Event detection in implantable hearing prosthesis

Abstract

Presented herein are techniques for monitoring the physical state of a stimulation assembly to, for example, detect the occurrence of an adverse event. More specifically, an elongate stimulation assembly comprising a plurality of longitudinally spaced contacts is at least partially implanted into a recipient. Electrical measurements are performed at one or more of the plurality of contacts, and the electrical measurements are evaluated relative to each other to determine a physical state of the stimulation assembly.

Description

[0001] This application is a continuation of International Application No. PCT / US2015 / 054593, filed September 2, 2015, which entered the Chinese national phase as Application No. 201580046956.8, filed March 1, 2017, entitled "Event Detection in an Implantable Auditory Prosthesis." Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application 62 / 044,595, filed September 2, 2014, entitled "Event Detection in an Implantable Auditory Prosthesis," the contents of which are incorporated by reference herein. BACKGROUND

[0003] Hearing loss, which can result from many different causes, is generally of two types: conductive and / or sensorineural. Conductive hearing loss occurs when the normal mechanical pathways of the outer ear and / or middle ear are impeded, for example, by damage to the ossicular chain or the ear canal. Sensorineural hearing loss occurs when there is impairment in the inner ear or its nerve supply from the inner ear to the brain.

[0004] Individuals with conductive hearing loss typically have some form of residual hearing because the hair cells in the cochlea are undamaged. As such, individuals with conductive hearing loss typically receive an auditory prosthesis that produces mechanical movement of the cochlear fluid. Such auditory prostheses include, for example, acoustic hearing aids, bone conduction devices, and direct acoustic stimulators.

[0005] However, in many profoundly deaf people, the cause of their deafness is sensorineural hearing loss. Those with certain forms of sensorineural hearing loss do not get adequate benefit from auditory prostheses that produce mechanical movement of the cochlear fluid. Such individuals can benefit from an implantable auditory prosthesis that stimulates the recipient's neural cells of the auditory system in other ways, e.g., electrically, optically, etc. When the sensorineural hearing loss is due to the absence or destruction of cochlear hair cells that transduce acoustic signals into neural impulses, a cochlear implant is typically proposed. When the recipient experiences sensorineural hearing loss due to damage to the auditory nerve, an auditory brainstem stimulator can also be proposed. SUMMARY

[0006] In one aspect of the application, a system is provided. The system includes an elongated stimulating assembly configured to be implanted in a recipient, wherein the stimulating assembly includes a plurality of longitudinally spaced apart contacts; and an event detection processor configured to determine a physical state of the stimulating assembly using a change in an electrical measurement between two or more of the contacts.

[0007] In another aspect of the application, a method for monitoring an implantable stimulation assembly comprising a plurality of longitudinally spaced-apart contacts is provided. The method comprises delivering electrical stimulation between two or more of the contacts, measuring electrical parameters at a selected number of the plurality of contacts in response to the delivered electrical stimulation, and evaluating the measured electrical parameters relative to one another to determine a physical state of the stimulation assembly.

[0008] In another aspect of the application, one or more non-transitory computer- readable storage devices are provided, encoded with software comprising computer- executable instructions for monitoring an implantable stimulation assembly comprising a plurality of longitudinally spaced-apart contacts. When the software is executed, the software is operable to deliver electrical stimulation between two or more of the contacts, measure electrical parameters at a selected number of the plurality of contacts in response to the delivered electrical stimulation, and evaluate the measured electrical parameters relative to one another to determine a physical state of the stimulation assembly.

[0009] In another aspect of the application, a cochlear implant system is provided. The cochlear implant system comprises an intra-cochlear stimulation assembly comprising a plurality of contacts and configured to deliver electrical stimulation between two or more of the contacts, an implantable stimulator unit, and a processor. The processor is configured to measure electrical parameters at a selected number of the plurality of contacts via the implantable stimulator unit in response to the delivered electrical stimulation, and evaluate the measured electrical parameters relative to one another to determine a physical state of the stimulation assembly. BRIEF DESCRIPTION OF DRAWINGS

[0010] Embodiments of the application are described herein with reference to the accompanying drawings, in which:

[0011] Figure 1 is a schematic illustration of a cochlear implant according to the embodiments presented herein;

[0012] Figure 2A is a schematic illustration of a stimulation assembly during insertion into a cochlea of a recipient;

[0013] Figure 2B is a schematic illustration of an adverse event that can occur during insertion of a stimulation assembly into a cochlea of a recipient;

[0014] Figure 2C is a schematic illustration of another adverse event that can occur during insertion of a stimulation assembly into a cochlea of a recipient;

[0015] Figure 3 is a flowchart of a local monitoring method according to the embodiments presented herein;

[0016] Figure 4A is a schematic illustration of a stimulation assembly during insertion into a cochlea of a recipient; Figure 3a plot of electrical measurements obtained by the local monitoring method of

[0017] Figure 4B is a plot illustrating electrical measurements obtained by the local monitoring method of Figure 3

[0018] Figure 4C is a plot illustrating electrical measurements obtained by the local monitoring method of Figure 3

[0019] Figure 5 is a flowchart of a bipolar monitoring method according to the embodiments presented herein;

[0020] Figure 6A is a plot illustrating electrical measurements obtained by the bipolar monitoring method of Figure 5

[0021] Figure 6B is a plot illustrating electrical measurements obtained by the bipolar monitoring method of Figure 5

[0022] Figure 6C is a plot illustrating electrical measurements obtained by the bipolar monitoring method of Figure 5

[0023] Figure 7 is a block diagram of a cochlear implant configured to perform monitoring techniques according to the embodiments presented herein;

[0024] Figure 8 is a block diagram of a process configured to perform monitoring techniques according to the embodiments presented herein; and

[0025] Figure 9 is a flowchart of a method according to the embodiments presented herein. DETAILED DESCRIPTION

[0026] Presented herein are techniques for monitoring a physical state of a stimulation assembly, for example, to detect the occurrence of an adverse event. More specifically, an elongate stimulation assembly including a plurality of longitudinally spaced apart contacts is implanted at least partially into a recipient. Electrical measurements are performed at one or more of the plurality of contacts, and the electrical measurements are evaluated relative to one another to determine a physical state of the stimulation assembly.

[0027] ​​​​​There are different types of hearing prostheses that can be partially or fully implanted in a recipient, including electrically stimulating hearing prostheses such as cochlear implants and auditory brainstem stimulators. It will be appreciated that the monitoring techniques presented herein can be used in conjunction with any of the above or other implantable hearing prostheses. However, for ease of description, embodiments of the application are primarily described herein with reference to cochlear implants.

[0028] Figure 1 is a perspective view of an exemplary cochlear implant 100 in accordance with the embodiments presented herein. The cochlear implant 100 includes an external component 102 and an internal / implantable component 104. The external component 102 is directly or indirectly attached to the recipient's body and generally includes an external coil 106 and generally includes a magnet (not shown in Figure 1 ) fixed relative to the external coil 106. The external component 102 also includes one or more sound input elements 108 (e.g., microphones, telecoils, etc.) and a sound processing unit 112 for detecting sound. The sound processing unit 112 can include, for example, a power source (not shown in Figure 1 ) and a sound processor (not shown in Figure 1 ). The sound processor is configured to process electrical signals generated by the sound input elements 108, which in the depicted embodiment are positioned by the recipient's pinna 110. The sound processor provides the processed signals to the external coil 106 via a cable (not shown in Figure 1 ).

