WO1997009012A1

WO1997009012A1 - Percutaneous multiplexer for therapeutic systems

Info

Publication number: WO1997009012A1
Application number: PCT/AU1995/000577
Authority: WO
Inventors: Peter Misha Seligman
Original assignee: Cochlear Pty. Limited
Priority date: 1995-09-05
Filing date: 1995-09-05
Publication date: 1997-03-13
Also published as: AU3377795A

Abstract

A system for providing therapy, such as for example, a cochlear implant system, includes an external portion (312) and an internal portion (314) receiving signals from the external portion (312). The internal portion (314) applies therapy to the patient in accordance with the signals received from the external portions (312). A connector (328) is provided for exchanging signals between the external portion (312) and the implanted portion (314) using a hard wired scheme such as a serial signal or duplex scheme. In this manner, the connector (328) may be used which has only two connection pins. Additional connection pins may be used for auxiliary functions such as power, clocking signals or duplex transmission.

Description

PERCUTANEOUS MULTIPLEXER FOR THERAPEUTIC SYSTEMS

TECHNICAL FIELD

This invention pertains to therapeutical systems having an internal, i.e. implanted, section and an external section, and more particularly to a device providing communication between said sections. The system may be, for example, a cochlear implant.

BACKGROUND ART

Various systems which have implanted and external sections are presently used to provide therapy to a patient suffering from different illnesses. The sections

communicate with each other through a communication scheme to exchange various information pertaining to the operation of the system. The present invention shall be described in relation to a cochlear implant system, however, it may be applicable to other therapeutic systems as well.

Cochlear implant systems are used to aid patients with acute hearing loss, by applying electrical stimulus

directly to the patient's cochlear nerve. As illustrated in Fig. 1, a typical percutaneous cochlear implant system 10 includes, as previously mentioned, an external section 12 and an internal section 14. The external section 12 consists of a microphone 16 and a speech processor 18. The speech processor 18 is made up of a housing 20 holding a signal processor 22, electronic stimulating circuit 24 and a power supply 26.

The internal section 14 includes an electrode cable 28 terminating in electrode array 24. The array 24 consists of a plurality of individual electrodes, such as electrode 30A, each electrode contacting a portion of the cochlear nerve 32.

Ambient sounds are picked by microphone 16 and

converted into corresponding electrical signals. These electrical signals are fed to processor 22 which uses a preselected scheme to generate corresponding processor signals. The processor signals are received by the

electrode stimulating circuitry 24 which converts them into cochlear electrode stimulating signals. These signals are transmitted to the electrode array 30 and stimulate the nerve 32 accordingly. The patient senses the signals applied to the nerve 32 and based on these sensations, he is able to recognize the sounds picked up by the microphone 16. Details of a cochlear system 10 are described, for example, in U.S. Patents No. 4,532,930 and 5,271,397, incorporated herein by reference.

In the system 10 shown in Fig. 1, the communication between the electrode cable 28 and the speech processor IS is provided via a multi-way percutaneous connector 34.

This connector is surgically mounted and affixed on the skin 36 of the patient and provides a separate conductor 38 for each electrode 30A. In essence, the elecrode array 30 is hard wired in parallel through the connector 34 and conductors 38 to the speech processor 18. Thus, the number of the conductors 38 and the size of the connector 34 is determined by the number of electrodes 30A. Since this number can be relatively large, for example, twenty two, the hard wired parallel communication scheme of Fig. 1 is unreliable. Moreover, such a large connector 34 is

difficult to install surgically, and is unsightly

especially for patients with short hair.

Fig. 2 shows another prior art scheme for providing communication in a cochlear implant system. In system 110, the processor signals from the signal processor 22 in the external section 112 are fed to a data encoder 150 which generates corresponding encoded data signals. The encoded data signals are fed to a data and power transmitter 152 which converts the data signals into radio frequency signals suitable for transmission across an inductive link. The radio signals are transmitted to a transmitter coil 154. The implanted section of the system 110 includes cable 28 terminating in the array 30 as described above. The implant section 114 also includes a receiver stimulator 156 consisting of a housing 158. The housing 158 contains a data and power receiver 160, and a data decoder 162 and electrode stimulating circuitry 24. The power and data receiver receives data and power through a receiver coil 162.

In operation, the transmitter coil 154 is positioned so that it is inductively coupled to the receiver coil 162 to transmit the analog signals from transmitter 152. These signals are inductively transmitted through the skin 36 of the patient. The data signals from the receiver 160 are fed to the data decoder where they are decoded into

processor signals. The processor signals are fed to the electronic stimulating circuitry 24 which then generates corresponding electrode stimulating signals to cable 28 in a manner similar to the one shown in Fig. 1. In addition, the energy of the signals received by coil 162 is also used by the receiver 160 to generate power for the receiver stimulator 156.

