EP1191815B1 - At least partially implantable hearing system with direct mechanical stimulation of a lymphatic space of the internal ear - Google Patents

Abstract

An at least partially implantable sensor for rehabilitation of a hearing disorder having at least one acoustic sensor for picking up acoustic sensor signals and converting the acoustic sensor signals into corresponding electrical audio sensor signals; an electronic signal processing unit for audio signal processing and amplification of the electric sensor signals; an electrical power supply unit which supplies individual components of the system with energy, and an actoric output arrangement for direct mechanical stimulation of a lymphatic inner ear space, wherein the actoric output arrangement has an intracochlear electromechanical transducer.

Description

The present invention relates to an at least partially implantable system for the rehabilitation of a hearing impairment with at least one sound-absorbing sensor (microphone), an electronic arrangement for audio signal processing and amplification, an electrical power supply unit which supplies individual components of the system with power, and an output-side actuator array for direct mechanical stimulation of a lymphatic space of the inner ear.

In the present case, the term "hearing impairment" should be understood to mean all types of inner ear damage, combined inner and middle ear damage as well as occasional or permanent ear noises (tinnitus).

The rehabilitation of sensory hearing disorders with partially implantable electronic systems has received significant attention in recent years. In particular, this applies to the patient group in which the hearing by accident, illness or other influences completely failed or is not functional from birth. If in these cases only the inner ear (cochlea) and not the centrally leading neuronal hearing are affected, the remaining auditory nerve can be stimulated with electrical stimulus signals and thus a hearing impression can be generated, which can lead to an open speech understanding. In these so-called cochlear implants, a stimulus electrode array is introduced into the cochlea, which is driven by an electronic system, this hermetically sealed and biocompatible encapsulated electronics module is operatively embedded in the bony area behind the ear (mastoid). However, the electronic system essentially contains only decoder and driver circuits for the stimulating electrodes; The acoustic sound recording, the conversion of this sound signal into electrical signals and their further processing is basically external in a so-called speech processor, which is worn on the outside of the body. The speech processor converts the preprocessed signals corresponding encoded to a high-frequency carrier signal, which is transmitted to the implant via an inductive coupling through the closed skin (transcutaneously). The sound-absorbing microphone is invariably outside the body and, in most applications, in a back-of-the-ear (BTE) case worn on the pinna and is equipped with a cable connected to the speech processor. Such cochlear implant systems, their components and principles of transcutaneous signal transmission are exemplary in US-A-5 070 535 . US-A-4,441,210 and US-A-5,626,629 described. Methods for speech processing and coding in cochlear implants are, for example, in US Pat. No. 5,597,380 . US-A-5 601 617 and U.S.-A-5,603,726 specified.

In addition to the rehabilitation of deaf or deaf patients with cochlear implants have long been approaches to provide patients with a sensorineural hearing impairment that is not surgically recoverable, with partially or fully implantable hearing aids better rehabilitation than with conventional hearing aids. The principle in the predominant embodiments is to stimulate an ossicle of the middle ear or the inner ear directly via a mechanical or hydromechanical stimulus and not via the amplified acoustic signal of a conventional hearing aid, in which the amplified sound signal is supplied to the external auditory canal. The actuatoric stimulus of these electromechanical systems is realized with various physical transducer principles, such as electromagnetic and piezoelectric systems. The advantage of these methods is seen mainly in the compared to conventional hearing aids improved sound quality and fully implanted systems in the invisibility of the hearing prosthesis. Such partially and fully implantable electro-mechanical hearing aids are exemplified by H. Leysieffer et al. "A completely implantable hearing aid for hearing impaired people: TICA LZ 3001" ENT 46: 853-863 and HP Zenner et al. "Totally implantable hearing device for sensorineural hearing loss", The Lancet Vol. 352, no. 9142, page 1751 as well as in numerous patents described, so inter alia in US-A-5,360,388 . US-A-5,772,575 . U.S. Patent 5,814,095 and US-A-5,984,859 ,

Recently, such partially and fully implantable hearing systems for the rehabilitation of an inner ear damage in clinical application. Depending on the used physical principle of the output-side electromechanical transducer and in particular its coupling to the ossicles of the middle ear, it can be seen that the achieved results of the improvement of the speech understanding can be very different. In addition, in some patients, a sufficient volume level can not be achieved; this aspect is spectrally very different, which may mean that for example medium and high frequencies the generated loudness is sufficient, but not at low frequencies or vice versa. Furthermore, the transmittable spectral bandwidth can be limited, such as in electromagnetic transducers to low and medium frequencies or in piezoelectric transducers to medium and high frequencies. In addition, nonlinear distortions, which are particularly pronounced in electromagnetic transducers, can occur are to negatively impact the resulting sound quality. The lack of loudness in particular means that the audiological indication range for the implantation of an electromechanical hearing system is very limited, which means that patients, for example, with a sensorineural hearing loss greater than 50 dB HL (= hearing loss, hearing loss) in the low frequency range with a piezoelectric system can only be supplied insufficiently. In contrast, pronounced high-frequency losses are difficult to supply with electromagnetic transducers.

Many patients with inner ear damage additionally suffer from temporary or permanent tinnitus (tinnitus), which can not be surgically repaired and against which no approved medical treatment forms exist to date. Therefore, so-called tinnitus maskers are available; These are small, battery-powered devices that are similar to a hearing aid worn behind or in the ear and by artificial sounds that are emitted via a hearing aid speaker, for example, in the ear canal, the tinnitus in a psychoacoustic manner hide ("mask") and the disturbing noise of the ear as low as possible below the threshold of perception. The artificial sounds are often narrow-band noise (for example, third-octaves), which can be adjusted in their spectral position and volume levels via a programmer to allow the best possible adaptation to the individual ear noise situation. In addition, there is recently the so-called "retraining method", whereby by the combination of a mental training program and the presentation of a broadband sound (noise) near the rest hearing threshold, the perceptibility of tinnitus should also be largely suppressed ( H. Knör, "Tinnitus Retraining Therapy and Hearing Acoustics" Journal "Hörakustik" 2/97, pages 26 and 27 ). These devices are also called "Noiser".

