Pinging-Pulse ECAP Sensing for Paresthesia-Free Stimulation
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Solution Overview
Problem
Conventional spinal cord stimulation (SCS) techniques face challenges in accurately measuring evoked compound action potentials (ECAPs) due to low signal strength and noise ratios, especially in paresthesia-free stimulation methods like high-frequency and burst stimulation, which can result in ineffective assessment of neural recruitment efficacy.
Innovation Solution
Implementing non-therapeutic pinging-pulses, such as monophasic cathodic or biphasic charge-balanced pulses, interleaved or postfixed with therapeutic bursts, to elicit ECAPs without inducing paresthesia, allowing for reliable signal measurement and analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SCS techniques are used to measure ECAPs, then neural recruitment can be assessed, but signal strength is weak and noise ratio is high making measurement unreliable
Solution Approach 1:
The patent applies periodic action by delivering ECAP elicitation pulses at specific intervals between therapeutic stimulation bursts. The system periodically inserts test pulses (e.g., every 10-100 bursts) to elicit and measure ECAPs, allowing reliable assessment of neural recruitment while maintaining the therapeutic paresthesia-free stimulation regimen. This periodic measurement approach enables accurate monitoring without continuous interference.
Solution Approach 2:
The patent uses an intermediary approach by introducing separate ECAP elicitation pulses that are distinct from the therapeutic stimulation pulses. These intermediary test pulses are designed with specific parameters (amplitude, width, polarity) optimized for ECAP elicitation, acting as a mediator between the therapeutic stimulation and the measurement process. This allows independent optimization of therapeutic and diagnostic functions.
2Object-affected harmful factors
If paresthesia-free stimulation is implemented, then patient comfort is improved, but ECAP measurement becomes difficult due to low signal strength
Solution Approach 1:
The patent applies parameter changes by adjusting the amplitude, pulse width, and polarity of ECAP elicitation pulses independently from the therapeutic stimulation parameters. The system uses higher amplitude test pulses (e.g., 2-5 mA) with optimized pulse widths (50-200 microseconds) specifically tuned to elicit detectable ECAPs without triggering paresthesia. This parameter optimization enables reliable ECAP measurement while maintaining patient comfort during paresthesia-free therapy.
3Object-affected harmful factors
If high-frequency stimulation is used, then paresthesia-free therapy is achieved, but ECAP elicitation is compromised due to frequency interference
Solution Approach 1:
The patent applies segmentation by separating the therapeutic high-frequency stimulation from the diagnostic ECAP elicitation pulses. The system divides the stimulation train into therapeutic bursts (delivered continuously at high frequency) and diagnostic test pulses (inserted periodically at lower frequency). This temporal and functional segmentation allows the high-frequency therapy to maintain paresthesia-free operation while the separately-timed test pulses successfully elicit and measure ECAPs without frequency interference.
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
Enables accurate assessment of neural recruitment and adjustment of stimulation parameters without altering the paresthesia-free therapy, ensuring effective pain management and therapeutic efficacy.
Implementation Method 1
sensing responsive signals, such as evoked compound action potentials (ECAPs), in association with implementation of paresthesia-free stimulation techniques
Data Source
AI summary
Systems and methods which provide for and enable sensing responsive signals with respect to the application of paresthesia-free stimulation are described. Sensing signal initiators may be utilized comprising one or more non-therapeutic and/or non-tonic pulses in the form of pinging-pulses configured for invoking responsive signals suitable for measurement and/or analysis in association with the application of neural stimuli. A sensing signal initiator technique may provide an interleaved implementation to introduce one or more pinging-pulses between burst groups of a burst stimulation regimen. Additionally or alternatively, a sensing signal initiator technique may provide a postfixed implementation to introduce one or more pinging-pulses by modifying a therapeutic stimulation burst so that the last phase of the passive discharge is replaced with pinging-pulse providing an active discharge.