[0029] The implantable component 104 includes an implant body 114, a lead region 116, and an elongated intracochlear stimulation assembly 118. The implant body 114 includes a stimulator unit 120, an internal / implantable coil 122, and an internal receiver / transceiver unit 124 (sometimes referred to herein as a transceiver unit 124). The transceiver unit 124 is connected to the internal coil 122 and is generally connected to a magnet (not shown) fixed relative to the internal coil 122.

[0030] The magnets in the external component 102 and the implantable component 104 facilitate operational alignment of the external coil 106 with the internal coil 122. The operational alignment of the coils enables the implantable coil 122 to transmit power and data to / from the external coil 106. More specifically, in certain examples, the external coil 106 transmits electrical signals (e.g., power and stimulation data) to the implantable coil 122 via a radio frequency (RF) link. The implantable coil 122 is typically a wire antenna coil composed of multiple turns of electrically insulated single or multi-stranded platinum or gold wire. The electrical insulation of the implantable coil 122 is provided by a flexible molding (e.g., a silicone molding). In use, the transceiver unit 124 can be positioned in a recess of the recipient's temporal bone. Various other types of energy transfer, such as infrared (IR) transfer, electromagnetic transfer, capacitive transfer, and inductive transfer, can be used to transfer power and / or data from an external device to a cochlear implant, and Figure 1 Only one example arrangement is illustrated.

[0031] The elongate stimulation assembly 118 is configured to be implanted at least partially in the cochlea 130 and includes a plurality of intra-cochlear contacts 128. The contacts 128 collectively form a contact array 126 and can include electrical contacts and / or optical contacts.

[0032] The stimulation assembly 118 extends through an opening in the cochlea 130 (e.g., a cochleostomy 132, a round window 134, etc.) and has a proximal end that is connected to the stimulator unit 120 via a lead region 116 that extends through the mastoid bone 119. The lead region 116 couples the stimulation assembly 118 to the implant body 114, and more specifically, to the stimulator unit 120.

[0033] Intra-cochlear stimulation assemblies, such as the stimulation assembly 118, can be perimodiolar stimulation assemblies or non-perimodiolar stimulation assemblies. Perimodiolar stimulation assemblies are stimulation assemblies that are configured to assume a curved configuration during and / or after implantation in a recipient's cochlea so as to position a distal segment proximate to a wall of the recipient's modiolus (i.e., close to the modiolus wall). The modiolus is a conical central region in the cochlea around which the cochlear channels (i.e., the scala tympani, the scala media, and the scala vestibuli) spiral. The modiolus is composed of the spongy bone in which the cochlear nerve cells, sometimes referred to herein as spiral ganglion cells, reside. The cochlear channels typically turn around the modiolus 2.5 times.

[0034] In general, the sound processor in the sound processing unit 112 is configured to perform sound processing and encoding to convert the detected sound into an encoded signal corresponding to an electrical signal for delivery to the recipient. The encoded signal generated by the sound processor is then transmitted to the stimulator unit 120 via the RF link between the external coil 106 and the internal coil 122. The stimulator unit 120 includes one or more circuits that use the encoded signal received via the transceiver unit 124 in order to output a series of electrical stimulation signals (stimulation current) via one or more stimulation channels that terminate in one or more of the intracochlear stimulation contacts 128. As such, the stimulation current is delivered to the recipient via the intracochlear stimulation contacts 128. In this way, the cochlear implant 100 stimulates the recipient's auditory nerve cells, thereby bypassing the absent or defective hair cells that normally transduce acoustic vibrations into neural activity.

[0035] To insert the intracochlear stimulation assembly 118 into the recipient, an opening (facial recess) is created through the recipient's mastoid bone 119 to access the recipient's middle ear cavity 141. The surgeon then creates an opening from the middle ear into the cochlea 130 through, for example, the round window, oval window, promontory, etc. of the cochlea 130. The surgeon then gently pushes the stimulation assembly 118 forward into the cochlea 130 until the stimulation assembly 118 reaches the desired location.

[0036] In conventional intracochlear stimulation assembly insertion techniques, the surgeon operates "blindly." That is, due to the nature of the access (through the facial recess and middle ear cavity), the surgeon cannot actually see the stimulation assembly 118 once it enters the cochlea 130. Thus, the surgeon relies solely on touch / feel during the insertion.

[0037] Most stimulation assembly insertions occur without incident, due to the design of the stimulation assembly, surgical guidelines, and surgeon skill. However, there are instances in which an incident occurs during stimulation assembly insertion, which can be referred to as "adverse," in that the incident can result in increased trauma to the cochlea, and / or negatively impact the performance or placement of the stimulation assembly.

[0038] Figure 2A The stimulation assembly 118 is illustrated during a normal (good) insertion of the recipient's cochlea 130 (i.e., an insertion in which no adverse incident occurs). Figure 2B And Figure 2C Several adverse incidents that can occur during insertion of the stimulation assembly 118 into the recipient's cochlea 130 are illustrated.

[0039] The stimulation assembly 118 includes a carrier member 244 formed of a resiliently flexible material, such as silicone. A plurality of spaced-apart contacts 128 are mounted or disposed in / on at least a first surface 246 of the carrier member 244 and collectively form the contact array 126. It should be appreciated that the particular combination of terms mounted / disposed in / on, etc., as used herein, is not to be construed as referring to any particular manufacturing technique or structural relationship.

[0040] In Figures 2A-2C In a particular example, the stimulation assembly 118 includes twenty-two (22) intracochlear contacts. For ease of reference, the contacts 128 are sequentially numbered as contacts 128(1) through 128(22), such that contact 128(1) is the proximal-most contact (i.e., the contact disposed at the proximal end of the contact array 126) and contact 128(22) is the distal-most contact (i.e., the contact disposed at the distal / tip 236 of the contact array 126). It should be appreciated that the number of contacts shown in Figures 2A-2C The number of contacts shown in FIG. 1 is merely illustrative, and a different number of contacts can be present in other embodiments.

[0041] As noted above, Figure 2A FIG. 2 illustrates normal insertion of the stimulation assembly 118 smoothly traveling through the cochlear channel (e.g., the scala tympani) 250. That is, as the surgeon inserts the stimulation assembly 118, the distal end 236 (i.e., the top-most end of the distal region 237) travels toward the cochlear apex 252 without any adverse events occurring. In contrast, Figure 2B FIG. 3 illustrates an example in which an obstruction, friction, and / or other force causes the distal end 236 of the stimulation assembly 118 to stick (i.e., get caught) on a wall of the cochlea 130, such as the inner wall 238, rather than smoothly traveling down the length of the cochlea. In this example, not only can the surgeon not see the distal end 236 caught on the inner wall 238, but he / she can also not feel the resistance provided by the wall. As such, the surgeon can continue to push the stimulation assembly 118 into the cochlea 130, and the stimulation assembly can fold over on itself. This type of event is commonly referred to as tip folding, and can cause damage to the soft tissue structures within the cochlea, resulting in trauma and potential loss of residual hearing. Additionally, the contacts of the stimulation assembly 118 within the "folded" region (e.g., 128(22) through 128(18) in FIG. 3) can become unusable, thereby reducing the benefits of the recipient's cochlear implant 100. Figure 2B

[0042] In Figure 2C ​In another example shown, the stimulation assembly 118 is deformed or buckled at a point along the length of the stimulation assembly (as shown by region 240). For example, the deformation can occur when the distal end 236 of the stimulation assembly 118 catches on a structure inside the cochlea 130 within its insertion path. The deformation, which the surgeon cannot see, can result in damage to the soft tissue structure. Additionally, the contact points of the stimulation assembly 118 (e.g., Figure 2C

[0043] As noted above, these adverse events can diminish the benefit of the cochlear implant to the recipient, i.e., by increasing trauma and reducing performance. Most surgeons use post-operative X-rays to check for the occurrence of these adverse events. Because these X-rays are taken after the wound is closed, correction of the adverse event requires the surgeon to reopen the wound. Currently, there is no technology to provide the surgeon with real-time information about the physical state of the stimulation assembly in the cochlea. Instead, as noted, evidence of adverse events is only available to the surgeon if a post-operative check is performed.

