WO2018173010A1

WO2018173010A1 - Advanced electrode array location evaluation

Info

Publication number: WO2018173010A1
Application number: PCT/IB2018/052015
Authority: WO
Inventors: Nicholas Charles PAWSEY; Ryan Orin MELMAN
Original assignee: Cochlear Limited
Priority date: 2017-03-24
Filing date: 2018-03-24
Publication date: 2018-09-27
Also published as: EP3600531A4; EP3600531A1

Abstract

A method, including sequentially activating a plurality of respective electrode pairs of an implanted cochlear implant, at least one of the electrodes of the respective electrode pairs being a respective electrode of an electrode array implanted in a cochlea, thereby generating respective localized electric fields, concurrently respectively measuring, for the plurality of activated respective electrode pairs, an electrical characteristic between the respective electrodes of the respective electrode pairs resulting from the respective localized electric fields, thereby obtaining a measurement set, determining, from the measurement set, a distance between the electrode array and a wall of the cochlea.

Description

ADVANCED ELECTRODE ARRAY LOCATION EVALUATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[oooi] This application claims priority to U.S. Provisional Application No. 62/476,295, entitled ADVANCED ELECTRODE ARRAY LOCATION EVALUATION, filed on March 24, 2017, naming Nicholas Charles PAWSEY of Mechelen, Belgium as an inventor, the entire contents of that application being incorporated herein by reference in its entirety.

BACKGROUND

[0002] Hearing loss, which may be due to many different causes, is generally of two types: conductive and sensorineural. Sensorineural hearing loss is due to the absence or destruction of the hair cells in the cochlea that transduce sound signals into nerve impulses. Various hearing prostheses are commercially available to provide individuals suffering from sensorineural hearing loss with the ability to perceive sound. One example of a hearing prosthesis is a cochlear implant.

[0003] Conductive hearing loss occurs when the normal mechanical pathways that provide sound to hair cells in the cochlea are impeded, for example, by damage to the ossicular chain or the ear canal. Individuals suffering from conductive hearing loss may retain some form of residual hearing because the hair cells in the cochlea may remain undamaged.

[0004] Individuals suffering from hearing loss typically receive an acoustic hearing aid. Conventional hearing aids rely on principles of air conduction to transmit acoustic signals to the cochlea. In particular, a hearing aid typically uses an arrangement positioned in the recipient's ear canal or on the outer ear to amplify a sound received by the outer ear of the recipient. This amplified sound reaches the cochlea causing motion of the perilymph and stimulation of the auditory nerve. Cases of conductive hearing loss typically are treated by means of bone conduction hearing aids. In contrast to conventional hearing aids, these devices use a mechanical actuator that is coupled to the skull bone to apply the amplified sound.

[0005] In contrast to hearing aids, which rely primarily on the principles of air conduction, certain types of hearing prostheses commonly referred to as cochlear implants convert a received sound into electrical stimulation. The electrical stimulation is applied to the cochlea, which results in the perception of the received sound.

[0006] It is noted that in at least some instances, there is utilitarian value to fitting a hearing prosthesis to a particular recipient. In some examples of some fitting regimes, there are methods which entail a clinician or some other professional presenting sounds to a recipient of the hearing prosthesis such that the hearing prosthesis evokes a hearing percept. Information can be obtained from the recipient regarding the character of the resulting hearing percept. Based on this information, the clinician can adjust or otherwise establish settings of the hearing prosthesis such that the hearing prosthesis operates according to these settings during normal use.

[0007] It is also noted that the electrode array of the cochlear implant generally shows utilitarian results if it is inserted in a cochlea.

SUMMARY

[0008] In accordance with an exemplary embodiment, there is a method, comprising sequentially activating a plurality of respective electrode pairs of an implanted cochlear implant, at least one of the electrodes of the respective electrode pairs being a respective electrode of an electrode array implanted in a cochlea, thereby generating respective localized electric fields concurrently respectively measuring, for the plurality of activated respective electrode pairs, an electrical characteristic between the respective electrodes of the respective electrode pairs resulting from the respective localized electric fields, thereby obtaining a measurement set and determining, from the measurement set, a distance between the electrode array and a wall of the cochlea.

[0009] In accordance with another embodiment, there is a method, comprising obtaining first data by operating a first set of electrodes as a source and sink in and/or on a mammal while operating a second set of electrodes as recorder electrodes in and/or on a mammal thereby obtaining first electrical data from the second set of electrodes, obtaining second data by operating a third set of electrodes as a source and sink in and/or on the mammal, the third set being different than the first set, while operating the second set of electrodes as recorder electrodes in and/or on a mammal and thereby obtaining second electrical data from the second set of electrodes, evaluating data by evaluating the first electrical data and the second electrical data, and determining spatial positioning data based on the evaluation of the data.

[ooio] In accordance with another embodiment, there is a method, comprising executing vertical electrical sounding utilizing electrodes of an electrode array of a cochlear implant located in a cochlea and determining a positional feature of the electrode array based on the vertical electrical sounding.

[ooii] In accordance with another embodiment, there is a method, comprising energizing an electrode implanted in a recipient, the electrode being part of an assembly located in and/or on a recipient receiving data from one or more recording electrodes located in and/or on a recipient; and determining spatial position data of the assembly based on the received data.

[0012] In accordance with another embodiment, there is a method, comprising energizing an electrode implanted in a recipient, the electrode being part of an assembly located in and/or on a recipient, receiving data from one or more recording electrodes located in and/or on a recipient; and determining spatial position data of the assembly based on the received data. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments are described below with reference to the attached drawings, in which:

[0014] FIG. 1 is a perspective view of an exemplary hearing prosthesis in which at least some of the teachings detailed herein are applicable;

[0015] FIG. 2 is a side view of an embodiment of an insertion guide for implanting a cochlear implant electrode assembly such as the electrode assembly illustrated in FIG. 1;

[0016] FIGS. 3A and 3B are side and perspective views of an electrode assembly extended out of an embodiment of an insertion sheath of the insertion guide illustrated in FIG. 2;

[0017] FIGS. 4A-4E are simplified side views depicting the position and orientation of a cochlear implant electrode assembly insertion guide tube relative to the cochlea at each of a series of successive moments during an exemplary implantation of the electrode assembly into the cochlea;

[0018] FIG. 5A is a side view of a perimodiolar electrode assembly partially extended out of a conventional insertion guide tube showing how the assembly may twist while in the guide tube;

[0019] FIGS. 5B-5I are cross-sectional views of the electrode assembly illustrated in FIG.

5A;

[0020] FIG. 6 is a cross-sectional view of a conventional electrode assembly;

[0021] FIG. 7 depicts an exemplary functional diagram of an exemplary embodiment;

[0022] FIG. 8 depicts an exemplary implantable component of a cochlear implant according to an exemplary embodiment;

[0023] FIG. 9 depicts a component that places the cochlear implant of FIG. 8 into signal communication with another component;

[0024] FIG. 10 depicts the cochlear implant of FIG. 8in signal communication with a communication device that enables communication between the cochlear implant and a control unit according to an exemplary embodiment;

[0025] FIGs. 11-14 depict some exemplary arrangements of source and sink and recorder electrodes in a functional manner for conceptual purposes; [0026] FIGs. 15-23 conceptually depict current spread in some embodiments, which current spread forms the foundation in some embodiments for the methods detailed herein;

[0027] FIG. 24 depicts in a conceptual manner distances of an electrode from a tissue of interest;

[0028] FIGs. 25-33 conceptually depict data obtention according to an exemplary method;

[0029] FIGs. 34-44 present flowcharts for exemplary methods;

[0030] FIGs. 45-47 depict schematics of data resulting from some embodiments;

[0031] FIGs. 48 and 50 and 51 and 55 present respective schematics associated with an electrode array;

[0032] FIG. 49 presents a schematic of a conceptual dipole;

[0033] FIG. 52 presents a chart of conceptual data;

[0034] FIG. 53 presents a conceptual schematic of different heights relative to an array;

[0035] FIG. 54 presents a chart of conceptual data;

[0036] FIG. 56 presents conceptual data in a two dimensional manner;

[0037] FIG. 57 presents some schematics and some details associated with a theory of operation of an embodiment;

[0038] FIGs. 58 and 59 present additional conceptual schematics of a theory of operation; and

[0039] FIG. 60 presents exemplary waveforms.

DETAILED DESCRIPTION

[0031] FIG. 1 is a perspective view of an exemplary cochlear implant 100 implanted in a recipient having an outer ear 101, a middle ear 105, and an inner ear 107. In a fully functional ear, outer ear 101 comprises an auricle 110 and an ear canal 102. Acoustic pressure or sound waves 103 are collected by auricle 110 and channeled into and through ear canal 102. Disposed across the distal end of ear canal 102 is a tympanic membrane 104 that vibrates in response to sound waves 103. This vibration is coupled to oval window or fenestra ovalis 112 through the three bones of the middle ear 105, collectively referred to as the ossicles 106, and comprising the malleus 108, the incus 109, and the stapes 111. Ossicles 106 filter and amplify the vibrations delivered by tympanic membrane 104, causing oval window 112 to articulate, or vibrate. This vibration sets up waves of fluid motion of the perilymph within cochlea 140. Such fluid motion, in turn, activates hair cells (not shown) inside the cochlea which in turn causes nerve impulses to be generated which are transferred through spiral ganglion cells (not shown) and auditory nerve 114 to the brain (also not shown) where they are perceived as sound.

[0032] The exemplary cochlear implant illustrated in FIG. 1 is a partially implanted stimulating medical device. Specifically, cochlear implant 100 comprises external components 142 attached to the body of the recipient, and internal or implantable components 144 implanted in the recipient. External components 142 typically comprise one or more sound input elements for detecting sound, such as microphone 124, a sound processor (not shown), and a power source (not shown). Collectively, these components are housed in a behind-the-ear (BTE) device 126 in the example depicted in FIG. 1. External components 142 also include a transmitter unit 128 comprising an external coil 130 of a transcutaneous energy transfer (TET) system. Sound processor 126 processes the output of microphone 124 and generates encoded stimulation data signals which are provided to external coil 130.

[0033] Internal components 144 comprise an internal receiver unit 132 including a coil 136 of the TET system, a stimulator unit 120, and an elongate stimulating lead assembly 118. Internal receiver unit 132 and stimulator unit 120 are hermetically sealed within a biocompatible housing commonly referred to as a stimulator/receiver unit. Internal coil 136 of receiver unit 132 receives power and stimulation data from external coil 130. Stimulating lead assembly 118 has a proximal end connected to stimulator unit 120, and extends through mastoid bone 119. Lead assembly 118 has a distal region, referred to as electrode assembly 145, a portion of which is implanted in cochlea 140.

