Objective measures for stimulation configuration

Abstract

Presented herein are systems and methods for the identification of optimal electrical stimulation configurations for use in implantable medical devices, such as cochlear implants, based on one or more objective measures obtained from the recipient.

Description

OBJECTIVE MEASURES FOR STIMUEATION CONFIGURATIONBACKGROUNDField of the Invention[oooi] The present invention relates generally to systems and methods for optimizing electrical stimulation configurations in implantable medical devices based on one or more objective measures.Related Art

[0002] Medical devices have provided a wide range of therapeutic benefits to recipients over recent decades. Medical devices can include internal or implantable components / devices, external or wearable components / devices, or combinations thereof (e.g., a device having an external component communicating with an implantable component). Medical devices, such as traditional hearing aids, partially or fully-implantable hearing prostheses (e.g., bone conduction devices, mechanical stimulators, cochlear implants, etc.), pacemakers, defibrillators, functional electrical stimulation devices, and other medical devices, have been successful in performing lifesaving and / or lifestyle enhancement functions and / or recipient monitoring for a number of years.

[0003] The types of medical devices and the ranges of functions performed thereby have increased over the years. For example, many medical devices, sometimes referred to as “implantable medical devices,” now often include one or more instruments, apparatus, sensors, processors, controllers or other functional mechanical or electrical components that are permanently or temporarily implanted in a recipient. These functional devices are typically used to diagnose, prevent, monitor, treat, or manage a disease / injury or symptom thereof, or to investigate, replace or modify the anatomy or a physiological process. Many of these functional devices utilize power and / or data received from external devices that are part of, or operate in conjunction with, implantable components.SUMMARY

[0004] In one aspect, a method is provided. The method comprises: delivering, with an implantable medical device, at least one series of electrical stimulation signals to nerve cells of a recipient; recording at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipient; and analyzing the atleast one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals.

[0005] In another aspect, an implantable medical device system is provided. The implantable medical device system comprises: a memory storing computer-readable instructions; and a processor configured to execute the computer-readable instructions to: initiate delivery of at least one series of electrical stimulation signals to nerve cells of a recipient; obtain at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipient; and analyze the at least one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals.

[0006] In another aspect, a second method is provided. The second method comprises: delivering one or more stimulation signals to an inner ear of a recipient; obtaining, via at least one of a plurality of electrodes configured to be implanted in the inner ear of the recipient, a neural response set evoked by the one or more stimulation signals, wherein the neural response set includes at least one inner ear neural response, at least one auditory nerve response, and at least one evoked brain response of the recipient during a period following delivery of the one or more stimulation signals; analyzing the neural response set to assess an efficacy of the one or more stimulation signals; and setting one or more parameters of subsequent stimulation signals based on the analyzing of the neural response set.

[0007] In another aspect, a non-transitory computer readable medium is provided. The non- transitory computer readable medium comprises instructions that, when executed by a processor, cause the processor to : control delivery of stimulation to a recipient utilizing a hybrid stimulation mode in which a combination of electrical stimulation and acoustic stimulation are used simultaneously; obtain measurements of evoked nerve / brain responses of the recipient resulting from the combination of electrical stimulation and acoustic stimulation; analyze the measurements of the evoked nerve / brain responses of the recipient to assess an efficacy of the combination of electrical stimulation and acoustic stimulation; and adapt one or more of the electrical stimulation and the acoustic stimulation based on the analyzing of the measurements of the evoked nerve / brain responses.

[0008] In another aspect, a system is provided. The system comprises: one or more electrodes configured to deliver at least one series of electrical stimulation signals to nerve cells of a recipient; at least one amplifier configured to record at least one recovery potential of the nerve cells resulting from delivery of the series of electrical stimulation signals to the recipient; andat least one processor configured to analyze the at least one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Embodiments of the present invention are described herein in conjunction with the accompanying drawings, in which:

[0010] FIG. 1A is a schematic diagram illustrating a cochlear implant system with which aspects presented herein can be implemented;[ooii] FIG. IB is a side view of a recipient wearing a sound processing unit of the cochlear implant system of FIG. 1A;

[0012] FIG. 1C is a schematic view of components of the cochlear implant system of FIG. 1 A;

[0013] FIG. ID is a block diagram of the cochlear implant system of FIG. 1A;

[0014] FIG. IE is a schematic diagram illustrating a computing device with which aspects presented herein can be implemented;

[0015] FIGs. 2A and 2B are example recordings to illustrate the concept of a recovery potential, which can be used in embodiments presented herein;

[0016] FIG. 3 is a graph illustrating recovery potential amplitude (pV) as a function of frequency (Hz) for four different currents (pA), which can be used in embodiments presented herein;

[0017] FIG. 4 is a schematic diagram illustrating a cochlear implant fitting system with which aspects of the embodiments presented herein can be implemented;

[0018] FIG. 5 is a flowchart of a first method, according to an example embodiment;

[0019] FIG. 6A is a block diagram of an implant system, according to an example embodiment;

[0020] FIG. 6B is a block diagram of the implant system in communication with an external device, according to another example embodiment;

[0021] FIG. 6C is a diagram illustrating an example of an evoked nerve / brain response potential, in terms of amplitude as a function of time;

[0022] FIGs. 6D-6F illustrate a series of example evoked brain response recordings, according to an example embodiment;

[0023] FIG. 7 is a flowchart of a second method, according to an example embodiment;

[0024] FIG. 8 is a flowchart of a third method, according to an example embodiment;

[0025] FIG. 9 is a schematic diagram illustrating a vestibular stimulator system with which aspects presented herein can be implemented; and

[0026] FIG. 10 is a schematic diagram illustrating a retinal prosthesis system with which aspects presented herein can be implemented.DETAILED DESCRIPTION

[0027] Presented herein are systems and methods for “configuring” or “fitting” medical devices, such as implantable medical devices, for a specific recipient. As explained in detail below, implantable medical devices are usually configured by medical professionals, referred to herein as clinicians. In operation, the clinicians receive data from the implantable medical devices and, in turn, can determine operating parameters for the implantable medical device and return the parameters to the implantable medical device to configure, update, improve, or otherwise alter the operation of the implantable medical device. The embodiments of the present disclosure provide for the identification of optimal electrical stimulation configurations for use in implantable medical devices, such as cochlear implants, based on one or more objective measures obtained from the recipient.

[0028] There are a number of different types of devices in / with which embodiments of the present invention may be implemented. Merely for ease of description, embodiments presented herein are primarily described with reference to a specific device in the form of a cochlear implant system. However, it is to be appreciated that the embodiments presented herein may also be partially or fully implemented by any of a number of different types of devices, including hearing devices, implantable medical devices, consumer electronic devices (e.g., mobile phones), wearable devices (e.g., smartwatches), etc. As used herein, the term “hearing device” is to be broadly construed as any device that delivers sound signals to a user in any form, including in the form of acoustical stimulation, mechanical stimulation, electrical stimulation, etc. As such, a hearing device can be a device for use by a hearing -impaired person (e.g., hearing aids, middle ear auditory prostheses, bone conduction devices, direct acoustic stimulators, electro-acoustic hearing prostheses, auditory brainstem stimulators, bimodal hearing prostheses, bilateral hearing prostheses, dedicated tinnitus therapy devices, tinnitus therapy device systems, combinations or variations thereof, etc.) or a device for use by a personwith normal hearing (e.g., consumer devices that provide audio streaming, consumer headphones, earphones and other listening devices). In other examples, the embodiments presented herein can be implemented by, or used in conjunction with, various implantable medical devices, such as vestibular devices (e.g., vestibular implants), visual devices (i.e., bionic eyes), sensors, pacemakers, drug delivery systems, defibrillators, functional electrical stimulation devices, catheters, seizure devices (e.g., devices for monitoring and / or treating epileptic events), sleep apnea devices, electroporation devices, etc.

[0029] FIGs. 1A-1D illustrates an example cochlear implant system 102 with which aspects of the embodiments presented herein can be implemented. The cochlear implant system 102 comprises an external component 104 that is configured to be directly or indirectly attached to the body of the user, and an intemal / implantable component 112 that is configured to be implanted in or worn on the head of the user. In the examples of FIGs. 1A-1D, the implantable component 112 is sometimes referred to as a “cochlear implant.” FIG. 1A illustrates the cochlear implant 112 implanted in the head 154 of a user, while FIG. IB is a schematic drawing of the external component 104 worn on the head 154 of the user. FIG. 1C is another schematic view of the cochlear implant system 102, while FIG. ID illustrates further details of the cochlear implant system 102. For ease of description, FIGs. 1A-1D will generally be described together.

[0030] In the examples of FIGs. 1A-1D, the external component 104 comprises a sound processing unit 106, an external coil 108, and generally, a magnet fixed relative to the external coil 108. The cochlear implant 112 includes an implantable coil 114, an implant body 134, and an elongate stimulating assembly 116 configured to be implanted in the user’s cochlea. In one example, the sound processing unit 106 is an off-the-ear (OTE) sound processing unit, sometimes referred to herein as an OTE component, that is configured to send data and power to the implantable component 112. In general, an OTE sound processing unit is a component having a generally cylindrically shaped housing 111 and which is configured to be magnetically coupled to the user’s head 154 (e.g., includes an integrated external magnet 150 configured to be magnetically coupled to an intemal / implantable magnet 152 in the implantable component 112). The OTE sound processing unit 106 also includes an integrated external (headpiece) coil 108 (the external coil 108) that is configured to be inductively coupled to the implantable coil 114.

[0031] It is to be appreciated that the OTE sound processing unit 106 is merely illustrative of the external devices that could operate with implantable component 112. For example, inalternative examples, the external component 104 may comprise a behind-the-ear (BTE) sound processing unit configured to be attached to, and worn adjacent to, the recipient’s ear. In general, a BTE sound processing unit comprises a housing that is shaped to be worn on the outer ear of the user and is connected to the separate external coil assembly via a cable, where the external coil assembly is configured to be magnetically and inductively coupled to the implantable coil 114. It is also to be appreciated that alternative external components could be located in the user’s ear canal, worn on the body, etc.

[0032] Although the cochlear implant system 102 includes the sound processing unit 106 and the cochlear implant 112, as described below, the cochlear implant 112 can operate independently from the sound processing unit 106, for at least a period, to stimulate the user. For example, the cochlear implant 112 can operate in a first general mode, sometimes referred to as an “external hearing mode,” in which the sound processing unit 106 captures sound signals which are then used as the basis for delivering stimulation signals to the user. The cochlear implant 112 can also operate in a second general mode, sometimes referred as an “invisible hearing” mode, in which the sound processing unit 106 is unable to provide sound signals to the cochlear implant 112 (e.g., the sound processing unit 106 is not present, the sound processing unit 106 is powered-off, the sound processing unit 106 is malfunctioning, etc.). As such, in the invisible hearing mode, the cochlear implant 112 captures sound signals itself via implantable sound sensors and then uses those sound signals as the basis for delivering stimulation signals to the user. Further details regarding operation of the cochlear implant 112 in the external hearing mode are provided below, followed by details regarding operation of the cochlear implant 112 in the invisible hearing mode. It is to be appreciated that reference to the external hearing mode and the invisible hearing mode is merely illustrative and that the cochlear implant 112 could also operate in alternative modes.

[0033] In FIGs. 1A and 1C, the cochlear implant system 102 is shown with an external device 110, configured to implement aspects of the embodiments presented. The external device 110, which is shown in greater detail in FIG. IE, is a computing device, such as a personal computer (e.g., laptop, desktop, tablet), a mobile phone (e.g., smartphone), remote control unit, etc. The external device 110 and the cochlear implant system 102 (e.g., sound processing unit 106 or the cochlear implant 112) wirelessly communicate via a bi-directional communication link 126. The bi-directional communication link 126 may comprise, for example, a short-range communication, such as Bluetooth link, Bluetooth Low Energy (BLE) link, a proprietary link, etc.