[0044] Presented herein are techniques for monitoring the physical state of an implantable stimulation assembly in real-time (e.g., intra-operatively) in order to provide real-time feedback about the occurrence of adverse events within the cochlea, thereby helping the surgeon to obtain immediate information about the quality of the stimulation assembly insertion. The physical state of the stimulation assembly refers to the shape / configuration of the stimulation assembly within the recipient's cochlea, brainstem, etc. Generally speaking, the physical state monitoring techniques presented herein use changes in measured electrical parameters (electrical data, such as voltage and impedance) taken from various locations along the contact array to provide an indication of the physical state of the stimulation assembly, and thus determine whether any adverse events occurred during insertion.

[0045] Evidence of adverse events such as tip folding and deformation / buckling can be derived from information about the positions of the stimulation assembly contacts relative to each other within the space of the cochlea. That is, the incorrect positioning and / or obstruction of the stimulation assembly caused by adverse events can cause certain stimulation assembly contacts to be closer to each other than would normally occur in a normal (good) insertion. The unexpected close proximity of certain contacts results in a change in the direction of the electric field, resulting in electrical measurements recorded at the stimulation assembly contacts that are different from the electrical measurements of a normal insertion. To detect the occurrence of adverse events, the presented methods take advantage of this difference in the direction of the electric field.

[0046] ​Electrical information can be obtained by delivering a stimulus (i.e., an electrical current signal) from at least one point along an array of contacts, and then recording an electrical parameter (e.g., voltage or impedance) from at least one other point along the same array of contacts. These measurements can be performed in real-time, such that electrical data is continuously obtained throughout the insertion. Only simple post-processing of the recorded data is required to generate a plot of the electrical measurements.

[0047] The proposed techniques do not rely on specific values of the measured data to determine whether an adverse event has occurred. Rather, the relative magnitudes of the recorded values and the shape of the plot they generate are used for this determination. The data is analyzed for key features and trends that indicate whether the insertion outcome was normal / expected or that any adverse event has occurred

[0048] The techniques proposed herein include several methods for monitoring the physical state of a stimulation assembly in order to, for example, detect the occurrence of an adverse event during insertion of the stimulation assembly. The monitoring methods proposed herein can demonstrate the physical state of the stimulation assembly using one single set of data points (i.e., one set of measured data recorded for a selected number of contacts within the array of contacts in response to a single stimulation pattern). As further described below, the single stimulation pattern can refer to the delivery of a local current signal (with a subsequent measurement at each of the selected number of contacts) or the subsequent delivery of a bipolar current signal between a first contact and each of the selected number of contacts (with a subsequent measurement at each of the selected number of contacts). As further described below, the monitoring methods described herein can utilize various interfaces for initiating and controlling the electrical measurements using cochlear implants, auditory brainstem implants, etc.

[0049] Figure 3 is a flowchart of a first method 300 for monitoring the physical state of a stimulation assembly by using local stimulation. Since this method uses the delivery of a local stimulus (i.e., an electrical current signal) to induce a voltage at a plurality of other contacts, it is sometimes referred to as a local monitoring method. Figure 3 The method 300 of is sometimes referred to as a local monitoring method. For ease of illustration, the method 300 will be described with reference to Figure 1 the cochlear implant 100 of Figures 2A-2C the details of the stimulation assembly 118 shown in

[0050] The method 300 begins at 302, where a current signal is delivered / supplied at a selected intracochlear contact. In one particular example, the current signal is delivered at the distal-most / apical contact 128(22), and is absorbed at the second distal-most contact 128(21) (i.e., the contact adjacent to the contact 128(22)). The contact that delivers the current signal (i.e., the contact 128(22)) is referred to herein as the "stimulation" or "source" contact, and the contact that absorbs the current signal (i.e., the contact 128(21)) is referred to herein at times as the "return" contact. Additionally, the two contacts between which the current signal is delivered (i.e., the distal-most / apical contact 128(22) and the second distal-most contact 128(21)) are collectively referred to herein as the "stimulation pair." The remaining contacts that are not part of the stimulation pair are disconnected from system ground (i.e., are "floating" electrically). Figure 3 In the embodiment of FIG. 1, the distal-most / apical contact 128(22) and the second distal-most contact 128(21) are collectively referred to herein as the "stimulation pair." The remaining contacts that are not part of the stimulation pair are disconnected from system ground (i.e., are "floating" electrically).

[0051] In general, two intracochlear contacts are selected for delivering the current. However, alternative embodiments can use extracochlear contacts to supply / absorb current. Additionally, it should be appreciated that the use of the distal-most contacts for supplying / absorbing current is illustrative, and that other contacts can be used in alternative embodiments.

[0052] As noted above, the stimulation assembly 118 is inserted into the recipient's scala tympani 250. This scala tympani 250 is essentially filled with a conductive fluid known as perilymph. As such, when a current signal is delivered at one of the intracochlear contacts, at least a portion of the current will diffuse through the perilymph. For example, as shown in FIG. 2, after the current signal is delivered at the contact 128(22), the conductive nature of the perilymph will cause at least some current to flow away from the contact in the general direction illustrated by the arrow 254(A) and the arrow 254(B). The flow of current through the perilymph will cause a voltage to be induced at the other intracochlear stimulation contacts. That is, although the stimulation is localized, due to the conductive perilymph, the electric field spreads and induces a voltage at the other contacts. Figures 2A-2C

[0053] At 304, voltage measurements are performed at a selected number of other intracochlear contacts after the current signal is delivered at the contact 128(22). That is, the voltage induced at the selected other contacts as a result of the current signal being delivered at the contact 128(22) is measured. The contacts in which the voltage is measured are referred to herein at times as the "measurement" contacts. In the embodiment of FIG. 1, the measurement contacts can include any of the contacts 128(1) through 128(22). Figure 3

[0054] ​​In some embodiments, the cochlear implant 100 associated with the stimulation component 118 is configured to perform multiple voltage measurements substantially simultaneously in response to the delivery of a stimulus. In such embodiments, a single set of local current signals is applied, and the voltages sensed at a selected number of measurement contacts are measured substantially simultaneously at the measurement contacts. In other embodiments, the cochlear implant 100 is configured to measure the voltage at a single contact in response to the delivery of a set of current signals. In such embodiments, multiple sets of local current signals are sequentially applied at contact 128 (22), and the voltage is measured at different contacts after each sequential stimulation. Thus, in Figure 3 In the context of this, the delivery of a single stimulus pattern can refer to the delivery of a set of current signals (with subsequent substantially simultaneous measurements at each of the selected measurement contacts) or the sequential delivery of multiple sets of current signals (with subsequent measurements at one of the selected measurement contacts after the delivery of each set of current signals).

