IPG ECAP Algorithm for Desynchronized Neural Firing

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Solution Overview

Problem

Current spinal cord stimulation systems using implantable pulse generators (IPGs) often cause paresthesia, a tingling sensation, due to synchronous firing of neurons at low-frequency stimulation, which is undesirable and difficult to mitigate with high-frequency stimulation that requires more power and larger batteries.

Innovation Solution

An improved IPG with control circuitry and an Evoked Compound Action Potential (ECAP) algorithm that senses neuronal firing synchronicity and adjusts the stimulation program to promote desynchronous firing by adding active electrodes, modifying pulse timing, frequency, or amplitude, reducing paresthesia while maintaining therapeutic effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If low-frequency stimulation is used, then power consumption is reduced and battery size is minimized, but synchronous neuronal firing occurs causing paresthesia

Engineering Contradiction:

ImproveparesthesiaVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts stimulation parameters including frequency, pulse width, and amplitude based on real-time ECAP monitoring to achieve desynchronized neuronal firing while maintaining power efficiency. The stimulation program is not fixed but adapts to physiological feedback, allowing the system to operate at optimal power consumption levels without causing paresthesia.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes multiple stimulation parameters simultaneously (frequency, pulse width, amplitude, electrode configuration) to transition from synchronous to desynchronized neuronal firing patterns. By modifying these parameters based on ECAP analysis, the system eliminates paresthesia without necessarily increasing power consumption, as the parameter changes optimize rather than simply increase energy delivery.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If high-frequency stimulation is used to reduce paresthesia, then neuronal firing becomes desynchronized, but power consumption increases and battery size must be larger

Engineering Contradiction:

ImproveparesthesiaVSAvoidbattery size

Core Design Contradiction:

Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

The system uses ECAP feedback to monitor neuronal response in real-time and adjusts stimulation parameters accordingly. This closed-loop control allows the system to achieve desynchronized firing patterns that eliminate paresthesia while consuming less power than continuous high-frequency stimulation, thereby reducing battery size requirements.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

Rather than using fixed high-frequency stimulation, the system dynamically modulates frequency and other parameters based on ECAP measurements. This dynamic approach achieves the therapeutic benefit of desynchronized firing without the continuous high power demand of static high-frequency protocols, reducing overall energy consumption and battery size.

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If stimulation parameters are adjusted to promote desynchronous firing, then paresthesia is reduced, but device complexity increases due to ECAP algorithm and control circuitry

Engineering Contradiction:

ImproveparesthesiaVSAvoidcontrol circuitry

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The IPG performs multiple functions using the same hardware components: it delivers stimulation, records ECAPs, processes signals through the algorithm, and adjusts parameters all through integrated control circuitry. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby limiting the increase in device complexity despite the advanced capabilities required for desynchronized firing control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If ECAP algorithm is implemented to monitor and adjust stimulation, then therapeutic effectiveness is improved, but power consumption increases

Engineering Contradiction:

Improvetherapeutic effectivenessVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The ECAP monitoring and parameter adjustment occur periodically rather than continuously. The system measures ECAPs at intervals and adjusts stimulation parameters in a cyclical manner, which reduces the average power consumption compared to continuous monitoring and adjustment, while still maintaining therapeutic effectiveness through regular optimization.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12128236B2Pulse generator system for promoting desynchronized firing of recruited neural populations

Publication Date: 2024.10.29 BOSTON SCI NEUROMODULATION CORP

AI summary

An Implantable Pulse Generator (IPG) is disclosed that is capable of sensing a degree to which recruited neurons in a patient's tissue are firing synchronously, and of modifying a stimulation program to promote desynchronicity and to reduce paresthesia. An evoked compound action potential (ECAP) of the recruited neurons is sensed as a measure of synchronicity by at least one non-active electrode. An ECAP algorithm operable in the IPG assesses the shape of the ECAP and determines one or more ECAP shape parameters that indicate whether the recruited neurons are firing synchronously or desynchronously. If the shape parameters indicate significant synchronicity, the ECAP algorithm can adjust the stimulation program to promote desynchronous firing.