[0034] Electrode assembly 145 can be inserted into cochlea 140 via a cochleostomy 122, or through round window 121, oval window 112, promontory 123, or an opening in an apical turn 147 of cochlea 140. Integrated in electrode assembly 145 is an array 146 of longitudinally- aligned and distally extending electrode contacts 148 for stimulating the cochlea by delivering electrical, optical, or some other form of energy. Stimulator unit 120 generates stimulation signals each of which is delivered by a specific electrode contact 148 to cochlea 140, thereby stimulating auditory nerve 114.

[0035] Electrode assembly 145 may be inserted into cochlea 140 with the use of an insertion guide. FIG. 2 is a side view of an embodiment of an insertion guide for implanting an elongate electrode assembly generally represented by electrode assembly 145 into a mammalian cochlea, represented by cochlea 140. The illustrative insertion guide, referred to herein as insertion guide 200, includes an elongate insertion guide tube 210 configured to be inserted into cochlea 140 and having a distal end 212 from which an electrode assembly is deployed. Insertion guide tube 210 has a radially-extending stop 204 that may be utilized to determine or otherwise control the depth to which insertion guide tube 210 is inserted into cochlea 140.

[0036] Insertion guide tube 210 is mounted on a distal region of an elongate staging section 208 on which the electrode assembly is positioned prior to implantation. A robotic arm adapter 202 is mounted to a proximal end of staging section 208 to facilitate attachment of the guide to a robot, which adapter includes through holes 203 through which bolts can be passed so as to bolt the guide 200 to a robotic arm, as will be detailed below. During use, electrode assembly 145 is advanced from staging section 208 to insertion guide tube 210 via ramp 206. After insertion guide tube 210 is inserted to the appropriate depth in cochlea 140, electrode assembly 145 is advanced through the guide tube to exit distal end 212 as described further below.

[0037] FIGS. 3A and 3B are side and perspective views, respectively, of representative electrode assembly 145, which electrode array is utilized, in some embodiments, to execute some of the method actions detailed herein vis-a-vis source and/or sink and/or recorder electrodes. As noted, electrode assembly 145 comprises an electrode array 146 of electrode contacts 148. Electrode assembly 145 is configured to place electrode contacts 148 in close proximity to the ganglion cells in the modiolus. Such an electrode assembly, commonly referred to as a perimodiolar electrode assembly, is manufactured in a curved configuration as depicted in FIGS. 3 A and 3B. When free of the restraint of a stylet or insertion guide tube, electrode assembly 145 takes on a curved configuration due to it being manufactured with a bias to curve, so that it is able to conform to the curved interior of cochlea 140. As shown in FIG. 3B, when not in cochlea 140, electrode assembly 145 generally resides in a plane 350 as it returns to its curved configuration. That said, it is noted that embodiments of the insertion guides detailed herein and/or variations thereof can be applicable to a so-called straight electrode array, which electrode array does not curl after being free of a stylet or insertion guide tube etc., but instead remains straight

[0038] FIGS. 4A-4E are a series of side-views showing consecutive exemplary events that occur in an exemplary implantation of electrode assembly 145 into cochlea 140. Initially, electrode assembly 145 and insertion guide tube 310 are assembled. For example, electrode assembly 145 is inserted (slidingly or otherwise) into a lumen of insertion guide tube 300. The combined arrangement is then inserted to a predetermined depth into cochlea 140, as illustrated in FIG. 4A. Typically, such an introduction to cochlea 140 is achieved via cochleostomy 122 (FIG. 1) or through round window 121 or oval window 112. In the exemplary implantation shown in FIG. 4A, the combined arrangement of electrode assembly 145 and insertion guide tube 300 is inserted to approximately the first turn of cochlea 140.

[0039] As shown in FIG. 4A, the combined arrangement of insertion guide tube 300 and electrode assembly 145 is substantially straight. This is due in part to the rigidity of insertion guide tube 300 relative to the bias force applied to the interior wall of the guide tube by pre- curved electrode assembly 145. This prevents insertion guide tube 300 from bending or curving in response to forces applied by electrode assembly 145, thus enabling the electrode assembly to be held straight, as will be detailed below.

[0040] As noted, electrode assembly 145 is biased to curl and will do so in the absence of forces applied thereto to maintain the straightness. That is, electrode assembly 145 has a memory that causes it to adopt a curved configuration in the absence of external forces. As a result, when electrode assembly 145 is retained in a straight orientation in guide tube 300, the guide tube prevents the electrode assembly from returning to its pre-curved configuration. This induces stress in electrode assembly 145. Pre-curved electrode assembly 145 will tend to twist in insertion guide tube 300 to reduce the induced stress. In the embodiment configured to be implanted in scala tympani of the cochlea, electrode assembly 145 is pre-curved to have a radius of curvature that approximates the curvature of medial side of the scala tympani of the cochlea. Such embodiments of the electrode assembly are referred to as a perimodiolar electrode assembly, and this position within cochlea 140 is commonly referred to as the perimodiolar position. In some embodiments, placing electrode contacts in the perimodiolar position provides utility with respect to the specificity of electrical stimulation, and can reduce the requisite current levels thereby reducing power consumption.

[0041] As shown in FIGS. 4B-4D, electrode assembly 145 may be continually advanced through insertion guide tube 300 while the insertion sheath is maintained in a substantially stationary position. This causes the distal end of electrode assembly 145 to extend from the distal end of insertion guide tube 300. As it does so, the illustrative embodiment of electrode assembly 145 bends or curves to attain a perimodiolar position, as shown in FIGS. 4B-4D, owing to its bias (memory) to curve. Once electrode assembly 145 is located at the desired depth in the scala tympani, insertion guide tube 300 is removed from cochlea 140 while electrode assembly 145 is maintained in a stationary position. This is illustrated in FIG. 4E.

[0042] Conventional insertion guide tubes typically have a lumen dimensioned to allow the entire tapered electrode assembly to travel through the guide tube. Because the guide tube is able to receive the relatively larger proximal region of the electrode assembly, there will be a gap between the relatively smaller distal region of the electrode assembly and the guide tube lumen wall. Such a gap allows the distal region of the electrode assembly to curve slightly until the assembly can no longer curve due to the lumen wall.

[0043] Returning to FIGS. 3A-3B, perimodiolar electrode assembly 145 is pre-curved in a direction that results in electrode contacts 148 being located on the interior of the curved assembly, as this causes the electrode contacts to face the modiolus when the electrode assembly is implanted in or adjacent to cochlea 140. Insertion guide tube 500 retains electrode assembly 145 in a substantially straight configuration, thereby preventing the assembly from taking on the configuration shown in FIG. 3B. The inability of electrode assembly 145 to curve to accommodate the bias force induces stress in the assembly. Pre-curved electrode assembly 145 will tend to twist while exiting insertion guide tube 510 to reduce this stress. With the distal end of the electrode assembly curved to abut the lumen wall, the assembly twists proximally.

[0044] This is illustrated in FIGS. 5A-5I. FIG. 5A is a side view of perimodiolar electrode assembly 145 partially extended out of a conventional insertion guide tube 500, showing how the assembly may twist while in the guide tube. FIGS. 5B-5F are cross-sectional views taken through respective sections 5B-5B, 5C-5C, 5D-5D, 5E-5E, and 5F-5F of electrode assembly 145 in FIG. 5A.

[0045] As shown in FIGS. 5A-5F, the portion of electrode assembly 145 in insertion guide tube 510 is twisted about its longitudinal axis, resulting in electrode contacts 148 in the twisted region to have a different radial position relative to insertion guide tube 510. As shown in FIGS. 5 A and 5G-I, as electrode assembly 145 exists insertion guide tube 500, the assembly is free to curve in accordance with its bias force. However, the orientation of electrode contacts in the deployed region of the assembly is adversely affected by the twisted region of the assembly remaining in guide tube 510.

[0046] Accordingly, the insertion guide can have an insertion guide tube that maintains a perimodiolar or other pre-curved electrode assembly in a substantially straight configuration while preventing the electrode assembly from twisting in response to stresses induced by the bias force which urges the assembly to return to its pre-curved configuration. This generally ensures that when the electrode assembly is deployed from the distal end of the insertion guide tube, the electrode assembly and insertion guide tube have a known relative orientation.

[0047] As shown in FIG. 6, electrode assembly 145 has a rectangular cross-sectional shape, with the surface formed in part by the surface of the electrode contact, referred to herein as top surface 650, and the opposing surface, referred to herein as bottom surface 652, are substantially planar. To be clear, it is noted that the electrode assembly / electrode array shown in the figures is but an exemplary embodiment, and in other embodiments, a round, oval, etc., shaped electrode array, straight or curved, can be used.

[0048] More particularly, as will now be detailed, in some exemplary embodiments, the electrode array is utilized to obtain data regarding electrode array position within the cochlea, such as by way of example only and not by way of limitation, position information indicating relative location to the modiolus wall. FIG. 7 depicts an exemplary system for utilizing the cochlear implant to obtain such information. Presented in functional terms, there is a test unit 3960 in signal communication with unit 8310, which in turn is in signal communication, optionally with a unit 7720 and a unit 8320, the details of which will be described below.

[0049] Unit 3960 can correspond to an implantable component of a cochlear implant, as seen in FIG. 8. More specifically, FIG. 8 depicts an exemplary high-level diagram of a receiver/stimulator 8710 of a cochlear implant, looking downward. As can be seen, the receiver/stimulator 8710 includes a magnet 160 that is surrounded by a coil 137 that is in two- way communication (although in other embodiments, the communication is one-way) with a stimulator unit 122, which in turn is in communication with the electrode array 145. Receiver/stimulator 8710 further includes a cochlear stimulator unit 122, in signal communication with the coil 137. The coil 137 and the stimulator unit 122 are encased in silicon as represented by element 199. In an exemplary embodiment, receiver/stimulator 8710 is utilized as test unit 3960, and is used to acquire information about electrode array position.

[0050] FIG. 9 depicts an exemplary RS (receiver/stimulator) interface 7444 which is presented by way of concept. An inductance coil 7410 is configured to establish a magnetic inductance field so as to communicate with the corresponding coil of the receiver-stimulator of the cochlear implant. Interface 7444 includes a magnet 7474 so as to hold the inductance coil 7410 against the coil of the receiver/stimulator of the cochlear implant in a manner analogous to how the external component of the cochlear implant is held against the implanted component, and how the coils of those respective components are aligned with one another. As can be seen, an electrical lead extends from the coil 7410 to control unit 8310, representing signal communication between interface 7444, and control unit 8310.

[0051] FIG. 10 depicts an exemplary embodiment of the receiver/stimulator 8710 in signal communication with the control unit 8310 via electrical lead that extends from the interface device 7444 having coil 7410 about a magnet 7474 as can be seen. The interface device 7444 communicates via an inductance field with the inductance coil of the receiver/stimulator 8710 so that the data acquired by the implantable component 8710 (receiver/stimulator) can be transferred to the control unit 8310.

[0052] Note also that in at least some alternate exemplary embodiments, control unit 8310 can communicate with the so-called "hard ball" reference electrode of the implantable component of the cochlear implant so as to enable communication of data from the receiver/stimulator 8710 to control unit 8310 and/or vice versa.