[0055] As noted above, the stimulus delivered at the stimulating contact will affect other contacts, and this effect can depend on several factors. However, the primary factor controlling the effect of the stimulus is the distance between the stimulating and measuring contacts. For example, in Figure 3 In the embodiment, when a stimulus is delivered at contact 128 (22), the voltage measured at other contacts should decrease progressively for contacts located further away from the stimulus contact 128 (22). Therefore, in Figure 3 In 306, the induced voltage measured at each of the measurement contacts in response to a single stimulus pattern is evaluated relative to each other to determine the relative distance between the stimulus contact 228 (22) and each of the measurement contacts (i.e., the contact where the voltage is measured). See below for reference. Figures 4A-4C As further described, evaluating voltages relative to each other enables the determination of the physical state of the stimulation component 118. Also as further described below, based on evaluations measured relative to each other, the cochlear implant 100 or its connected device can generate feedback to a surgeon or other user, providing information about the physical state of the stimulation component 118 and / or the occurrence of adverse events.

[0056] Figure 4A Figure 460(A) illustrates the voltage measured during the execution of local monitoring method 300 according to one embodiment during a typical normal insertion (i.e., where no adverse events occur). Figure 460(A) has a vertical (Y) axis representing the measured voltage and a horizontal (X) axis representing selected measurement contacts 128(1) to 128(21). The selected measurement contacts 128(1) to 128(21) are shown in descending order on the horizontal axis (i.e., starting with the measurement contact 128(21) closest to the stimulation contact 128(22)).

[0057] As indicated, the stimulus is delivered at contact 128 (22), such that the measured voltage is highest at the measuring contact 128 (21), which is located closest to the stimulus contact 128 (22). Figure 4A As shown, the voltage measured at each subsequent measurement contact decreases with increasing distance from the stimulation contact 128 (22). That is, the measured voltage is graphically represented by a decay curve 462 (A), where the maximum recorded voltage occurs at the measurement contact 128 (21) adjacent to the stimulation contact 128 (22), and the minimum recorded voltage occurs at the nearest measurement contact 128 (1).

[0058] and Figure 4A on the contrary, Figure 4B The diagram illustrates what appears in it, such as Figure 2B Figure 460(B) shows the voltage measured during the execution of local monitoring method 300 during the insertion of an adverse event with a tip folding pattern. Similar to... Figure 4A Figure 460(B) has a vertical axis representing the measured voltage and a horizontal axis representing the selected measuring contacts 128(1) to 128(21). The selected measuring contacts 128(1) to 128(21) are again shown in descending order on the horizontal axis.

[0059] As noted, the stimulus is delivered at contact 128 (22), such that the measured voltage is highest at the measuring contact 128 (21), which is closest to the stimulus contact 128 (22). Figure 4B As shown, the voltage measured at each subsequent measurement contact generally decreases with increasing distance from the stimulation contact 128 (22). That is, the measured voltage is graphically represented by a decay curve 462 (B), where the maximum recorded voltage occurs at the measurement contact 128 (21) adjacent to the stimulation contact 128 (22), and the minimum recorded voltage occurs at the nearest measurement contact 128 (1).

[0060] However, with Figure 4A Unlike the example, attenuation curve 462(B) includes those that do not conform to... Figure 4A Abnormal / irregular areas of the general decreasing trend 464 (B). Figure 4BThe irregular region 464(B) is a voltage peak indicating an increase in the voltage measured at contact 128(15). More specifically, the measured voltage typically decreases from measuring contact 128(20) to 128(18). The measured voltage increases from measuring contact 128(18) to 128(15) and then decreases from measuring contact 128(15) to 128(1). The voltage increases from measuring contact 128(18) to 128(15), and the voltage peak at measuring contact 128(15) indicates that measuring contact 128(15) is physically closer to stimulating contact 128(22) than at least measuring contacts 128(18) to 128(16) (and possibly other stimulating contacts). As noted above, this physical proximity between measuring contact 128(15) and stimulating contact 128(22) is inappropriate and thus indicates the occurrence of an adverse event. The specific shape of the irregular region 464(B) (i.e., a voltage peak with a normally reduced voltage on either side of the peak) indicates tip folding.

[0061] Figure 4C The diagram illustrates what appears in it, such as Figure 2C Figure 460(C) shows the voltage measured during the execution of local monitoring method 300 during the insertion of another adverse event in a modified form. Similar to... Figure 4A Figure 460(C) has a vertical axis representing the voltage being measured and a horizontal axis representing the selected measuring contacts 128(1) to 128(21). The selected measuring contacts 128(1) to 128(21) are again shown in descending order on the horizontal axis.

[0062] As noted, the stimulus is delivered at contact 128 (22), such that the measured voltage is highest at the measuring contact 128 (21), which is closest to the stimulus contact 128 (22). Figure 4C As shown, the voltage measured at each subsequent measurement contact typically decreases with increasing distance from the stimulation contact. That is, the measured voltage is graphically represented by decay curve 462 (C), where the maximum recorded voltage occurs at the measurement contact 128 (21) adjacent to the stimulation contact 128 (21), and the minimum recorded voltage occurs at the nearest measurement contact 128 (1).

[0063] However, with Figure 4A Unlike the example, attenuation curve 462(C) includes those that do not conform to... Figure 4A The abnormal / irregular area 464 (C) of the general decreasing trend. Figure 4CThe irregular region 464(C) is a generally flat / layered region that indicates that the voltage measured at multiple measuring contacts is substantially the same. More specifically, the measured voltage generally decreases from measuring contact 128(20) to measuring contact 128(14). However, the voltage measured at measuring contacts 128(13) to 128(8) is substantially the same as that at measuring contact 128(11) with only a slight decrease. The measured voltage then decreases from measuring contact 128(7) to 128(1). The generally flat / layered region 464(C) indicates that measuring contacts 128(13) to 128(8) are generally located at substantially the same physical distance from the stimulation contact 128(22). The substantially identical physical distance between measuring contacts 128(13) to 128(8) and stimulation contact 128(22) is inappropriate and thus indicates the occurrence of an adverse event. The specific shape of the irregular region 464 (C) (i.e., the generally flat region) indicates the deformation at the region from the measuring contacts 128 (13) to 128 (8).

[0064] Figure 3 and Figures 4A-4C The embodiments have been described with reference to the use of two distal contacts for delivering local stimulation. It should be understood that the use of two distal contacts is illustrative, and other contacts may be used for delivering local stimulation. For example, in an alternative embodiment, other contacts within distal region 237 (such as contacts 128(21) or 120(20)) may be used as stimulating or returning contacts. In another alternative arrangement, contacts 128(15) and 128(16) located in the intermediate region of stimulation assembly 118 may be used for delivering local stimulation. Such embodiments may be used alone (e.g., if the distal contact and / or associated wire breaks), or in combination with… Figure 3 The illustrative embodiments are used in combination (e.g., as a verification mechanism).

[0065] Figure 3 and Figures 4A-4C The embodiments have also been described with reference to the measurement of voltage values ​​at the measuring contacts. Other embodiments may deliver local stimulation in the same manner as described above, but then measure the impedance at the measuring contacts. The impedance measurement can then be used to determine the physical state of the stimulation component.

