Method and apparatus for application of a neural stimulus

A method of suppressing pain by applying therapeutic neural stimuli, the method comprising:

• delivering a therapeutic stimulus from at least one stimulus electrode to an electrically excitable tissue in the dorsal column of a patient;
• measuring a neural response sensed at at least one sense electrode and evoked in response to the therapeutic stimulus;
• measuring one or more of orientation and movement of the at least one stimulus electrode simultaneously with the measurement of the neural response;
• determining an estimate of posture for the patient based on, at least, the measured orientation;
• effecting feedback control of a subsequent therapeutic stimulus delivery in response to receiving the measured neural response, wherein the feedback control takes into account the measured one or more of orientation and movement,
• wherein effecting feedback control of the subsequent therapeutic stimulus delivery comprises altering a parameter of the therapeutic stimulus to bring the measured neural response closer to a target value;
• and
• setting a slow response threshold of the feedback control based on the estimate of posture,
• wherein the slow response is a neural response associated with motor response that is observable at least 2 ms after the therapeutic stimulus.

A neuromodulation system comprising:

• an implantable device comprising:
• a plurality of electrodes including at least one stimulus electrode and at least one sense electrode;
• a stimulus source for providing therapeutic stimuli to be delivered from the at least one stimulus electrode to an electrically excitable tissue in a dorsal column of a patient;
• and
• measurement circuitry for measuring neural responses sensed at the at least one sense electrode, each neural response evoked by and in response to a therapeutic stimulus;
• an accelerometer configured to measure one or more of orientation and movement of the implantable device simultaneously with the measurement of a neural response of the measured neural responses;
• and
• a processor configured to:
• control the stimulus source to provide the therapeutic stimulus;
• receive, from the implantable device, the measured neural response and the one or more of orientation and movement measured by the accelerometer;
• and
• effect feedback control of a subsequent therapeutic stimulus provided by the stimulus source in response to receiving the measured neural response by iteratively altering a parameter of the therapeutic stimulus provided by the stimulus source to bring the measured neural response closer to a target value,
• wherein the feedback control takes into account the one or more of orientation and movement measured by the accelerometer,
• wherein the processor is configured to set a slow response threshold of the feedback control based on an estimate of posture for the patient determined based on, at least, the orientation measured by the accelerometer, and
• wherein the slow response is a neural response associated with motor response that is observable at least 2 ms after the therapeutic stimulus.