[0053] It is noted that in the embodiment of FIG. 10, control unit 8310 is in signal communication with the various other components as detailed herein, which components are not depicted in FIG. 10 for purposes of clarity.

[0054] Also functionally depicted in FIG. 7 is the optional embodiment where an electrode array insertion robotic system / actuator system 7720 and an input device 8320 is included in the system. In an exemplary embodiment, the input device 8320 could be a trigger of a hand held device that controls the actuator system 7720 and can stop and/or start insertion of the electrode array. In an exemplary embodiment, the input device 8320 could be a trigger on the tool 8200.

[0055] Control unit 8310 can be a signal processor or the like or a personal computer or the like or a mainframe computer or the like etc., that is configured to receive signals from the test unit 3960 and analyze those signals to evaluate an insertion status of the electrode array. More particularly, the control unit 8310 can be configured with software the like to analyze the signals from test unit 3960 in real time and/or in near real time as the electrode array is being advanced into the cochlea by actuator assembly 7720 (if present, and if not present, while the array is being inserted / advanced by hand). The control unit 8310 analyzes the input from test unit 3960 as the electrode array advanced by the actuator assembly 7720 and evaluates the input to determine if there exists an undesirable insertion status of the electrode array and/or evaluates the input to determine if the input indicates that a scenario could occur or otherwise there exists data in the input that indicates that a scenario is more likely to occur relative to other instances where the insertion status of the electrode array will become undesirable if the electrode array is continued to be advanced into the cochlea, all other things remaining the same (e.g., insertion angle / trajectory, etc., which can be automatically changed as well - more on this below). In an exemplary embodiment, upon such a determination, control unit 8310 could halt the advancement of the array into the cochlea by stopping the actuator(s) of actuator assembly 7720 and/or could slow the actuator(s) so as to slow rate of advancement of the electrode array into the cochlea and/or could reverse the actuator(s) so as to reverse or otherwise retract the electrode array within the cochlea (either partially or fully). Alternatively, in embodiments where actuator assembly 7720 is not present, control unit 8310 could provide an indication to the surgeon or the like to halt and/or slow the insertion, etc. In at least some exemplary embodiments, control unit 8310 can be configured to override the input from input unit 8320 input by the surgeon or the user. Control unit 8310 can be programmed to execute one or more or all of the teachings detailed herein.

[0056] Some exemplary embodiments utilize the receiver/stimulator 8710 as a test unit 3910 that enables vertical electrical sounding techniques or resistivity tomography techniques to be executed in the cochlear to determine spatial relationships (or other information - this is by way of example and not by limitation) between the electrode array and the structure of the cochlea or other structures of the recipient. In an exemplary embodiment, the receiver/stimulator 8710 is utilized to execute one or more or all of the method actions detailed below, alone or in combination with an external component of a cochlear implant, and/or with the interface 7444, which can be used after the receiver/stimulator 8710 is fully implanted in the recipient and the incision to implant such has been closed (e.g., days, weeks, months or years after the initial implantation surgery). The interface 7444 can be used to control the receiver/stimulator to execute at least some of the method actions detailed herein (while in some other embodiments, the receiver/stimulator can execute such in an autonomous or semi-autonomous manner, without being in communication with an external component) and/or can be used to obtain data from the receiver/stimulator after execution of such method actions.

[0057] More specifically, because the electrode array includes a plurality of electrodes (in some embodiments, 22 electrodes), many if not all of which can be individually used as sources and/or sinks and many if not all of which can be utilized as "read" electrodes, the techniques of vertical electrical sounding and resistivity tomography can be applied utilizing a cochlear electrode array. Briefly, while the standard technology utilizes the placement and subsequent movement of source and sink electrodes and measurement electrodes at the surface of the earth to obtain information, where the relative movement is recorded so that the process can be executed, here, the different electrodes are utilized to replicate the movement feature of the vertical electrical sounding/resistivity tomography techniques.

[0058] Without being bound by theory, vertical electrical sounding (VES) is a geophysical method for investigation of a geological medium. The method is based on the estimation of the electrical conductivity or resistivity of the medium. The estimation is performed based on the measurement of voltage/electrical field induced by the distant grounded electrodes (current electrodes). Figures 11 -14 depict some exemplary configurations of possible measurement setups. The electrodes A and B are current electrodes which are connected to a current source; N and M are potential electrodes (measurement electrodes) which are used for the voltage measurements. As source, the direct current or low frequency alternating current is used. It is noted that ture direct current sometimes can have deleterious effects on tissue, and thus in some other embodiments, instead of using direct current, embodiments approximate direct current by measuring after transient effects of a current pulse (or other AC waveform) have subsided. The interpretation of the measurements can be performed based on the apparent resistivity values. The depth of investigation can depend on the distance between the current electrodes. In some embodiments, a location of the recording pair with respect to the current electrodes can also infludence the depth of investigation. For example, such can relate to a current path created by the dipole. The current can form an "arc" between the two dipoles (source/sink electrodes) with the maximum current penetration mid way between the source/sink electrodes. In some embodiments, if the measurement electrodes are adjacent one of the source/sink electrodes then the current penetration depth is less than the maximum. In order to obtain the apparent resistivity as the function of depth, the measurements for each position are performed with several different distances between current electrodes. The apparent resistivity is calculated as

here, k is a geometric factor, U_MN is voltage between electrodes M and N, I_AB is current in the line AB. The geometric factor is defined by

here r is the distance between electrodes. [0059] It is noted that in some embodiments, the numerator for the geometric factor is 4π, as the equations above are for a hemisphere (i.e. the air acts as an insulation on one side of the array for geophysical applications).

[0060] The equation here is for a hemisphere (i.e. the air acts as an insulation on one side of the array for geophysical applications). In some embodimetns, interpretation of gathered data is performed based on the dependency p_k(AB/2). The application of large electrode arrays allows for reconstructing complex 3D structure of geological media (such as that which results from electrical resistivity tomography). However, the interpretation of such measurement is rather difficult. In this case, advanced interpretation techniques based on numerical methods can be applied.

[0061] Some embodiments utilize the basic idea is that voltage equals the charge divided the value that equals 4 times pie times the square of the distance from the source times the resistance (or impedance). Conversely, the electric fields differential of the voltage gradient drops off at a rate of 1 over the distance cubed (as opposed to the voltage fall-off at a rate of 1 over the distance squared). (It is briefly noted that the term resistance is sometimes used herein with respect to impedance and visa-versa. Any disclosure of a resistance / resistance related feature corresponds to a disclosure of an impedance / impedance related feature, and visa-versa, providing that the art enables such.)

[0062] It is noted that some embodiments detailed herein modify or otherwise adapt the VES for geological exploration to that which can be utilized for a cochlea. For example, adapting the VES teachings in the art of geological exploration to take into account that there is no air layer that prevents the current from traveling in a spherical manner (as opposed to a hemispherical manner vis-a-vis application in geological exploration). Thus, any disclosure herein for VES or the like includes a disclosure where such is modified to take into account the environment of a cochlea with (or without) perilymph therein.

[0063] Generally applying the above techniques to an electrode array in a cochlea, FIG. 15 functionally depicts an electrode array 145 in a cochlea, with current flow lines 1500 emanating from electrode 15 as a source A and traveling to electrode 18 as a sink B (or vice versa). (It is noted that the region above the electrode can be considered, in some embodiments, to be infinite in impedance for the demonstrated current spreads.) Figure 15 functionally represents that the deepest current flows occur halfway between the stimulating electrode pair (electrodes 15 and 18). The amount of current flowing at depth Z reduces with the cube of the depth (where r in the above equations has been replaced by the variable Z). With respect to a unitized value based on the distance between the electrodes, the depths of the three layers depicted in figure 15 each correspond to one half the electrode spacing. As can be seen, 50% of the current is located in the first layer, which corresponds to the layer having a distance of half the distance between the electrodes, 20% of the current exist in the second layer, and then about 9.5% of the current exists in the third layer. (The layers are equally spaced.) The teachings herein and the calculations treat the electrodes as points for simplicity. But in other embodiments, such need not be the case. In some embodiments, one can integrate over the surface area of the electrode, to increase accuracy, and then calculate the charge distribution generated by the shape. Additionally, charge emerges from the perimeter of a conductor at high frequencies (because, in some instances, these measurements are taken lO's of after engaging the current source, we are measuring a high frequency response). Due to symmetry, and for simplicity the centerline to centerline can be utilitarian for a distributed conductor.

[0064] FIG. 15 depicts the electrode array 145 located in perilymph of the cochlea in general isolation from other tissue, where the impedance to electrical conduction of the perilymph is relatively low relative to other tissue of the recipient, such as for example bone. FIG. 16 depicts the electrode array 145 in perilymph, except also relative to the bony tissue of the modiolus wall, or other high-resistance tissue (high resistance relative to the perilymph) / high-impedance tissue. (It is noted that the bottom layers in which the remaining 20 or so percent of the current exists have been lumped into a single layer for convenience. In reality, there will be a plurality of layers between the third layer and the bone/high resistance tissue / high impedance tissue, each layer corresponding to a layer having a thickness of half the distance between the source and sink electrodes). FIG. 16 depicts the distance Dl which is the distance from the electrode array to the bottom of the second layer, which distance Dl corresponds to the distance between the source and the sink electrodes, which corresponds to the fact that each layer has been defined as a layer having a thickness of half of the distance Dl.

[0065] The idea with FIG. 16 is that the further the electrode array 145 in general, and the source and sink electrodes in particular (and/or recording electrodes in particular) are away from the modiolus wall or other high resistive tissue, the lower the impedance to current between the source and sink electrodes. That is, because there will be more perilymph for the bulk of the electrical current to flow through relative to that which would be the case if the electrode array 145 was closer to the modiolus wall / tissue of higher resistivity relative to the perilymph, the impedance will be lower. Accordingly, figure 16 depicts the electrode array 145 a distance from the bone / high resistance tissue (e.g. modiolus wall) a distance where basically none of the electrical current between electrodes 15 and 18 will travel through the bone. Thus, the impedance to electrical current in the homogeneous medium (perilymph) is relatively low, and the effective impedance between the source and the sink electrodes, as determined by for example, the recording electrodes 16 and 17, will be relatively low, indicating that the bone/high resistance tissue is relatively far away from the electrodes.

[0066] For purposes of discussion, the resistivity of current flow between the source and the sink will be conceptually unitized as 1 for the arrangement of FIG. 16.

[0067] FIG. 17 schematically depicts a scenario where the electrode array 145 is located closer to the modiolus wall / the tissue of high resistivity relative to that which is the case in figure 16. Basically, the tissue of high resistivity is located within an area in which a recognizable percentage of the charge flows. Here, about 0.01% of the charge flows through the tissue of higher resistivity. This is a relatively minor amount. However, this changes the resistivity of the current flow between the source and sink electrodes. For purposes of discussion, the resistivity of current flow between the source and sink will be conceptually unitized as 1.1 for the arrangement of FIG. 17. In this regard, by measuring the resistivity or other electrical features of the electrode array in this arrangement, a determination can be made that the tissue of higher resistivity (e.g., modiolus wall) is closer than that which is the case for the scenario of FIG. 16.