[0066] In short, Figure 3 and Figures 4A-4C The illustration depicts a localized monitoring technique where a stimulus is applied between two contacts, and electrical parameters (e.g., voltage or impedance) are acquired from successive contacts along the stimulating component. The electrical measurements are evaluated relative to each other to determine the relative distance, and thus the physical state / location of the stimulating component, enabling the detection of adverse events.

[0067] Figure 5 This is a flowchart of another method 500 for monitoring the physical state of a stimulation component using bipolar stimulation. Thus, Figure 5 Method 500 is sometimes referred to in this paper as the bipolar monitoring method. For ease of explanation, reference will be made to... Figure 1 Cochlear implant 100 and Figures 2A-2C The details of the stimulation component 118 shown in the figure describe method 500.

[0068] Method 500 begins at 502, wherein a stimulus (i.e., one or more current signals) is delivered between a first intracochlear contact and a second intracochlear contact. In a specific example, a stimulus is first delivered between the distal / apical contact 128 (22) and the second distal contact 128 (21) (i.e., the contact adjacent to contact 128 (22)). The contact that delivers the current signal (i.e., contact 128 (22)) is sometimes referred to herein as the “stimulus” or “source” contact, and the contact that absorbs the current (i.e., contact 128 (21)) is sometimes referred to herein as the “return” contact. Additionally, the two contacts that deliver the stimulus between them (e.g., the two distal / apical contacts) are collectively referred to herein as the “stimulus pair”. The remaining contacts that are not part of the stimulus pair are disconnected from system ground (i.e., electrically “floating”).

[0069] Generally, two intracochlear contacts are selected for delivering bipolar stimulation. However, alternative embodiments may use external cochlear contacts to supply / absorb current.

[0070] In 504, after a current signal is delivered between the stimulation contact 128 (22) and the return contact 128 (21), an electrical measurement is performed at the return contact. For example, the voltage induced at the return contact 128 (21) due to the delivery of the current signal at contact 128 (22) is measured. Because the electrical measurement is performed at the return contact 128 (21), the return contact is sometimes referred to herein as the “measuring” contact.

[0071] The bipolar monitoring method 500 uses multiple electrical measurements performed at a selected number of different contacts to determine the physical state of the stimulation component 118. Therefore, electrical measurements are also required at additional contacts (i.e., in addition to contact 128 (21)). Thus, in 506, it is determined whether electrical measurements have been performed at all selected number of contacts. Similar to... Figure 3 In the embodiments, the contacts in which measurements can be performed are sometimes referred to herein as measurement contacts. Since any of the contacts 128(1) to 128(22) can be used to perform electrical measurements, they can be used as measurement contacts.

[0072] If it is determined in 506 that no electrical measurement has been performed at all selected number of measuring contacts, then in 508, another measuring contact serves as the return contact for the stimulus pair. For example, by electrically connecting contact 128 (20) to ground and disconnecting the previous return contact (i.e., contact 128 (21)) from ground (i.e., to make the previous return contact electrically float), contact 128 (20) (i.e., the next contact in contact array 126)) can be made as the return contact. As a result, the stimulus pair then includes the stimulus contact 128 (22) and the measuring contact 128 (20).

[0073] After changing the return contact, method 500 returns to 502, where a stimulus is delivered between the stimulus contact 128 (22) and the return contact 128 (20). In 504, after the delivery of a current signal between the stimulus contact 128 (22) and the return contact 128 (20), an electrical measurement is performed at the return contact. Method 500 then returns to 506 to further determine whether electrical measurements have been performed at all selected number of measurement contacts. The loop defined by 508, 502, 504, and 506 continues until measurements have been performed at all selected measurement contacts.

[0074] Once it is determined in 506 that measurements have been taken at all selected measuring contacts, method 500 proceeds to 510, whereby the electrical measurements are evaluated relative to each other to determine the relative proximity between the stimulation contact 228 (22) and each of the measuring contacts. See below for reference. Figure 5 A to Figure 5 As further described in C, the evaluation of measurements relative to each other enables the determination of the physical state of the stimulation component 118. Also as further described below, based on the evaluation of measurements relative to each other, the cochlear implant 100 or the connected device can generate feedback to the surgeon or other user, providing information about the physical state of the stimulation component 118 and / or the occurrence of adverse events.

[0075] Figure 6A Figure 660(A) illustrates the voltage measured during normal insertion (i.e., in the absence of adverse events) during the execution of bipolar monitoring method 500 according to one embodiment. Figure 660(A) has a vertical axis representing the measured bipolar voltage and a horizontal axis representing selected measurement contacts 128(1) to 128(21). The selected measurement contacts 128(1) to 128(21) are shown in descending order on the horizontal axis (i.e., starting with the measurement contact 128(21) closest to the stimulation contact 128(22)).

[0076] For a properly inserted stimulation component, the measured bipolar voltage increases toward the base of the stimulation component. That is, as the distance between the stimulation contact 128 (22) and the measuring contact increases, the bipolar voltage also increases. Therefore, as... Figure 6A As shown, the measured bipolar voltage is graphically represented as growth curve 662 (A), where the minimum voltage occurs at the measurement contact 128 (21) adjacent to the stimulation contact 128 (22), and the maximum voltage occurs at the nearest end / base measurement contact 128 (1).

[0077] Figure 6B Figure 660(B) illustrates the bipolar voltage measured during the execution of the bipolar monitoring method 500 during insertion of an insertion process in which a defective event, as shown in Figure 6, occurs in the form of a tip fold. Similar to... Figure 6A Figure 660(B) has a vertical axis representing the bipolar voltage being measured and a horizontal axis representing the selected measurement contacts 128(1) to 128(21). The selected measurement contacts 128(1) to 128(21) are again shown in descending order on the horizontal axis.

[0078] like Figure 6B As shown, the measured bipolar voltage typically increases at each subsequent measurement contact with increasing distance from the stimulation contact 128 (22). That is, growth curve 662 (B) illustrates that the bipolar voltage typically increases as the distance between the stimulation contact 128 (22) and the measurement contact increases. However, compared to... Figure 6A Unlike the examples, growth curve 662(B) includes those that do not conform to... Figure 6A Abnormal / irregular areas of the general increasing trend 664 (B). Figure 6B The irregular region 664(B) is a voltage groove indicating a decrease in voltage measured around contact 128(15). The decrease in voltage around contact 128(15) indicates that the measuring contact 128(15) is unexpectedly physically closer to the stimulating contact 128(22). This physical proximity between the measuring contact 128(15) and the stimulating contact 128(22) is inappropriate and thus indicates the occurrence of an adverse event. The specific shape of the irregular region 664(B) (i.e., a voltage groove with increased voltage on either side of the groove) indicates tip folding.

[0079] Figure 6C The diagram illustrates what appears in it, such as Figure 2C Figure 660(C) shows the bipolar voltage measured during the execution of bipolar monitoring method 500 during the insertion of another adverse event, as illustrated by a modified form of this figure. Similar to... Figure 6AFigure 660(C) has a vertical axis representing the bipolar voltage being measured and a horizontal axis representing the selected measurement contacts 128(1) to 128(21). The selected measurement contacts 128(1) to 128(21) are again shown in descending order on the horizontal axis.

