ECAP-Guided Stimulation Control for Transient Overstimulation
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Solution Overview
Problem
Existing electrical stimulation therapies face challenges in managing transient overstimulation due to patient movement, which can cause discomfort or pain as electrodes move closer to target tissues, and reduced efficacy when they move farther away, due to changes in distance and neural recruitment.
Innovation Solution
A medical device adjusts stimulation parameters based on evoked compound action potentials (ECAPs) by reducing intensity when a characteristic exceeds a threshold and restoring it when the characteristic falls below the threshold, using a semi-closed-loop technique to prevent transient overstimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intensity of electrical stimulation pulses is increased to maintain therapeutic efficacy when electrodes move farther from target tissue, then the therapeutic effect is preserved, but transient overstimulation and patient discomfort increase when electrodes move closer
Solution Approach 1:
The stimulation parameter is made dynamic by automatically adjusting the intensity of electrical pulses based on real-time ECAP measurements. The system transitions from a fixed predetermined intensity to a variable intensity that adapts to changing electrode-tissue distance, resolving the contradiction between maintaining therapeutic efficacy and preventing overstimulation
Solution Approach 2:
The system implements feedback control by measuring ECAPs in response to stimulation pulses and using these measurements to adjust subsequent stimulation parameters. The ECAP characteristic serves as feedback indicating electrode-tissue distance changes, enabling the system to compensate for movement and maintain optimal therapeutic effect without causing overstimulation
2Object-affected harmful factors
If the intensity of electrical stimulation pulses is decreased to prevent transient overstimulation when electrodes move closer to target tissue, then patient discomfort is reduced, but therapeutic efficacy is compromised when electrodes move farther away
Solution Approach 1:
The stimulation intensity is dynamically adjusted based on ECAP measurements rather than being fixed at a reduced level. This allows the system to prevent overstimulation when electrodes are close while restoring full therapeutic intensity when electrodes move farther away, eliminating the need to compromise efficacy
Solution Approach 2:
ECAP measurements provide feedback on electrode-tissue distance, enabling the system to intelligently modulate stimulation intensity. When ECAP characteristics indicate close proximity (risk of overstimulation), intensity is reduced; when ECAP characteristics indicate farther distance (risk of insufficient therapy), intensity is increased, thus resolving the contradiction
3Adaptability or versatility
If a closed-loop system is implemented to automatically adjust stimulation parameters based on ECAP feedback, then transient overstimulation is managed effectively, but device complexity increases
Solution Approach 1:
The system implements feedback control by measuring ECAPs in response to stimulation pulses and using these measurements to adjust subsequent stimulation parameters. The ECAP characteristic serves as feedback indicating electrode-tissue distance changes, enabling the system to compensate for movement and maintain optimal therapeutic effect without causing overstimulation
Solution Approach 2:
The system performs self-adjustment of stimulation parameters based on its own ECAP measurements without requiring external intervention. The device autonomously monitors its performance through ECAP feedback and automatically modifies its operation, reducing the need for manual programming and simplifying the user interface
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
This approach effectively manages transient overstimulation by adjusting stimulation parameters, ensuring consistent therapeutic efficacy while minimizing discomfort or pain, by utilizing ECAPs as feedback to adjust stimulation intensity.
Implementation Method 1
An evoked compound action potential (ECAP) is synchronous firing of a population of neurons which occurs in response to the application of a stimulus including, in some cases, an electrical stimulus by a medical device.
Data Source
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AI summary
Evoked compound action potentials (ECAPs) may be used to determine therapy. For example, a medical device includes stimulation generation circuitry and processing circuitry. The processing circuitry is configured to determine if a characteristic of a first ECAP is greater than a threshold ECAP characteristic value. Based on the characteristic of the first ECAP being greater than the threshold ECAP characteristic value, the processing circuitry is configured to decrease a parameter of a first set of pulses delivered by the stimulation generation circuitry after the first ECAP. Additionally, the processing circuitry is configured to determine if a characteristic of a second ECAP is less than the threshold ECAP characteristic value and based on the characteristic of the second ECAP being less than the threshold ECAP characteristic value, increase a parameter of a second set of pulses delivered by the stimulation generation circuitry after the second ECAP.