[0068] FIG. 18 schematically depicts a scenario where the electrode array 145 is located closer to the modiolus wall / the tissue of high resistivity relative to that which is the case in figure 17. Basically, the tissue of high resistivity is located within an area in which a recognizable percentage of the charge flows. Here, about 10% of the charge flows through the tissue of higher resistivity. This changes the resistivity of the current flow between the source and sink electrodes. For purposes of discussion, the resistivity of current flow between the source and sink will be conceptually unitized as 10 for the arrangement of FIG. 18. In this regard, by measuring the resistivity or other electrical features of the electrode array in this arrangement, a determination can be made that the tissue of higher resistivity (e.g., modiolus wall) is closer than that which is the case for the scenario of FIG. 17.

[0069] FIG. 19 schematically depicts an scenario where the electrode array 145 is located closer to the modiolus wall / the tissue of high resistivity relative to that which is the case in figure 18. Basically, the tissue of high resistivity is located within an area in which a recognizable percentage of the charge flows. Here, about 20.5% of the charge flows through the tissue of higher resistivity. This changes the resistivity of the current flow between the source and sink electrodes. For purposes of discussion, the resistivity of current flow between the source and sink will be conceptually unitized as 50 for the arrangement of FIG. 19. In this regard, by measuring the resistivity or other electrical features of the electrode array in this arrangement, a determination can be made that the tissue of higher resistivity (e.g., modiolus wall) is closer than that which is the case for the scenario of FIG. 18.

[0070] FIG. 20 schematically depicts a scenario where the electrode array 145 is located closer to the modiolus wall / the tissue of high resistivity relative to that which is the case in figure 19. Here, it is located at the distance Dl (the distance that equals the distance between the source and sink electrodes). Basically, the tissue of high resistivity is located within an area in which a recognizable percentage of the charge flows. Here, about 30% of the charge flows through the tissue of higher resistivity. This changes the resistivity of the current flow between the source and sink electrodes. For purposes of discussion, the resistivity of current flow between the source and sink will be conceptually unitized as 150 for the arrangement of FIG. 20. In this regard, by measuring the resistivity or other electrical features of the electrode array in this arrangement, a determination can be made that the tissue of higher resistivity (e.g., modiolus wall) is closer than that which is the case for the scenario of FIG. 18.

[0071] FIG. 21 schematically depicts a scenario where the electrode array 145 is located closer to the modiolus wall / the tissue of high resistivity relative to that which is the case in figure 20. Here, the wall is located at half the distance Dl (the distance that equals the distance between the source and sink electrodes). Basically, the tissue of high resistivity is located within an area in which a recognizable percentage of the charge flows. Here, about 50% of the charge flows through the tissue of higher resistivity. This changes the resistivity of the current flow between the source and sink electrodes. For purposes of discussion, the resistivity of current flow between the source and sink will be conceptually unitized as 700 for the arrangement of FIG. 21. In this regard, by measuring the resistivity or other electrical features of the electrode array in this arrangement, a determination can be made that the tissue of higher resistivity (e.g., modiolus wall) is closer than that which is the case for the scenario of FIG. 20.

[0072] FIG. 22 schematically depicts a scenario where the electrode array 145 is located closer to the modiolus wall / the tissue of high resistivity relative to that which is the case in figure 21. Here, the wall is located essentially right against the electrodes. Basically, the tissue of high resistivity is located within an area in which a recognizable percentage of the charge flows. Here, almost all of the charge flows through the tissue of higher resistivity. This changes the resistivity of the current flow between the source and sink electrodes. For purposes of discussion, the resistivity of current flow between the source and sink will be conceptually unitized as 3000 for the arrangement of FIG. 22. In this regard, by measuring the resistivity or other electrical features of the electrode array in this arrangement, a determination can be made that the tissue of higher resistivity (e.g., modiolus wall) is closer than that which is the case for the scenario of FIG. 21.

[0073] In an exemplary embodiment, because the spacing of the source and sink electrodes is known, by measuring the resistivity (or impedance, or any pertinent electrical property) utilizing one or more of the electrodes of the electrode array or other components of a system that can enable the teachings detailed herein, a distance from the electrode array to the modiolus wall (or other tissue of interest) can be determined.

[0074] Note that spacing between the source and sink electrodes changes the depth of penetration vis-a-vis the percentage of current that travels through a given layer. As noted above, Dl is a value that is based on the distance between the source and sink electrodes. Increase Dl, and the distance of the layers changes. This is depicted in FIG. 23, where the percentage values of the current flow in a given layer are presented, corresponding to spacing A- B (electrodes 15 and 18), and the percentage values the current flow corresponding to spacing A'-B' (electrodes 14 and 19) are also presented. As can be seen, the depth from the electrode array that 50% of the current flows therein becomes larger with the increased electrode spacing. Accordingly, in a scenario where, for example, the relatively high resistivity tissue is located at the level where 50% of the current flow for electrodes A' and B' (corresponding to the location where 70% of the current flows for electrodes A and B) the effective total impedance for A' and B' could be unitized as 350 (as opposed to the unitized resistivity of 150 for electrodes A and B - the arrangement of FIG. 20). Accordingly, by varying the distance of the source and sink electrodes, the different resulting effective resistivities (or other measured electrical phenomenon) will provide information regarding the distance from the electrode array to the tissue of relatively higher resistivity (e.g., bone of the modiolus wall).

[0075] FIG. 24 depicts an exemplary scenario of an electrode array 145 spaced away from the modiolus wall (bone) but at distances that are different with respect to location along the length of the electrode array. More specifically, three exemplary heights are presented, with Dl being larger than D2, and D2 being larger than D3. The distances are indicated at the location equidistant between the source and sink electrodes (the electrodes are labeled for D2 - the same would be the case for Dl and D3). In an exemplary embodiment, electrode 15 and electrode 18 are utilized as the source and sink, respectively, and electrode 16 and electrode 17 (M and N) are utilized as the measurement electrodes. The resistivity / impedance at electrodes 16 and 17 is measured for a given charge applied to electrodes 15 and 17. Next (or before), electrode 14 and electrode 19 are utilized as the source and sink, respectively, and electrodes 16 and 17 are utilized as the measurement electrodes. That said, electrodes 15 and 18 can be utilized as the measurement electrodes. The resistivity/impedance at electrodes 16 and 17 (or 15 and 18) is measured for a given charge applied to electrodes 14 and 18. Based on these measurements, the distance D2 can be determined. (Additional measurements can be utilized, by, for example, further spacing the source and sink electrodes, etc.) This process can be duplicated to determine Dl and D3 as well.

[0076] It is noted that in some embodiments, electrode B (or A) can be further than those detailed. Indeed, in some exemplary embodiments, electrode B (or A) can be the ball electrode / the extra cochlear electrode).

[0077] It is noted that the depth of median current flow can be asymmetrical. This can be determined by separation of electrodes from the stimulating polar electrodes. Electrical sensitivity can be dependent on inhomogeneities between the measurement electrodes, as well as the source electrode and one or both of the measurement electrodes (or the sink electrode and one or both of the measurement electrodes). In some exemplary embodiments, two recording measurements are taken, one with A left of the measurement electrodes and one with A right of the reader electrodes, and the results are combined to compensate for asymmetry.

[0078] FIG. 25 conceptually illustrates an exemplary scenario where one of the source / sink electrodes (electrode B) is sufficiently far that effects of asymmetry or the like can be neglected. Here, the voltages can be calculated using the equations presented in FIG. 25, and reproduced below:

[0079] In some exemplary embodiments, a rule of thumb is applied where the separation |AM| < 20x|AB| for errors to be less than 5%. K is effectively the correction factor for the voltage spread with distance, and is determined by the geometric arrangement of electrodes.

[0080] In view of the above, it can be seen that in some exemplary embodiments, because the location of the investigation is known, and because the depth of the investigation is approximately known, one can build depth projection based on current.

[0081] FIGs. 26-32 conceptually illustrate an exemplary embodiment where the electrodes of the electrode array are utilized as source and sink electrodes and as recorder electrodes. Figure 26 depicts an exemplary embodiment where electrodes 12 and 15 are utilized as the source and sink electrodes, and electrodes 13 and 14 are utilized as the measurement electrodes. This results in data 1 being developed, which data is correlated to a generic depth of current travel (where, as noted above, the further the source and sink, the further the depth of current travel). In an exemplary embodiment, data 1 corresponds to the voltage between electrodes 13 and 14. Figure 27 depicts an exemplary embodiment where electrodes 13 and 16 are utilized as the source and sink electrodes, and electrodes 14 and 15 are utilized as the measurement electrodes. This results in data 2 being developed, which data is correlated to the generic depth. In an exemplary embodiment, data 2 corresponds to the voltage between electrodes 14 and 15. Figure 28 depicts an exemplary embodiment where electrodes 14 and 17 are utilized as the source and sink electrodes, and electrodes 15 and 16 are utilized as the measurement electrodes. This results in data 3 being developed, which data is correlated to the generic depth. In an exemplary embodiment, data 3 corresponds to the voltage between electrodes 15 and 16.

[0082] The source and sink and recorder electrodes are moved for some or all of the electrodes of the electrode array. FIG. 29 conceptually represents data 1 to 7 developed utilizing electrode pairs that are spaced apart from one another by two electrodes (the measurement electrodes), where alignment for the given data corresponds to the halfway point between the source and sink electrodes utilized to develop the data (e.g., for data 7, electrodes 18 and 21 were the source and sink electrodes, and electrodes 19 and 20 were the measurement electrodes). Additional data points or fewer data points can be developed depending on the embodiment.

[0083] FIG. 29 also depicts data 9, which data is developed using electrodes 13 and 18 as the source and sink electrodes, and electrodes 15 and 16 are utilized as the measurement electrodes. This results in data 9 being developed, which data is correlated to the generic depth. In an exemplary embodiment, data 9 corresponds to the voltage between electrodes 15 and 16. FIG. 30 depicts data 10, which data is developed using electrodes 13 and 18 as the source and sink electrodes, and electrodes 16 and 17 are utilized as the measurement electrodes. This results in data 10 being developed, which data is correlated to the generic depth. In an exemplary embodiment, data 10 corresponds to the voltage between electrodes 16 and 17. FIG. 31 depicts data 11, which is developed using electrodes 14 and 15 as the measurement electrodes and electrodes 13 and 18 as the source and sink.

[0084] FIG. 32 depicts data 12, which is developed using electrodes 13 and 18 as the source and sink electrodes, and electrodes 14 and 16 as the measurement electrodes. [0085] Variations of the above exemplary embodiments can be executed to obtain various data points having utilitarian value.