[0080] like Figure 6B As shown, the measured bipolar voltage typically increases at each subsequent measurement contact with increasing distance from the stimulation contact 128 (22). That is, growth curve 662 (B) illustrates that the bipolar voltage also increases with increasing distance between the stimulation contact 128 (22) and the measurement contact. However, compared to... Figure 6A Unlike the examples, curve 662(C) includes those that do not conform. Figure 6A The abnormal / irregular area 664 (C) of the general increasing trend. Figure 6C The irregular region 664(C) is a generally flat / layered region that indicates that the voltage measured at multiple measuring contacts is substantially the same. More specifically, the measured voltage typically increases from measuring contacts 128(21) to 128(14). However, the voltage measured at measuring contacts 128(13) to 128(8) is substantially the same, while at measuring contact 128(11) there is only a slight increase. The voltage then increases from measuring contacts 128(7) to 128(1). The generally flat / layered region 664(C) indicates that measuring contacts 128(13) to 128(8) are generally located at substantially the same physical distance from the stimulation contact 128(22). The substantially identical physical proximity between measuring contacts 128(13) to 128(8) and stimulation contact 128(22) is inappropriate and thus indicates the occurrence of an adverse event. The specific shape of the irregular region 664(C) (i.e., the generally flat region) indicates the deformation at the region from the measuring contacts 128(13) to 128(8).

[0081] Figure 6 and Figures 6A-6C The measurement of voltage values ​​at the measuring contacts has also been described. Other embodiments may deliver bipolar stimulation in the same manner as described above, but then measure the impedance at the measuring contacts. The impedance measurement can then be used to determine the physical state of the stimulation assembly.

[0082] In short, Figure 5 and Figures 6A-6C An embodiment in which bipolar stimulation is delivered sequentially between a specific contact (i.e., the stimulation contact) and other contacts in an array is illustrated. Electrical parameters (e.g., voltage or impedance) obtained from the return contact are evaluated relative to each other to determine the relative distance, and thus to determine the physical state / location of the stimulation component, thereby enabling the detection of adverse events.

[0083] The results of evaluations performed using local or bipolar monitoring methods can be presented as feedback to the surgeon or other users to provide an indication of the physical state of the stimulating component. The feedback can take several different forms to effectively depict the physical state information. For example, in one embodiment, a graph of electrical measurements can be visually displayed to the surgeon. The surgeon, surgical assistant, etc., can monitor the graph indicating changes that have occurred or are about to occur.

[0084] In another embodiment, other visual cues / feedback (such as a flashlight), the display of an image of the estimated shape of the stimulus component, etc., can be used to indicate when an adverse event has occurred or is about to occur. For example, light-emitting diodes (LEDs) on an external sound processor can be used to provide visual cues to the surgeon.

[0085] In other embodiments, audible cues (such as beeps or tones) can be used to indicate when an adverse event has occurred or is about to occur. For example, an audible warning can be generated if it is determined that an event has occurred or is about to occur (e.g., an audible warning can be generated when the tip of the stimulating component is stuck or has begun to contact or perforate the basement membrane). In another embodiment, tactile (haptic) cues can be used to indicate when an adverse event has occurred or is about to occur. For example, a vibration or hum can be generated if it is determined that an event has occurred or is about to occur. It should also be understood that different types of feedback (i.e., visual presentation on the display screen and audible warnings when an event has occurred or is about to occur) can be used in combination with each other.

[0086] Figure 7 This is a block diagram illustrating further details of a cochlear implant 700 configured for monitoring the physical state of a stimulation component according to an embodiment presented herein. The cochlear implant 700 includes an external component 702 and an implantable component 704.

[0087] The implantable component 704 is disposed beneath the recipient's skin / tissue 755 and includes an implant body 714 connected via a lead region 716 to an elongated stimulation assembly 718. The stimulation assembly 718 includes a plurality of contacts 728 forming a contact array 726. For ease of illustration, in Figure 7 Only a subset of contacts 728 in the contact array 726 is shown. The implant body 714 includes an stimulator unit 720, a transceiver unit 724, and an implantable coil 722.

[0088] External component 702 may be, for example, a behind-the-ear device, a body-worn sound processor, a coil (button) processor, etc. External component 702 includes a user interface 768, one or more sound input elements 708 for sound detection (e.g., microphone, pickup coil, etc.), one or more processors 770 (e.g., including a sound processor), a power supply 771 (e.g., a battery), a transceiver unit 772, an external coil 706, and a memory 774. Memory 774 includes measurement logic 775 and evaluation logic 776.

[0089] Memory 774 may include read-only memory (ROM), random access memory (RAM), disk storage media device, optical storage media device, flash memory device, electrophysical / tangible memory storage device, optical physical / tangible memory storage device, or other physical / tangible memory storage device. One or more processors in processor 770 are, for example, microprocessors or microcontrollers that execute instructions for measurement logic 775 and evaluation logic 776. Thus, in general, memory 774 may include one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded using software including computer-executable instructions, and when the software (by processor 770) is executed, it is operable to perform the operations described herein in conjunction with the monitoring methods described herein. More specifically, measurement logic 775 may be executed by processor 770 to generate signals / commands that cause stimulator unit 720 to: (1) generate stimulation (i.e., local stimulation or bipolar stimulation), and (2) obtain an electrical measurement at the measurement contact. Evaluation logic 776 may be executed by processor 770 to evaluate the measurement and generate feedback to the surgeon or other user. exist Figure 7 In the example, the processor 770 that executes measurement logic 775 and evaluation logic 776 is sometimes referred to herein as the event detection processor.

[0090] Measurements are obtained as measurement signals 778 from measurement contacts 728(1) to 728(21) via stimulator unit 720. Measurement signal 778 can be transmitted to external component 702 for processing. That is, transceiver unit 724 transmits measurement signal 778 to transceiver unit 772 via implantable coil 722 and external coil 706. Once measurement signal 778 is received at external component 702, the signal can be processed by processor 770 executing measurement logic 775. Processor 770 can also execute evaluation logic 776 to determine the physical state of stimulation component 718 and generate feedback to the user.

[0091] In some embodiments, the measurement signal 778 may be stored in memory 774 before being used by processor 770. The measurement signal 778 may be stored temporarily (e.g., during measurement collection and / or during processing) or semi-permanently (i.e., for subsequent export to another device).

[0092] Figure 7 An example of a cochlear implant 700 including an external component 702 with an external sound processor is illustrated. It should be understood that the use of the external component is merely illustrative, and the monitoring techniques presented herein can be used in arrangements with implantable sound processors (e.g., fully implantable cochlear implants). It should also be understood that the various components referenced herein (e.g., sound input element 708 and sound processor) can be distributed across more than one auditory prosthesis (e.g., two cochlear implants) and, in fact, across more than one type of device, such as the cochlear implant 700 and a user electronic device or a remote control for the cochlear implant 700.

[0093] It should be understood that monitoring functionality may not necessarily be achieved as described above. Figure 7 A portion of the cochlear implant shown. For example, Figure 8 This is a block diagram of an alternative layout, in which the monitoring functionality is part of a separate computing device 880. For ease of reference, the reference will be... Figure 7 The implantable component 704 is described in recipient 881. Figure 8 Examples of implementations.