While this scheme resolves some of the problems

associated with the direct hard wired scheme of Fig. 1, it still has some disadvantages. One disadvantage is that the inductive link normally has a power transfer efficiency of substantially less then 50%, which is a waste of power, especially in the context of a lightweight, battery powered system. Another disadvantage is that properties inherent to the inductive link, for example, ringing in the receiver coil, necessitate the use of special data protocols (see for example, U.S. Patent No. 4,532,930) which have a lowered data rate in order to preserve substantially error free operation. A further disadvantage is that the coils 154 and 162 must be precisely aligned. If they are

misaligned power transfer efficiency may be reduced thereby degrading the performance of the system. This problem may be resolved or at least alleviated (see for instance, U.S. Patent No. 4,654,880), but only at the cost of additional components, which increases the complexity of the system and its cost. DISCLOSURE OF THE INVENTION

According to one aspect of the invention there is provided a system for providing therapy to a patient, said system having an external portion, an internal portion constructed and arranged to provide a preselected therapy in response to signals from the external portion, and means for sending information from the external to the internal component, said means including a connector providing hard wired electrical paths between said portions, an encoder for encoding said information into serial data for

transmission on said electrical paths, and a decoder for decoding said serial data. The data encoder and decoder are preferably disposed in the external and internal portions, respectively. Power for the internal portion may be derived from the serial data. Alternatively, a separate electrical path may be defined through the connector for a power lead and/or other dedicated functions such as timing.

According to another aspect of the invention there is provided a cochlear implant system for aiding a patient having acute hearing loss, said system comprising:

an external portion including sound receiving means for receiving sounds and generating electrical signals

corresponding to said sounds, signal processing means receiving said electrical signals for produce processed signals; and encoding means for receiving said processed signals and producing encoded signals;

an implanted portion including decoding means for receiving said encoded signals and for decoding said encoded signals to produce decoded signals, processing means for receiving said decoded signals and in response for generating received processed signals and electrode means for transmitting said received processed signals to the patient's auditory nerve; and

a connector disposed on the patient's skin, said connector transmitting encoded signals from said external to said implanted portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a block diagram for a prior art cochlear system with a multi-wire percutaneous connection;

Fig. 2 shows a block diagram for another prior art cochlear system with an inductive coupling;

Fig. 3 shows a block diagram for a cochlear system constructed in accordance with this invention; and

Fig. 4 shows a somewhat diagrammatic, orthogonal view for an alternate embodiment of the invention.

MODES FOR CARRYING OUT THE INVENTION

Referring now to Fig. 3, a system 210 constructed in accordance with this invention includes two portions; an external portion 212, and an implanted portion 214. The external portion includes a microphone and a speech processor 270 which is arranged and constructed to be worn by a patient. The processor 270 includes a housing 220 containing a signal processor 22, a data encoder 272 and a power supply 26. Power to both the processor 22 and data encoder/multiplexer 272 is provided by a power supply 26. The implanted portion 214 includes a housing containing a data decoder/demultiplexer 274, an electrode stimulating circuit 24 and an internal power supply 276. The implanted portion 214 includes a housing containing a data

decoder/demultiplexer 274, an electrode stimulating circuit 24 and an internal power supply 275. The implanted portion 214 further includes a cable 28 terminating in an electrode array 30, each electrode 30A of the array being in contact with the cochlear nerve 32.

At a section of patient's skin 36 adjacent to housing

258 a percutaneous connector 238 is installed surgically. In the embodiment of Fig. 3, the connector 238 is a two-way connector because it provides two connection pins 278, 280. Pins 278, 280 are connected by a pair of wires 282 to the data encoder/multiplexer 272 and by a second pair of wires 284 to the data decoder/demultiplexer 274.

The system operates as follows. The signal processor 22 receives the electrical signals from microphone 16 corresponding to ambient sounds, and generates in parallel a set of corresponding processed signals on lines 271, each line 271 corresponding to one of the electrodes 30A. The data encoder/multiplexer takes the signals from each of the lines 271 and converts them into communication signals suitable for transmission to the implanted portion 214. Importantly, the encoder/multiplexer 272 also multiplexes these signals using, for example, time-division

multiplexing and transmits the same, serially, on lines 282. The signals from speech processor 270 are transmitted via lines 282, connector 238 and lines 284 to the data decoder/demultiplexer 274. The data decoder/demultiplexer first demultiplexes the received signals and then decodes them to obtain a set of processed signals substantially identical to the signals received by the data

encoder/multiplexer 272 from lines 271. These processed signals are fed on lines 277, to the elected stimulating circuitry 24. In response, this circuitry generates separate electrode stimulating signals for cable 28. Each signal stimulates the nerve 32 along a preselected location to produce an excitation as discussed above. The set of all excitation signals from the various electrodes 30A are interpreted by the patient as sounds.

It should be understood that any two-wire encoding scheme may be used for encoding and decoding the signals between the external and implanted portions 212, 214. The simplest type of encoding is an asynchronous simplex encoding. Alternatively, a duplex encoding can be used if the information, rather than flowing one way from the external to the implant portion, flows both ways.