[0086] FIG. 33 depicts data 13 and 14, which data was developed utilizing, respectively, electrodes 17 and 18 as measurement electrodes, and electrodes 15 and 20 as the source and sink electrodes, and electrodes 18 and 19 as the measurement electrodes, and electrodes 16 and 21 as the source and sink electrodes. FIG. 33 also depicts data 15, which data was developed using electrodes 13 and 20 as the source and sink, and electrodes 16 and 17 as the measurement electrodes. Using electrodes 13 and 20 as the source and sink electrodes, data 17 is developed using electrodes 14 and 15 as the measurement electrodes, data 16 is developed using electrodes 15 and 16 as the measurement electrodes, data 18 is developed using electrodes 17 and 18 as the measurement electrodes, data 19 is developed using electrodes 18 and 19 as the measurement electrodes, etc.

[0087] Consistent with the teachings detailed above, as the distance between the source and sink expands, the further the electrical field will radiate from the electrode array (e.g., the further 50% of the current generated by the electrical field will be located from the electrode array). The further that the electrical field radiates from the electrical array, the more the electrical field will radiate through the relatively highly resistive bone of the cochlea (relative to the resistivity of the perilymph), which will result in different readings for the respective data. For example, where the voltage is measured between electrodes 16 and 17, for a given current, the voltage of data 4 should be lower than the voltage of data 10 and the voltage of data 10 should be lower than the voltage of data 15, etc. Without being bound by theory, at some point (where the distance between the source and sink electrodes has increased by a certain amount), the voltage between electrodes 16 and 17 should noticeably spike, indicating that a substantial amount of the current extends into the bone of the cochlea (modiolus wall, for example), Relative to that which was the case when the source and sink electrodes were closer to each other.

[0088] From the above, it is to be understood that in an exemplary embodiment, the various electrodes of the electrode array can be sequentially activated and other electrodes of the electrode array can be utilized as measurement electrodes to obtain electrical characteristics associated therewith resulting from the electrical field that results from the activation electrodes. Because the distance between the source and sink electrodes is known (and because the distance between the measurement electrodes is known), the data from the measurement electrodes can be correlated to determine the distance of the electrode array to the modiolus wall. In an exemplary embodiment, this is done utilizing vertical electrical sounding techniques. That is, a data set can be developed by activating various permutations of the electrodes as source and sinks, and utilizing various permutations of the electrodes as measurement electrodes, and applying vertical electrical sounding techniques, because the distance between the electrodes is known, the distance from the electrode array to bone of the cochlea (modiolus wall, for example), or other structure that has a different resistivity than the perilymph in the cochlea, can be determined.

[0089] FIG. 34 depicts an exemplary flowchart for an exemplary method, method 3400, which includes method action 3410, which includes sequentially activating a plurality of respective electrode pairs of an implanted cochlear implant, at least one of the electrodes of the respective electrode pairs being a respective electrode of an electrode array implanted in a cochlea, thereby generating respective localized electric fields. In an exemplary embodiment, this corresponds to utilizing electrodes 12 and 15 as a source and a sink, and then using electrodes 13 and 16 as a source and a sink, and so on.

[0090] Method 3400 also includes method action 3420, which includes concurrently respectively measuring, for the plurality of activated respective electrode pairs, an electrical characteristic between the respective electrodes of the respective electrode pairs resulting from the respective localized electric fields, thereby obtaining a measurement set. In an exemplary embodiment, this corresponds to utilizing electrodes 13 and 14 as the measurement electrodes when the electrode pair corresponds to electrodes 12 and 15, and utilizing electrodes 14 and 15 as the measurement electrodes when the electrode pair corresponds to electrodes 13 and 16. From the measurements of the measurement electrodes, a correlated data set is developed.

[0091] Method 3400 also includes method action 3430, which includes determining, from the measurement set, a distance between the electrode array and a wall of the cochlea. Consistent with the teachings detailed above, the measurement set can comprise, in some embodiments, respective voltages measured between the respective electrodes of the respective electrode pairs. That said, in other embodiments, other electrical characteristics can be used to establish the measurement set. Combinations of electrical characteristics can be utilized to establish the measurement set. Any electrical characteristic that can enable the teachings detailed herein and/or variations thereof can be utilized in at least some exemplary embodiments.

[0092] As will be understood from the above, in some exemplary embodiments of method action 3420, the electrical characteristic includes measuring an electrical characteristic using first and second electrodes of the electrode array, which electrodes are different from the electrodes of the electrode pair. In at least some embodiments, the electrode pairs used to create the measurement set comprises a unique pair of electrodes. In some embodiments, a respective first electrode of each electrode pair is selected from a first set of consecutive electrodes, a respective second electrode of each electrode pair is selected from a second set of consecutive electrodes, and respective third and fourth electrodes are disposed between the respective first and second electrodes, the third and fourth electrodes being utilized to measure the electrical characteristic. In some exemplary embodiments, the respective first and second electrodes are disposed symmetrically about the respective third and fourth electrodes. In some exemplary embodiments, both of the electrodes of the respective electrode pairs are respective electrodes of the electrode array implanted in the cochlea. This as opposed to some embodiments where, for example, one of the electrodes of the pairs is an extra-cochlear electrode (e.g., the so called hardball electrode, etc.).

[0093] FIG. 35 presents a flowchart for an exemplary method, method 3500, including method action 3510, which includes obtaining first data by operating a first set of electrodes as a source and sink in and/or on a mammal (e.g., electrodes of a cochlear electrode array located in a cochlea) while operating a second set of electrodes as recorder electrodes in and/or on a mammal (again, for example, the cochlear electrode array located in a cochlea) thereby obtaining first electrical data from the second set of electrodes. In an exemplary embodiment, the first electrical data corresponds to voltage measurements at the electrodes of the second set of electrodes. Again, consistent with the teachings detailed herein, any electrical characteristic that can enable the teachings detailed herein can be utilized in some embodiments.

[0094] Method 3500 further includes method action 3520, which includes obtaining second data by operating a third set of electrodes as a source and sink in and/or on the mammal, the third set being different than the first set, while operating the second set of electrodes as recorder electrodes in and/or on the mammal and thereby obtaining second electrical data from the second set of electrodes. Method 3500 also includes method action 3530, which includes evaluating data by evaluating the first electrical data and the second electrical data, and method action 3540, which includes determining spatial positioning data based on the evaluation of the data, wherein the spatial positioning data is a distance of one or more of the electrodes of the first set or second set from a structure within the mammal.

[0095] In an exemplary embodiment, the first electrical data is a first impedance based data (voltage, current, impedance - any data that is based on impedance) between the electrodes of the second set. The second electrical data is a second impedance based data between the electrodes of the second set. Further, the action of evaluating the first electrical data and the second electrical data includes comparing the first electrical data to the second electrical data, and the action of determining the spatial positioning data includes determining a distance of the second set of electrodes from a gradient. In some exemplary embodiments, the gradient is a resistivity gradient. For example, a gradient established between the perilymph and bone of the cochlea.

[0096] It is noted that the gradient can also be established by the membrane that is located between bone of the cochlea and the perilymph, if such is present.

[0097] In some embodiments, the electrodes of the first set are located closer to one another than the electrodes of the third set and are between electrodes of the third set.

[0098] In an exemplary embodiment, there is a method 3600 as represented by the flowchart on FIG. 36, which method includes method action 3610, which includes executing method 3500. Method 3610 also includes method action 3620, which includes obtaining third data by operating a fourth set of electrodes as a source and sink in and/or on the mammal, the fourth set different than the third set, while operating the second set of electrodes as recorder electrodes in and/or on the mammal, thereby obtaining third electrical data from the second set of electrodes. In an exemplary embodiment, the action of evaluating data includes evaluating the third electrical data while also evaluating the second electrical data and the first electrical data, and the electrodes of the first set are located closer to one another than the electrodes of the third set and are between electrodes of the third set, and the electrodes of the third set are located closer to one another and between electrodes of the fourth set. [0099] In some embodiments, the recorder electrodes are part of a cochlear electrode array that is located in a cochlea, as noted above. Also, the determined spatial positioning data is distance data of the recorder electrodes from a modiolus wall of the cochlea. In some embodiments, the determined spatial positioning data is an orientation of the recorder electrodes relative to structure of the cochlea. For example, the orientation can be whether the electrodes face directly at the modiolus wall, or whether the electrodes face away from the modiolus wall. In an exemplary embodiment, the orientation is an approximate angle from a centerline of the electrode to a centerline of the modiolus wall. In an exemplary embodiment, the orientation is an approximate angle that represents the difference from the ideal orientation of the electrodes relative to the modiolus wall and the actual angle.

[ooioo] FIG. 37 represents an exemplary flowchart for an exemplary method, method 3700, which includes method action 3710, which includes executing method 3500. Method 3700 further includes method action 3720, which includes, obtaining third data by operating a fourth set of electrodes as a source and sink in and/or on the mammal, the fourth set different than the third set, while operating a fifth set of electrodes as recorder electrodes in and/or on the mammal, thereby obtaining third electrical data from the second set of electrodes. Method 3700 further includes method action 3730, which includes obtaining fourth data by operating a sixth set of electrodes as a source and sink in and/or on a mammal, the sixth set different than the fourth set, while operating the fifth set of electrodes as recorder electrodes in and/or on the mammal, thereby obtaining fourth electrical data from the seventh set of electrodes. In this exemplary method, in an exemplary embodiment, the action of evaluating data includes also evaluating the third electrical data and the fourth electrical data, the electrodes are part of a cochlear electrode array that is located in a cochlea, and the action of determining spatial positioning data based on the evaluation of the data includes determining a distance of the electrodes of the second set from a modiolus wall of the cochlea based on the evaluation of the second and first electrical data and determining a distance of the electrodes of the fifth set from a modiolus wall of the cochlea based on the evaluation of the third electrical data and the fourth electrical data.

[ooioi] FIG. 38 depicts a flowchart for an exemplary method, method 3800, which includes method action 3810, which includes executing method 3500. Method 3800 also includes method actions 3820 and 3830, which respectively include executing method actions 3720 and 3730. Method 3800 also includes method action 3840, which includes obtaining distance data of a seventh set of electrodes used as recording electrodes from the modiolus wall, the seventh set being different than the second set and the fifth set. Subsequent to this, method 3800 includes method action 3850, which includes determining that the electrode array is at least one of over inserted into the cochlea, has experienced a tip fold over, or is angularly misaligned by comparing the distance data of at least two of the seventh set, fifth set and second set to one another. Some additional details of such features are described below.