In both above-mentioned methods for apparative therapy of tinnitus hearing-device-like, technical equipment outside the body in the ear area to carry visible that stigmatize the wearer and therefore are not happy to be worn.

In the US-A-5 795 287 For example, an implantable tinnitus masker with "direct drive" of the middle ear is described, for example, via an electromechanical transducer coupled to the ossicular chain. This directly coupled converter may preferably be a so-called "Floating Mass Transducer" (FMT). This FMT corresponds to the converter for implantable hearing aids, which in U.S. Patent 5,624,376 is described.

In DE-C-198 58 398 and DE-A-198 59 171 implantable systems for the treatment of tinnitus by masking and / or Noiserfunktionen be described in which the signal processing electronic path of a partially or fully implantable hearing system is supplemented by appropriate electronic modules so that the tinnitus masking or for Noiserfunktion necessary signals are fed into the signal processing path of the hearing aid function and the associated signal parameters can be adjusted by other electronic measures to the pathological needs individually. This adaptability can be realized in that the necessary setting data of the signal generation and supply electronics in the same physical and logical data storage area of the implant system hardware and software stored or programmed and control the supply of the masker or noise signal in the audio path of the hearing implant via corresponding electronic actuators ,

The above-described, at least partially implantable hearing aid rehabilitation based on an output-side electromechanical transducer, differ essentially from conventional conventional hearing aids essentially only in that the output side acoustic stimulus (an amplified sound signal in front of the eardrum) by an enhanced mechanical Stimulus of the middle or inner ear is replaced. The acoustic stimulus of a conventional hearing aid finally leads via the mechanical stimulation of the eardrum and the subsequent middle ear to a vibratory, that is mechanical stimulus of the inner ear. With regard to the meaningful audio signal preprocessing, fundamentally similar or identical requirements exist. Furthermore, in both embodiments, ultimately, a locally localized vibratory stimulus is directed to the damaged inner ear on the output side (for example, reinforced mechanical vibration of the stirrup in the oval window of the inner ear).

In deafness-bordering deafness implantable, electromechanical systems are so far not applicable for the reasons mentioned inadequate volume level; Here come cochlear implants (CIs) with purely electrical irritation of the inner ear in question, which naturally can expect no sound quality that allows, for example, an acceptable music transfer, but are designed primarily to obtain or restore a sufficient understanding of speech as possible without lip reading. Due to the electrical stimulation reaching to complete deafening hearing loss in a spectrally broad audiological area are possible.

In a widespread middle ear damage, the so-called otosclerosis, in particular, the mobility of the ligament of the stirrup suspension in the oval window is limited or completely prevented by calcification, is used by the surgical method of stapedectomy (English Stapedotomy) a passive prosthesis, on the one hand by a Bracket is usually fixed on the long incus process and on the other hand with its mostly circular shaft in an artificially introduced opening in the stirrup foot plate is used. The stirrup can also be completely removed. The vibrations of the eardrum are transmitted via the hammer on the anvil and thus cause corresponding vibrations of the passive prosthesis, which lead to dynamic volume shifts in the perilymph of the inner ear, thereby triggering traveling waves on the basilar membrane and ultimately to a listening experience. This method has been used for decades as a reconstructive Mittelohroperation very safe and successful. The introduction of the opening in the stirrup footplate is achieved by fine surgical instruments or, in particular, by laser techniques.

For a short time now, it has been scientifically known from CI implantations that CIs can be successfully used even in cases of incomplete deafness if sufficient speech discrimination can no longer be achieved with a conventional hearing aid. Interestingly, it could be shown that the essential inner ear structures, which allow the acoustic residual hearing, can be partially or largely long-term stable, when a CI-electrode is introduced into the cochlea ( Ruh, S. et al .: "Cochlear Implant in Resting Hearing", Laryngo-Rhino-Otol. 76 (1997), 347-350 ; Müller-Deile, J. et al. Cochlear implant delivery in non-deaf patients ?, Laryngo-Rhino-Otol 77 (1998), 136-143 ; Lehnhardt, E .: "Intracochlear placement of cochlear implant electrodes in soft surgery technique", EN 41 (1993), 356-359 ). It can be concluded that in anticipated further clinical and audiological research in the foreseeable future, CI electrodes can be clinically placed intracochlear in residual hearing so that the remaining inner ear structures are long-term stable and thus on biologically adequate way, that is, vibratory, further stimulable are and lead to a usable listening experience.

The older one EP patent application 00 119 195.6 describes a hearing system having a plurality of electromechanical transducers distributed along the cochlea to excite the fluid-filled inner ear spaces by forming a traveling wave configuration on the basilar membrane. The older one EP patent application 01 109 191.5 discloses a hearing system with a dual intracochlear assembly having in combination a stimulator assembly with at least one stimulator element for at least indirect mechanical stimulation of the inner ear and an electrically acting stimulation electrode assembly with at least one cochlear implant electrode for electrical stimulation of the inner ear. These hearing systems make relatively complicated surgical procedures necessary.

In US-A-5,977,689 a hearing system microactuator is described with a hollow body implantable in the middle ear, which is filled with an incompressible liquid and in the at least one connected to a relatively large-area membrane piezoelectric transducer is housed. The interior of the hollow body is in communication with a nozzle which is inserted into an artificial fenestration of Promontoriums and which is closed at its end remote from the hollow body of a small compared to the transducer membrane. The transducer, when applied with appropriate electrical signals, exerts force on the fluid in the hollow body, thereby deflecting the small nozzle end diaphragm of the microactuator in fluid contact with the inner tube.

Out US-A-5,772,575 and US-A-5,984,859 a system of the aforementioned type is known, in which a microactuator with a flat flexible membrane is provided as the output-side actuator arrangement. The Mikroaktuatormembran forms the end face of a screw which is screwed into an artificial fenestration in Promontorium, or the microactuator is inserted directly into such a fenestration such that its planar membrane in the inner tube located fluid contacts. In accordance with another embodiment, the microactuator sits in the stem of a passive stapedectomy prosthesis of the type discussed above to provide for combined passive and active stimulation.