In addition to provide the data, the signals received on line 284 may also be used to provide power to power supply 276 which in turn transmit the power to the data encoder/demultiplexer and the electrode stimulating circuit 24. For this purpose, the power supply 276 may include for example a diode 292 and a capacitor 294. Although in Fig. 3, connection 278 is shown as having solid wire connections, it should be understood that preferably the connector 278 is in fact made of a male and a mating female portion, as discussed below.

Another embodiment of the invention is shown in Fig. 4 wherein a system 310 is shown having an external portion 312, an internal portion 314 and a connector 328. The connector 328 includes a male section 328A and a female section 328B. The male section 328A is provided with three pins 300A, 300B, 300C. Pins 300A and 300B are connected by a pair of wires 382A, 382B to data/encoder multiplexer 272. Pin 300C is connected by wire 382C to the power supply 26.

Female section 328B is provided with sockets 302A, 302B and 302C arranged and constructed to mate with pins 300A, 300B, 300C, respectively. These sockets 302A, 302B and 302C are connected by wires 384A, 384B to data decoder demultiplexer 274 and by wire 384C to a power distribution block 376. Female section 328B is implanted just under the skin of the patient with the sockets 302A, 302B, 302C being exposed so that they can be coupled to pins 300A, 300B,

300C respectively. The difference between the embodiments of Figs. 3 and 4 is that instead of deriving power from the serial data signals, in fig. 4, a separate hard wired connection is provided by wire 382C, pin 300C, socket 302C, and wire 384C between the power supply 26 and power

distribution block 376.

Preferably the external speech processor portion of system 210 or 310 is enclosed in a common housing arranged and constructed so that it can be worn behind the ear by the patient. Coupling between the external and internal sections is accomplished by mating the connector sections.

Although the invention has been described with

reference to several particular embodiments, it is to be understood that these embodiments are merely illustrative of the application of the principles of the invention.

Accordingly, the embodiments described in particular should be considered exemplary, not limiting, with respect to the follwwing claims.

Claims

1. A therapeutic system comprising:

an external portion;

an implanted portion, said implanted portion applying a therapy to a patient in response to information from said external portion; and

connecting means for transmitting said information from said external to said implanted portions, said connection means including encoder means for encoding said information into serial data signals, hardwired interface means for transmitting said data signals and decoding means for decoding said data signals.

The system of Claim 1 wherein said hardwired interface means is a connector disposed on the skin of the patient.

3. The system of claim 2 wherein said connector includes two pins extending through said connector, a first pair of wires extending from said pins to said external portion and a second pair of wires extending from said pins to said implanted portion, said data being transmitted through said wires and said pins.

The system of Claim 3 wherein said connector interface means further includes a further hard wired connection for transmitting power from said external portion to said implanted portion.

5. The system of Claim 3 wherein said connector interface means further comprises a clock line for exchanging clock signals between said external and said implanted portions.

6. A system for providing therapy for the patient, said system comprising:

an external portion including signal generating means for generating a plurality of transmitted therapeutic signals and encoding means for encoding said therapeutic signals into encoded signals;

a connector attached to the skin of the patient of passing said encoded signals into the patient's body; and an implanted portion, said implanted portion including means for receiving said encoded signals from said

connector and decoding said signals into decoded signals and implant signal generating means receiving said decoded signals and generating corresponding internal signals for applying therapy to the patient.

7. The system of Claim 6 wherein said encoding means encodes said data signals into serial data signals.

8. The system of Claim 7 further comprising a first set of lines for serially transmitting said data signals from said external portion to said connector, and a second set of lines for transmitting said serial data signals from said connector to said implanted portion.

9. The system of Claim 6 wherein said encoding means includes multiplexing means for multiplexing the encoded signals before transmission to said implanted portion; and wherein said implanted section includes demultiplexing means for demultiplexing said encoded signals.

10. The system of Claim 6 further comprising power lime means for transmitting power from said external portion to said internal portion through said connector.

11. The system of Claim 6 further comprising clock line means for transmitting clock signals from said external portion to said implanted portion.

12. A cochlear implant system for aiding a patient having acute hearing loss, said system comprising:

13. The system of Claim 12 wherein said encoding means encodes said transmitted processed signals into serial data signals .

14. The system of Claim 12 wherein said encoder includes multiplexing means for multiplexing said transmitted processed signals and said decoder means includes

demultiplexing means for demultiplexing said decoded signals.

15. The system of Claim 12 wherein said electrode means includes an array of electrodes, each electrode contacting said nerve, and wherein each processed signal is assigned to a preselected electrode.

16. The system of Claim 12 wherein said connector is a two way connector.

17. The system of Claim 12 wherein said connector includes a first set of connection means for transmitting said encoded signals and a second set of connection means for transmitting power from said external to said implanted portions.

18. The system of Claim 12 wherein said connector includes a first connection means for transmitting said encoded signals and a second connection means for exchanging clocking signals between said external and said implanted portions.