Spinal Cord Stimulator Feedback for Lead Migration Compensation
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Solution Overview
Problem
Existing spinal cord stimulation (SCS) systems face challenges with electrode migration, leading to ineffective or noxious stimulation due to inadequate adjustment of electrical current as the leads move, and existing anchoring methods risk nerve damage or are ill-suited for spinal cord stimulation.
Innovation Solution
An IPG system incorporating electrical resistivity monitoring with NIR reflectometry to detect lead migration, automatically adjusting stimulation signals based on optical and resistivity thresholds to maintain optimal spinal cord segment targeting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical lead is implanted in epidural space for spinal cord stimulation, then pain relief is achieved through electrical current delivery to spinal cord, but lead migration occurs causing ineffective or noxious stimulation
Solution Approach 1:
The patent implements a feedback mechanism where the IPG continuously monitors lead position using optical reflectometry sensors and electrical impedance measurements. When migration is detected, the system automatically adjusts stimulation parameters or alerts the clinician, creating a closed-loop control system that maintains therapeutic efficacy despite lead movement
Solution Approach 2:
The patent replaces mechanical anchoring methods (surgical fixation to bone or ligament) with a sensor-based detection and compensation system. Instead of relying on physical restraint, the system uses optical and electrical fields to monitor and respond to lead position changes, eliminating the need for invasive anchoring procedures
2Stability of the object's composition
If existing anchoring methods are used to secure lead, then lead migration is reduced, but nerve damage risk increases or spinal cord stimulation becomes unsuitable
Solution Approach 1:
The patent introduces optical reflectometry sensors and electrical impedance measurements as intermediary detection mechanisms. These intermediaries indirectly monitor lead position without requiring direct mechanical contact or anchoring to neural structures, thereby detecting migration while avoiding nerve damage
Solution Approach 2:
The system enables the lead to self-monitor its own position through integrated sensors that detect changes in optical reflectance and electrical impedance characteristics. This self-service capability eliminates the need for external surgical anchoring, allowing the lead to maintain position stability through active detection and compensation rather than passive mechanical restraint
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 system effectively compensates for lead migration, ensuring consistent and non-noxious spinal cord stimulation by dynamically adjusting electrical current, thereby maintaining therapeutic efficacy.
Implementation Method 1
determine both optically and electrically if migration occurs between the electrodes
Implementation Method 2
An optical signal can be transmitted into the surrounding tissue and collected by a sensor to calculate the approximate distance between the electrode and the spinal canal
Data Source
AI summary
In the present invention, an IPG incorporates electrical resistivity monitoring with a reflectometry trigger. The IPG is configured to determine both optically and electrically if migration occurs between the electrodes. If the light intensity variation in the optical trigger is greater than an optical threshold value, then the system will pause stimulation and conduct a resistivity test. A resistivity test is also conducted periodically in the absence of the reflectometry trigger to verify that no lead migration has occurred. The stimulation signal is automatically adjusted if a variation in resistivity values is detected above a resistivity threshold value. The resistivity threshold value is set above the normal variation that occurs due to routine movement of the spinal cord in the spinal canal.