A generic system is from the DE 42 21 866 A1 known, which relates to a fully implantable hearing aid with trained as liquid sonic Ausgantswandler, which dips into the perilymph and stored in a borehole Stapesfussplatte, wherein the liquid sound transmitter as bending transducer from bimorph Piezokeramik or PVDF film or after the electrodynamic principle working with permanent magnet and a magnet surrounding the magnet may be formed.

The invention has for its object to provide an at least partially implantable system for the rehabilitation of hearing impairment, which is able to provide for improved rehabilitation of sensory hearing disorders.

This object is achieved in that in an at least partially implantable system for the rehabilitation of a hearing disorder with at least one sound-absorbing sensor (microphone), an electronic device for audio signal processing and amplification, an electrical power unit which supplies power to individual components of the system, and a Output-side actuator array for direct mechanical stimulation of a lymphatic space of the inner ear, according to the invention, the output-side actuator array consists of an intracochlear electromechanical transducer.

The main advantages of an intracochlear transducer structure according to the invention are, on the one hand, in particular that the mechanical stimulus can be generated over a relatively large area directly in the inner ear and no additional masses, stiffnesses of the suspension and / or lossy joints of the middle ossicles lie in the mechanical transmission path, in particular to linear distortions of the can lead to transmitted frequency response of the converter. On the other hand, it can be assumed that the interindividual reproducibility of the mechanical stimulation is significantly better by direct inner ear stimulation than in the case of transmission by coupling elements to the middle ear particles, because thereby always anatomical fluctuations and in particular the personal approach of the surgeon play an important role.

Another advantage of the present invention is that the occurrence of feedback (coupling of the output signal into the sensor / microphone) is expectedly largely reduced by a direct, electromechanical stimulation of the cochlea, because the ossicular chain and thus the eardrum is not or significantly reduced to vibrations is stimulated. This is particularly advantageous when a sound sensor (microphone function) is applied in the immediate vicinity of the eardrum ( DE-C-196 38 158 and US-A-5,999,632 ).

The presently used electromechanical transducer operates on the principle of dynamic volume change due to a dynamic surface enlargement or reduction in accordance with the electrical, driving converter AC voltage signal. An optimal effect of the transducer of the present invention can be expected to be achieved if it is ensured by constructive measures that as possible the entire surface of the intracochlear transducer oscillates (ideal ball vibrator), because thereby a maximum volume shift and thus the highest possible stimulation level for a given electrical Drive power of the converter is achieved by the preprocessing electronic system.

The operative access for the intracochlear transducer is preferably through the oval or an artificial cochlear window, for example a promontorial window. After, as described above, the stapedectomy with the introduction of an opening in the Stirrupfußplatte has long been proven as a safe Mittelohroperation, it can be assumed that such an opening and thus direct access to the inner ear is possible without increased risk of damage, if none Otosclerosis is present and the foot plate is still fully mobile, that is in the presence of a pure inner ear hearing. This means that the proven surgical techniques of stapedectomy are presently applicable to transducer implantation.

The intracochlear transducer is advantageously arranged at the end of a flexible support structure, in particular a polymer support structure.

Basically, all physical transducer principles come into consideration, such as electromagnetic, electrodynamic, piezoelectric, dielectric (capacitive) and magnetostrictive. Particularly preferred here is the piezoelectric principle, since with simple transducer design the ideal of the surface vibrator can be most easily met. In particular, the intracochlear transducer, preferably with the use of geometric Shape transformations, in particular the bimorph principle, the unimorph principle or the heteromorphic principle with passive material partners, be designed so that it generates a maximum volume change with a minimum electrical power consumption for a given transducer voltage.

The intracochlear transducer is particularly easy to manufacture and easy to implant if it has a piezoelectric tube section of cylindrical cross-section, the inner and outer circumferential surfaces of which are provided with a surface metallization to form electrical conversion electrodes.

The intracochlear piezoelectric transducer can be constructed on the basis of lead zirconate titanate (PZT). But is also particularly suitable single or multilayer winding thin polyvinylidene fluoride film (PVDF). Suitably, the transducer element is provided with a biocompatible sheath, preferably made of an elastic polymer, for example silicone. In this case, the entire transducer element can be surrounded by the biocompatible sheathing. According to a modified embodiment, the sheath has at least one opening - and preferably at least two openings at the lower end of the tube and in the upper region of the sheath - for the entry and exit of intracochlear lymph. Which is designed such that a dynamic change in the radius of the transducer directly a lymphatic displacement and thus an intracochlear volume shift is achieved. In particular, the tube surface of the intracochlear transducer and the cross-sectional area of the inlet and outlet openings can be designed to achieve a hydraulic transformation that results in higher lymph velocity and thus higher cochlear stimulation levels than by direct surface modification by the transducer itself.

As it is US-A-5,277,694 As is known, the converter is designed to be highly tuned, that is, the first mechanical resonance frequency is at the upper spectral end of the transmission range. Thus, the frequency response is at voltage impressed on a piezoelectric transducer, for example, and thus largely free of linear distortions. The intracochlear transducer may suitably have a transmission range of about 100 Hz to about 10 kHz.

In a further embodiment of the invention, a mechanical damping element can be provided which decouples the vibrations of the intracochlear transducer from a transducer lead, so as to prevent or substantially reduce at least partial resonant oscillation of the middle ossicles due to mechanical contact with this transducer lead. Such a swinging could otherwise lead to disturbing feedback when using eardrum close sensors (microphones). The material of the damping element is preferably selected with a similar cross-sectional geometry as that of the carrier, that in order to achieve high attenuation values there is a large mechanical impedance difference to the carrier material.

The intracochlear transducer may suitably be designed for volume changes of about 2 x 10 ^-4 microliters. The total diameter of the intracochlear transducer array may advantageously be in the range of 0.2 mm to 2.0 mm, and the depth of immersion of the intracochlear transducer and the length of its active transducer element may preferably be between 0.3 and 2 mm.

