Closed Loop Neurostimulation Using Evoked Potential Analysis
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Solution Overview
Problem
Traditional spinal cord stimulation systems using burst waveforms face challenges in recording evoked potential signals effectively, leading to a lack of patient feedback and increased risk of over-stimulation due to the non-coherent neuronal activation, which hinders closed-loop adjustment.
Innovation Solution
A method and system that deliver a non-paresthesia stimulation waveform with pulses arranged in bursts separated by inter-burst delays, where an analysis window is positioned to overlap with the refractory state induced by preceding pulses to measure and analyze evoked potential signals, allowing for adjustment of therapy parameters based on activity data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If burst waveform stimulation is used to relieve pain symptoms, then patient comfort is improved, but patient feedback capability deteriorates due to lack of paresthesia
Solution Approach 1:
The patent introduces evoked potential measurement as a feedback mechanism to monitor neural response during burst waveform stimulation. The system measures EP signals during inter-burst delay periods when neurons are in a refractory state, allowing real-time adjustment of stimulation parameters based on actual neural activation levels, thereby compensating for the lack of patient subjective feedback.
Solution Approach 2:
The patent uses evoked potential signals as an intermediary indicator to indirectly assess neural activation and stimulation effectiveness. Since direct patient feedback is unavailable during burst waveform stimulation, the EP signals serve as a mediator that provides objective information about neural response, enabling automated control and adjustment of stimulation parameters.
2Ease of manufacture
If burst waveform stimulation is used to avoid paresthesia, then stimulation comfort is improved, but measurement precision deteriorates due to non-coherent neuronal activation
Solution Approach 1:
The patent positions the analysis window during the inter-burst delay period, before the next burst of stimulation pulses begins. This preliminary timing allows the system to capture evoked potential signals generated by the previous burst while avoiding interference from subsequent stimulation pulses, thereby improving measurement precision despite the non-coherent activation pattern of burst waveforms.
Solution Approach 2:
The patent exploits the periodic structure of burst waveform stimulation, specifically the inter-burst delay intervals, to systematically sample evoked potential signals. By synchronizing measurement with the periodic rhythm of the stimulation protocol, the system can reliably capture neural responses at consistent time points, improving measurement precision across multiple cycles.
3Measurement precision
If analysis window is positioned during refractory state to measure evoked potentials, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent dynamically adjusts the analysis window timing based on the stimulation protocol parameters, specifically positioning it during inter-burst delay periods when neurons are in a refractory state. This dynamic timing strategy allows the system to automatically optimize measurement conditions without requiring complex manual configuration, balancing measurement precision with system usability.
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 enables precise adjustment of the stimulation waveform, improving patient feedback and reducing the risk of over-stimulation by accurately recording evoked potential signals and adapting therapy parameters, thus enhancing the efficacy of spinal cord stimulation.
Implementation Method 1
application of electrical pulses depolarize neurons and generate propagating action potentials into certain regions or areas of nerve tissue
Implementation Method 2
The evoked potential signals may be generated by neuronal transmembrane currents of neurons activated following or in response to the SCS
Data Source
AI summary
Systems and methods to control non-paresthesia stimulation of nerve tissue of a patient are herein disclosed. The systems and methods deliver a non-paresthesia stimulation waveform to at least one electrode proximate to target nerve fibers, and define an analysis window that is positioned to occur at an intermediate point within at least one of a first burst or an inter-burst delay. Additionally, the systems and methods, during the analysis window, measure evoked potential (EP) signals from the target nerve fibers. The systems and methods also analyze the EP signals to obtain activity data for select nerve fiber components, and adjust at least one therapy parameter to change the non-paresthesia stimulation waveform based on the activity data.