ECAP Feature Detection Using Test Pulses in Paresthesia-Free Stimulation
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Solution Overview
Problem
Conventional methods for measuring evoked compound action potentials (ECAPs) in paresthesia-free neurostimulation techniques, such as burst and high-frequency spinal cord stimulation, face challenges due to low signal strength and noise ratios, making accurate assessment of neural response difficult.
Innovation Solution
Implementing sensing signal stimulation techniques that include pinging-pulses to evoke responsive signals, such as ECAPs, without eliciting paresthesia, by delivering non-therapeutic pulses configured to facilitate measurement and analysis, even in paresthesia-free stimulation regimens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-frequency or burst stimulation is used to provide paresthesia-free pain relief, then patient comfort is improved, but the signal strength and signal-to-noise ratio for ECAP measurement deteriorate
Solution Approach 1:
The stimulation protocol is segmented into two distinct phases: a conditioning phase that delivers high-frequency or burst stimulation for pain relief, and a test phase that delivers isolated test pulses to elicit ECAPs. This segmentation allows the system to benefit from both paresthesia-free pain management and reliable neural response measurement without interference between the two functions.
Solution Approach 2:
The system performs preliminary ECAP measurement during the conditioning phase by incorporating test pulses within or between the high-frequency/burst stimulation cycles. This preliminary action enables the system to assess neural response while the patient experiences pain relief, allowing for real-time optimization of stimulation parameters without requiring separate measurement sessions.
2Measurement precision
If test pulses are delivered at high amplitude to ensure detectable ECAPs, then measurement precision is improved, but the risk of eliciting paresthesia increases
Solution Approach 1:
Different pulse amplitudes are applied to different phases of the stimulation protocol: high amplitudes are used during the conditioning phase to ensure ECAP detectability, while lower amplitudes are used during the test phase to minimize paresthesia risk. The system locally optimizes pulse parameters for each specific function being performed.
Solution Approach 2:
The system delivers excessive stimulation (high amplitude test pulses) only when necessary for measurement purposes, rather than continuously. By limiting high-amplitude pulses to specific measurement windows within the broader stimulation protocol, the system achieves accurate ECAP measurement while minimizing overall paresthesia exposure.
3Device complexity
If conventional ECAP measurement methods are used with paresthesia-free stimulation, then device complexity is reduced, but measurement precision deteriorates due to low signal-to-noise ratio
Solution Approach 1:
The system employs periodic test pulses interspersed within or between the high-frequency/burst stimulation cycles. These periodic measurements allow the system to accumulate multiple ECAP signals over time, improving the signal-to-noise ratio through signal averaging while maintaining a relatively simple measurement architecture.
Solution Approach 2:
The system uses ECAP measurements as feedback to optimize the conditioning stimulation parameters in real-time. By continuously monitoring neural response and adjusting stimulation amplitude, frequency, or pattern based on measured ECAPs, the system improves measurement precision while keeping the overall device architecture manageable through automated closed-loop control.
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 reliable measurement and analysis of ECAPs, allowing for effective closed-loop feedback control of neurostimulation therapy, ensuring pain relief without inducing paresthesia.
Implementation Method 1
an electrode array present on a distal end of a lead may be implanted so as to be disposed within the epidural space for delivery of the electrical stimulation
Implementation Method 2
A sensing element may be disposed at a distal end of the lead, rostrally to the electrode array, and configured to sense an evoked compound action potential (ECAP) signal
Data Source
AI summary
Systems and methods are disclosed for conducting spinal cord stimulation or other neurostimulation and sensing evoked compound action potential (ECAP) signals. The sensed signals may be processed to isolate ECAP features from noise and/or interfering signals. The isolated ECAP features may be used to control neurostimulation therapy for the patient and/or guide an implant procedure.