[00102] Table I below depicts an exemplary regime utilizing a 22 electrode array according to the teachings detailed herein, where each row can correspond to any of the first set of electrodes and second set of electrodes of method action 3510, and where, in an exemplary embodiment, method action 3510 is executed C number of times, and in an exemplary embodiment, each time for a different first set, where C can be 19 times for 22 electrode array, or 27 times for a 30 electrode array, etc. In an exemplary embodiment, C is any integer between 1 and 3 minus the number of electrodes of the array, or any number between 1 and 2 minus the number of electrodes of the array (where, for example, an extra cochlear electrode is used). Any different row from that previously used can corresponds to the third set of electrodes of method action 3520, and method action 3520 can be executed C minus 1 times (to avoid duplication, but in some other embodiments, can be executed C times, as duplication does not prevent method 3500 from being executed - it is just an additional action) or C minus 1 minus the aforementioned minuses.

[00103] Table II below depicts an exemplary regime utilizing a 22 electrode array according to the teachings detailed herein, where each row can correspond to any of the first set of electrodes and second set of electrodes of method action 3510 (and the second sets can be the measurement electrodes as listed, or one of the measurement electrodes with the alternate electrode, or both (actually all three - with respect to the first row, the measurement electrodes can be 2 and 3, 2 and 4 and/or 3 and 4 (three sets in total maximum)), and where, in an exemplary embodiment, method action 3510 is executed D number of times (and potentially more to accommodate for the fact that for a given source and sink, there can be various applications of the measurement electrodes, as just noted), and in an exemplary embodiment, each time for a different first set, where D can be 18 times for 22 electrode array, or 26 times for a 30 electrode array, etc. In an exemplary embodiment, D is any integer between 1 and 4 minus the number of electrodes of the array, or any number between 1 and 3 minus the number of electrodes of the array (where, for example, an extra cochlear electrode is used). Any different row from that previously used can corresponds to the third set of electrodes of method action 3520, and method action 3520 can be executed D minus 1 times (to avoid duplication, but in some other embodiments, can be executed D times, as duplication does not prevent method 3500 from being executed - it is just an additional action) or D minus 1 minus the aforementioned minuses.

[00104] Table III below depicts an exemplary regime utilizing a 22 electrode array according to the teachings detailed herein, where each row can corresponds to any of the first set of electrodes and second set of electrodes of method action 3510, and where, in an exemplary embodiment, method action 3510 is executed E number of times (and potentially more to accommodate for the fact that for a given source and sink, there can be various applications of the measurement electrodes, as just noted), and in an exemplary embodiment, each time for a different first set, where E can be 17 times for 22 electrode array, or 25 times for a 30 electrode array, etc. In an exemplary embodiment, E is any integer between 1 and 5 minus the number of electrodes of the array, or any number between 1 and 4 minus the number of electrodes of the array (where, for example, an extra cochlear electrode is used). Any different row from that previously used can correspond to the third set of electrodes of method action 3520, and method action 3520 can be executed E minus 1 times (to avoid duplication, but in some other embodiments, can be executed E times, as duplication does not prevent method 3500 from being executed - it is just an additional action) or E minus 1 minus the aforementioned minuses.

[00105] It is noted that the below table indicates that the second set of electrodes of method action 3510 can be any combination of the measurement electrodes. For example, for a source and sink corresponding to electrodes 1 and 6, the measurement electrodes can be 2 and 3, 2 and 4, 2 and 5, 3 and 4, 3 and 5 or 4 and 5.

[00106] From the above, it can be seen that embodiments include expanding the trend above, one electrode at a time to expand the source and sink distance, while, for each expansion, the measurement electrodes can be varied accordingly to the trend above. Table IV below depicts a genericized version of the tables above.

In the above table, N is the increment for each iteration. For a 22 electrode array, N can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or 21 (as limited by the top end - e.g., when A is electrode 16, N cannot be 20).

[00107] It is noted that while the read / measurement electrodes in the above tables are located between the source and sink electrodes, in some embodiments, as noted above, one measurement electrode is between the source and sink electrode, and one is outside / not in between the source and sink. Further, in some embodiments, both measurement electrodes are outside the source and sink (not between the source and sink).

[00108] Note also that in some embodiments, more than 2 measurement electrodes can be used for a given activation of a source and sink. Indeed, in some embodiments, for a given source and sink activation, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 or more electrodes can be used as the measurement electrodes. For example, in the case where there electrodes 2 and 5 are the source and sink, electrode 3 and 4 and 6 and 7 and 8 and 9 and 10 etc. can simultaneously be the measurement electrodes (e.g., the voltage difference between electrodes 3 and 4, 3 and 6, 3 and 7, 3 and 8, 3 and 9, 3 and 10, 4 and 6, 4 and 7, 4 and 8, 4 and 9, 4 and 10, 6 and 7, 6 and 8, 6 and 9, 6 and 10, 7 and 8, 7 and 9, 7 and 10, 8 and 9, 8 and 10 and 9 and 10 can all potentially be simultaneously read or read in sequence in any order.

From the above, it can be seen that embodiments include expanding the trend above, one electrode at a time to expand the source and sink distance, while, for each expansion, the measurement electrodes can be varied accordingly to the trend above. Table V below depicts a genericized version based on the above.

[00109] In the above table, the measurement electrodes are only limited as noted.

[ooiio] Also, in some embodiments, an extra-cochlea electrode can be used as the source or the sink electrode (in some embodiments, there is high utility for using the extra-cochlear electrode as the sink) for greater depth sensing. In which case, table V would result in the elimination of one of the electrodes as the source or sink and the inclusion of that electrode as one of the measurement electrodes. [ooiii] To be clear, methods include any one or more permutations of the above, where data is obtained from the pertinent measurement electrodes. In some embodiments, every permutation is executed with the electrode array. In some embodiments, only some permutations are presented.

[00112] FIG. 39 presents another exemplary flowchart for an exemplary method, method 3900, which includes method action 3910, which includes executing vertical electrical sounding utilizing electrodes of an electrode array of a cochlear implant located in a cochlea. This is executed using any of the method actions, alone or in combination, detailed herein, or variations thereof, or any other technique that will enable vertical electrical sounding utilizing electrodes and electrode array of a cochlear implant located in the cochlea. Method 3900 also includes method action 3920, which includes determining a positional feature of the electrode array based on the vertical electrical sounding. In an exemplary embodiment, the determined positional feature is a distance of the electrode array from a modiolus wall of the cochlea. In an exemplary embodiment, the determined positional feature is a distance of the electrode array from a lateral wall of the cochlea. In an exemplary embodiment, the determined positional feature is respective distances from structure of the cochlea (lateral wall, modiolus wall, etc.) for one or more respective locations of the electrode array. For example, the one or more respective distances can be the respective distances from any one or more of electrodes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and/or 22 to the structure, and, if an array with more electrodes are present, for those additional electrodes. For example, these can be distances from locations L9, L10, Ll l, L12, L13, L14, L15, LI 6, and L17 in FIG. 5A, and for the other electrodes not shown accordingly. In an exemplary embodiment, the one or more respective distances can be the respective distances from any location in between, including the location on the electrode array in the geometric center (e.g., 50% of the way between) between any group of two or more electrodes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and/or 22 to the structure, and, if an array with more electrodes are present, for those additional electrodes. For example, these can be distances from locations LI, L2, L3, L4, L5, L6, L7 and L8 in FIG. 5A, and for other respective locations for the electrodes not shown.

[00113] In an exemplary embodiment, relative to distance from the distal tip of the electrode array, the one or more respective distances can be the respective distances from any one or more locations at or about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9. 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or 8.0 cm along the array from the tip, depending on the length of the array, of course, or any value or range of values therebetween in 0.01 cm increments, providing that the array enables such.

[00114] In an exemplary embodiment of the method action 3920, the determined positional feature is a tip fold over of the electrode array. In an exemplary embodiment, this is determined by determining distances for respective locations along the array from a given structure of the cochlea, and determining that a distance value or values "does not make sense" relative to other distance values other than in a scenario where there is a tip fold over (or that such is a possibility). Any data that results from vertical electrical tomography or any of the other techniques detailed herein that can be utilized to determine or otherwise estimate that a tip fold over has occurred, can be utilized in at least some exemplary embodiments.

[00115] In an exemplary embodiment, the determined positional feature of method action 3920 is a puncture of the electrode array through a wall of the cochlea. Again, such a determination can be achieved, in an exemplary embodiment, by evaluating or otherwise determining distances for respective locations along the array from a given structure of the cochlea, and determining that a distance value or values is inconsistent with a properly positioned array, and is otherwise indicative of an array that has punctured a wall of the cochlea. In an exemplary embodiment, the determined positional feature of method action 3920 is in over insertion of the electrode array to the cochlea, while in some embodiments of the method action 3920, the determined positional feature is a longitudinal location of the electrode array within the cochlea. It is noted that the various positional features detailed herein are not mutually exclusive when executing method action 3920. That is, in an exemplary embodiment, the method action 3920 is executed, a number of different positional features can be determined based on a single set of data.

[00116] In some exemplary embodiments, there is an exemplary method, such as method 4000 represented by the flow chart on FIG. 40, wherein the method includes method action 4010, which includes executing method 3900, which results in the determined positional feature being a longitudinal location of the electrode array within the cochlea. Method 4000 also includes method action 4020, which includes the action of determining based on the longitudinal location of the electrode array within the cochlea that an electrode array fixation failure has occurred. In an exemplary embodiment, method action 4020 is executed during the surgical process in which the electrode array has been inserted (e.g., subsequent to insertion, during closure of the access incision through the outer skin of the recipient, etc.), while in an exemplary embodiment, method action 4020 is executed after the recipient has left the surgery room. In an exemplary embodiment, method action 4020 is executed after 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 months or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 years after implantation and fixture of the electrode array.

[00117] In an exemplary embodiment, the determined positional feature is a distance from fibrous tissue that has grown since the array was implanted in the recipient. In this regard, the determined position feature can be executed after 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 months or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 years after implantation of the electrode array.

[00118] FIG. 41 presents a flowchart for an exemplary method, method 4100, which includes method action 4110, which includes energizing an electrode implanted in a recipient, the electrode being part of an assembly located in and/or on a recipient. In an exemplary embodiment, the assembly is an electrode array of a cochlear implant, and the electrode that is energized is intracochlear electrode array, although as noted above, in embodiments where an extra cochlear electrode array is utilized as the source under the sink, where such is utilized as the source, and extra cochlear electrode array can be energized. Method 4100 also includes method action 4120, which includes receiving data from one or more recording electrodes located in and/or on a recipient. In an exemplary embodiment, this can correspond utilizing the measurement electrodes that are located along the array as noted above. Method 4100 also includes method action 4130, which includes determining spatial position data of the assembly based on the received data. In an exemplary embodiment, the spatial position data can be any of the data detailed herein or variations thereof, such as the distance from the modiolus wall, etc. As will be understood, in an exemplary embodiment, the actions of energizing, receiving, and determining can be, in some embodiments, actions that are part of a vertical electrical sounding method applied to a mammal. [00119] It is noted that by spatial position data, such does not include mere indicators that an event has occurred (e.g., that the electrode array has moved, etc.). The spatial position data obtained in method action 4130 is data that indicates a position of the array.