[0094] The computing device 880 is a computing device that includes multiple interfaces / ports 882(1) to 882(N), memory 884, processor 886, user interface 888, display device (e.g., screen) 890, and audio device (e.g., speaker) 892. The memory 884 includes measurement logic 875 and evaluation logic 876.

[0095] Interfaces 882(1) to 882(N) may include any combination of, for example, 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. Figure 8 In the example, interface 882 (1) is connected to external coil 806 and / or an external device (not shown) that communicates with external coil 806. Interface 678 (1) can be configured to communicate with external coil 806 (or other devices) via wired or wireless connections (e.g., telemetry, Bluetooth, etc.).

[0096] Memory 884 may include ROM, RAM, disk storage media devices, optical storage media devices, flash memory devices, electrophysical / tangible memory storage devices, optical physical / tangible memory storage devices, or other physical / tangible memory storage devices. Processor 886 is, for example, a microprocessor or microcontroller that executes instructions for measurement logic 875 and evaluation logic 876. Thus, in general, memory 884 may include one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded using software including computer-executable instructions, and when the software (by processor 886) is executed, it is operable to perform the operations described herein in conjunction with the monitoring methods described herein. More specifically, measurement logic 875 may be executed by processor 886 to generate signals / commands that cause stimulator unit 720 to: (1) generate stimulation (i.e., local stimulation or bipolar stimulation), and (2) obtain an electrical measurement at the measurement contact. Evaluation logic 876 may be executed by processor 886 to evaluate the measurement and generate feedback to the surgeon or other user. Figure 8 In the example, the processor 875 that executes measurement logic 875 and evaluation logic 876 is sometimes referred to as the event detection processor in this document.

[0097] The computing device 880 can be any of several different hardware platforms configured to perform the monitoring techniques described herein. In one embodiment, the computing device 880 is a computer (e.g., a laptop computer, desktop computer, etc.) located in the operating room. In another embodiment, the computing device 880 is an intraoperative remote assistant. In yet another embodiment, the computing device 880 is an off-the-shelf device, such as a mobile phone or tablet, to which the measurement logic 875 and evaluation logic 876 are downloaded as applications or programs. Figure 8 In these various embodiments, the control and evaluation results of the measurement are displayed / notified via the computing device 880.

[0098] Figure 9 This is a flowchart of a method 900 for monitoring a stimulation assembly comprising a plurality of longitudinally spaced contacts. Method 900 begins at 902, wherein an electrical stimulus is delivered between two or more contacts. In 904, in response to the delivered electrical stimulus, electrical parameters are measured at a selected number of the plurality of contacts. In 906, the measured electrical parameters are evaluated relative to each other to determine the physical state of the stimulation assembly.

[0099] As detailed above, this paper presents a technique for real-time (e.g., intraoperative) monitoring of a stimulation component to determine its physical state and thus detect adverse events such as tip folding or deformation. As further described below, this monitoring utilizes changes in electrical measurements, such as impedance and voltage. Real-time algorithms use these electrical measurements to determine the state of the stimulation component within the cochlea and thus detect tip folding and / or deformation. In some embodiments, the event detection technique presented herein provides the surgeon with a real-time indication that an adverse event has occurred, enabling the surgeon to correct the insertion. This can provide improved confidence in the quality of stimulation component insertion, reduce the need for corrective surgery, and improve recipient hearing performance outcomes. The technique presented herein also enables consistent insertion across substantially all recipients, making the insertion process more repeatable and independent of the surgeon's experience. Confirming the state of the stimulation component during surgery also reduces the need for postoperative imaging, translating into cost and time benefits for both the recipient and the hospital, and reducing recipient radiation exposure. Data obtained from each insertion can also be registered and used for traceability, trend analysis, or product development.

[0100] The monitoring techniques according to embodiments of the present invention have been described primarily with reference to the delivery of bipolar stimulation for the detection of various adverse events. It should be understood that other embodiments of the monitoring techniques may use multipolar stimulation modes (e.g., current guidance, current / voltage shaping / focusing, etc.) to detect adverse events.

[0101] The monitoring techniques presented in this paper can provide one or more benefits to recipients, surgeons, or other users. In particular, the monitoring techniques can provide surgeons with a method for determining the state of the stimulus during insertion. This allows for immediate correction of the insertion in the event of an adverse event. Confirming the physical state of the stimulus component during surgery also reduces the need for postoperative imaging. This translates to cost and time benefits for both the recipient and the hospital, and reduces the recipient's radiation exposure, which is typically associated with current postoperative imaging techniques.

[0102] Preventing adverse events also reduces the risk of trauma to the soft tissue structures of the cochlea. Furthermore, real-time monitoring of the stimulation component insertion and the ability to respond appropriately to adverse events improve confidence in insertion quality. This reduces the need for reconstructive surgery, improves recipient hearing performance outcomes, and ultimately provides recipients with a better and smoother cochlear implant experience. Additionally, the proposed invention enables consistent insertion across all recipients, making insertion more repeatable, regardless of the surgeon's experience level and training.

[0103] It should be understood that the above embodiments are not mutually exclusive and can be combined with each other in various arrangements.

[0104] The invention described and claimed herein is not limited to the specific preferred embodiments disclosed herein, as these embodiments are intended to illustrate several aspects of the invention and not to limit it. Any equivalent embodiments are intended to be within the scope of the invention. In fact, various modifications to the invention, in addition to those shown and described herein, will become apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.

Claims

1. A system comprising: an elongated stimulating assembly configured to be implanted in a recipient, wherein the stimulating assembly includes longitudinally spaced-apart contacts; and an event detection processor configured to determine a physical state of the stimulating assembly by: delivering a local stimulating current signal between a first contact and a second contact, the first and second contacts selected from the longitudinally spaced-apart contacts to serve as a stimulating contact and a return contact, respectively; performing electrical measurements of induced voltages or impedances at each of a selected number of intracochlear contacts and the second contact in response to the delivered electrical stimulation, the selected number of intracochlear contacts being different from the first and second contacts; and evaluating the electrical measurements of induced voltages or impedances relative to one another to determine the physical state of the stimulating assembly.

2. The system of claim 1, wherein, To evaluate the electrical measurements of induced voltages or impedances relative to one another to determine the physical state of the stimulating assembly, the event detection processor is configured to: determine the proximity of a contact located at the distal end of the stimulating assembly to one or more other contacts.

3. The system of claim 1, wherein, To deliver a local stimulating current signal at a selected intracochlear contact, the event detection processor is configured to: deliver a local stimulating current signal between two substantially adjacent contacts.

4. The system of claim 1, wherein, The event detection processor is configured to generate feedback to a user indicative of the physical state of the stimulating assembly.

5. The system of claim 1, wherein, The stimulating assembly is an intracochlear stimulating assembly configured to be implanted in a cochlea of the recipient, and wherein the event detection processor is part of a cochlear implant.

6. The system of claim 1, wherein, The event detection processor is part of an external computing device.

7. A method for monitoring an implantable stimulating assembly including longitudinally spaced-apart contacts, comprising: delivering a local stimulating current signal between a first contact and a second contact, the first and second contacts selected from the longitudinally spaced-apart contacts to serve as a stimulating contact and a return contact, respectively; measuring electrical parameters of induced voltages or impedances at each of a selected number of intracochlear contacts and the second contact in response to the delivered electrical stimulation, the selected number of intracochlear contacts being different from the first and second contacts; and evaluating the measured induced voltages or impedances relative to one another to determine a physical state of the stimulating assembly.

