# US 10,500,399 B2 · Method and device for feedback control of neural stimulation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,500,399 B2 - Document ID: US10500399B2 - Status: Granted - Kind: B2 - Application number: 15/535,008 - Filed: 2015-12-11 - Published: 2017-12-21 - Granted: 2019-12-10 - Earliest claimed: 2014-12-11 - Assignees: Saluda Medical Pty Ltd - Applicants: Saluda Medical Pty Ltd - Inventors: Peter Scott Vallack Single - Web page: https://patentgrep.com/patent/US10500399B2 ## CPC - A61N 1/36139: {with automatic adjustment} - A61N 1/0551: {Spinal or peripheral nerve electrodes} - A61N 1/36062: {Spinal stimulation} - A61N 1/36071: {Pain} - A61N 1/36067: {Movement disorders, e.g. tremor or Parkinson disease (stimulating motor muscle A61N1/36003)} - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) ## Abstract A method of controlling a neural stimulus by use of feedback. The neural stimulus is applied to a neural pathway in order to give rise to an evoked action potential on the neural pathway. The stimulus is defined by at least one stimulus parameter. A neural compound action potential response evoked by the stimulus is measured. From the measured evoked response a feedback variable is derived. A feedback loop is completed by using the feedback variable to control the at least one stimulus parameter value. The feedback loop adaptively compensates for changes in a gain of the feedback loop caused by electrode movement relative to the neural pathway. ## Claims ### Claim 1 A method of controlling a neural stimulus, the method comprising: applying the neural stimulus to a neural pathway in order to give rise to an evoked action potential on the neural pathway, the stimulus being defined by at least one stimulus parameter; measuring a neural compound action potential response evoked by the stimulus, and deriving from the measured evoked response a feedback variable; completing a feedback loop by using the feedback variable to control the at least one stimulus parameter value; and adaptively compensating for changes in a gain of the feedback loop caused by electrode movement relative to the neural pathway, wherein adaptively compensating for changes in the feedback loop comprises maintaining a corner frequency of the feedback loop at a desired value or within a desired range; and wherein the desired value or range of the corner frequency is selected to suitably attenuate low frequency noise such as heartbeat as well as high frequency noise such as electrical amplifier noise. ### Claim 2 A method of controlling a neural stimulus, the method comprising: applying the neural stimulus to a neural pathway in order to give rise to an evoked action potential on the neural pathway, the stimulus being defined by at least one stimulus parameter; measuring a neural compound action potential response evoked by the stimulus, and deriving from the measured evoked response a feedback variable; completing a feedback loop by using the feedback variable to control the at least one stimulus parameter value; and adaptively compensating for changes in a gain of the feedback loop caused by electrode movement relative to the neural pathway, wherein adaptively compensating for changes in the feedback loop comprises maintaining a corner frequency of the feedback loop at a desired value or within a desired range; and wherein the desired value or range of the corner frequency is selected to bias attenuation of heartbeat and noise while the recipient is in a more or most sensitive posture. ### Claim 3 (depends on 1) The method of claim 1 wherein the feedback loop is a first order feedback loop. ### Claim 4 (depends on 1) The method of claim 1 wherein the feedback loop is a second order feedback loop. ### Claim 5 (depends on 1) The method of claim 1 further comprising determining an estimate P′ of a slope P of a current ECAP growth curve. ### Claim 6 (depends on 5) The method of claim 5 wherein the estimation P′ is produced from an empirical relationship of stimulus current to measured ECAP amplitude. ### Claim 7 (depends on 5) The method of claim 5 wherein the estimation P′ is estimated as P′=(V+K)/I, where V is ECAP amplitude, K is a constant or function which relates P to a stimulus threshold T, and I is stimulus current amplitude. ### Claim 8 (depends on 5) The method of claim 5 wherein the estimate P′ is introduced into the feedback loop to counteract the effect of P. ### Claim 9 (depends on 8) The method of claim 8 wherein an error signal of the feedback loop is scaled by 1/P′. ### Claim 10 (depends on 1) The method of claim 1 wherein the feedback variable is an amplitude measure of the evoked compound action potential. ### Claim 11 (depends on 1) The method of claim 1 wherein the stimulus parameter is stimulus current. ### Claim 12 (depends on 1) The method of claim 1 wherein the set point of the feedback loop is configured so as to seek a constant value of ECAP amplitude. ### Claim 13 (depends on 1) The method of claim 1 wherein the set point of the feedback loop is configured so as to seek a target ECAP amplitude which changes over time as defined by a therapy map. ### Claim 14 An implantable device for controllably applying a neural stimulus, the device comprising: a plurality of electrodes including one or more nominal stimulus electrodes and one or more nominal sense electrodes; a stimulus source for providing a stimulus to be delivered from the one or more stimulus electrodes to a neural pathway in order to give rise to an evoked action potential on the neural pathway; measurement circuitry for recording a neural compound action potential signal sensed at the one or more sense electrodes; and a control unit configured to: control application of a neural stimulus as defined by at least one stimulus parameter; measure via the measurement circuitry a neural compound action potential response evoked by the stimulus; determine from the measured evoked response a feedback variable; complete a feedback loop by using the feedback variable to control the at least one stimulus parameter value; and adaptively compensate for changes in a gain of the feedback loop caused by electrode movement relative to the neural pathway, by maintaining a corner frequency of the feedback loop at a desired value or within a desired range, and wherein the desired value or range of the corner frequency is selected to suitably attenuate low frequency noise such as heartbeat as well as high frequency noise such as electrical amplifier noise. ### Claim 15 A non-transitory computer readable medium for controllably applying a neural stimulus, comprising the following instructions for execution by one or more processors: computer program code means for applying the neural stimulus to a neural pathway in order to give rise to an evoked action potential on the neural pathway, the stimulus being applied as defined by at least one stimulus parameter; computer program code means for measuring a neural compound action potential response evoked by the stimulus and deriving from the measured evoked response a feedback variable; computer program code means for completing a feedback loop by using the feedback variable to control the at least one stimulus parameter value; and computer program code means for adaptively compensating for changes in a gain of the feedback loop caused by electrode movement relative to the neural pathway, by maintaining a corner frequency of the feedback loop at a desired value or within a desired range, and wherein the desired value or range of the corner frequency is selected to suitably attenuate low frequency noise such as heartbeat as well as high frequency noise such as electrical amplifier noise. ### Claim 16 (depends on 14) The implantable device of claim 14 wherein the feedback loop is a first order feedback loop. ### Claim 17 (depends on 14) The implantable device of claim 14 wherein the feedback loop is a second order feedback loop. ### Claim 18 (depends on 14) The implantable device of claim 14 wherein the control unit is further configured to determine an estimate P′ of a slope P of a current ECAP growth curve. ### Claim 19 (depends on 18) The implantable device of claim 18 wherein the control unit is configured to produce the estimate P′ from an empirical relationship of stimulus current to measured ECAP amplitude. ### Claim 20 (depends on 18) The implantable device of claim 18 wherein the control unit is further configured to estimate P′ as P′=(V+K)/I, where V is ECAP amplitude, K is a constant or function which relates P to a stimulus threshold T, and I is stimulus current amplitude.