According to a further embodiment of the present invention, a digital signal processor is provided which performs the audio signal processing and conditioning and / or generates digital signals for tinnitus masking.

The signal processor can be designed statically in such a way that corresponding software modules are stored once on the basis of scientific findings in a program memory of the signal processor and remain unchanged. But later, for example, based on recent scientific findings improved algorithms for speech signal processing and processing before and should they be used by an invasive, surgical patient intervention, the entire implant or implant module containing the corresponding signal processing unit, against a new with the changed Operating software to be replaced. This procedure brings new medical risks for the patient and is associated with high costs. This problem can be addressed by the fact that in a further embodiment of the invention, a preferably PC-based, telemetry device for transmitting data between an implanted part of the system and an external unit, in particular an external programming system is provided, and that the signal processor for recording and reproducing an operating program associated with a rewritable implantable memory device, wherein at least portions of the operating program may be changed or replaced by data communicated from the external device via the telemetry device. In this way, after implantation of the implantable system, the operating software, including software for controlling the intracochlear transducer, as such change or completely exchange. This makes it possible to implement more advanced scientific knowledge, for example, with respect to speech signal processing strategies in the implant, without the implant must be replaced by surgery.

The design is preferably such that, in addition, in fully implantable systems, operating parameters, that is, patient-specific, are also known per se Data, such as fitting audiological data, or changeable implant system parameters (for example as a variable in a software program for driving the intracochlear transducer or for regulating a battery recharge) after implantation can be transcutaneously, ie wirelessly transmitted through the closed skin, into the implant and thereby changed can. In this case, the software modules are preferably dynamic, or in other words adaptive, designed to come to the best possible rehabilitation of the respective hearing impairment. In particular, the software modules may be designed to be adaptive, and parameter adjustment may be done by "training" by the implant carrier and other aids.

Furthermore, the signal processing electronics may include a software module that achieves the best possible stimulation on the basis of a learning neural network. The training of this neural network can be done by the implant wearer and / or with the help of other external aids.

The memory arrangement for storing operating parameters and the memory arrangement for recording and reproducing the operating program can be implemented as independent memories; However, it can also be a single memory in which both operating parameters and operating programs can be stored.

The present solution allows an adaptation of the system to conditions that are detectable only after implantation of the implantable system. Thus, for example, in an at least partially implantable hearing system for the rehabilitation of a monaural or binaural inner ear disorder and tinnitus with mechanical stimulation of the inner ear, the sensory (sound sensor or microphone) and actoric (intracochlear transducer) biological interfaces are always dependent on the anatomical, biological and neurophysiological conditions, for example, of the interindividual healing process. These interface parameters can be individual and also time-variant, in particular. Thus, for example, the transmission behavior of an implanted microphone due to tissue layers and the transmission behavior of the coupled to the inner ear intracochlear electromechanical transducer due to different coupling quality vary individually and individually. Such differences in the interface parameters, which can not even be reduced or eliminated in the devices known from the prior art by exchanging the implant, can be optimized here by changing or improving the signal processing of the implant.

• Sprachanalyseverfahren (zum Beispiel Optimierung einer Fast-Fourier-Transformation (FFT)),
• statische oder adaptive Störschallerkennungsverfahren,
• statische oder adaptive Störschallunterdrückungsverfahren,
• Verfahren zur Optimierung des systeminternen Signal-Rauschabstandes,
• optimierte Signalverarbeitungsstrategien bei progredienter Hörstörung,
• ausgangspegelbegrenzende Verfahren zum Schutz des Patienten bei Implantatfehlfunktionen beziehungsweise externen Fehlprogrammierungen,
• Verfahren zur Vorverarbeitung mehrerer Sensor-(Mikrofon-)signale, insbesondere bei binauraler Positionierung der Sensoren,
• Verfahren zur binauralen Verarbeitung zweier oder mehrerer Sensorsignale bei binauraler Sensorpositionierung, zum Beispiel Optimierung des räumlichen Hörens beziehungsweise Raumorientierung,
• Phasen- beziehungsweise Gruppenlaufzeit-Optimierung bei binauraler Signalverarbeitung,
• Verfahren zur optimierten Ansteuerung der Ausgangsstimulatoren, insbesondere bei binauraler Positionierung der Stimulatoren.

In an at least partially implantable hearing system, it may be useful or necessary to implement improved signal processing algorithms after implantation. Here are in particular to call:

• Speech analysis method (for example, optimization of a Fast Fourier Transform (FFT)),
• static or adaptive noise detection methods,
• static or adaptive noise reduction methods,
• Method for optimizing the system-internal signal-to-noise ratio,
• optimized signal processing strategies for progressive hearing impairment,
• Output level limiting method for protecting the patient in case of implant malfunction or external malfunction programming,
• Method for preprocessing a plurality of sensor (microphone) signals, in particular for binaural positioning of the sensors,
• Method for the binaural processing of two or more sensor signals in the case of binaural sensor positioning, for example optimization of spatial hearing or spatial orientation,
• Phase or group delay optimization in binaural signal processing,
• Method for optimized control of the output stimulators, in particular for binaural positioning of the stimulators.

• Verfahren zur Optimierung des Betriebsverhaltens des intracochleären Ausgangswandlers (zum Beispiel Frequenz- und Phasengangoptimierung, Verbesserung des Impuls-übertragungsverhaltens),
• Sprachsignal-Kompressionsverfahren bei Innenohrschwerhörigkeiten,
• Signalverarbeitungsmethoden zur Recruitment-Kompensation bei Innenohrschwerhörigkeiten.

With the present system, the following signal processing algorithms can also be implemented after implantation, inter alia:

• Method for optimizing the operating behavior of the intracochlear output transducer (for example frequency and phase response optimization, improvement of the pulse transmission behavior),
• Speech signal compression method for inner ear hearing loss,
• Signal processing methods for recruitment compensation for inner ear hearing loss.

