Spinal Cord Stimulation Lead Coupling With Optical Reflectometry

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Solution Overview

Problem

Existing implantable pulse generators (IPGs) for spinal cord stimulation face challenges such as long-term survival in the harsh in vivo environment, degradation of surrounding tissue, inaccurate lead coupling, and extended recharge times due to eddy currents during battery recharging.

Innovation Solution

The improved IPG design incorporates a non-metallic case for reduced eddy currents during charging, a super ellipse curve shape to minimize erosion, and advanced optical reflectometry for precise lead coupling and dynamic modulation of electrode current based on spinal cord position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metallic case is used in the IPG, then structural strength is improved, but eddy currents are generated during battery recharging causing extended recharge times

Engineering Contradiction:

Improvestructural strengthVSAvoidrecharge time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The patent replaces the metallic case with a non-metallic case material that is substantially free of metal. This substitution eliminates the generation of eddy currents during electromagnetic induction charging, thereby resolving the contradiction between structural strength and recharge time by removing the harmful electromagnetic interaction while maintaining case integrity through alternative materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If a traditional IPG shape is used, then manufacturing is simplified, but surrounding tissue degradation occurs due to erosion

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidtissue degradation

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies a super ellipse curve shape to the IPG case, which features continuously varying curvature without sharp edges or corners. This curved geometry distributes mechanical stress evenly across the tissue-interface, preventing localized erosion and tissue degradation while maintaining manufacturability through modern molding techniques.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Device complexity

If standard lead coupling methods are used, then device complexity is reduced, but measurement accuracy of spinal cord position deteriorates

Engineering Contradiction:

Improvecoupling system complexityVSAvoidspinal cord position accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an optical fiber as an intermediary component that transmits light between the IPG and the spinal cord. This optical intermediary enables precise measurement of spinal cord position and movement through light reflectometry, achieving high measurement precision while keeping the overall system complexity manageable through the use of established optical coupling techniques.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution enhances the longevity of the IPG by reducing mechanical degradation and maintaining a stable optical signal, while also optimizing spinal cord stimulation by dynamically adjusting electrode current, thus improving therapeutic efficacy and reducing noxious stimulation.

Implementation Method 1

the optical fiber is inserted into the stylet channel of the lead body such that the distal end of the optical fiber is in proximity to the distal end of the lead. The IPG includes an optoelectronic device in communication with the optical fiber for transmitting light to and from the spinal cord

Methodology Applied

Scientific EffectOptical reflectometry: Reflection

Implementation Method 2

Extended recharge times due to eddy currents during battery recharging

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Data Source

PatentUS20250186763A1Surgical electrode and lead for use with implanted pulse generator and method of use

Publication Date: 2025.06.12 WAVEGATE CORP

AI summary

An implantable pulse generator (IPG) system and method for spinal cord stimulation (SCS) are disclosed, incorporating advanced percutaneous lead placement, optical fiber integration, and secure lead coupling. A method is provided for inserting and securing an optical fiber within a stylet channel, ensuring precise optical alignment using a frustoconical centering surface and buffer gap. A percutaneous lead placement method is also disclosed, utilizing a Touhy needle-guided approach, securing leads in the IPG header with anchor screws and ferrule alignment mechanisms. The system further includes an optical threading assembly that facilitates fiber insertion, reducing damage and improving optical signal transmission. These innovations enhance stimulation precision, signal stability, and device longevity, reducing power consumption and noxious stimulation. The disclosed methods improve surgical accuracy and lead retention, optimizing spinal cord therapy by maintaining consistent electrode positioning and optical feedback for dynamic current modulation.