[0034] Returning to the example ofFIGs. 1A-1D, the sound processing unit 106 of the external component 104 also comprises one or more input devices configured to capture and / or receive input signals (e.g., sound or data signals) at the sound processing unit 106. The one or more input devices include, for example, one or more sound input devices 118 (e.g., one or more external microphones, audio input ports, telecoils, etc.), one or more auxiliary input devices 128 (e.g., audio ports, such as a Direct Audio Input (DAI), data ports, such as a Universal Serial Bus (USB) port, cable port, etc.), and a short-range wireless transmitter / receiver (wireless transceiver) 120 (e.g., for communication with the external device 110), each located in, on or near the sound processing unit 106. However, it is to be appreciated that one or more input devices may include additional types of input devices and / or less input devices (e.g., the short- range wireless transceiver 120 and / or one or more auxiliary input devices 128 could be omitted).

[0035] The sound processing unit 106 also comprises the external coil 108, a charging coil 130, a closely-coupled radio frequency transmitter / receiver (RF transceiver) 122, at least one rechargeable battery 132, and an external sound processing module 124. The external sound processing module 124 can be configured to perform a number of operations, and can be formed by one or more processors (e.g., one or more Digital Signal Processors (DSPs), one or more uC cores, etc.), firmware, software, etc. arranged to perform operations described herein. That is the external sound processing module 124 can be implemented as firmware elements, partially or fully implemented with digital logic gates in one or more application-specific integrated circuits (ASICs), partially or fully in software, etc.

[0036] Returning to the example of FIGs. 1A-1D, the implantable component 112 comprises an implant body (main module) 134, a lead region 136, and the intra-cochlear stimulating assembly 116, all configured to be implanted under the skin (tissue) 115 of the user. The implant body 134 generally comprises a hermetically-sealed housing 138 that includes, in certain examples, at least one power source 125 (e.g., one or more batteries, one or more capacitors, etc.), in which RF interface circuitry 140 and a stimulator unit 142 are disposed. The implant body 134 also includes the intemal / implantable coil 114 that is generally external to the housing 138, but which is connected to the RF interface circuitry 140 via a hermetic feedthrough (not shown in FIG. ID).

[0037] As noted, stimulating assembly 116 is configured to be at least partially implanted in the user’s cochlea. Stimulating assembly 116 includes a plurality of longitudinally spaced intra-cochlear electrical stimulating contacts (electrodes) 144 that collectively form a contactarray (electrode array) 146 for delivery of electrical stimulation (current) to the recipient’s cochlea. Stimulating assembly 116 extends through an opening in the recipient’s cochlea (e.g., cochleostomy, the round window, etc.) and has a proximal end connected to stimulator unit 142 via lead region 136 and a hermetic feedthrough (not shown in FIG. ID). Lead region 136 includes a plurality of conductors (wires) that electrically couple the electrodes 144 to the stimulator unit 142. The implantable component 112 also includes an electrode outside of the cochlea, sometimes referred to as the extra-cochlear electrode (ECE) 139.

[0038] As noted, the cochlear implant system 102 includes the external coil 108 and the implantable coil 114. The external magnet 150 is fixed relative to the external coil 108 and the intemal / implantable magnet 152 is fixed relative to the implantable coil 114. The external magnet 150 and the intemal / implantable magnet 152 fixed relative to the external coil 108 and the intemal / implantable coil 114, respectively, facilitate the operational alignment of the external coil 108 with the implantable coil 114. This operational alignment of the coils enables the external component 104 to transmit data and power to the implantable component 112 via a closely-coupled wireless link 148 formed between the external coil 108 with the implantable coil 114. In certain examples, the closely-coupled wireless link 148 is a radio frequency (RF) link. However, various other types of energy transfer, such as infrared (IR), electromagnetic, capacitive and inductive transfer, may be used to transfer the power and / or data from an external component to an implantable component and, as such, FIG. ID illustrates only one example arrangement.

[0039] As noted above, sound processing unit 106 includes the external sound processing module 124. The external sound processing module 124 is configured to process the received input audio signals (received at one or more of the input devices, such as sound input devices 118 and / or auxiliary input devices 128), and convert the received input audio signals into output control signals for use in stimulating a first ear of a recipient or user (i.e., the external sound processing module 124 is configured to perform sound processing on input signals received at the sound processing unit 106). Stated differently, the one or more processors (e.g., processing element(s) implementing firmware, software, etc.) in the external sound processing module 124 are configured to execute sound processing logic in memory to convert the received input audio signals into output control signals (stimulation signals) that represent electrical stimulation for delivery to the recipient.

[0040] As noted, FIG. ID illustrates an embodiment in which the external sound processing module 124 in the sound processing unit 106 generates the output control signals. In analternative embodiment, the sound processing unit 106 can send less processed information (e.g., audio data) to the implantable component 112 and the sound processing operations (e.g., conversion of input sounds to output control signals 156) can be performed by a processor within the implantable component 112.

[0041] In FIG. ID, according to an example embodiment, output control signals (stimulation signals) are provided to the RF transceiver 122, which transcutaneously transfers the output control signals (e.g., in an encoded manner) to the implantable component 112 via external coil 108 and implantable coil 114. That is, the output control signals (stimulation signals) are received at the RF interface circuitry 140 via implantable coil 114 and provided to the stimulator unit 142. The stimulator unit 142 is configured to utilize the output control signals to generate electrical stimulation signals (e.g., current signals) for delivery to the user’s cochlea via one or more of the stimulating contacts (electrodes) 144. In this way, cochlear implant system 102 electrically stimulates the user’s auditory nerve cells, bypassing absent or defective hair cells that normally transduce acoustic vibrations into neural activity, in a manner that causes the recipient to perceive one or more components of the input audio signals (the received sound signals).

[0042] As detailed above, in the external hearing mode the cochlear implant 112 receives processed sound signals from the sound processing unit 106. However, in the invisible hearing mode, the cochlear implant 112 is configured to capture and process sound signals for use in electrically stimulating the user’s auditory nerve cells. In particular, as shown in FIG. ID, an example embodiment of the cochlear implant 112 can include a plurality of implantable sound sensors 165(1), 165(2) that collectively form a sensor array 160, and an implantable sound processing module 158. Similar to the external sound processing module 124, the implantable sound processing module 158 may comprise, for example, one or more processors and a memory device (memory) that includes sound processing logic. The memory device may comprise any one or more of: Non-Volatile Memory (NVM), Ferroelectric Random Access Memory (FRAM), read only memory (ROM), random access memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical, or other physical / tangible memory storage devices. The one or more processors are, for example, microprocessors or microcontrollers that execute instructions for the sound processing logic stored in memory device.

[0043] In the invisible hearing mode, the implantable sound sensors 165(1), 165(2) of the sensor array 160 are configured to detect / capture input sound signals 166 (e.g., acoustic soundsignals, vibrations, etc.), which are provided to the implantable sound processing module 158. The implantable sound processing module 158 is configured to convert received input sound signals 166 (received at one or more of the implantable sound sensors 165(1), 165(2)) into output control signals 156 for use in stimulating the first ear of a recipient or user (i.e., the implantable sound processing module 158 is configured to perform sound processing operations). Stated differently, the one or more processors (e.g., processing element(s) implementing firmware, software, etc.) in implantable sound processing module 158 are configured to execute sound processing logic in memory to convert the received input sound signals 166 into output control signals 156 that are provided to the stimulator unit 142. The stimulator unit 142 is configured to utilize the output control signals 156 to generate electrical stimulation signals (e.g., current signals) for delivery to the user’s cochlea, thereby bypassing the absent or defective hair cells that normally transduce acoustic vibrations into neural activity.

[0044] It is to be appreciated that the above description of the so-called external hearing mode and the so-called invisible hearing mode are merely illustrative and that the cochlear implant system 102 could operate differently in different embodiments. For example, in one alternative implementation of the external hearing mode, the cochlear implant 112 could use signals captured by the sound input devices 118 and the implantable sound sensors 165(1), 165(2) of sensor array 160 in generating stimulation signals for delivery to the user.

[0045] As also illustrated in FIG. ID, in certain examples, a measurement and analysis module 170 is incorporated into implantable sound processing module 158 of implant body 134. The measurement and analysis module 170 can be configured to obtain results of objective measurements (e.g., voltage, current, impedance, potentials, recovery potentials, etc.) responsive to the delivery of stimulation to a recipient, and to analyze the objective measurements for various purposes (e.g., output for display, assess neural activity / health, determine adjustments to one or more operational settings and / or stimulation parameters, etc.), as explained in further detail below. In some example embodiments, one or more stimulating contacts / electrodes 144 of the stimulating assembly 116 can implement a measuring / recording function, in addition to a stimulation function. In some other example embodiments, one or more sensors (dedicated contacts / electrodes) may be provided to implement the measuring / recording function. For hearing devices that include an implantable sound processing module, such as implantable sound processing module 158 that includes analysis module 170, the embodiments presented herein may be implemented by a totally-implantablecochlear implant (TICI) device (i.e., the implantable / intemal component 112) without an external processor (i.e., without external component 104 / sound processing unit 106). Accordingly, a hearing device that includes an intemal / implantable component 112 (implant body 134) and lacks an external component 104 (sound processing unit 106) may be configured to implement the embodiments presented herein.

[0046] FIG. IE is a block diagram illustrating one example arrangement for an external computing device 110 configured to perform one or more operations in accordance with certain embodiments presented herein. As shown in FIG. IE, in its most basic configuration, the external computing device 110 includes at least one processing unit 183 and a memory 184. The processing unit 183 includes one or more hardware or software processors (e.g., Central Processing Units) that can obtain and execute instructions. The processing unit 183 can communicate with and control the performance of other components of the external computing device 110. The memory 184 is one or more software or hardware-based computer-readable storage media operable to store information accessible by the processing unit 183. The memory 184 can store, among other things, instructions executable by the processing unit 183 to implement applications or cause performance of operations described herein, as well as other data. The memory 184 can be volatile memory (e.g., RAM), non-volatile memory (e.g., ROM), or combinations thereof. The memory 184 can include transitory memory or non-transitory memory. The memory 184 can also include one or more removable or non-removable storage devices. In examples, the memory 184 can include random access memory (RAM), read only memory (ROM), EEPROM (Electronically-Erasable Programmable Read-Only Memory), flash memory, optical disc storage, magnetic storage, solid state storage, or any other memory media usable to store information for later access. By way of example, and not limitation, the memory 184 can include wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media or combinations thereof. In certain embodiments, the memory 184 comprises logic 195 that, when executed, enables the processing unit 183 to perform aspects of the embodiments presented.

[0047] In the illustrated example of FIG. IE, the external computing device 110 further includes a network adapter 186, one or more input devices 187, and one or more output devices 188. The external computing device 110 can include other components, such as a system bus, component interfaces, a graphics system, a power source (e.g., a battery), among other components. The network adapter 186 is a component of the external computing device 110 that provides network access (e.g., access to at least one network 189). The network adapter186 can provide wired or wireless network access and can support one or more of a variety of communication technologies and protocols, such as ETHERNET, cellular, BLUETOOTH, near-field communication, and RF (Radiofrequency), among others. The network adapter 186 can include one or more antennas and associated components configured for wireless communication according to one or more wireless communication technologies and protocols. The one or more input devices 187 are devices over which the external computing device 110 receives input from a user. The one or more input devices 187 can include physically- actuatable user-interface elements (e.g., buttons, switches, or dials), a keypad, keyboard, mouse, touchscreen, and voice input devices, among other input devices that can accept user input. The one or more output devices 188 are devices by which the computing device 110 is able to provide output to a user. The output devices 188 can include, a display 190 (e.g., a liquid crystal display (LCD)) and one or more speakers 191, among other output devices for presentation of visual or audible information to the recipient, a clinician, an audiologist, or other user.

[0048] It is to be appreciated that the arrangement for the external computing device 110 shown in FIG. IE is merely illustrative and that aspects of the embodiments presented herein can be implemented at a number of different types of systems / devices including any combination of hardware, software, and / or firmware configured to perform the functions described herein. For example, the external computing device 110 can be a personal computer (e.g., a desktop or laptop computer), a hand-held device (e.g., a tablet computer), a mobile device (e.g., a smartphone), a surgical system, and / or any other electronic device having the capabilities to perform the associated operations described elsewhere herein.