Furthermore, in implant systems with a secondary power supply unit, that is to say a rechargeable battery system, but also in systems with a primary battery supply, it can be assumed that these electrical energy storage devices are progressing Technology to enable ever longer lifetimes and thus increasing residence times in the patient. It is expected that basic and applied science research will make rapid progress in signal processing algorithms. The need or the patient's desire for an operating software adaptation or change is therefore likely to occur before the end of the life of the internal implant energy source. The system described here allows such an adaptation of the operating programs of the implant even in the already implanted state.

Preferably, a buffer memory arrangement is further provided, in which data transmitted by the external unit via the telemetry device can be buffered before forwarding to the signal processor. In this way, the transmission process from the external unit to the implanted system can be completed before the data transmitted via the telemetry device are forwarded to the signal processor.

Furthermore, a check logic may be provided which subjects the data stored in the latch arrangement to a check prior to routing to the signal processor. It may be a microprocessor module, in particular a microcontroller, provided for implant-internal control of the signal processor via a data bus, expediently the verification logic and the buffer arrangement are implemented in the microprocessor module and wherein via the data bus and the telemetry and program parts or entire software modules between the outside world, the Microprocessor module and the signal processor can be transmitted.

The microprocessor chip is preferably associated with an implantable memory device for storing a work program for the microprocessor chip, and at least parts of the work program for the microprocessor chip may be changed or replaced by data transmitted from the external device via the telemetry device.

In a further embodiment of the invention, at least two memory areas may be provided for recording and reproducing at least the operating program of the signal processor. This contributes to the error safety of the system, in that by the multiple presence of the memory area which contains the operating program (s), for example after a transmission from external or when the implant is switched on, a check can be carried out for the correctness of the software.

Analogously, the buffer memory arrangement can also have at least two memory areas for recording and playback from the external unit via the telemetry device Have transmitted data, so that after a data transmission from the external unit or in the area of the cache memory, a check of the accuracy of the transmitted data can be made. The memory areas can be designed for, for example, complementary storage of the data transmitted by the external unit. However, at least one of the memory areas of the buffer arrangement can also be designed to accommodate only a part of the data transmitted by the external unit, in which case the checking of freedom from error of the transmitted data takes place in sections.

In order to ensure that transmission errors can be restarted, the signal processor may also be associated with a preprogrammed non-rewritable memory area in which the instructions and parameters required for a "minimum operation" of the system are stored, for example instructions following a "Crash" at least ensure error-free operation of the telemetry device for receiving an operating program and instructions for storing the same in the control logic.

As already mentioned, in addition to receiving operating programs from the external unit, the telemetry device is also advantageously designed for the transmission of operating parameters between the implantable part of the system and the external unit, such that on the one hand such parameters are provided by a physician, a hearing healthcare professional or the wearer On the other hand, the system can also transmit parameters to the external unit, for example, to check the status of the system.

A fully implantable hearing system of the type described here can have at least one implantable sound sensor and a rechargeable electrical storage element next to the intracochlear transducer and the signal processing unit, in which case a wireless, transcutaneous charging device for charging the storage element is preferably provided. However, it is understood that for power supply, a primary cell or another power supply unit may be present, which does not require transcutaneous recharge. This is especially true when one considers that in the near future, especially by further development of the processor technology with substantial reduction of the energy demand for electronic signal processing is to be expected, so that for implantable hearing systems new forms of energy are practically applicable, for example, a Seebeck effect using energy supply as they are in DE-C 198 27 898 is described. Preferably, a wireless is also Remote control for controlling the implant functions by the implant carrier available.

In teilimplantierbarer training of the hearing system at least one sound sensor, the electronic signal processing unit, the power supply unit and a modulator / transmitter unit in a externally on the body, preferably on the head above the implant to be worn external module included. The implant has the output side electromechanical intracochlear transducer, but is energetically passive and receives its operating and control data for the intracochlear transducer via the modulator / transmitter unit in the external module.

The system described can be designed monaural or binaural in vollimplantierbarer design as well as teilimplantierbarem structure. A binaural system for rehabilitation of hearing impairment in both ears has two system units, each associated with one of the two ears. In this case, the two system units can be substantially equal to each other. However, one system unit may also be designed as the master unit and the other system unit as a slave unit controlled by the master unit. The signal processing modules of the two system units can communicate with each other in any way, in particular via a wired implantable line connection or via a wireless connection, preferably a bidirectional high-frequency link, a structure-borne sound-coupled ultrasound link or a data transmission path utilizing the electrical conductivity of the tissue of the implant carrier, such that in both system units an optimized binaural signal processing and transducer array drive is achieved.

FIG. 1

schematisch einen Schnitt durch einen Teil des menschliches Mittelohres mit implantiertem intracochleärem Wandler,

FIG. 2

schematisch den prinzipiellen Aufbau des intracochleären Wandlers gemäß FIG. 1,

FIG. 3

einen Schnitt entlang der Linie III-III der FIG. 4 für eine abgewandelte Ausführungs- form des intracochleären Wandlers gemäß FIG. 1,

FIG. 4

eine Seitenansicht des intracochleären Wandlers gemäß FIG. 3,

FIG. 5

ein Blockschaltbild eines vollimplantierbaren Hörsystems zur Rehabilitation einer Mittel- und/oder Innenohrstörung und/oder eines Tinnitus,

FIG. 6

ein vollimplantierbares Hörsystem gemäß vorliegender Erfindung sowie

FIG. 7

ein teilimplantierbares Hörsystem gemäß vorliegender Erfindung.

Preferred embodiments of the hearing system according to the invention or of possible partially and fully implantable overall systems are described in more detail below with reference to the accompanying drawings. Show it:

FIG. 1

FIG. 2 schematically shows a section through part of the human middle ear with implanted intracochlear transducer, FIG.

FIG. 2

schematically the basic structure of the intracochlear transducer according to FIG. 1 .

FIG. 3

a section along the line III-III of FIG. 4 for a modified embodiment of the intracochlear transducer according to FIG FIG. 1 .

FIG. 4

a side view of the intracochlear transducer according to FIG. 3 .

FIG. 5

a block diagram of a fully implantable hearing system for the rehabilitation of a middle and / or inner ear disorder and / or tinnitus,

FIG. 6

a fully implantable hearing system according to the present invention as well as

FIG. 7

a partially implantable hearing system according to the present invention.