8. The method of claim 7, wherein, Evaluating the measured induced voltages or impedances relative to one another to determine the physical state of the stimulating assembly includes: using variations in the measured induced voltages or impedances taken from various locations along the stimulating assembly to determine a relative proximity of a first contact to one or more other contacts.

9. The method of claim 7, wherein, Evaluating the measured induced voltages or impedances relative to one another to determine the physical state of the stimulating assembly includes: determining a proximity of a contact located at the distal end of the stimulating assembly to one or more other contacts.

10. The method of claim 7, further comprising: generating feedback to a user indicative of the physical state of the stimulating assembly.

11. The method of claim 7, wherein delivering a local stimulation current signal at a selected intracochlear contact includes: delivering local stimulation between two substantially adjacent contacts located at a distal end of the stimulation assembly.

12. The method of claim 7, further comprising: implanting the stimulation assembly in the recipient’s cochlea.

13. One or more non-transitory computer-readable storage devices encoded with software, the software comprising computer-executable instructions for monitoring an implantable stimulation assembly comprising longitudinally spaced contacts, and when the software is executed, is operable to: instruct an implantable stimulator unit to deliver a local stimulation current signal between a first contact and a second contact, the first and second contacts being selected from the longitudinally spaced contacts to serve as a stimulation contact and a return contact, respectively; instruct the implantable stimulator unit to measure an induced electrical voltage or impedance electrical parameter at each of a selected number of intracochlear contacts and the second contact in response to the delivered electrical stimulation, the selected number of intracochlear contacts being different from the first and second contacts; and evaluate the measured induced electrical voltage or impedance electrical parameters relative to one another to determine a physical state of the stimulation assembly.

14. The one or more non-transitory computer-readable storage devices of claim 13, wherein, the instructions operable to evaluate the measured induced electrical voltage or impedance electrical parameters relative to one another to determine a physical state of the stimulation assembly include instructions operable to: determine a relative proximity of a first contact to one or more other contacts using changes in the measured induced electrical voltage or impedance electrical parameters taken from various locations along the stimulation assembly.

15. The one or more non-transitory computer-readable storage devices of claim 13, wherein, the instructions operable to evaluate the measured induced electrical voltage or impedance electrical parameters relative to one another to determine a physical state of the stimulation assembly include instructions operable to: determine a proximity of a contact located at a distal end of the stimulation assembly to one or more other contacts.

16. The one or more non-transitory computer-readable storage devices of claim 13, further comprising instructions operable to: generate feedback to a user indicative of the physical state of the stimulation assembly.

17. The one or more non-transitory computer-readable storage devices of claim 13, wherein, the instructions operable to instruct the implantable stimulator unit to deliver a local stimulation current signal at a selected intracochlear contact include instructions operable to: instruct the implantable stimulator unit to deliver a local stimulation current signal between two substantially adjacent contacts located at a distal end of the stimulation assembly.

18. A cochlear implant system, comprising: an intracochlear stimulation assembly comprising longitudinally spaced contacts and configured to deliver a local stimulation current signal between a first contact and a second contact, the first and second contacts being selected from the longitudinally spaced contacts to serve as a stimulation contact and a return contact, respectively; an implantable stimulator unit; and a processor configured to: measuring, via the implantable stimulator unit, an induced electrical voltage or impedance electrical parameter at each of a selected number of intracochlear contacts different from the first and second contacts in response to the delivered electrical stimulation, and evaluating the measured induced electrical voltage or impedance electrical parameters relative to one another to determine a physical state of the stimulation assembly.

19. The cochlear implant system of claim 18, wherein, To evaluate the measured induced electrical voltage or impedance electrical parameters relative to one another to determine a physical state of the stimulation assembly, the processor is configured to: determine a relative proximity of the first contact to one or more other contacts using changes in the measured induced electrical voltage or impedance electrical parameters taken from various locations along the stimulation assembly.

20. The cochlear implant system of claim 18, wherein, The processor is configured to: generate feedback to a user indicative of the physical state of the stimulation assembly.

21. A method comprising: inserting a stimulation assembly into a cochlea of a recipient, wherein the stimulation assembly comprises a plurality of longitudinally spaced-apart contacts; and delivering a bipolar current signal sequentially between a stimulation contact and each of a selected number of contacts, wherein the sequentially delivering a bipolar current signal comprises: iteratively sourcing current via the stimulation contact; sequentially absorbing the sourced current via each of the selected number of contacts of the stimulation assembly in response to each iteration of the sourcing of current via the stimulation contact; measuring a voltage at each of the selected number of contacts in response to each iteration of the sourcing of current via the stimulation contact; collecting the measured voltages to generate a plurality of voltage sets in response to each iteration of the sourcing of current via the stimulation contact; and evaluating a voltage profile generated from the plurality of voltage sets to detect at least one of a fold or kink in the stimulation assembly.

22. The method of claim 21, wherein measuring a voltage at each of the selected number of contacts in response to each iteration of the sourcing of current via the stimulation contact comprises: substantially concurrently measuring the voltage at each of the selected number of contacts.

23. The method of claim 21, wherein measuring a voltage at each of the selected number of contacts in response to each sequential sourcing or absorption of current comprises: sequentially measuring the voltage at each of the selected number of contacts.

24. The method of claim 21, wherein the stimulation contact is an extracochlear contact.

25. The method of claim 21, wherein evaluating a voltage profile generated from the plurality of voltage sets to detect at least one of the fold or kink in the stimulation assembly further comprises: analyzing relative magnitudes of the voltages relative to one another to determine a location of the at least one of the fold or kink in the stimulation assembly.

26. The method of claim 21, wherein evaluating a voltage profile generated from the plurality of voltage sets to detect at least one of the fold or kink in the stimulation assembly further comprises: detecting a global maximum and a local maximum in the relative magnitude of the voltage indicative of a presence of a fold in the stimulation assembly.

27. The method of claim 21, further comprising: storing the measured voltage in response to each iteration of the current supplied via the stimulation contacts.

28. The method of claim 27, further comprising: storing the measured voltage in response to each iteration of the current supplied via the extracochlear contacts in a voltage matrix.

29. The method of claim 21, wherein evaluating the voltage profile generated from the plurality of voltage sets to detect at least one of a fold or a kink in the stimulation assembly comprises: normalizing the measured voltage in response to each iteration of the current supplied via the at least one extracochlear electrode.

30. The method of claim 21, wherein measuring the voltage at each of the selected number of contacts in response to each iteration of the current supplied via the stimulation contacts comprises: disconnecting electrodes that do not supply or absorb current from system ground.

31. The method of claim 21, further comprising: generating feedback to a user indicative of a presence of at least one of the fold or the kink in the stimulation assembly.

32. The method of claim 31, wherein generating feedback to a user indicative of the presence of at least one of the fold or the kink in the stimulation assembly comprises: displaying an image of an estimated shape of the stimulation assembly at a display screen.

33. The method of claim 21, further comprising: determining a relative proximity of each electrode of the stimulation assembly relative to one another based on the relative magnitude of the voltage within the plurality of voltage sets; and estimating a shape of the stimulation assembly based on the relative proximity of each electrode of the stimulation assembly relative to one another.

34. The method of claim 33, further comprising: displaying an image of the estimated shape of the stimulation assembly at a display screen.

Images