[0049] As noted, cochlear implant system 102 includes one or more sound input devices 118 that receive electrical signals and / or convert audio signals into electrical input signals. The sound processing unit 106 processes the electrical input signals and generates stimulation data for use in delivering stimulation to the recipient in accordance with various operating parameters dictated by one of a number of selectable settings or modes of operation. The various selectable settings or modes of operation may be in the form of executable programs or sets of parameters for use in a program. The settings may accommodate any of a number of specific configurations that influence / control the operation of the cochlear implant. For example, the settings may include different digital signal and sound processing algorithms, processes and / or operational parameters for different algorithms, other types of executable programs (such as system configuration, user interface, etc.), or operational parameters for suchprograms. In certain examples, the selectable settings would be stored in a memory of the cochlear implant system 102 and relate to different optimal settings for different listening situations or environments encountered by the recipient (i.e., noisy or quiet environments, windy environments, etc.).

[0050] Additionally, since the dynamic range for electrical stimulation is relatively narrow and varies across recipients and stimulating contacts, programs used in a sound processor are typically individually tailored to optimize the perceptions presented to a particular recipient (i.e., tailor the characteristics of electrical stimulation for each recipient). For example, many speech processing strategies rely on a customized set of stimulation settings which provide, for a particular recipient, the threshold levels (T -levels) and comfortable levels (C-levels) of stimulation for each frequency band. Once these stimulation settings are established, the sound processor may then optimally process and convert the received acoustic signals into stimulation data for use by the stimulator unit 142 in delivering stimulation signals to the recipient.

[0051] As such, a typical cochlear implant has many parameters / settings which determine the sound processing, sound coding, and other operations of the device. The individualized programs, commands, data, settings, parameters, instructions, modes, and / or other information that define the specific characteristics used by cochlear implant system 102 to process electrical input signals and generate stimulation data therefrom are generally and collectively referred to herein as the recipient’s “operational settings” or the recipient’s “map” (e.g., the “map” of the recipient of the implantable medical device). The recipient’s map (i.e., the collection operational settings) is determined / set by medical practitioners (clinicians) in a process known as “fitting” of the cochlear implant. As described in detail below with reference to FIG. 4, external device 110 may be configured to send data to a fitting system (see fitting system 470 of FIG. 4) via, for example, a computer network, such as a wide area network (WAN) or a local area network (LAN). This permits clinicians to use online technologies to individualize the programs, commands, data, settings, parameters, instructions, modes, and / or other information that define the specific operating characteristics used by cochlear implant system 102. In other words, the operational settings (map) can be set and adjusted by the clinician to define, update, and improve the operation of the device. For ease of reference, the term “map” will generally be used to refer to the settings of the implantable medical device that are determined through one or more fitting processes. As used herein, the term “map” can include any of a number of different configuration settings / parameters and is not limited to any specific settings or context.

[0052] As noted, cochlear implants can be fitted with a range of stimulation configurations. The optimal stimulation configuration to be used is subject of ongoing debate, but it is generally accepted that the default configuration provided by the manufacturer needs to be customized for particular recipients. However, finding the optimum configuration for each individual has traditionally been a cumbersome and lengthy process (e.g., involving speech testing, learning curves, etc.), which is often no longer possible with increasing recipient load. For example, the compound activity evoked by individual pulses (e.g. via Electrically evoked Compound Action Potentials (ECAPs) recorded with Neural Response Telemetry (NRT)) in a pulse train could be analyzed to identify the overall neural activity evoked by a stimulus train, but this is very time consuming. Therefore, most recipients are fitted with a default configuration, which can often be different at different clinics.

[0053] According to one aspect of the present disclosure, systems and methods for identifying optimal electrical stimulation configuration in cochlear implant users (e.g., for a general recipient population or a specific recipient) utilizing one or more objective measures are provided. In certain embodiments, the one or more objective measures can include an objective measure referred to herein as a “recovery potential,” which represents ensemble neural activity. The recovery potential can be seen as a compound potential of the neuronal “after-potentials” that occur when a series of action potentials have been evoked in a neuron, for example.

[0054] As used herein, a “recovery potential” is an electrophysiological potential that occurs after prolonged induced activity and that represents so-called “ensemble neural activity” (e.g., the activation of a group of nerve cells to prolonged electrical stimulation in the form of pulses, sinusoidal waves, etc.). The recovery potential has been shown to exist in the auditory nerve in animal studies (e.g., guinea pig) making use of electrical stimulation (e.g. a sinusoidal electrical stimulus or a burst including multiple electrical pulses with a duration of about 100ms) to evoke neural activity, and in theory can also be recorded in humans implanted with a cochlear implant.

[0055] FIG. 2A shows a dedicated recording of a recovery potential 210 that fully identifies the morphology of the recovery potential, which has an oscillating character. The diagram of the stimulus includes an electrical stimulus with a duration of about 100ms followed by a recording period (e.g., masker stimulus followed by a probe stimulus). As shown in FIG. 2A, the recovery potential 210 has a local minimum 214 (Nl) around 20-30ms after the stimulus 212 is delivered, followed by a local maximum 216 (Pl) around 90-110ms after the stimulus 212 is delivered. The amplitude 218 (Al) of the recovery potential can be calculated byobtaining the difference between the voltage at the local maximum 216 and the voltage at the local minimum 214 (i.e., Al = P1 - Nl). It may be possible that the local maximum (Pl) could be absent or be hidden in the noise, in which case an average voltage (Pa) can be measured over a longer time window (instead of using the local maximum voltage (Pl) and 100ms recording window).

[0056] FIG. 2B shows dedicated recordings of recovery potentials 230 for different stimulus frequencies (e.g., using a sinusoidal electrical stimulus, without a probe). The recovery potentials 230 are shown as a series of traces 231, 233, 235, 237, 239, 241, 243, 345, 247, 249 (corresponding to frequencies of 100 Hz, 300 Hz, 500 Hz, 700 Hz, 900 Hz, 2 kHz, 4 kHz, 6 kHz, 8 kHz, 10 kHz, respectively). As shown in FIG. 2B, the impulse at the beginning of each trace is a stimulus artefact, and the shape (amplitude) of the different curves vary depending on the frequency. The relationship of the amplitude of the response in relation to frequency is described further below with reference to FIG. 3.

[0057] The inventors have determined that the amplitude of the recovery potential (induced after prolonged stimulation activity in the form of pulses, sinusoidal waves, etc.) has a relationship with the evoked neural activity, namely, the higher the evoked neural activity, the bigger the recovery potential (i.e., the larger the amplitude of the recovery potential). The inventors have discovered that this recovery potential response can thus be used to identify the neural activity evoked by different stimulus configurations and, in turn, customize or fit stimulation parameters to the particular recipient.

[0058] To measure a slow recovery potential during or after cochlear implant (CI) surgery, an external electrophysiological system (e.g., an EABR machine) can be triggered by the stimulus from the cochlear implant, or the measurement functionality of an application embedded in the cochlear implant itself can be used to measure the recovery potential. Such an application can be used for electrophysiological recording of electrically evoked responses, such as Electrically Evoked Compound Action Potentials (EECAPs) of the auditory nerve, or acoustically evoked responses in the cochlea (e.g., ElectroCochleography (ECochG) methods). For example, a low-pass (LP) filter (LP amplifier) can be used, since the spectrum of the recovery potential is mainly in the low frequency domain. Care needs to be taken that the bandwidth of the LP filter / amplifier is optimized for measurement of the recovery potential. For this, the spectrum of the potential can be analyzed, and the bandwidth can be adjusted to minimize noise and artefact and optimize the measurement of the recovery potential. In addition, the sample rateand sample window can be optimized to focus on the most informative aspects (peaks) of the recovery potential.

[0059] The start of the recording is triggered at the end of the electrical stimulus, and can be delayed some number of milliseconds (ms) in order to minimize the stimulation artefact. Due to limited memory resources, the recordings could be repeated over consecutive time windows and “stitched” together (similar to a process that is done for ECochG and electrically evoked brainstem or EEG recordings obtained with a cochlear implant system) to obtain the full response. The time windows of these recordings can overlap, which can help to compensate for any eventual drift in the recording system when the recordings are stitched together. Such compensation for the minimization of “stitching artefacts” can be achieved by shifting consecutive recordings based on the average of the overlapping time windows, for example. Other possible solutions may include the use of lower sampling rates to help increase the total recording window, and / or focusing the recordings on the baseline and peaks in the response to measure the amplitude of the recovery potential.

[0060] “Stimulus artefacts” are a well-known problem in recordings of electrophysiological responses. The use of recovery potentials as described herein addresses the stimulus artefact problem often seen in electrophysiology. In accordance with the embodiments presented herein, the stimulus and the recovery-potential are separated in time, thereby minimizing the artefact problem.

[0061] As noted, it is presumed that the amplitude of a slow wave electrical recovery potential indicates the effectiveness of ensemble neural activity of the auditory nerve. This measure can then be used to identify optimal stimulation configurations for a recipient population or individual recipients, and advise on stimulation mode, stimulation rate, electrical pulse configuration (e.g., pulse width, inter pulse gap, pulse shape, etc.), and the like. The optimization of consecutive measurements to identify the optimal stimulus configuration may depend on the stimulus configurations available in the commercial cochlear implant, but can also go beyond for research purposes to guide development of new commercial coding and fitting practices.

[0062] An algorithm used to determine an optimal stimulus configuration of the recipient can include measurement of activity evoked by a single channel / electrode (e.g., optimal rate, optimal pulse width, optimal inter-pulse gap, some combination thereof, etc.), but can also include measurement of activity evoked by multiple channels / electrodes (which may beoverlapping). For example, knowing that the ACE strategy selects maxima on nearby electrodes, by using pulse trains on nearby and far apart electrodes, the optimal rate of the channel can be determined. In this example, the overlap can be identified, then single channels and multiple channels can be tested to see whether they sum (e.g., increase in peak vs. decrease in peak).

[0063] The measure of the recovery potential can also be used for implant fitting (e.g., selection of coding strategy or setting of the masker curves, such as MP3000 coding). For example, the recovery potential indicates local neural health of the spiral ganglion, and can guide activation of stimulation channels. The potential can provide insight on overlapping excitation fields and problems with overlapping excitation fields, and can guide maxima selection or dispersion of activity for masking functions (e.g., MP3000 coding). In addition, the solution can be integrated into implant fitting software, and the recovery potential can help to further develop new fitting and coding strategies in which the neural activity is optimized. Further, the potential could also be used to predict recipient outcomes (e.g., hearing performance outcomes). Thus, the present disclosure provides systems and methods for the measurement of recovery potentials and the identification of optimal stimulation / coding configurations based thereon.

[0064] FIG. 3 shows recovery potentials 310 in terms of amplitude 311 (pV) as a function of frequency 319 (kHz) for four different currents 320. As noted above, FIG. 3 illustrates the relationship of the amplitude of the response (the amplitude of the recovery potential) in relation to frequency. The recovery potential 322 corresponds to a current of 1000 pA. the recovery potential 324 corresponds to a current of 500 pA, the recovery potential 326 corresponds to a current of 250 pA, and the recovery potential 328 corresponds to a current of 125 pA.

[0065] Looking at the recovery potential with a stimulus pulse train would yield the same or similar results. The stimulus is typically a pulse train (as in a cochlear implant), but can also be a sinusoid or square wave or saw tooth. The recording starts after the stimulus (after a short delay) so that there is no electrical stimulus artefact of the stimulus itself. There should be a way to ensure that the amplifier does not evoke an oscillation based on the electrical stimulus, however. The measure shown in FIG. 3 is the recovery potential that occurs when the stimulus has ended. While not bound by theory, the recovery potential response is most likely related to a homeostatic mechanism (e.g., changes in extracellular ionic environment, ionic pumps in the neuronal membrane and passive flow of ions through K and Na channels) that occurs whenneurons have been forced to fire by the electrical stimulus. The more the neurons have fired, the more the homeostasis (= resting membrane potential) is out of bound and the bigger the amplitude of the recovery potential. In this sense, the recovery potential can reflect how effective the stimulus was in evoking neural activity.