FIG. 1 schematically shows a section through a portion of the human middle ear with the long anvil process 10, the stirrup with the here perforated base plate 11, the Stirrup superstructure (leg 12 and head 13) and the ligament 14, with the stirrup in the oval window of the bony cochleären Wall 15 is suspended.

Through the perforation of the stirrup base plate 11, an intracochlear electromechanical transducer 18, 18 'is introduced into the inner ear as a whole. In the FIG. 1 shown in dashed lines of the transducer 18, 18 'lead to dynamic volume shifts of the perilymph 19 in the scala tympani of the inner ear. The transducer 18, 18 'is connected to an implant lead 20, the inside of the in FIG. 2 shown electrical converter leads 21 leads. Surgical sealing of the implant lead 20 in the stapes footplate perforation is expedient, as known from stapes prosthetics, by rearrangement with fascia or other endogenous thin tissue 23. The lead 20 may be provided with a deformable and preferably metallic hook or loop known from stapes prosthetics 25 are fixed to the long anvil process 10. In principle, the implant lead 20 and the mounting of the transducer 18, 18 'are constructed at the distal end of this lead as in the case of an intracochlear cochlear implant electrode. That is, at the distal end of the implant lead 20 there is a mechanical support 26 for the transducer 18, 18 '. This support preferably consists essentially of a flexible polymer (preferably silicone) molding of preferably circular cross-section.

Furthermore, a mechanical damping element 28 can be provided which decouples the vibrations of the transducer 18, 18 'from the feed line 20 and thus avoids or at least reduces transmission of the transducer vibrations to the middle ossicles when using a local sound sensor (microphone) of the implantable hearing system could lead to unwanted feedback.

The electromechanical transducer 18, 18 'operates on the principle of dynamic volume change due to a dynamic surface enlargement or reduction in accordance with the electrical, driving converter AC voltage signal. The required volume changes for an adequate, equivalent sound pressure level of about 100 dB SPL result in about 2 · 10 ^-4 microliters. The overall diameter of the transducer assembly is in the range of 0.2 mm to 2.0 mm. The immersion depth of the transducer is in the range of 0.3 to 2 mm, the length of the active transducer element in the same area.

FIG. 2 schematically shows the basic structure of the transducer 18 when using a piezoelectric pipe section 30 with a cylindrical cross section, preferably of lead zirconate titanate (PZT). In this case, a surface metallization is applied on the inner and the outer peripheral surface of the pipe section 30, which forms electrical transformer electrodes 31 and 32. The transducer can preferably also be constructed from a single-layer or multi-layer winding of thin polyvinylidene fluoride film (PVDF). The surface metallization material consists of biocompatible metal, preferably pure gold, platinum, platinum-iridium, titanium, tantalum, stainless steels and their biocompatible alloys. The electrical connections of the transducer electrodes 31 and 32 are made via the two transducer leads 21. The same choice applies to the material of the leads as for the metallization of the transducer.

Upon application of an electrical alternating voltage to the piezoelectric tube section 30, a corresponding dynamic change in radius results, which leads to the described dynamic volume displacement in the intracochlear fluid. The entire transducer element 30, 31, 32 is preferably surrounded in this embodiment with a biocompatible thin sheath 33. The sheath 33 is preferably made of an elastic polymer such as silicone, which has proven to be excellent as a carrier material for cochlear implant electrodes.

The FIGS. 3 and 4 schematically show a modified embodiment of the converter according to FIG. 2 , In this case, the transducer 18 'is not completely surrounded by the polymer jacket 33. Rather, at the open lower end 35 of the pipe section 30 and a communicating with the interior 36 of the pipe section 30 transverse opening 37 in the upper region of the sheath 33 of the inlet and outlet of intracochlear lymph in or out of the tube interior 36 is possible, as in FIG. 3 indicated by arrows 39 and 40. Due to the dynamic radius change of the transducer 18 'therefore directly a lymphatic displacement and thus an intracochlear volume shift can be achieved. With appropriate design of the tube surface of the transducer and the cross-sectional area of the inlet and outlet openings 35, 37, a transformation can be achieved according to the hydraulic principle, which leads to higher speed of the lymph and thus to higher stimulation levels of the cochlea than by the direct surface change by the transducer even.

FIG. 5 shows the possible structure of a signal processing electronics module 41 of the at least partially implantable hearing system according to the present invention. One or more Microphones 42 pick up the sound signal and convert it into corresponding electrical signals. These sensor signals are each selected in a unit 43, preprocessed and converted analog-to-digital (A / D). The preprocessing may, for example, consist in an analogue linear or non-linear preamplification and filtering (for example antialiasing filtering). The digitized sensor signal (s) are applied to a digital signal processor (DSP) 44 which performs the intended function of the hearing implant, such as audio signal processing in a system for inner ear hearing loss and / or signal generation in the case of a tinnitus masker or noise. The signal processor 44 contains a non-rewritable read-only memory area S ₀ , in which the instructions and parameters required for a "minimum operation" of the system are stored, and a memory area S ₁ , in which the operating software of the intended function or functions of the implant system are stored. Preferably, this memory area is duplicated (S ₁ and S ₂ ). The rewritable program memory for holding the operating software may be based on EEPROM or RAM cells, in which case it should be ensured that this RAM area is always "buffered" by the power supply system.

The digital output signals of the signal processor 44 are converted into analog signals in a digital-to-analog converter (D / A) and driver unit 45 and brought to the desired level for driving the converter 18, 18 '. Under certain circumstances, this unit 45 can be completely dispensed with if, for example, when using an electromagnetic intracochlear output transducer, an example pulse-width-modulated, serial digital output signal of the signal processor 44 is transmitted directly to the output transducer.

At the in FIG. 5 In the embodiment shown, the signal processing components 43, 44 and 45 are controlled by a microcontroller 47 (μC) with one or two associated memories S ₄ and S ₅ via a bidirectional data bus 48. In particular, the operating software portions of the implant management system may be stored in the memory area S ₄ and S ₅ , for example, administration monitoring and telemetry functions. In the memories S ₁ and / or S ₂ also externally variable, patient-specific, such as audiological fitting parameters can be stored. Furthermore, the microcontroller 47 has a repeatedly writable memory S ₃ , in which a work program for the microcontroller 47 is stored.

