ECAP-Based Stimulation Control for Neural Devices
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Solution Overview
Problem
Medical devices delivering electrical stimulation face challenges in maintaining effective therapy as the distance between electrodes and target nerves changes due to patient movement, leading to variations in neural recruitment and perception of stimulation, which can result in discomfort or loss of therapeutic efficacy.
Innovation Solution
A system that adjusts the parameters of electrical stimulation pulse trains based on evoked compound action potential (ECAP) signals, using a combination of control and informed pulses to maintain a target ECAP value, thereby compensating for changes in electrode-nerve distance and ensuring consistent therapeutic effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical stimulation is delivered via implanted electrodes, then therapeutic effect is achieved, but the distance between electrodes and target nerves changes with patient movement, causing variation in neural recruitment and perception
Solution Approach 1:
The system senses ECAP signals from the target nerve in response to stimulation pulses and uses the characteristic value of the ECAP signal as feedback to automatically adjust stimulation parameters. This closed-loop feedback mechanism compensates for changes in electrode-nerve distance caused by patient movement, maintaining consistent neural recruitment and therapeutic effect.
Solution Approach 2:
The system dynamically adjusts stimulation parameters (amplitude, pulse width, frequency) based on real-time ECAP signal characteristics. Rather than using fixed parameters, the system adapts the stimulation delivery in response to changing electrode-nerve distances, making the therapy reliable despite patient movement.
2Reliability
If stimulation parameters are adjusted to compensate for distance changes, then consistent neural recruitment is maintained, but system complexity increases due to ECAP sensing and automatic adjustment mechanisms
Solution Approach 1:
The same electrodes used for delivering stimulation are also used for sensing ECAP signals. This multi-functionality reduces the need for separate sensing electrodes and simplifies the overall system architecture while enabling closed-loop control.
Solution Approach 2:
The system uses the patient's own neural tissue to generate the ECAP signal that serves as feedback. The biological system itself provides the sensing mechanism, eliminating the need for complex external sensors and reducing overall system complexity.
3Reliability
If ECAP sensing is used to adjust stimulation parameters, then therapeutic efficacy is maintained, but energy consumption increases due to continuous sensing and adjustment operations
Solution Approach 1:
The system delivers stimulation in discrete pulse trains and senses ECAP signals at specific intervals following each pulse train. This periodic sensing and adjustment approach, rather than continuous operation, reduces energy consumption while maintaining therapeutic efficacy through regular feedback cycles.
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 maintains consistent neural recruitment and therapeutic efficacy by dynamically adjusting stimulation parameters in response to changes in electrode-nerve distance, reducing discomfort and maintaining effective pain relief or symptom management.
Implementation Method 1
The system may sense an ECAP signal elicited by a pulse of the base pulse train
Data Source
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AI summary
Systems, devices, and techniques for adjusting electrical stimulation based on sensed ECAP signals. For example, processing circuitry is configured to control delivery of a first train of electrical stimulation pulses at a first frequency to a first target tissue and control delivery of a second train of electrical stimulation pulses at a second frequency to a second target tissue different from the first target tissue. The processing circuitry can also receive an ECAP signal elicited by a pulse of the second train of electrical stimulation pulses, adjust, based on the ECAP signal, a first value of a parameter that at least partially defines the first tram of electrical stimulation pulses to a second value, and, responsive to adjusting the first value of the parameter to the second value, control delivery of subsequent pulses of the first tram of electrical stimulation pulses according to the second value of the parameter.