[0066] Turning now to FIG. 4, depicted therein is a block diagram illustrating an example fitting system 470 configured to execute the embodiments presented herein. For example, the fitting system 470 can be used to display an indication of measured potentials, including recovery potentials, based on signals received from one or more sensors or contacts / electrodes. Fitting system 470 is, in general, a computing device that comprises a plurality of interface s / ports 478(1)-478(N), amemory 480, a display device 482 (e.g., a screen), aprocessor 484, and a user interface 486.

[0067] The interfaces 478(1)-478(N) may comprise, for example, any combination of network ports (e.g., Ethernet ports), wireless network interfaces, Universal Serial Bus (USB) ports, Institute of Electrical and Electronics Engineers (IEEE) 1394 interfaces, PS / 2 ports, etc. In the example of FIG. 4, interface 478(1) is connected to cochlear implant system 102 having components (e.g., stimulating assembly) implanted in a recipient 471. Interface 478(1) may be directly connected to the cochlear implant system 102, or alternatively, may be connected to an external device 110 that is in communication with the cochlear implant system 102. Interface 478(1) may be configured to communicate with cochlear implant system 102 via a wired or wireless connection (e.g., telemetry, Bluetooth, etc.).

[0068] The user interface 486 includes one or more output devices, such as a display screen (e.g., a liquid crystal display (LCD)) and a speaker, for presentation of visual or audible information to a clinician, audiologist, or other user. The user interface 486 may also comprise one or more input devices that include, for example, a keypad, keyboard, mouse, touchscreen, etc.

[0069] The memory 480 includes configuration management logic 481, recovery potential measurement logic 483, recovery potential analysis logic 485, and stimulation adaption logic 487. The configuration management logic 481 may be executed to obtain recipient-specific data and results of objective evaluations of a recipient that are relevant to implant fitting, and determine or set a default configuration for the cochlear implant 102 of a particular recipient based on the recipient-specific data and objective evaluations, where the default configuration comprises multiple operational settings and stimulation parameters. In certain embodiments,the configuration management logic 481 can store historical data associated with the recipient (e.g., a history of maps, actions, adjustments made to settings / parameters, previous objective measurements, etc.) in the memory 480.

[0070] The recovery potential measurement logic 483 may be executed to monitor potentials (e.g., obtain measurements of recovery potentials) at the stimulating contacts / electrodes 144 and / or process signals from the stimulating contacts / electrodes 144. In certain embodiments, one or more recovery potential measurements 489 obtained via the recovery potential measurement logic 483 can be output for display on the display device 482.

[0071] The recovery potential analysis logic 485 may be executed to analyze the one or more recovery potential measurements 489 in order to assess the overall neural activity, which is indicative of the recipient’s neural health. In certain embodiments, various types of feedback can be displayed on the display device 482 (e.g., indications, notifications, alerts, warnings, etc.) with respect to the neural activity / health of the recipient.

[0072] The stimulation adaption logic 487 executes an algorithm that analyzes the correlated results of the objective evaluations, and the recovery potential measurements 489 from multiple stimulating contacts / electrodes and / or a reference contact / electrode, to identify correlated stimulation parameters (e.g., operational settings) that are optimized for the particular recipient. One or more of the operational settings and / or stimulation parameters that are optimized for the particular recipient may vary / differ from the default configuration based on the assessment of neural activity / health of the recipient by the recovery potential analysis logic 485. In some example embodiments, the optimal operational settings and / or stimulation parameters for the particular recipient can be displayed on the display device 482 (e.g., to inform the clinician of any suggested / recommended adjustments to be made to the settings / parameters by the clinician) based on the analysis. In some other example embodiments, the stimulation adaption logic 487 may be configured to automatically adjust one or more operational settings or stimulation parameters (i.e., without the need for any user input from the clinician) based on the analysis.

[0073] Memory 480 may comprise read only memory (ROM), random access memory (RAM), magnetic disk storage media devices, optical storage media devices, flash memory devices, electrical, optical, or other physical / tangible memory storage devices. The processor 484 is, for example, a microprocessor or microcontroller that executes instructions for the configuration management logic 481, the recovery potential measurement logic 483, therecovery potential analysis logic 485, and the stimulation adaption logic 487, respectively. Thus, in general, the memory 480 may comprise one or more tangible (non-transitory) computer readable storage media (e.g., a memory device) encoded with software comprising computer executable instructions and when the software is executed (by the processor 484) it is operable to perform the embodiments described herein in connection with the configuration management logic 481, the recovery potential measurement logic 483, the recovery potential analysis logic 485, and the stimulation adaption logic 487, respectively.

[0074] The correlated stimulation parameters identified through execution of the stimulation adaption logic 487 are sent to the cochlear implant system 102 for instantiation as the cochlear implant’s current correlated stimulation parameters. However, in certain embodiments, the correlated stimulation parameters identified through execution of the stimulation adaption logic 487 are first displayed on the display device 482 for further evaluation and / or adjustment by a user (e.g., a clinician or audiologist). Through the use of various objective measurements (e.g., electrical or electro-neural properties, such as voltage, current impedance, evoked neural potentials, recovery potentials, etc.) that are obtained via one or more sensors or contacts / electrodes in response to the delivery of stimulation signals, the fitting system 470 of FIG. 4 may execute algorithms to provide clinicians with direct and real-time feedback in connection with the stimulation and objective measurements. As such, the user has the ability to refine the correlated stimulation parameters before the stimulation parameters are sent to the cochlear implant system 102.

[0075] Preferably, the stimulating contacts / electrodes 144 may be configured to perform electrical or electro-neural measurements, in addition to performing stimulation. That is, providing additional sensors or contacts / electrodes that are dedicated to the objective measurement functionality described herein (e.g., voltages, currents, impedances, potentials, recovery potentials, etc.) may not be necessary when the existing stimulating contacts / electrodes can be adapted to perform the objective measurement function. The stimulating contacts / electrodes 144 can operate as sensors that measure the potential at (adjacent to) the stimulating contacts / electrodes 144, and the arrangement of FIG. 4 can provide the clinician with real-time feedback. Thus, the stimulating contacts / electrodes 144 can be used to continually (or periodically) monitor the potential adjacent to the respective contact / electrode. The system may be configured to perform multiple real-time measurements substantially simultaneously, and use these multiple measurements to make one or more deductions with respect to the stimulation signals, the evoked responses (e.g., potentials,recovery potentials, etc.), the overall neural activity / health of the recipient, and / or various adjustments to operational settings and / or stimulation parameters that will improve or optimize perception by the recipient.

[0076] In some other example embodiments, a stimulating assembly 116 may comprise a plurality of stimulating contacts / electrodes 144 and one or more “low impedance” contacts / electrodes 175 (i.e., a measuring contact / electrode, a recording contact / electrode - not shown in Figures). A low impedance contact / electrode 175 operates as a sensor configured to record slow “recovery potentials” (i.e., potentials present in the cochlea after presentation of a train of electrical stimulation pulses via one or more stimulating contacts / electrodes 144). That is, the low impedance electrode contact / electrode 175 can be used to record slow changes in local potential during stimulation. In certain embodiments, the recovery potentials that are measured / recorded via the low impedance electrode contact / electrode 175 could be stored and subsequently used to determine optimal operational settings (e.g., an optimal rate of stimulation for delivery to the stimulating contacts / electrodes 144) for the recipient. In particular, the recovery potentials may correspond to neural activity in manner that enables use of the recorded recovery potentials to predict stimulation rate effectiveness.

[0077] As noted above, an implantable sensor or contact / electrode is able to gather information about some parameter (e.g., electrical, electro-neural, etc.) and output a signal corresponding to that parameter. Example embodiments of the present invention are configured to use of the signal(s) provided by implantable sensors / contacts / electrodes in a number of different manners. For example, the stimulation adaption logic 487 can be configured to determine one or more adjustments to one or more operational settings of the recipient’s current map based on the results obtained via the recovery potential measurement logic 483 (the recovery potential measurements 489) and the recovery potential analysis logic 485 (the assessment of neural activity / health). Further, the stimulation adaption logic 487 can be configured to implement the one or more adjustments to the one or more operational settings of the recipient’s current map on the implantable medical device, with or without any user input from the clinician.

[0078] For example, the fitting system 470 can be configured to communicate with the cochlear implant 102 to transmit the one or more adjustments to the one or more operational settings (e.g., the amount of the change to be made, which corresponds to the difference between the current operational setting and the adjusted operational setting), or can transmit one or more adjusted operational settings (the actual updated value that is to be set), to the cochlear implant 102 to cause the cochlear implant 102 to implement the adjustments oradjusted operational settings. In another example, the fitting system 470 can communicate with the cochlear implant 102 to directly reconfigure the implantable medical device by updating the one or more operational settings itself based on the one or more adjustments or the one or more adjusted operational settings. The fitting system 470 can be configured to perform these adjustments to the one or more operational settings automatically, with or without requiring a confirmation or explicit approval from the clinician.

[0079] As such, in certain embodiments, the stimulation adaption logic 487 may be configured to operate in accordance with one or more selected guidelines set by the clinician or audiologist via the user interface 486, in order to give the clinician some measure of control over these automated aspects of the system and methods described herein. For example, the clinician can configure which specific operational settings among the various operational settings of the implantable medical device may be adjusted automatically by the fitting system 470 (e.g., by enabling or disabling automatic adjustments for specific settings or parameters), and / or the clinician can set limits with respect to how much (i.e., the amount or degree of change) a particular operational setting may be automatically adjusted by the fitting system 470.

[0080] The recipient-specific data received at the computing device of the fitting system 470 may be received via the interface s / ports 478( l)-(N) illustrated in FIG. 4. Additionally, the system that receives the recipient-specific data, and that implements the other operations (e.g., objective measurement, analysis, adjustments, etc.), need not be specific to one particular type of medical device. For example, a system according to embodiments of the present disclosure may receive data, such as the recipient-specific data, from a number of different medical device types, including implantable stimulation systems, vestibular stimulator systems, retinal prosthesis systems, and other types of medical devices known to the skilled artisan. Accordingly, the computing device used to implement the fitting system 470 of FIG. 4 may be configured to communicate with multiple cochlear implant systems 102, as well as other types of medical devices.

[0081] The recipient-specific data may be received via, for example, a fitting session during which a recipient’s medical device interfaces with a fitting system, such as fitting system 470 of FIG. 4. According to other example embodiments, the recipient-specific data may be received in response to a recipient connecting their medical device (e.g., external component 104 of FIGs. 1A-1D) or associated external device (e.g., external device 110 of FIGs. 1A-1E) to the Internet. For example, a recipient’s external device may be configured with anapplication, such as a smartphone application (“app”) that transfers recipient-specific data to a processing system using the Internet. This transfer of recipient-specific data may take place passively (e.g., without the recipient initiating the transfer) at regular intervals or in response to the external device connecting to the Internet, or may be actively initiated in response to a recipient or clinician command received at the external device.

[0082] The recipient-specific data can include hearing performance data, physiological measurement data, usage data, implant system technical information data, and contextual data, and may be considered fitting data (fitting quality check data), as this data may be used by a fitting system, such as fitting system 470 of FIG. 4. The recipient-specific fitting data may be automatically sent to the processing device (e.g., the processing devices described above, including fitting system 470 of FIG. 4) via the cochlear implant system 102. According to other example embodiments, the fitting system 470 may interface with the cochlear implant system 102 to initiate the transfer of this data to the fitting system, or the user of the cochlear implant system 102 may initiate the sending of this data to the fitting system 470. It should be appreciated that all of the clinical data types described above are not required, and only one clinical data type or only a subset (less than all) of the clinical data types may be received in various different implementations of the embodiments described herein.

[0083] FIG. 5 is a flowchart of a method 500, according to an example embodiment. Method 500 begins with an implantable medical device delivering at least one series of electrical stimulation signals to nerve cells of a recipient, in operation 510. In operation 520, at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipe is recorded. In operation 530, the at least one recovery potential is analyzed to assess an efficacy of the at least one series of electrical stimulation signals.

[0084] In the method 500 of FIG. 5, it is noted that the stimulation signal should have a certain duration to evoke a clear recovery function (e.g., one pulse stimulus is not sufficient), and this duration of the stimulus should be at least several milliseconds (ms). In one non-limiting example embodiment, an ideal duration of the stimulus could be around 50-100ms (approximately). Further, it should be appreciated that the stimulus signal can be a pulse train in some examples, but can instead be a sinusoidal stimulus or a triangle wave or a square wave, with a certain frequency and amplitude, for example.