[00120] In an exemplary embodiment of method action 4130, the spatial position data of the assembly is a distance of the assembly from a wall of tissue of the recipient (e.g., the modiolus wall, etc.). In an exemplary embodiment, the wall of tissue of the recipient is a wall that is a barrier of a cavity in the recipient that normally contains bodily fluid. In an exemplary embodiment, the wall of tissue of the recipient is a modiolus wall of a cochlea, the assembly is an electrode array of a cochlear implant, the electrode is located in a duct of the cochlea, and the spatial position is distance of the electrode array from the modiolus wall relative to the one or more recording electrodes or a location between two or more of the recording electrodes (anywhere between, such as a location 50% of the way between two electrodes). In some exemplary embodiments where the assembly is a cochlear electrode array, method 4100 includes determining, based on the determined spatial position data (e.g., such as the distance from the modiolus wall, or other structure of the cochlea, for one or more locations along the electrode array), that at least one or more of the following has occurred:

(i) a tip fold over;

(ii) a longitudinally local lateral angular position of the electrode array has shifted relative to another longitudinally local position;

(iii) the electrode array has been over inserted into a cochlea of the recipient;

(iv) the electrode array has become unfixed subsequent to full implantation into the recipient; or

(v) the electrode array has migrated during implantation.

[00121] Consistent with the teachings detailed herein, in an exemplary embodiment of method 4100 where the assembly is an electrode array assembly, the spatial position data can be a plurality of respective distance of the assembly at respective locations along the array from respective locations of a wall of tissue of the recipient.

[00122] FIG. 42 presents a flowchart for an exemplary method, method 4200, which includes method action 4210, which includes executing method 4100, wherein the actions of energizing, receiving and determining are actions that are part of a surgical procedure to implant the assembly in the recipient. Method 4200 further includes method action 4220, which comprises repositioning the electrode array based on the determined spatial position data. In this regard, in an exemplary embodiment, the spatial positioning data, such as the distance from the modiolus wall, for example, can be evaluated to determine that the electrode array is at a position that is less than utilitarian relative to that which would otherwise be the case if the electrode array was positioned at another location, such as by way of example only and not by way of limitation, at a location where one or more locations along the electrode array are located closer to the modiolus wall. Thus, in an exemplary embodiment, based on the spatial positioning data, when the determination is made that the electrode array should be repositioned, method action 4220 can be executed based on that data.

[00123] FIG. 43 presents an exemplary flowchart for an exemplary method, method 4300, which includes method action 4310, which includes obtaining electrical data from at least two electrodes implanted in a human head, such as by implementing the teachings detailed herein and/or variations thereof, such as by using a cochlear electrode array. Method 4300 also includes method action 4320, which includes determining a physiological feature of an interior of a duct of a cochlea based on the obtained electrical data. In an exemplary embodiment, the determined physiological feature is the relative absence of perilymph in the duct, while in some other embodiments, the determined physiological feature is the relative absence of fibrous tissue growth due to implantation of the electrode array into the duct of the cochlea (the latter having utilitarian value when method action 4320 is executed after 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,

16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 days or 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 months or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 years after implantation of the electrode array). In an exemplary embodiment, the determined physiological feature is the presence of significant fibrous tissue growth due to implantation of the electrode array into the duct of the cochlea (again, which can have utilitarian value when executed after 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 days or 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,

17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 months or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 years after implantation of the electrode array).

[00124] FIG. 44 depicts an exemplary flowchart for an exemplary method. Method 4400, which includes method action 4410, which includes executing method 4300, where the determined physiological feature is the presence of significant fibrous tissue growth due to implantation of the electrode array into the duct of the cochlea. Method 4400 also includes method action 4420, which includes executing NRT (Neural Response Telemetry) method, such as by using the electrodes of a cochlear electrode array implanted in a cochlea. In this regard, in an exemplary embodiment, cochlear implants according to some embodiments are configured to enable the execution of an NRT method. Method 4400 further includes method action 4430, which includes evaluating results of the NRT method by taking into account the presence of the significant fibrous tissue growth. In this regard, in an exemplary embodiment, the presence of significant fibrous tissue growth can skewer otherwise change the results of the NRT method. In an exemplary embodiment, by discounting the results of the NRT method based on the presence of the fibrous tissue growth, more utilitarian value of the NRT method can be obtained. In an exemplary embodiment, the method of method 4400 also includes the action of determining that the fibrous tissue has established a dead patch with respect to taking NRT measurements.

[00125] It is noted that sometimes, NRT is referred to in the art as evoked compound action potentials (ECAP).

[00126] In an exemplary embodiment, there is a cochlear implant configured to execute one or more of the actions detailed herein, which cochlear implant is configured to communicate the results of such actions to control unit 8310. Corollary to this is that control unit 8310 can be configured to activate the receiver/stimulator of the cochlear implant to execute one or more of the method actions detailed herein, such as the measurements / the collection of the data. In an alternative embodiment, the receiver/stimulator of the cochlear implant can execute such autonomously. The receiver/stimulator of the cochlear implant, can, in some embodiments, be configured to transmit the data based on or otherwise resulting from the execution of one or more of the method actions to the control unit 8310. Control unit 8310 analyzes the data in some embodiments. Indeed, in some embodiments, at least based in part on that data, control unit 8310 can control an automated robot that inserts an electrode array into a cochlea.

[00127] In an exemplary embodiment, the cochlear implant can be configured to take NRT / ECAP measurements to obtain the NRT / ECAP data, which cochlear implant is configured to communicate the results of such measurements to control unit 8310. In this regard, the ECAP measurement device / ECAP data collection device can correspond to a receiver/stimulator of a cochlear implant, which has an inductance coil and can be utilized as detailed above, albeit with respect to measuring ECAP or otherwise developing or collecting ECAP data and conveying such measurements to the control unit 8310. Corollary to this is that control unit 8310 can be configured to activate the receiver/stimulator of the cochlear implant to execute the measurements / the collection of the data. In an alternative embodiment, the receiver/stimulator of the cochlear implant can execute such autonomously. The receiver/stimulator of the cochlear implant, can transmit the data based on or otherwise resulting from the execution of NRT / ECAP measurements to the control unit 8310. Control unit 8310 analyzes the data in some embodiments, and, at least based in part on that data, in some embodiments, can control an automated robot that inserts an electrode array into a cochlea.

[00128] It is noted that in some exemplary embodiments, the electrode arrays detailed herein are utilized to obtain data analogous to the data obtained via Electrical resistivity tomography (ERT) or electrical resistivity imaging (ERI), and in some embodiments, the electrode array is utilized to execute such. These techniques are traditionally geophysical techniques for imaging subsurface structures from electrical resistivity measurements made at the surface. Accordingly, where the electrode array of the cochlear implant is used to execute such techniques, such can be used to obtain imaging.

[00129] For example, induced polarization, measures the transient response. In some embodiments, the cochlear implant and/or the system of which it is apart, such as the control unit noted above, are configured to execute ID, 2D and/or 3D Electrical Resistivity Tomography (ERT).

[00130] In an exemplary embodiment, the above-noted action of obtaining electrical data from at least two electrodes implanted in a human head includes doing so as part of an ERT / ERI method, and the action of determining a physiological feature of an interior of a duct of a cochlea based on the obtained electrical data results in an image.

[00131] FIG. 45 depicts an image that results from a synthetic model, and FIG. 46 depicts an image that results from resistive projection measurements, and FIG. 47 depicts an image of an inverted projection, where darker colors are lower impedance. In an exemplary embodiment, these images are obtained using ERT / ERI via a cochlear electrode array inserted into a cochlea, to obtain image information associated with the cochlea.

[00132] It is noted that any equations and/or theories detailed herein are presented for purposes of explanation and conceptual understanding only. In some embodiments, such equations and theories may be applicable. In other embodiments, such equations and theories may not be applicable, or otherwise may be applicable only with further modifications or variations. By way of example only and not by way of limitation, while some of the equations presented above are for a hemispherical scenario owing to the fact that air acts as an insulator when utilized in the geological regime, such is not the case with respect to utilization of an electrode array that is located in a cochlea that is filled with perilymph.

[00133] Still further, below is presented some exemplary teachings that can have utilitarian value with respect to at least some exemplary embodiments. It is noted that the below is for purposes of explaining some embodiments, in other embodiments may not utilize some or all of the following teachings. It is noted that in some exemplary embodiments, there are methods systems and/or apparatuses that use some or all of the following teachings. In this regard, in an exemplary embodiment, there is a method that is executed to obtain various data/results detailed herein utilizing one or more of the following teachings. In an exemplary embodiment, there is an apparatus and/or system that is configured to obtain various data/results detailed herein utilizing one or more of the following teachings. In this regard, in an exemplary embodiment, there is a system and/or apparatus that includes structure to execute some or all of the following teachings. By way of example only and not by way of limitation, in an exemplary embodiment, such structure can be a personal computer or the like that is programmed to achieve such goals, which personal computer is in signal communication with a controller of an electrode array that is implanted in a cochlea or the like. That said, in an alternate embodiment, the personal computer can be configured to receive data obtained by use of the controller of the electrode array, which data can be downloaded or the like or otherwise provided to the computer system (e.g., such as via utilization of a flash drive or the like, which flash drive contains data obtained from the cochlear implant). It is further noted that in at least some exemplary embodiments, computational techniques are utilized to obtain values or estimates for the various data/results detailed herein.

This is seen by way of example in FIG. 48, which depicts a stimulating electrode array.

spacing of the diploe as shown in FIG. 49.

Applying Equation 4 we observe that at its deepest 50 percent of the current sensitivity lies within the region of z=a, and around 70% of the current is flowing at a depth equal to the electrode separation.

For example, the Kumar four-point impedance method, which involves a BP+3

stimulation and recording between the intermediate two electrodes, is shown in FIG. 50 (this matches the Wenner / Schlumberger array when n = 1).

We can model the cochlear as a 2 layer system, i.e., the electrode array is perilymph with the second layer as otic bone as shown in FIG. 51.

A number of depth estimates at different electrodes can be combined to produce a depth profile as shown in FIG. 53, which shows a profile of layer "depth" measured at different electrodes.

There are a number of methods for estimating the depth of inhomogeneity:

1. The knee point, marked with a circle in FIG. 52, sits at the approximate depth of the second layer;

2. Forward modelling, adapting parameters (rhol, rho2 and h) to get a matching curve;

3. Mathematical Inversion methods.

shown in FIG. 54, which depicts a pseudo section of a Wenner array.

It is noted that the output becomes effectively a finite element mesh and can be solved as such.

In an exemplary embodiment, generation of pseudo sections (FIG. 46) from a synthetic model (FIG. 45) to calculate inversions FIG. 47 can be executed.

Compensating for Topography

We can combine these with depth of insertion measurements or a cochlear size measurements/estimation to achieve an approximate topological correction factor.

As the pseudo section is effectively an FEA matrix, we can warp the matrix according to a logarithmical spiral. Even if the size estimation is incorrect, it should be sufficient to achieve good estimates.