The microcontroller 47 communicates in the illustrated implantable embodiment via a data bus 49 with a telemetry system (TS) 50. This telemetry system For its part, 50 communicates wirelessly bidirectionally with an external programming system (PS) 52 via the closed skin indicated at 51, for example via an inductive coil coupling (not shown). The programming system 52 can advantageously be a PC-based system with corresponding programming, processing, presentation and management software be. The operating software of the implant system to be changed or completely exchanged is transmitted via this telemetry interface and initially stored temporarily in the memory area S ₄ and / or S _{5 of} the microcontroller 47. For example, the memory area S _{5 may be used} for complementarily storing the data transmitted from the external system, and a simple verification of the software transmission by a telemetry read operation may be performed to determine the coincidence of the contents of the memory areas S ₄ and S ₅ before the content of the rewritable memory S _{3 is} changed or exchanged.

According to the nomenclature used here, the operating software of the at least partially implantable hearing system should comprise both the operating software of the microcontroller 47 (for example housekeeping functions, such as energy management or telemetry functions) and the operating software of the digital signal processor 44. Thus, for example, a simple verification of the software transmission can be performed by a read operation via the telemetry interface, before the operating software or the corresponding signal processing components of this software are transferred to the program memory area S _{1 of} the digital signal processor 44 via the data bus 48. Furthermore, the work program for the microcontroller 47, which is stored, for example, in the repeatedly writable memory S ₃ , can be changed or replaced completely or partially via the telemetry interface 50 with the aid of the external unit 52.

All electronic components of the implant system are powered by a primary or secondary battery 30 with electrical operating energy.

FIG. 6 1 schematically shows the structure of a fully implantable hearing system with an intracochlear transducer 18 or 18 'according to FIGS FIGS. 1 to 4 and an implantable microphone 42. A wireless remote control 54 serves to control the implant functions through the implant carrier. Further, a charging system with a charger 55 for wireless transcutaneous recharging a secondary battery located in the implant for powering the hearing system, for example, the battery 53 in FIG. 5 , intended.

The microphone 42 may be advantageous in the U.S. Patent 5,814,095 constructed known manner and housed with a microphone capsule hermetically sealed on all sides in a housing is, as well as provided with an electrical feedthrough assembly for performing at least one electrical connection from the interior of the housing to the outside thereof, the housing having at least two legs, which are aligned at an angle with respect to each other, wherein the one leg receives the microphone capsule and is provided with a sound inlet membrane, wherein the other leg contains the electrical feedthrough assembly and is set back from the plane of the sound inlet membrane, and wherein the geometry of the microphone housing is selected so that when implanting the microphone in the mastoid of the leg containing the sound inlet membrane from the mastoid in an artificial hole protrudes into the posterior, bony canal wall and the sound inlet membrane touches the skin of the auditory canal wall. Laying down the microphone 40 may expedient a fixation of the US-A-5,999,632 be known, which has a sleeve which encloses the legs containing the sound inlet membrane with a cylindrical housing part and provided with against the ear canal facing the side of the ear canal wall engageable, projecting, elastic flange parts. In this case, the fixing element preferably includes a holder, which holds the said flange prior to implantation against an elastic restoring force of the flange in a bent-through the bore of the ear canal wall permitting the bent position.

To the charging system includes a connected to the output of the charger 55 charging coil 56, preferably in the off US-A-5,279,292 known type forms part of a transmission series resonant circuit which can be inductively coupled to a non-illustrated receive series resonant circuit. The reception series resonant circuit in the embodiment according to FIG. 6 Be part of the electronic module 41 and accordingly US-A-5,279,292 a constant current source for the battery 53 ( FIG. 5 ) form. In this case, the receive series resonant circuit is located in a battery charging circuit, which is closed in dependence on the respective phase of the charging current flowing in the charging circuit via the one or the other branch of a full-wave rectifier bridge.

The electronic module 41 is in the arrangement according to FIG. 6 connected via a microphone line 58 to the microphone 42 and the implant lead 20 to the intracochlear transducer 18 and 18 '.

FIG. 7 shows schematically the structure of a partially implantable hearing system with an intracochlear transducer 18 and 18 'according to the FIGS. 1 to 4 , In this partially implantable system, a microphone 42, an electronic module 62 for electronic signal processing are largely as appropriate FIG. 5 (but without the telemetry system 50), the power supply 53 and a modulator / transmitter unit 63 in an externally on the body, preferably on the head above the implant to be worn external module 64 included. The implant is energetically passive as in known partial implants. Its electronic module 65 (without battery 53) receives its operating power and converter control data via the modulator / transmitter unit 63 in the external part 64.

Both the fully implantable and the partially implantable hearing system can be designed to be monaural or binaural. A binaural system for rehabilitation of hearing impairment in both ears has two system units, each associated with one of the two ears. In this case, the two system units can be substantially equal to each other. However, one system unit may also be designed as the master unit and the other system unit as a slave unit controlled by the master unit. The signal processing modules of the two system units can communicate with each other in any way, in particular via a wired implantable line connection or via a wireless connection, preferably a bidirectional high-frequency link, a structure-borne sound-coupled ultrasound link or a data transmission path utilizing the electrical conductivity of the tissue of the implant carrier, such that in both system units an optimized binaural signal processing is achieved.