[0085] In some example embodiments, operation 520 may include initiating recording of the at least one recovery potential after a predetermined time period following delivery of the series of stimulation signals, and operation 530 may include analyzing an amplitude of the at least one recovery potential.

[0086] The operations of method 500 may be performed for a single channel in some embodiments, for two or more channels simultaneously in some other embodiments, or in an interleaved manner for two or more channels in some other embodiments. In some example embodiments, the recovery potential can be recorded at the same electrode where the stimulus was delivered, or alternatively, at electrodes away / apart from the stimulus. This could deliver information about the source of the recovery potential with respect to the source of the stimulus, for example.

[0087] In some example embodiments, method 500 may (optionally) include an additional operation 540 in which one or more parameters of subsequent electrical stimulation signals are set based on the analyzing. Setting the one or more parameters of the subsequent electrical stimulation signals may include one or more of setting a pulse width, setting a pulse rate (or a frequency, in the case of sinusoidal stimuli), setting an inter-pulse gap (IPG), and / or setting an amplitude for the subsequent electrical stimulation signals based on the analyzing.

[0088] In some example embodiments, the method may additionally include delivering a plurality of series of electrical stimulation signals, wherein each of the plurality of series of electrical stimulation uses a different stimulus configuration with one or more variable parameters, and recording a plurality of recovery potentials each corresponding to one of the plurality of series of electrical stimulation signals. The one or more variable parameters may include one or more of a stimulation mode (e.g., monopolar, common ground, bipolar, focused multi-polar, etc.), a pulse shape (e.g., symmetric biphasic, asymmetric biphasic, etc.), a pulse rate, a pulse width, an inter-pulse gap, and / or an amplitude. Different stimulation configurations, including but not limited to simultaneous focused multipolar stimulation or sequential stimulation on multiple electrodes, can be used, for example. The method may also include determining, from the plurality of recovery potentials, a selected optimum stimulus configuration from among the different stimulus configurations that maximizes a selected attribute (e.g., an amplitude) of a recovery potential of the nerve cells, and setting one or more parameters of subsequent electrical stimulation signals in accordance with the selected optimum stimulus configuration. These embodiments represent improvements to a fitting process for configuring a cochlear implant for a particular recipient.

[0089] Thus, the present disclosure provides a system and methods for recording neural activity at longer latencies (after ECAP) as a measure for effectiveness of the neurons with respect to the electric stimulation, and using this information to optimize stimulation parameters in cochlear implant fitting. Recovery potentials can be recorded for different stimulus configurations for a single channel / electrode making use of a pulse train with a variable pulse rate, a variable pulse width, and / or a variable inter-pulse gap, etc. Rather than focusing on the neuronal response evoked during stimulation or directly after a single electrical stimulus, the embodiments described herein focus on the neuronal response at a short delay after the single electrical stimulus has ended.

[0090] As noted, the method utilizes longer recording windows, and can make use of an external EEG amplifier system. This recovery potential can be measured during or after cochlear implant surgery, such as by using an EABR machine triggered by the stimulus from the implant, or by using the measurement functionality of the implant itself (e.g., similar to ECochG). Measuring this recovery potential addresses the stimulus artefact problem often seen in electrophysiology. The stimulus and the response are clearly separated in time, and therefore the artefact problem is minimized. The recovery potential response is of lower frequency and can be easily recorded without artefact with a LP amplifier, and is occurring after the electrical stimulus, and thus the response is not contaminated by electrical stimulus artefact. Preferably, the optimal stimulation rate can be found based on this recovery potential response, and then the optimal stimulation rate is simply set during implant fitting, for example. In one variation, however, this response could be used in a closed-loop feedback system during active use of the implant, as further described below.

[0091] Various benefits and advantages of the invention include enabling recipient centric fitting, introducing new fitting configurations, and looking for optimal configuration to substantiate the appropriate default. The recovery potential can give insight into the recipient’s neural health, and could have predictive value with regards to recipient outcomes. The recovery potential can be measured with stimuli on different electrodes and can give an idea of neural survival along the spiral ganglion. The recovery potential can be measured during active use of the implant, and could be included in an adaptive closed loop coding application. Thus, measurement of the recovery potential can serve as a new, additional, or supplementary diagnostic tool with respect to neural health and the effectiveness of stimulation.

[0092] Next, a system and method for adaptive stimulation based on evoked neural brain response diagnostics / analysis will be described. Current cochlear implant systems are open-loop systems that do not have “diagnostic capabilities” and do not obtain a feedback signal from the body on the physiological response of the nerves / brain to electrical stimulation. Since the current cochlear implant systems do not have a feedback loop that utilizes “brain responses,” per se, the effect of the electrical stimulation on the entire auditory pathway including brain is unknown. As a result, due to the lack of information / feedback on the physiological condition / response of the nerve auditory pathway to the electrical stimulation, the current implant systems do not have diagnostic capabilities and adaptive stimulation capabilities, and cannot optimize the efficiency of stimulation (and thus, are unable to achieve the best possible quality perception for a given implant recipient).

[0093] To address the above and other needs, presented herein are a closed-loop cochlear implant system and methods for adaptive stimulation based on recording evoked nerve / brain responses to electrical stimulation, and performing diagnostic analysis on the evoked nerve / brain responses. In addition, the implant system has a self-adjustment function based on the diagnostic analysis of the evoked nerve / brain responses. The closed-loop cochlear implant system is arranged to measure an evoked response along the auditory pathway (can be central and / or peripheral) and to dynamically adjust a stimulation parameter in real time. Preferably, the system includes an implanted battery, and a recording electrode which is arranged inside the cochlea.

[0094] The best way to assess the efficiency of an auditory (or any other nerve) stimulation is to measure the parameters (amplitude, latency, speed of activation, speed of relaxation, etc.) of the brain response signal. This allows the physiological condition of the entire auditory pathway to be evaluated and the most effective stimulation mode / method to be selected. The stimulation mode (monopolar, multipolar, bipolar etc.) and the stimulation pulse duration (speed of charge delivery) can be automatically selected and optimized based on the brain response. The brain responses (and associated perception) can vary over time on a day to day basis, as the physiological conditions of the entire nerve path to the brain and the brain itself can vary (e.g., for reasons relating to medicine intake, hormone changes, medical treatment, effect of the electrical stimulation on the nerve system, etc.), so the automatic adjustment of the stimulation will ensure optimum perception.

[0095] The embodiments described herein involve the implant system using evoked nerve / brain responses for automatic self-optimization of the stimulation, including but not limited to the stimulation mode (e.g., monopolar, bipolar, multipolar, monophasic, etc.), the stimulation rate, stimulation parameters (not only the amplitude), etc. The implant systemimplements closed-loop (feedback) control based on the evoked nerve / brain responses, and is configured to make real-time adjustments to a range of stimulation parameters as a function of day-to-day changing objective auditory measures. Thus, the implant system not only detects and measures the nerve and brain responses, but also automatically adapts / adjusts the stimulation parameters to achieve optimal perception.

[0096] The measures of this technology are about tracking changes to the responsiveness of the neural substrate in the auditory pathway, for perception optimization. Real-time adjustment or modulation of stimulation parameters (e.g., stimulation modes, stimulation rate, etc.) according to objective measures that include peripheral and / or central responses, for the purpose of dynamically optimizing a wide range of stimulation parameters (apart from adjusting the dynamic range), as measured by day-to-day changes of brain function.

[0097] The system and methods described herein can be used to identify the most efficient stimulation by measuring the amplitude, the delay / latency, the power / duration of the brain response(s), etc., as a function of the stimulation mode, rate, pulse amplitude, pulse duration, interphase gap, etc. The response, latency, delay, etc. can give information about the feedback. The latency of the brain response can be, for example, 250 milliseconds. The self-optimization function can be automatically performed on a regular basis, at predetermined time intervals, or activated by the recipient at any time suitable for them. As noted, the current cochlear implant systems do not have a self-initiation feature.

[0098] FIG. 6A is a block diagram of an implant system 612, according to an example embodiment. As shown in FIG. 6A, the implant system 612 includes one or more implantable sound sensors 660 (e.g., one or more microphones), an implantable sound processing module 658 (e.g., a digital signal processor (DSP)), a stimulator unit 642 (e.g., including a stimulation non-volatile memory, a stimulation controller, and an electrode driver), and an evoked brain response (EBR) analysis module 670. The implant system 612 also includes an implantable coil 614 (e.g., an antenna), RF interface circuitry 640 (e.g., a data decoder / telemetry, and a battery charger), and a power source 625 (e.g., a battery). The evoked brain response (EBR) analysis module 670 includes an EBR controller 671, an EBR amplifier 673, an analog-to- digital converter (ADC) 675, an EBR non-volatile memory 677, and an EBR power source 679. The EBR analysis module 670 (and its various components) can be used to implement the embodiments described herein.

[0099] FIG. 6B is a block diagram of the implant system 612 in communication with an external device 606, according to another example embodiment. The external device 606 includes an antenna 608 (e.g., a coil), a charger and an evoked brain response (EBR) analyzer 685. The EBR analyzer 685 can be used to implement the embodiments described herein.[ooioo] The stimulation adjustment, based on the nerve and brain response, can be performed automatically on a regular basis by the implant system 612 of FIG. 6A. Additionally or alternatively, the stimulation adjustment based on the nerve and brain response can be activated on-demand at any time by the recipient or clinician, through the use of an external device, such as the external device 606 of FIG. 6B.[ooioi] In certain embodiments, evoked nerve / brain responses can be obtained for different stimulation modes and different pulse durations. Evoked responses along the auditory pathway can be analyzed in terms of amplitude, latency, speed of activation, and speed of relaxation, among other factors / criteria, and can serve as a proxy for the perceptivity / efficiency of the auditory system which is receiving the therapeutic electrical stimulation. The evoked nerve / brain responses obtained from different stimulation modes and pulse durations are recorded / saved in a memory (e.g., EBRNVM 677), and are compared to each other in order to identify the optimum stimulation mode and parameters. In turn, stimulation can be optimized by real time adjustments of stimulation parameters, which can include stimulation mode adjustments (monopolar, multipolar, bipolar, etc.), pulse duration adjustments, among other examples. The system automatically selects and uses the optimum stimulation mode and parameters until the next stimulation adjustment, which is activated automatically on a regular basis or on-demand by the recipient.

[0102] FIG. 6C is a diagram 690 illustrating an example of an evoked nerve / brain response potential 691, in terms of amplitude as a function of time. The measurement and analysis of the evoked nerve / brain response potential 691 can be performed by the implant system 612 of FIG. 6A (via the EBR analysis module 670), alone or in combination with the external device 606 of FIG. 6B (via the EBR analyzer 685). As shown in FIG. 6C, the evoked response potential 691 includes a first response XI with a first positive peak 692(1) at a first latency (Ti) and then a first negative peak 694(1) thereafter, where Al denotes a first potential amplitude 696(1) defined by the magnitude difference between the first positive peak 692(1) and the first negative peak 694(1). The evoked response potential 691 also has an nth response Xn with an nth positive peak 692(n) (Xn) at an nth latency (Tn) and then an nth negative peak 694(n) thereafter, where An denotes an nth potential amplitude 696(n) defined by the magnitudedifference between the nth positive peak 692(n) and the nth negative peak 694(n). In FIG. 6C, the evoked response potential 691 represents the evoked response potential of the entire auditory pathway from the cochlea up to and including the brain, the first response XI (the first positive peak 692(1) and the first negative peak 694(1)) represents the response of the auditory nerve(s) located in proximity to (close to) the inner ear (i.e., XI represents a “nerve response”), and the nth response Xn (the nth positive peak 692(n) and the nth negative peak 694(n)) represents the response of the brain itself (i.e., Xn represents the first “brain response”).