FIG. 55 shows a double electrode stimulation for sub-electrode depth resolution.

Alternate Dipole Configurations

Note that there are a number of different array types, and are listed in FIG. 56, with their geometric factors. They each provide a tradeoff between resolution, depth of penetration and signal strength.

There are mathematical inversion methods, such as recursive Bessel for stratified layers, as shown in the lecture notes by Richard M. Allen, Introduction to Applied Geophysics Berkley University, such as Tangent Law: The electrical current is bent at a boundary, as represented by way of example in FIG. 57.

With reference to FIG. 58

* Can use for image theory for mu

boundaries. For two layer case:

Po!arisability metric is area under then iPG divided by the peak voltage Vm. Note we can use the trapazoidai ru!e, provided we can get two measurements on the IPG. This should be good enough.

FIG. 60, presents a graphic illustrating the above:

[00134] In an exemplary embodiment, there is a method, comprising, obtaining electrical data from at least two electrodes implanted in a human head and determining a physiological feature of an interior of a duct of a cochlea based on the obtained electrical data. In an exemplary embodiment of the method as described above and/or below, the determined physiological feature is the relative absence of perilymph in the duct. In an exemplary embodiment of the method as described above and/or below the determined physiological feature is the relative absence of fibrous tissue growth due to implantation of the electrode array into the duct of the cochlea. In an exemplary embodiment of the method as described above and/or below the determined physiological feature is the presence of significant fibrous tissue growth due to implantation of the electrode array into the duct of the cochlea. In an exemplary embodiment of the method as described above and/or below, the method further includes executing an NRT method, and evaluating results of the NRT method by taking into account the presence of the significant fibrous tissue growth. In an exemplary embodiment of the method as described above and/or below, the method further comprises determining that the fibrous tissue has established a dead patch with respect to taking NRT measurements. In an exemplary embodiment of the method as described above and/or below, the the determined physiological feature is a second puncture in a wall of the cochlea in addition to that through which the electrode array entered the cochlea.

[00135] In an exemplary embodiment, there is a method, comprising energizing an electrode implanted in a recipient, the electrode being part of an assembly located in and/or on a recipient, receiving data from one or more recording electrodes located in and/or on a recipient, and determining spatial position data of the assembly based on the received data. In an exemplary embodiment of this method, the actions of energizing, receiving and determining are actions that are part of a surgical procedure to implant the assembly in the recipient, the method further comprises repositioning the electrode array based on the determined spatial position data.

[00136] Any disclosure of any method action detailed herein corresponds to a disclosure of a device and/or a system for executing that method action. Any disclosure of any method of making an apparatus detailed herein corresponds to a resulting apparatus made by that method. Any functionality of any apparatus detailed herein corresponds to a method having a method action associated with that functionality. Any disclosure of any apparatus and/or system detailed herein corresponds to a method of utilizing that apparatus and/or system. Any feature of any embodiment detailed herein can be combined with any other feature of any other embodiment detailed herein providing that the art enables such, unless such is otherwise noted. Any embodiment or teaching disclosed herein can be explicitly excluded in some embodiments, providing that the art enables such unless otherwise noted. Any embodiment detailed herein can be explicitly excluded from combination with any feature of any other embodiment detailed herein providing that the art enables such, unless such is otherwise noted.

[00137] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope of the invention.

Claims

CLAIMS What is claimed is:

1. A method, comprising:

sequentially activating a plurality of respective electrode pairs of an implanted cochlear implant, at least one of the electrodes of the respective electrode pairs being a respective electrode of an electrode array implanted in a cochlea;

concurrently respectively measuring, for the plurality of activated respective electrode pairs, an electrical characteristic between the respective electrodes of the respective electrode pairs, thereby obtaining a measurement set; and

determining, from the measurement set, a distance between the electrode array and a wall of the cochlea.

2. The method of claim 1, wherein:

the measurement set comprises respective voltages measured between the respective electrodes of the respective electrode pairs.

3. The method of claim 1, wherein:

the action of concurrently respectively measuring, for the respective electrode pairs, an electrical characteristic includes measuring an electrical characteristic using first and second electrodes of the electrode array, which electrodes are different from the electrodes of the electrode pair.

4. The method of claim 1, wherein:

each of the electrode pairs used to create the measurement set comprises a unique pair of electrodes.

5. The method of claim 1, wherein:

a respective first electrode of each electrode pair is selected from a first set of consecutive electrodes,

a respective second electrode of each electrode pair is selected from a second set of consecutive electrodes, and

respective third and fourth electrodes are disposed between the respective first and second electrodes, the third and fourth electrodes being utilized to measure the electrical characteristic.

6. The method of claim 5, wherein:

the respective first and second electrodes are disposed symmetrically about the respective third and fourth electrodes.

7. The method of claim 1, wherein:

both of the electrodes of the respective electrode pairs are respective electrodes of the electrode array implanted in the cochlea

8. A method, comprising:

obtaining first data by:

operating a first set of electrodes as a source and sink in and/or on a mammal while operating a second set of electrodes as recorder electrodes in and/or on a mammal thereby obtaining first electrical data from the second set of electrodes;

obtaining second data by:

operating a third set of electrodes as a source and sink in and/or on the mammal, the third set being different than the first set, while operating the second set of electrodes as recorder electrodes in and/or on a mammal and thereby obtaining second electrical data from the second set of electrodes;

evaluating data by evaluating the first electrical data and the second electrical data; and determining spatial positioning data based on the evaluation of the data.

9. The method of claim 8, wherein:

the first electrical data is a first impedance based data between the electrodes of the second set;

the second electrical data is a second impedance based data between the electrodes of the second set; the action of evaluating the first electrical data and the second electrical data includes comparing the first electrical data to the second electrical data; and

the action of determining the spatial positioning data includes determining a distance of the second set of electrodes from a gradient.

10. The method of claim 8, wherein:

the electrodes of the first set are located closer to one another than the electrodes of the third set and are between electrodes of the third set.

11. The method of claim 8, further comprising:

obtaining third data by:

operating a fourth set of electrodes as a source and sink in and/or on the mammal, the fourth set different than the third set, while operating the second set of electrodes as recorder electrodes in and/or on the mammal, thereby obtaining third electrical data from the second set of electrodes, wherein

the action of evaluating data includes evaluating the third electrical data while also evaluating the second electrical data and the first electrical data, and

the electrodes of the first set are located closer to one another than the electrodes of the third set and between electrodes of the third set, and the electrodes of the third set are located closer to one another than the electrodes of the fourth set and between electrodes of the fourth set.

12. The method of claim 8, wherein:

the recorder electrodes are part of a cochlear electrode array that is located in a cochlea; and

the determined spatial positioning data is distance data of the recorder electrodes from a modiolus wall of the cochlea.

13. The method of claim 8, wherein:

the recorder electrodes are part of a cochlear electrode array that is located in a cochlea; and the determined spatial positioning data is an orientation of the recorder electrodes relative to structure of the cochlea.

14. The method of claim 8, further comprising:

obtaining third data by:

operating a fourth set of electrodes as a source and sink in and/or on the mammal, the fourth set different than the third set, while operating a fifth set of electrodes as recorder electrodes in and/or on the mammal, thereby obtaining third electrical data from the second set of electrodes,

obtaining fourth data by:

operating a sixth set of electrodes as a source and sink in and/or on the mammal, the sixth set different than the fourth set, while operating the fifth set of electrodes as recorder electrodes in and/or on the mammal, thereby obtaining fourth electrical data from the fifth set of electrodes, wherein

the action of evaluating data includes also evaluating the third electrical data and the fourth electrical data,

the electrodes are part of a cochlear electrode array that is located in a cochlea, and the action of determining spatial positioning data based on the evaluation of the data includes determining a distance of the electrodes of the second set from a modiolus wall of the cochlea based on the evaluation of the second and first electrical data and determining a distance of the electrodes of the fifth set from a modiolus wall of the cochlea based on the evaluation of the third electrical data and the fourth electrical data.

15. The method of claim 14, further comprising:

obtaining distance data of a seventh set of electrodes used as recording electrodes from the modiolus wall, the seventh set being different than the second set and the fifth set; and

determining that the electrode array is at least one of over inserted into the cochlea, experienced a tip fold over, or is angularly misaligned by comparing the distance data of at least two of the seventh set, fifth set and second set to one another.

A method, comprising: executing vertical electrical sounding utilizing electrodes of an electrode array of a cochlear implant located in a cochlea; and

determining a positional feature of the electrode array based on the vertical electrical sounding.

17. The method of claim 16, wherein:

the determined positional feature is a tip fold over of the electrode array.

18. The method of claim 16, wherein:

the determined positional feature is a distance of the electrode array from a modiolus wall of the cochlea.

19. The method of claim 16, wherein:

the determined positional feature is a puncture of the electrode array through a wall of the cochlea.

20. The method of claim 16, wherein:

the determined positional feature is an over insertion of the electrode array into the cochlea.

21. The method of claim 16, wherein:

the determined positional feature is a longitudinal location of the electrode array within the cochlea; and

the method further comprises determining based on the longitudinal location of the electrode array within the cochlea that an electrode array fixation failure has occurred.

22. The method of claim 16, wherein:

the determined positional feature is a longitudinal location of the electrode array within the cochlea;

the determined positional feature is determined while implanting the cochlear electrode array into the cochlea; and the method further comprises determining based on the longitudinal location of the electrode array within the cochlea that an electrode array migration has occurred.

23. The method of claim 16, wherein:

the determined positional feature is a distance from fibrous tissue that has grown since the array was implanted in the recipient.

24. A method, comprising:

energizing an electrode implanted in a recipient, the electrode being part of an assembly located in and/or on a recipient;

receiving data from one or more recording electrodes located in and/or on a recipient; and determining spatial position data of the assembly based on the received data.

25. The method of claim 1, wherein:

the spatial position data of the assembly is a distance of the assembly from a wall of tissue of the recipient.

26. The method of claim 25, wherein:

the wall of tissue of the recipient is a wall that is a barrier of a cavity in the recipient that normally contains bodily fluid.

27. The method of claim 25, wherein:

the wall of tissue of the recipient is a modiolus wall of a cochlea;

the assembly is an electrode array of a cochlear implant;

the electrode is located in a duct of the cochlea; and

the spatial position is distance of the electrode array from the modiolus wall relative to the one or more recording electrodes and/or a location between two or more of the recording electrodes.

28. The method of claim 24, wherein:

the assembly is a cochlear electrode array; the method further comprises:

determining, based on the determined spatial position data, that at least one or more of the following has occurred:

(i) a tip fold over;

(v) the electrode array has migrated during implantation.

29. The method of claim 24, wherein:

the assembly is an electrode array assembly;

the spatial position data is a plurality of respective distances of the assembly at respective locations along the array from respective locations of a wall of tissue of the recipient.

30. The method of claim 24, wherein:

the actions of energizing, receiving and determining are actions that are part of a vertical electrical sounding method applied to a mammal.