Spinal Cord Stimulator ECAP Feedback for Sub-Perception Therapy

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Solution Overview

Problem

Conventional spinal cord stimulation (SCS) systems often cause paresthesia, an uncomfortable side-effect due to orthodromic and antidromic propagation of action potentials, and struggle to deliver sub-perception therapy effectively.

Innovation Solution

The system employs an ECAP algorithm to sense Evoked Compound Action Potentials (ECAPs) using a sense electrode, allowing for adjustment of stimulation parameters to maintain therapy efficacy below patient perception thresholds, thereby minimizing paresthesia and optimizing therapeutic outcomes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional spinal cord stimulation is used to provide pain relief, then therapeutic efficacy is improved, but paresthesia occurs as an uncomfortable side-effect

Engineering Contradiction:

Improvepain relief efficacyVSAvoidparesthesia

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system employs an ECAP algorithm that continuously monitors evoked compound action potentials and provides feedback to adjust stimulation parameters. The algorithm detects neural responses and automatically modulates stimulation intensity to maintain therapeutic efficacy while preventing paresthesia by keeping stimulation below patient perception thresholds.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes stimulation parameters (intensity, pulse width, frequency) based on detected ECAP amplitudes and patient-specific thresholds. By adjusting these parameters in real-time, the system optimizes pain relief while minimizing paresthesia, delivering sub-perception therapy that is therapeutically effective but imperceptible to the patient.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If stimulation intensity is increased to improve pain relief, then therapeutic efficacy is improved, but patient perception and discomfort increase

Engineering Contradiction:

Improvepain relief efficacyVSAvoidpatient comfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The ECAP algorithm provides real-time feedback on neural response amplitude and patient perception threshold, enabling automatic adjustment of stimulation intensity. This feedback mechanism allows the system to deliver maximum effective stimulation while preventing patient discomfort by stopping before perception thresholds are reached.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs self-adjustment of stimulation parameters based on automated ECAP detection and analysis. The algorithm independently monitors neural responses and modulates stimulation without requiring manual intervention, optimizing the balance between pain relief efficacy and patient comfort.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If sub-perception therapy is delivered to avoid paresthesia, then patient comfort is improved, but difficulty in monitoring neural response increases

Engineering Contradiction:

Improvepatient comfortVSAvoidneural response detection

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system replaces subjective patient feedback (mechanical/physical sensation reporting) with objective electrical signal detection (ECAP measurement). By using the ECAP algorithm to detect neural responses electrically, the system can monitor therapy effectiveness without requiring patient perception, thus maintaining sub-perception comfort levels while enabling precise monitoring.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The ECAP signal serves as an intermediary between the stimulation electrode and the patient's perceptual system. The algorithm detects ECAPs that occur below perception thresholds, providing a measurable proxy for neural activation that correlates with therapeutic efficacy without causing patient discomfort.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Measurement precision

If ECAP detection is implemented to enable automatic adjustment, then therapy precision is improved, but device complexity increases

Engineering Contradiction:

Improveneural response measurementVSAvoidalgorithm and circuitry complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The ECAP algorithm is integrated into the existing implantable pulse generator, allowing the same device to perform both stimulation delivery and neural response detection. This multi-functionality reduces overall system complexity compared to separate detection and stimulation systems, as the algorithm leverages existing hardware resources for dual purposes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 ECAP algorithm enables precise adjustment of stimulation parameters, ensuring pain relief without paresthesia by detecting and responding to neural responses, thus enhancing the effectiveness of SCS therapy.

Implementation Method 1

sense Evoked Compound Action Potentials (ECAPs) in response to stimulation

Methodology Applied

Scientific EffectElectrical potential detection: Electric Field

Data Source

PatentUS12533519B2Automatic adjustment of sub-perception therapy in an implantable stimulator using detected compound action potentials

Publication Date: 2026.01.27 BOSTON SCI NEUROMODULATION CORP

AI summary

Medical device systems and methods for providing spinal cord stimulation (SCS) are disclosed. The SCS systems and methods provide therapy below the perception threshold of the patient. The methods and systems are configured to measure neurological responses to stimulation and use the neurological responses as biomarkers to maintain and adjust therapy. An example of neurological responses includes an evoked compound action potential (ECAP).