[0103] Also, the currently obtained evoked nerve / brain response data can be compared with reference evoked nerve / brain response data (e.g., previously obtained and stored during initial fitting / mapping for the recipient). The EBR analysis module 670 of the implant system 612 of FIG. 6A (and / or the EBR analyzer 685 of the external device 606) of FIG. 6B) can analyze the evoked nerve / brain response potential 689 to assess stimulation improvement based on the comparison of the currently obtained response data with the reference response data. Various factors in the objective measures can be indicative of stimulation improvement. Some nonlimiting examples of the criteria for assessing stimulation improvement can include: decrease of the brain time response (latency), increase of the brain amplitude response, increase of brain activation speed, and other similar metrics. This comparison is informative about the effect of the simulation on the physiological condition of the entire auditory pathway from the cochlea up to and including the brain (e.g., an improvement in the evoked nerve / brain response to the electrical stimulation vs. a decrease in performance).

[0104] FIGs. 6D-6F illustrate a series of example evoked brain response recordings, according to an example embodiment. Similar to FIG. 6C, the evoked response potential in each of FIGs. 6D, 6E, and 6F includes a first nerve response XI (i.e., a response of the auditory nerve(s) located in proximity or close to the inner ear) with a first positive peak at a first latency and then a first negative peak thereafter, where Al denotes the first potential amplitude of the first nerve response X 1 as defined by the magnitude difference between the first positive peak and the first negative peak. FIG. 6D shows a reference brain response 697 with a reference latency (Tn) and a reference amplitude (Ar). FIG. 6E shows a current brain response 698 with an increased latency (Tn + ATI) and a decreased amplitude (Ad), which is indicative of deteriorated perception for the recipient. The decreased amplitude “Ad” of FIG. 6E is less than the reference amplitude “Ar” of FIG. 6D. The current brain response 698 can be analyzed, the deteriorated condition can be identified based on a comparison with the reference response 697, and a determination can be made with respect to adjusting one or more operational settingsand / or stimulation parameters in order to improve the brain response and thereby optimize perception for the recipient. FIG. 6F shows a subsequent brain response 699 with a decreased latency (Tn - AT2) and an increased amplitude (Ai). The increased amplitude “Ai” of FIG. 6F is greater than the decreased amplitude “Ad” of FIG. 6E. In the example of FIG. 6F, the increased amplitude “Ai” can be greater than the reference amplitude “Ar” of FIG. 6D. In some other example embodiments, however, it should be appreciated that the increased amplitude “Ai” of FIG. 6F could be greater than the decreased amplitude “Ad” of FIG. 6E but less than or equal to the reference amplitude “Ar” of FIG. 6D. The subsequent brain response699 is an example of automatically adapted stimulation based on the analysis of the current brain response 698 of FIG. 6E in relation to the reference brain response 697 of FIG. 6D, resulting in optimum perception (i.e., the subsequent brain response 699 represents an improved response of the brain itself) for the recipient, according to the embodiments described herein.

[0105] FIG. 7 is a flowchart of a method 700, according to an example embodiment. Method700 begins with delivering one or more stimulation signals to an inner ear of a recipient, in operation 710. In operation 720, a neural response set evoked by the one or more stimulation signals is obtained via at least one of a plurality of electrodes configured to be implanted in the inner ear of the recipient. The neural response set includes at least one inner ear neural response, at least one auditory nerve response, and at least one evoked brain response of the recipient, during a period following delivery of the one or more stimulation signals. In operation 730, the neural response set is analyzed in order to assess an efficacy of the one or more stimulation signals. Then, in operation 740, one or more parameters of subsequent stimulation signals are set based on the analyzing of the neural response set. It should be appreciated that the term “neural response set” is a general term that encompasses both “nerve responses” as well as “brain responses.”

[0106] In some examples, delivering the one or more stimulation signals to the inner ear of the recipient (in operation 710) may include delivering one or more electrical stimulation signals, delivering one or more acoustic stimulation signals, or delivering a combination of electrical stimulation signals and acoustic stimulation signals. In some examples, obtaining the neural response set (in operation 720) may include recording a plurality of neural response sets over a period of time, and storing the plurality of neural response sets in a memory. In some examples, setting the one or more parameters of the subsequent stimulation signals (in operation 740) may include one or more of setting a pulse width, setting a pulse rate, and / orseting an amplitude for the subsequent electrical stimulation signals based on the analyzing of the neural response set.

[0107] In some example embodiments, analyzing the neural response set (in operation 730) may include analyzing one or more of a latency, a speed of activation, a speed of relaxation, and / or an amplitude of the neural response set. The terms “speed of activation / relaxation” for the stimulation signals relates to the shape of the stimulation signal (e.g., rectangular, triangular, trapezoidal, etc.), and refers to the speed of activation / relaxation of the audio nerve / brain path (i.e., the shape of the nerve / brain response signal is the indication of the activation / relaxation speed). The first derivative of the rising edge (AV / AT) of the nerve / brain response signal (e.g., rising edge of the positive peak of the nerve / brain response signal) defines the speed of nerve / brain activation. The first derivative of the falling edge (AV / AT) of the nerve / brain response signal (falling edge of the negative peak of the nerve / brain response signal) defines the speed of nerve / brain relaxation. That is, the term “activation speed” refers to the speed of applying / delivering the charge to the body to activate the audio nerve path (Phase 1 of the stimulation signal), while the “relaxation speed” refers to the speed of balancing the charge delivered to the body (Phase 2 of the stimulation signal), and these terms relate to the duration and shape of the stimulation signal (e.g., rectangular, triangular, trapezoidal, etc.).

[0108] In some example embodiments, analyzing the neural response set may include dynamically analyzing variations in recorded values of the neural response set over time, by comparing the recorded values of the at least one inner ear neural response, the at least one auditory nerve response, and the at least one evoked brain response to corresponding previously recorded reference values, to assess the efficacy of the one or more stimulation signals on physiological conditions of an auditory nerve pathway from the inner ear along the auditory nerve up to and including the brain of the recipient. In such example embodiments, seting the one or more parameters of the subsequent stimulation signals may include dynamically adapting at least one of a stimulation mode and a stimulation pulse duration of the subsequent stimulation signals over time based on the dynamically analyzing of the variations in the recorded values of the neural response set over time compared to the corresponding previously recorded reference values.

[0109] In some example embodiments, analyzing the neural response set may include comparing one or more measurements of the at least one inner ear neural response, the at least one auditory nerve response, and the at least one evoked brain response of the neural response set, for nerves across an auditory nerve pathway from the inner ear along the auditory nerve upto and including the brain of the recipient, to corresponding reference neural response data obtained during a mapping procedure for the recipient utilizing different stimulation modes and different pulse durations.[oono] In some example embodiments, setting the one or more parameters of the subsequent stimulation signals may include automatically adapting a stimulation mode used for the subsequent stimulation signals based on the analyzing of the neural response set. For example, this automatic adaption may include changing the stimulation mode from a first stimulation mode (e.g., one of monopolar, bipolar, multipolar, monophasic, etc.) used for the one or more stimulation signals, to a second stimulation mode (e.g., another one of these modes) that is different from the first stimulation mode, based on the analyzing of the neural response set.[oom] In some example embodiments, setting the one or more parameters of the subsequent stimulation signals may include automatically adapting a stimulation pulse duration used for the subsequent stimulation signals based on the analyzing of the neural response set (e.g., to adjust the amount of charge delivery). In some examples, setting the one or more parameters of the subsequent stimulation signals may include automatically adapting a stimulation mode and a stimulation pulse duration used for the subsequent stimulation signals based on the analyzing of the neural response set.

[0112] In some examples, setting the one or more parameters of the subsequent stimulation signals may include adapting the subsequent stimulation signals (e.g., by adjusting one or more of the stimulation pulse rate, pulse width / duration, pulse amplitude, and / or stimulation mode) so as to at least one of increase (maximize) amplitude, reduce (minimize) latency, and / or increase (maximize) activation speed of a subsequent neural response set evoked by the subsequent stimulation signals during a period following delivery of the subsequent stimulation signals. Ideally, the highest / largest “amplitude,” the shortest / smallest “latency,” and the fastest “activation speed” are desirable for the subsequent neural response signal.

[0113] In some examples, analyzing the neural response set may include identifying an optimum number of stimulation electrodes or an optimum combination of stimulating electrodes, from among the plurality of electrodes, to achieve optimum auditory perception by the recipient for a particular stimulation mode. In such examples, setting the one or more parameters of the subsequent stimulation signals may include utilizing the optimum number of stimulation electrodes or the optimum combination of stimulation electrodes, from among theplurality of electrodes, to deliver the subsequent stimulation signals to the inner ear of the recipient.

[0114] In some examples, analyzing the neural response set may include identifying an anomalous physiological condition along an auditory nerve pathway from the inner ear along the auditory nerve up to and including the brain of the recipient, based on the at least one inner ear neural response, the at least one auditory nerve response, and the at least one evoked brain response of the neural response set. For example, there may be a decreased performance resulting from sickness, disease, deterioration, etc. In some other examples, analyzing the neural response set may include quantifying an improvement in the efficacy of the one or more stimulation signals resulting from a particular therapeutic treatment for the recipient. For example, there may be an increased performance resulting from some new drug treatment, hormone therapy, rehabilitation, etc.

[0115] In some examples, the operations of method 700 may be automatically performed continuously or periodically. In some other examples, the operations of method 700 may be dynamically activated on-demand in response to user input received from an external device of the recipient or a clinician.

[0116] With current cochlear implant treatments, the most important parameter is often considered to be electric dynamic range, which does not require changes after an initial period. However, it may be beneficial to change various other parameters, according to the embodiments described herein. The nerve stimulation depends on the charge (Q) delivered to the nerve. The charge Q is calculated as the product of the current pulse amplitude (I) and the current pulse duration (T). The conductivity of the nerves and / or the speed of transferring the signal to the brain is not a constant and depends on the stimulation mode, stimulation rate etc. The embodiments presented herein are based on objective brain response measurement that enables the effect of each of the stimulation parameters on the perception to be assessed, and automatically change some or all of the stimulation parameters to obtain optimum perception (self-adjustment / self-adaptation). The current cochlear implant systems do not have feedback capabilities, hence if a recipient’s perception changes / deteriorates, then re -programming is required, which means a visit to the audiologist is needed.

[0117] The evoked auditory brain response signals can be used to detect and measure the quality of the brain perception. The evoked auditory brain response signals are the best indication for the physiological condition of the nerve path up to the brain and the brain itself.Identifying a change in the brain responses, the physiological condition of the nerve path up to the brain and the brain itself can be assessed. If drugs are taken by the recipient, the effect of the drugs can be automatically detected and analyzed / assessed. If the brain response signals indicate perception improvement (for example, a decrease of the response latency and / or an increase of the response amplitude, etc.), then a message can be sent from the implant system to an external device (for example a sound processor) to confirm and inform the recipient and the audiologist of the drug’s efficiency. If the brain response signals indicate perception deterioration (for example, an increase of the response latency and / or a decrease of the response amplitude, etc.), then the implant automatically can improve the perception by changing the stimulation strategy, levels, modulation etc. If the perception cannot be improved, a message can be sent from the implant to an external device (for example a sound processor) to inform the recipient to visit the clinic.

[0118] In all cases, the brain responses are automatically recorded into implant’s memory and can also be sent to external memory. The brain responses can be compared with the reference response(s). The brain responses can be reviewed any time by an authorized person to assess the improvement or the deterioration of the quality of the perception and to identify the reason for this deterioration (e.g., drugs, hormones, etc.). The system measures and detects the physiological condition of the nerve path up to the brain and the brain itself and automatically adjusts the stimulation mode, strategy, parameters (levels, duration, modulation), etc. to obtain the optimum / best perception for the recipient. The system automatically compensates any negative effects of factors (e.g., drugs, hormones, etc.) on the physiological condition of the nerve path to the brain and the brain itself, and adapts the stimulation to obtain the optimum / best perception for the recipient. If the automatic adaptation cannot be achieved within pre-determined limits, then the recipient / audiologist can be informed.

[0119] In an additional use case, the implant system records and analyzes the evoked nerve / brain response potentials along the audio nerve path (from the cochlea up to and including the brain) and identifies shape anomalies, which can indicate possible initial stages of sickness conditions (e.g., Alzheimer’s disease). Also, the implant system can record evoked nerve / brain responses and nerve / brain recovery potentials that can be indicative of phy siological / sickne ss conditions .

