiment, the connector may comprise an integral component of the secondary implantable module.

While not depicted as such, the primary receiveτ/stimulatoτ unit 90 and carrier member 200 could comprise at least part of a partially or totally implantable prosthesis, such as a partially or totally implantable cochlear implant. In this case, the implantable component 100 could be provided with some or all of the features necessary to allow the prosthesis to operate, for at least a period of time, in a stand-alone fashion. For example, the component 100 could include a microphone, a speech processor, a power source, a power source controller and/or a power monitor. In this case, the power source can comprise a rechargeable battery and so allow the implantable component to operate for a period of time without necessarily the need for an external component. For example, the controller can control when power is delivered and the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source. As described below, the power source controller and/or power monitor of the implantable component 100 can also be adapted to control and/or monitor, respectively, a power source present in the secondary implantable module 300. In anotheτ arrangement, the power source controller and/or power monitor can work in conjunction with similar devices also present in the secondary implantable module 300. The carrier member 200 can comprise a non-insertable portion and an insertable portion. The non-insertable portion can comprise a proximal portion of the carrier member (e.g. cable 130) and have no electrodes disposed thereon. The insertable portion can comprise a portion of the carrier member extending back from the leading end of the member. The insertable portion can have all of the electrodes 210 that are disposed on the carrier member. The carrier member 200 can decrease in diameter over at least a portion of its length towards the leading end. The carrier member 200 can be formed from an elastomeric material, such as a silicone. Each of the electrodes 210 can be formed from a biocompatible material, for example platinum. The electrodes 210 can comprise ring members. In one embodiment, the carrier member 200 can have 220 electrodes. In another embodiment, the carrier can have between about 200 and about 30 electrodes, or 30 or more than 30 electrodes. A series of wires 140 extend through the cable 130 to the plurality of electrodes 210. Not all of the wires 140 are depicted for ieasons of clarity.

As also depicted, the implantable component 100 can have at least one secondary electrode assembly 150 extending from the housing 110. The secondary electrode assembly 150 can have more one or more electrodes. In the case of a cochlear implant, the electrode assembly 150 can be mounted external the cochlea of an implantee.

The secondary implantable module 300 can be designed to be removable from the implantee if and when required and/or at least relatively more readily removable than the implantable component 100.

Once implanted, the secondary implantable module 300 can be designed to work in conjunction with and/or supplement the primary receiver/stimulator unit 90 of the implantable component 100. In this case, the secondary implantable module 300 may take over control of the operation of the prosthesis. However, it will be appreciated that the secondary implantable module 300 while adding functionality to the prosthesis may still be controlled by the implantable component 100. In another embodiment, the secondary implantable module 300 can be designed to replace the function of the primary receiver/stimulator unit 90, particularly if the unit 90 has failed or is no longer suitable for the implantee. In a further embodiment, the secondary implantable module 300 can also comprise a housing 320 containing powered and/or electronic componentry. This housing 320 can also be hermetically sealed and be formed from a biocompatible material, such as titanium. The powered componentry of the secondary implantable module 300 can comprise a secondary receiver/stimulator unit that outputs signals via the electrical connector 400 and the wires 210 that used to comprise the primary antenna 120 and into the housing 110 of the primary receiver/stimulator unit 90 which in turn delivers the signals to the electrode carrier member 200. The secondary implantable module 300 can house a signal encoder, a driver circuit, and impedance matching and isolation circuitry.

As depicted, the secondary implantable module 300 can have a secondary antenna coil 330 mounted thereon. The secondary antenna 330 replaces the function of the primary antenna 120 of the implantable component 100 that is modified by the method of the present invention. The secondary antenna 330 can have the same or different construction to that of primary antenna 120. The secondary antenna 330 can also be appropriately aligned with an external antenna coil to form a transcutaneous radio frequency (RF) magnetic induction link. The secondary implantable module 300 can also house the necessary receiver circuitry for the secondary antenna 330. For example, the secondary implantable module 300 can house a rectifier and decoding circuitry.

