ECAP-Servoed Neuromodulation Control Policy
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Solution Overview
Problem
Medical devices delivering electrical stimulation face challenges in maintaining effective therapy due to changes in the distance between implanted electrodes and target nerves caused by patient movements, leading to varying neural recruitment and sensitivity to stimulation, which affects therapeutic efficacy and comfort.
Innovation Solution
A system that uses evoked compound action potential (ECAP) signals to determine the type and category of movement-based aggressors, adjusting stimulation parameters such as pulse width, frequency, and shape to maintain optimal therapy delivery by employing control and informed pulses, and employing gain values to modulate stimulation based on detected ECAP characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is delivered to treat patient conditions, then therapeutic effect is achieved, but changes in electrode-nerve distance due to patient movement cause varying neural recruitment and sensitivity, reducing therapy consistency
Solution Approach 1:
The system employs closed-loop feedback by sensing ECAP signals and using them to adjust stimulation parameters. The processor monitors ECAP signal characteristics and automatically modifies pulse width, frequency, or amplitude to compensate for changes in electrode-nerve distance, thereby maintaining consistent therapeutic effect despite patient movement
Solution Approach 2:
The system dynamically adapts stimulation parameters in real-time based on detected ECAP signals. Instead of fixed parameters, the system continuously adjusts pulse width, frequency, and amplitude according to the sensed neural response, enabling the therapy to adapt to changing physiological conditions and patient positioning
2Measurement precision
If control stimulation pulses are delivered to detect ECAP signals, then ECAP detection is enabled, but the control pulses may not contribute to therapeutic effect
Solution Approach 1:
The system delivers control stimulation pulses at reduced amplitude or duration compared to therapeutic pulses, sufficient to elicit detectable ECAP signals but sub-therapeutic in intensity. This partial action enables ECAP monitoring while minimizing impact on overall therapeutic effect, with the understanding that the control pulses serve primarily as measurement probes
Solution Approach 2:
The control stimulation pulses serve as an intermediary mechanism to indirectly assess neural responsiveness. Rather than directly providing therapy, these pulses act as probes that elicit ECAP signals, which then inform the adjustment of separate therapeutic pulses, decoupling the measurement function from the therapeutic function
3Reliability
If stimulation parameter values are adjusted in real-time based on ECAP signals, then therapy effectiveness is maintained, but system complexity increases
Solution Approach 1:
The system performs self-adjustment by automatically processing ECAP signals and modifying stimulation parameters without external intervention. The integrated processor within the stimulation device autonomously analyzes the sensed signals and implements parameter changes, eliminating the need for manual programming or external control systems and thereby managing complexity within the device itself
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively adjusts electrical stimulation therapy in real-time to compensate for changes in electrode-nerve distance, ensuring consistent therapeutic effect and comfort by using ECAP signals to identify aggressors and adjust stimulation parameters, thereby improving treatment efficacy and reducing uncomfortable sensations.
Implementation Method 1
receive, from a sensing electrode located at a target region of a patient, a plurality of evoked compound action potential (ECAP) signals elicited from respective electrical stimuli delivered to the patient
Data Source
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AI summary
Systems, devices, and techniques for adjusting electrical stimulation are described. In some examples, processing circuitry is configured to receive, via a sensing electrode located at a target region of a patient, a plurality of evoked compound action potential (ECAP) signals elicited from respective electrical stimuli delivered to the patient; determine, based on the plurality of ECAP signals, an aggressor category for at least some ECAP signals of the plurality of ECAP signals, the aggressor category determined from a plurality of aggressor categories; determine, based on the aggressor category, a set of control policy parameters that at least partially define closed-loop control of stimulation therapy; and controlling delivery of the stimulation therapy according to at least the set of control policy parameters and one or more subsequent ECAP signals.