[0120] According to another aspect, an implantable auditory stimulation system having an implantable battery is provided in order to permit long recording windows (time periods) required for capturing higher order auditory measures to be used for diagnosis and / orstimulation modification. As the implant system is powered by its own battery (independent from external power), the evoked nerve / brain responses can be recorded for a time period, as long as required to cover the responses along the auditory nerve pathway from the cochlea up to an including the brain. This allows automatic self-optimization of the stimulation, assessment of the physiological condition of the auditory nerve pathway and the brain itself, and detection of any anomalies / sickness conditions. The system can have an intracochlear recording electrode for higher order measures, as enabled by the availability of an implantable battery. Existing cochlear implant systems do not have these capabilities.

[0121] According to yet another aspect, the implant system and methods described here can also be adapted for hybrid stimulation optimization. The implant system can operate in standalone mode, as well as in a hybrid stimulation mode in which combined acoustic and electrical stimulation are used simultaneously. In the hybrid stimulation mode, the embodiments described herein can be used to assess / diagnose the physiological condition of the auditory nerve pathway (from the cochlea up to and including the brain) by measuring the brain responses to: (1) acoustic stimulation only, (2) electrical stimulation only, and (3) hybrid stimulation (both acoustic and electrical stimulation simultaneously). The implant system can automatically adjust the hybrid stimulation parameters, such as by time synchronisation / shifting of the acoustic stimulation signals and / or the electrical stimulation signals and / or adjustment of the amplitude of the audio and electrical stimulation signals, in order to obtain optimum brain response and optimum audio perception.

[0122] FIG. 8 is a flowchart of a method 800, according to an example embodiment. Method 800 begins with the delivery of stimulation to a recipient utilizing a hybrid stimulation mode in which a combination of electrical stimulation and acoustic stimulation are used simultaneously, in operation 810. In operation 820, measurements of evoked nerve / brain responses of the recipient resulting from the combination of electrical stimulation and acoustic stimulation are obtained. In operation 830, the measurements of the evoked nerve / brain responses of the recipient are analyzed to assess an efficacy of the combination of electrical stimulation and acoustic stimulation. Then, in operation 840, one or more of the electrical stimulation and the acoustic stimulation is / are adapted based on the analyzing of the measurements of the evoked nerve / brain responses.

[0123] In some examples, operation 820 can record one or more parameters of the evoked nerve / brain responses to the electrical stimulation only, or record one or more parameters of the evoked nerve / brain responses to the acoustic stimulation only. In some other examples,operation 820 can record one or more parameters of the evoked nerve / brain responses to the combination of electrical stimulation and acoustic stimulation.

[0124] In some examples, operation 830 includes assessing / diagnosing physiological conditions of an auditory nerve pathway, from the cochlea up to and including the brain of the recipient, based on the measurements of the evoked nerve / brain responses.

[0125] In some examples, operation 840 includes automatically adjusting one or more hybrid stimulation parameters so as to achieve optimum auditory perception by the recipient in the hybrid stimulation mode . For example, an amplitude of one or both of the electrical stimulation and the acoustic stimulation can be adjusted, and / or time synchronization / shifting of at least one of the electrical stimulation and the acoustic stimulation can be performed.

[0126] By recording and analyzing the evoked neural response potentials from cochlear auditory nerves across the entire auditory pathway from the cochlea to the brain, including the brain response, the implant system can automatically adapt the stimulation mode and parameters so that the optimum and most efficient stimulation can be achieved. For example, the optimum number of the stimulation electrodes in multi-polar stimulation mode can be identified based on the analysis of the evoked brain response, among the many other illustrative examples described above. The implant system and methods described above can lead to better implant performance and optimum perception by recipients. The self-adjustment feature will be very useful for providing more personalized care as well as reducing the clinical workload.

[0127] As previously described, the technology disclosed herein can be applied in any of a variety of circumstances and with a variety of different devices. Example devices that can benefit from technology disclosed herein are described in more detail in FIGS. 9 and 10. The embodiments of the present disclosure can be applied to other devices, such as neurostimulators, cardiac pacemakers, cardiac defibrillators, sleep apnea management stimulators, seizure therapy stimulators, tinnitus management stimulators, and vestibular stimulation devices, as well as other medical devices that deliver stimulation to tissue. Further, technology described herein can also be applied to consumer devices. These different systems and devices can benefit from the technology described herein.

[0128] FIG. 9 illustrates an example vestibular stimulator system 902, with which embodiments presented herein can be implemented. As shown, the vestibular stimulator system 902 comprises an implantable component (vestibular stimulator) 912 and an external device / component 904 (e.g., external processing device, battery charger, remote control, etc.).The external device 904 comprises a transceiver unit 960. As such, the external device 904 is configured to transfer data (and potentially power) to the vestibular stimulator 912.

[0129] The vestibular stimulator 912 comprises an implant body (main module) 934, a lead region 936, and a stimulating assembly 916, all configured to be implanted under the skin / tissue (tissue) 915 of the recipient. The implant body 934 generally comprises a hermetically-sealed housing 938 in which RF interface circuitry, one or more rechargeable batteries, one or more processors, and a stimulator unit are disposed. The implant body 934 also includes an intemal / implantable coil 914 that is generally external to the housing 938, but which is connected to the transceiver via a hermetic feedthrough (not shown).

[0130] The stimulating assembly 916 comprises a plurality of electrodes 944(l)-(3) disposed in a carrier member (e.g., a flexible silicone body). In this specific example, the stimulating assembly 916 comprises three (3) stimulation electrodes, referred to as stimulation electrodes 944(1), 944(2), and 944(3). The stimulation electrodes 944(1), 944(2), and 944(3) function as an electrical interface for delivery of electrical stimulation signals to the recipient’s vestibular system.

[0131] The stimulating assembly 916 is configured such that a surgeon can implant the stimulating assembly adjacent the recipient’s otolith organs via, for example, the recipient’s oval window. It is to be appreciated that this specific embodiment with three stimulation electrodes is merely illustrative and that the embodiments presented herein may be used with stimulating assemblies having different numbers of stimulation electrodes, stimulating assemblies having different lengths, etc.

[0132] In operation, the vestibular stimulator 912, the external device 904, and / or another external device, can be configured to implement the embodiments presented herein. That is, the vestibular stimulator 912, possibly in combination with the external device 904 and / or another external device, can include an evoked biological response analysis system, as described elsewhere herein.

[0133] FIG. 10 illustrates a retinal prosthesis system 1001 that comprises an external device 1010 (which can correspond to the wearable device 100) configured to communicate with an implantable retinal prosthesis 1000 via signals 1051. The retinal prosthesis 1000 comprises an implanted processing module 1025 and a retinal prosthesis sensor-stimulator 1090 is positioned proximate the retina of a recipient. The external device 1010 and the processing module 1025 can communicate via coils 1008, 1014.

[0134] In an example, sensory inputs (e.g., photons entering the eye) are absorbed by a microelectronic array of the sensor-stimulator 1090 that is hybridized to a glass piece 1092 including, for example, an embedded array of microwires. The glass can have a curved surface that conforms to the inner radius of the retina. The sensor-stimulator 1090 can include a microelectronic imaging device that can be made of thin silicon containing integrated circuitry that convert the incident photons to an electronic charge.

[0135] The processing module 1025 includes an image processor 1023 that is in signal communication with the sensor-stimulator 1090 via, for example, a lead 1088 which extends through surgical incision 1089 formed in the eye wall. In other examples, processing module 1025 is in wireless communication with the sensor-stimulator 1090. The image processor 1023 processes the input into the sensor-stimulator 1090, and provides control signals back to the sensor-stimulator 1090 so the device can provide an output to the optic nerve. That said, in an alternate example, the processing is executed by a component proximate to, or integrated with, the sensor-stimulator 1090. The electric charge resulting from the conversion of the incident photons is converted to a proportional amount of electronic current which is input to a nearby retinal cell layer. The cells fire and a signal is sent to the optic nerve, thus inducing a sight perception.

[0136] The processing module 1025 can be implanted in the recipient and function by communicating with the external device 1010, such as a behind-the-ear unit, a pair of eyeglasses, etc. The external device 1010 can include an external light / image capture device (e.g., located in / on a behind-the-ear device or a pair of glasses, etc.), while, as noted above, in some examples, the sensor-stimulator 1090 captures light / images, which sensor-stimulator is implanted in the recipient.

[0137] As should be appreciated, while particular uses of the technology have been illustrated and discussed above, the disclosed technology can be used with a variety of devices in accordance with many examples of the technology. The above discussion is not meant to suggest that the disclosed technology is only suitable for implementation within systems akin to that illustrated in the figures. In general, additional configurations can be used to practice the processes and systems herein and / or some aspects described can be excluded without departing from the processes and systems disclosed herein.

[0138] This disclosure described some aspects of the present technology with reference to the accompanying drawings, in which only some of the possible aspects were shown. Otheraspects can, however, be embodied in many different forms and should not be construed as limited to the aspects set forth herein. Rather, these aspects were provided so that this disclosure was thorough and complete and fully conveyed the scope of the possible aspects to those skilled in the art.

[0139] As should be appreciated, the various aspects (e.g., portions, components, etc.) described with respect to the figures herein are not intended to limit the systems and processes to the particular aspects described. Accordingly, additional configurations can be used to practice the methods and systems herein and / or some aspects described can be excluded without departing from the methods and systems disclosed herein.

[0140] According to certain aspects, systems and non-transitory computer readable storage media are provided. The systems are configured with hardware configured to execute operations analogous to the methods of the present disclosure. The one or more non-transitory computer readable storage media comprise instructions that, when executed by one or more processors, cause the one or more processors to execute operations analogous to the methods of the present disclosure.

[0141] Similarly, where steps of a process are disclosed, those steps are described for purposes of illustrating the present methods and systems and are not intended to limit the disclosure to a particular sequence of steps. For example, the steps can be performed in differing order, two or more steps can be performed concurrently, additional steps can be performed, and disclosed steps can be excluded without departing from the present disclosure. Further, the disclosed processes can be repeated.

[0142] Although specific aspects were described herein, the scope of the technology is not limited to those specific aspects. One skilled in the art will recognize other aspects or improvements that are within the scope of the present technology. Therefore, the specific structure, acts, or media are disclosed only as illustrative aspects. The scope of the technology is defined by the following claims and any equivalents therein.

[0143] It is also to be appreciated that the embodiments presented herein are not mutually exclusive and that the various embodiments may be combined with another in any of a number of different manners.

Claims

CLAIMSWhat is claimed is:

1. A method comprising : delivering, with an implantable medical device, at least one series of electrical stimulation signals to nerve cells of a recipient; recording at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipient; and analyzing the at least one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals.

2. The method of claim 1, further comprising: setting one or more parameters of subsequent electrical stimulation signals based on the analyzing.

3. The method of claim 2, wherein setting the one or more parameters of the subsequent electrical stimulation signals comprises: setting a pulse width of the subsequent electrical stimulation signals based on the analyzing.

4. The method of claim 2, wherein setting the one or more parameters of the subsequent electrical stimulation signals comprises: setting a pulse rate of the subsequent electrical stimulation signals based on the analyzing.

5. The method of claim 2, wherein setting the one or more parameters of the subsequent electrical stimulation signals comprises: setting an inter-pulse gap of the subsequent electrical stimulation signals based on the analyzing.

6. The method of claim 2, wherein setting the one or more parameters of the subsequent electrical stimulation signals comprises:setting an amplitude of the subsequent electrical stimulation signals based on the analyzing.

7. The method of claim 1, 2, 3, 4, 5, or 6, further comprising: delivering a plurality of series of electrical stimulation signals, wherein each of the plurality of series of electrical stimulation uses a different stimulus configuration with one or more variable parameters; and recording a plurality of recovery potentials each corresponding to one of the plurality of series of electrical stimulation signals.

8. The method of claim 7, further comprising: determining, from the plurality of recovery potentials, a selected optimum stimulus configuration from among the different stimulus configurations that maximizes a selected attribute of a recovery potential of the nerve cells; and setting one or more parameters of subsequent electrical stimulation signals in accordance with the selected optimum stimulus configuration.