Irrespective of whether the implantable component 100 has a power source or not, the secondary implantable module 300 can house a power source. The power source can comprise a rechargeable battery.

The secondary implantable module 300 can also house a power source controller that controls the operation of the power source and/or a power monitor. For example, the controller can control when power, is delivered and the magnitude of the delivered voltage. The power monitor can watch the operation of the power source and provide feedback to the controller. The power monitor can also provide an output that can be delivered to an external component to allow the implantee or a third party to determine at least some aspects of the operation of the power source. As mentioned above, the power source controller and/or power monitor of the implantable component 100 can also be adapted to control and/or monitor, respectively, a power source present in the secondary implantable module 300. In another arrangement, the power source controller and/or power monitor of the implantable component 100 can work in conjunction with the power source controller and/or power monitor present in the implantable module 300.

The secondary implantable module 300 can also house or support one or more microphone assemblies. Other possible componentry can comprise one or more of a temperature sensor, a humidity sensor, an impact or shock sensor, such as an accelerometer, and/oτ an optical communications or stimulation interface.

If and when desired, the implantable component 100 and secondary implantable module 300 can work in conjunction with an external component The external component can be used to recharge the power source, where present, in either the primary receiver/stimulator unit 90 or secondary implantable module 300. Still further, it can be used in conjunction with the implantable component 100 and/or secondary implantable module 300 to provide a hearing sensation to an implantee. It will be appreciated that a different or the same external component can be used to recharge the power source and work in conjunction with the implantable component 100 and/or secondary implantable module 300 to provide the hearing sensation. In one embodiment, the external component can have a microphone for detecting sound, a speech processor that converts the detected sounds, particularly speech, into a coded signal, a power source such as a battery, and an external transmitter antenna coil. The primary receiver/stimulator unit 90 of the implantable component 100 oτ the secondary implantable module 300 can receive the coded signal transmitted from the speech processor, process the coded signal and output a stimulation signal. The stimulation signal can be output to the carrier member 200. The carrier member 200 then delivers electrical stimulation to the auditory nerve of the implantee so producing a hearing sensation corresponding to the original detected sound. The implantable component 100 and/or the secondary implantable module 30 can work to use the input from the external component when it is present but rely on on-board componentry when the external component is not being used. In this latter embodiment, the primary and secondary implantable modules can work together to form a partially or fully implantable prosthesis, such as a cochlear implant system.

In the method according to the present invention, once electrical connection has been made between the housing 110 of the primary receiver/stimulator unit 90 and the housing 320 of the secondary implantable module 300, the incision site is surgically closed. Closure can be made using stitches, staples and/or adhesive.

The method described herein provides a technique for modifying the implantable component 100 of a tissue-stimulating prosthesis, such as the primary receiver/stimulator 90 of a cochlear implant as depicted in the drawings. The modification technique can be performed when it is desired to upgrade or otherwise modify the performance of the implantable component 10 of the prosthesis. It can also be used if the implantable component 100 has failed in some way. The advantage of the present invention is that it provides a technique for modifying or restoring operation without the need of removing the electrode carrier member 200 from the cochlea. This is considered important in the case of cochlear implants where it is at least desirable to not have to remove the intracochlear electrode array from its position within the cochlea once in place.

The method can also be used for children. For children under three years of age, it is currently considered preferable to not implant a totally implantable cochlear implant as the head undergoes rapid growth during this period, As early implantation is also critical to ensure an infant is capable of processing sounds, the present invention provides the option of firstly implanting a traditional implantable component for the first few years of life. At the appropriate time, the method of the present invention can be performed to place the secondary implantable module 300 in position within the implantee. This secondary implantable module 300 allows the implantee to potentially have the benefit of a totally implantable prosthesis without the risk of having to harm the relatively delicate structures of the cochlea of the implantee.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.