• Beide Elektronikmodule können jeweils einen digitalen Signalprozessor gemäß vorstehender Beschreibung enthalten, wobei die Betriebssoftware beider Prozessoren wie beschrieben transkutan veränderbar ist. Dann sorgt die Verbindung beider Module im wesentlichen für den Datenaustausch zur optimierten binauralen Signalverarbeitung zum Beispiel der Sensorsignale.
• Nur ein Modul enthält den beschriebenen digitalen Signalprozessor, wobei dann die Modulverbindung neben der Sensordatenübertragung zur binauralen Schallanalyse und -verrechnung auch für die Ausgangsignalübermittlung zu dem kontralateralen Wandler sorgt, wobei in dem kontralateralen Modul der elektronische Wandlertreiber untergebracht sein kann. In diesem Fall ist die Betriebssoftware des gesamten binauralen Systems nur in einem Modul abgelegt und wird auch nur dort transkutan über eine nur einseitig vorhandene Telemetrieeinheit von extern verändert. In diesem Fall kann auch die energetische Versorgung des gesamten binauralen Systems in nur einem Elektronikmodul untergebracht sein, wobei die energetische Versorgung des kontralateralen Moduls drahtgebunden oder drahtlos geschieht.

The following combination options are foreseeable:

• Both electronic modules can each contain a digital signal processor according to the above description, wherein the operating software of both processors as described transcutaneously changeable. Then, the connection of both modules essentially ensures the exchange of data for optimized binaural signal processing, for example of the sensor signals.
• Only one module contains the digital signal processor described, in which case the module connection, in addition to the sensor data transmission for binaural sound analysis and accounting, also provides the output signal transmission to the contralateral converter, wherein the electronic converter driver can be accommodated in the contralateral module. In this case, the operating software of the entire binaural system is stored only in one module and is only transactively changed externally via a single-sided telemetry unit. In this case, the energetic supply of the entire binaural system can be accommodated in only one electronic module, wherein the energetic supply of the contralateral module is wired or wireless.

Claims (19)

1. An at least partially implantable hearing system for rehabilitation of a hearing disorder comprising at least one sensor, such as a microphone (42), for picking up sound, an electronic arrangement (41; 62, 65) for audio signal processing and amplification, an electrical power supply unit (53) which supplies individual components of the system with power, and an actoric output-side arrangement for direct mechanical stimulation of a lymphatic inner ear space, wherein the actoric output-side arrangement consists of an intracochlear electromechanical transducer (18, 18'), characterized in that the intracochlear electromechanical transducer (18, 18') operates according to the principle of dynamic volume change as a result of dynamic surface enlargement or reduction in conformity with an electrical alternating voltage transducer control signal.
2. The hearing system of claim 1, characterized in that the intracochlear transducer (18, 18') has a surface at least a major portion of which is designed to vibrate.
3. The hearing system of one of the preceding claims, characterized in that the intracochlear transducer (18, 18') is adapted for surgical access through the oval window or an artificial cochlear window, such as a promontorial window.
4. The hearing system of one of the preceding claims, characterized in that the intracochlear transducer (18, 18') is disposed at the end of a flexible carrier (26), particularly a polymer carrier.
5. The hearing system of one of the preceding claims, characterized in that the intracochlear transducer (18, 18') is a piezoelectric electromechanical transducer.
6. The hearing system of claim 5, characterized in that the intracochlear transducer (18, 18') comprises a piezoelectric tube section (30) with a cylindrical cross-section, the inner and outer circumferential surfaces of which having metal coatings which define electrical transducer electrodes (31, 32).
7. The hearing system of one of the preceding claims, characterized in that the intracochlear transducer (18, 18') has an active transducer element (30, 31, 32), wherein at least this transducer element has a biocompatible cover (33) which in particular is made of an elastic polymer such as silicone.
8. The hearing system of claim 7, characterized in that at least one opening (35, 37) of the cover (33) for entry and exit of intracochlear lymph is adapted to cause by means of a dynamic change of radius of the transducer (18') direct lymph displacement and hence an intracochlear volume displacement.
9. The hearing system of claims 6 and 8, characterized in that openings (35, 37) are provided at the lower tubular end and in the upper part of the cover (33).
10. The hearing system of claim 9, characterized in that the tubular surface of the intracochlear transducer (18') and the cross-sectional surface of the entry and exit openings (35, 37) are designed to provide for a hydraulic transformation such that higher lymph velocities and consequently higher cochlea stimulation levels are attained than those obtained by a direct surface change of the transducer itself.
11. The hearing system of one of the preceding claims, characterized in that the intracochlear transducer (18, 18') is designed such that its first mechanical resonance frequency is at the upper spectral end of the transmission range.
12. The hearing system of one of the preceding claims, characterized in that a mechanical attenuation element (28) is provided which decouples vibrations of the intracochlear transducer (18, 18') from the transducer feed line (20).
13. The hearing system of claims 4 and 12, characterized in that the material of the attenuation element (28) at a cross-section geometry similar to that of the carrier (26) is selected such that there is a large mechanical impedance difference as compared to the carrier material in order to achieve high attenuation values.
14. The hearing system of one of the preceding claims, characterized in that a digital signal processor (44) is provided for audio signal processing and conditioning and/or for generating digital signals for tinnitus masking.
15. The hearing system of claim 14, characterized by a preferably computer-based telemetry means (50) for transmitting data from an implanted part (41) of the system to an external unit (52), particularly to an external programming system.
16. The hearing system of claim 14 or 15, characterized in that a rewritable implantable storage arrangement (S₁, S₂) is assigned to the signal processor (44) for storage and retrieval of an operating program, and in that at least parts of the operating program are adapted to be modified or replaced by data transmitted from the external unit (52) via the telemetry means (50).
17. The hearing system of claim 16, characterized in that additionally a buffer storage arrangement (S₄, S₅) is provided which is adapted to buffer data transmitted from the external unit (52) via the telemetry means (50) before said data being relayed to the signal processor (44), and in that preferably a checking logic (47) is provided for checking data stored in the buffer storage arrangement (S₄, S₅) before said data being relayed to the signal processor (44).
18. The hearing system of claim 17, characterized by a microprocessor module (47) for control of the audio signal processing and conditioning arrangement (43, 44, 45) and/or for generating digital signals for tinnitus masking.
19. The hearing system according to claim 18, characterized in that an implantable storage arrangement (S3) for storage of an operating program for the microprocessor module is assigned to the microprocessor module (47), and in that at least parts of the operating program for the microprocessor module are adapted to be modified or replaced by data transmitted from the external unit (52) via the telemetry means (50).

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