9. The method of claim 8, wherein the selected attribute is an amplitude of the recovery potential.

10. The method of claim 7, wherein the one or more variable parameters of the series of electrical stimulation signals include one or more of a stimulation mode, a pulse shape, a pulse rate, a pulse width, an inter-pulse gap, or an amplitude.

11. The method of claim 1, 2, 3, 4, 5, or 6, wherein recording the at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipient comprises: initiating recording of the at least one recovery potential after a predetermined time period following delivery of the series of stimulation signals.

12. The method of claim 1, 2, 3, 4, 5, or 6, wherein analyzing the at least one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals comprises: analyzing an amplitude of the at least one recovery potential.

13. The method of claim 1, 2, 3, 4, 5, or 6, wherein the delivering, the recording, and the analyzing are performed for a single channel.

14. The method of claim 1, 2, 3, 4, 5, or 6, wherein the delivering, the recording, and the analyzing are performed for two or more channels simultaneously.

15. The method of claim 1, 2, 3, 4, 5, or 6, wherein the delivering, the recording, and the analyzing are performed in an interleaved manner for two or more channels.

16. An implantable medical device system comprising: a memory storing computer-readable instructions; and a processor configured to execute the computer-readable instructions to: initiate delivery of at least one series of electrical stimulation signals to nerve cells of a recipient; obtain at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipient; and analyze the at least one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals.

17. The implantable medical device system of claim 16, wherein, to obtain at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipient, the processor is configured to: record the at least one recovery potential of the nerve cells using a measurement function of an application embedded in the implantable medical device, wherein the application is triggered to record the at least one recovery potential of the nerve cells after a predetermined delay time period has elapsed following the delivery of the at least one series of electrical stimulation signals.

18. The implantable medical device system of claim 16 or 17, wherein the processor is configured to: determine an amplitude of the at least one recovery potential of the nerve cells.

19. The implantable medical device system of claim 16 or 17, wherein, to analyze the at least one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals, the processor is configured to: analyze the at least one recovery potential to assess neural activity or neural health of the nerve cells of the recipient.

20. The implantable medical device system of claim 16 or 17, wherein the processor is configured to: set one or more parameters of subsequent electrical stimulation signals based on the analyzing.

21. The implantable medical device system of claim 16 or 17, further comprising: an external electrophysiological measurement device in communication with the implantable medical device and configured to: record the at least one recovery potential of the nerve cells resulting from delivery of the at least one series of electrical stimulation signals to the recipient.

22. The system of claim 21, wherein the external electrophysiological measurement device is triggered to record the at least one recovery potential of the nerve cells by the delivery of the at least one series of electrical stimulation signals to the recipient by the implantable medical device.

23. The system of claim 22, wherein the external electrophysiological measurement device begins recording the at least one recovery potential after a predetermined delay time period has elapsed following the delivery of the at least one series of electrical stimulation signals.

24. A method comprising:delivering one or more stimulation signals to an inner ear of a recipient; obtaining, via at least one of a plurality of electrodes configured to be implanted in the inner ear of the recipient, a neural response set evoked by the one or more stimulation signals, wherein the neural response set includes at least one inner ear neural response, at least one auditory nerve response, and at least one evoked brain response of the recipient during a period following delivery of the one or more stimulation signals; analyzing the neural response set to assess an efficacy of the one or more stimulation signals; and setting one or more parameters of subsequent stimulation signals based on the analyzing of the neural response set.

25. The method of claim 24, wherein the subsequent stimulation signals comprise electrical stimulation signals, and setting the one or more parameters of the subsequent stimulation signals comprises: setting a pulse width of the subsequent stimulation signals based on the analyzing of the neural response set.

26. The method of claim 24, wherein the subsequent stimulation signals comprise electrical stimulation signals, and setting the one or more parameters of the subsequent stimulation signals comprises: setting a pulse rate of the subsequent stimulation signals based on the analyzing of the neural response set.

27. The method of claim 24, wherein the subsequent stimulation signals comprises electrical stimulation signals, and setting the one or more parameters of the subsequent stimulation signals comprises: setting an inter-pulse gap of the subsequent stimulation signals based on the analyzing of the neural response set.

28. The method of claim 24, wherein the subsequent stimulation signals comprises electrical stimulation signals, and setting the one or more parameters of the subsequent stimulation signals comprises:setting an amplitude of the subsequent stimulation signals based on the analyzing of the neural response set.

29. The method of claim 24, 25, 26, 27, or 28, wherein analyzing the neural response set to assess an efficacy of the one or more stimulation signals comprises: analyzing one or more of a latency, a speed of activation, a speed of relaxation, or an amplitude of the neural response set.

30. The method of claim 24, 25, 26, 27, or 28, wherein delivering the one or more stimulation signals to an inner ear of the recipient comprise: delivering, via one or more of the plurality of electrodes, one or more electrical stimulation signals to the inner ear of the recipient.

31. The method of claim 24, 25, 26, 27, or 28, wherein delivering the one or more stimulation signals to an inner ear of the recipient comprises: delivering, via one or more of the plurality of electrodes, one or more electrical stimulation signals to the inner ear of the recipient; and delivering one or more acoustic stimulation signals to the inner ear of the recipient.

32. The method of claim 24, 25, 26, 27, or 28, further comprising: delivering the subsequent stimulation signals to the inner ear of the recipient.

33. The method of claim 24, 25, 26, 27, or 28, further comprising: recording, over a period of time, a plurality of neural response sets; and storing the plurality of neural response sets in a memory.

34. The method of claim 33, wherein analyzing the neural response set comprises: dynamically analyzing variations in recorded values of the neural response set over time, by comparing the recorded values of the at least one inner ear neural response, the at least one auditory nerve response, and the at least one evoked brain response to corresponding previously recorded reference values, to assess the efficacy of the one or morestimulation signals on physiological conditions of an auditory nerve pathway from the inner ear along the auditory nerve up to and including the brain of the recipient.

35. The method of claim 34, wherein setting the one or more parameters of the subsequent stimulation signals comprises: dynamically adapting at least one of a stimulation mode and a stimulation pulse duration of the subsequent stimulation signals over time based on the dynamically analyzing of the variations in the recorded values of the neural response set over time compared to the corresponding previously recorded reference values.

36. The method of claim 24, 25, 26, 27, or 28, wherein analyzing the neural response set comprises: comparing one or more measurements of the at least one inner ear neural response, the at least one auditory nerve response, and the at least one evoked brain response of the neural response set, for nerves across an auditory nerve pathway from the inner ear along the auditory nerve up to and including the brain of the recipient, to corresponding reference neural response data obtained during a mapping procedure for the recipient utilizing different stimulation modes and different pulse durations.

37. The method of claim 24, 25, 26, 27, or 28, wherein setting the one or more parameters of the subsequent stimulation signals comprises: automatically adapting a stimulation mode used for the subsequent stimulation signals based on the analyzing of the neural response set.

38. The method of claim 37, wherein automatically adapting the stimulation mode used for the subsequent stimulation signals comprises: changing the stimulation mode from a first stimulation mode used for the one or more stimulation signals, to a second stimulation mode that is different from the first stimulation mode, based on the analyzing of the neural response set.

39. The method of claim 24, 25, 26, 27, or 28, wherein setting the one or more parameters of the subsequent stimulation signals comprises: automatically adapting a stimulation pulse duration used for the subsequent stimulation signals based on the analyzing of the neural response set.

40. The method of claim 24, 25, 26, 27, or 28, wherein setting the one or more parameters of the subsequent stimulation signals comprises: automatically adapting a stimulation mode and a stimulation pulse duration used for the subsequent stimulation signals based on the analyzing of the neural response set.

41. The method of claim 24, 25, 26, 27, or 28, wherein setting the one or more parameters of the subsequent stimulation signals comprises: adapting the subsequent stimulation signals so as to at least one of increase or maximize amplitude, reduce or minimize latency, and increase or maximize activation speed of a subsequent neural response set evoked by the subsequent stimulation signals during a period following delivery of the subsequent stimulation signals.

42. The method of claim 24, 25, 26, 27, or 28, wherein analyzing the neural response set comprises: identifying an optimum number of stimulation electrodes or an optimum combination of stimulating electrodes, from among the plurality of electrodes, to achieve optimum auditory perception by the recipient for a particular stimulation mode.

43. The method of claim 42, wherein setting the one or more parameters of the subsequent stimulation signals comprises: utilizing the optimum number of stimulation electrodes or the optimum combination of stimulation electrodes, from among the plurality of electrodes, to deliver the subsequent stimulation signals to the inner ear of the recipient.

44. The method of claim 24, 25, 26, 27, or 28, wherein analyzing the neural response set comprises: quantifying an improvement in the efficacy of the one or more stimulation signals resulting from a particular therapeutic treatment for the recipient.

45. The method of claim 24, 25, 26, 27, or 28, wherein analyzing the neural response set comprises: identifying an anomalous physiological condition along an auditory nerve pathway from the inner ear along the auditory nerve up to and including the brain of the recipient, based on the at least one inner ear neural response, the at least one auditory nerve response, and the at least one evoked brain response of the neural response set.

46. The method of claim 24, 25, 26, 27, or 28, wherein the obtaining, the analyzing, and the setting are automatically performed continuously or periodically.

47. The method of claim 24, 25, 26, 27, or 28, wherein the obtaining, the analyzing, and the setting are dynamically activated on-demand in response to user input received from an external device of the recipient or a clinician.

48. One or more non-transitory computer-readable storage media comprising instructions that, when executed by a processor, cause the processor to: control delivery of stimulation to a recipient utilizing a hybrid stimulation mode in which a combination of electrical stimulation and acoustic stimulation are used simultaneously; obtain measurements of evoked nerve / brain responses of the recipient resulting from the combination of electrical stimulation and acoustic stimulation; analyze the measurements of the evoked nerve / brain responses of the recipient to assess an efficacy of the combination of electrical stimulation and acoustic stimulation; and adapt one or more of the electrical stimulation and the acoustic stimulation based on the analyzing of the measurements of the evoked nerve / brain responses.

49. The one or more non-transitory computer-readable storage media of claim 48, wherein, to obtain the measurements of the evoked nerve / brain responses of the recipient, the instructions when executed cause the processor to: record one or more parameters of the evoked nerve / brain responses to the electrical stimulation only.

50. The one or more non-transitory computer-readable storage media of claim 48, wherein, to obtain the measurements of the evoked nerve / brain responses of the recipient, the instructions when executed cause the processor to: record one or more parameters of the evoked nerve / brain responses to the acoustic stimulation only.

51. The one or more non-transitory computer-readable storage media of claim 48, wherein, to obtain the measurements of the evoked nerve / brain responses of the recipient, the instructions when executed cause the processor to: record one or more parameters of the evoked nerve / brain responses to the combination of electrical stimulation and acoustic stimulation.

52. The one or more non-transitory computer-readable storage media of claim 48, 49, 50, or 51, wherein analyzing the measurements of the evoked nerve / brain responses of the recipient includes diagnosing physiological conditions of an auditory nerve pathway, from the cochlea up to and including the brain of the recipient, based on the measurements of the evoked nerve / brain responses.

53. The one or more non-transitory computer-readable storage media of claim 48, 49, 50, or 51, wherein adapting the one or more of the electrical stimulation and the acoustic stimulation based on the analyzing of the measurements of the evoked nerve / brain responses of the recipient comprises: automatically adjusting one or more hybrid stimulation parameters so as to achieve optimum auditory perception by the recipient in the hybrid stimulation mode.

54. The one or more non-transitory computer-readable storage media of claim 53, wherein, to automatically adjust the one or more hybrid stimulation parameters, the instructions when executed cause the processor to at least one of: adjust an amplitude of one or both of the electrical stimulation and the acoustic stimulation; or perform time synchronization / shifting of at least one of the electrical stimulation and the acoustic stimulation.

55. A system, comprising: one or more electrodes configured to deliver at least one series of electrical stimulation signals to nerve cells of a recipient; at least one amplifier configured to record at least one recovery potential of the nerve cells resulting from delivery of the series of electrical stimulation signals to the recipient; and at least one processor configured to analyze the at least one recovery potential to assess an efficacy of the at least one series of electrical stimulation signals.

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