ECAP-Based Implantable Lead Location for Spinal Cord Stimulation
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Solution Overview
Problem
During the placement of medical leads near the spinal cord, especially under general anesthesia, surgeons face challenges in determining the optimal position for effective spinal cord stimulation without patient feedback.
Innovation Solution
An implantable medical device (IMD) system that determines the position of stimulating and/or sensing electrodes based on evoked compound action potential (ECAP) signal characteristics, allowing incremental movement of the lead laterally while providing stimuli and recording ECAP signals to identify the desired placement location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If direct visualization of the dura via laminectomy is performed, then the surgeon can visually locate the spinal cord, but the patient cannot provide feedback about stimulation effectiveness
Solution Approach 1:
The system uses ECAP signal feedback to replace patient feedback. The sensing circuitry detects ECAP signals generated by neural tissue in response to stimulation, providing objective feedback about lead placement quality and stimulation effectiveness without requiring patient awareness or response
Solution Approach 2:
The ECAP signal acts as an intermediary between the stimulation and the assessment of therapeutic effectiveness. Instead of directly relying on patient subjective feedback, the system uses the ECAP signal as a mediator to objectively indicate whether the lead is properly positioned and stimulating the intended neural structures
2Ease of operation
If the lead is placed under general anesthesia, then the patient is comfortable and surgery can proceed, but the patient cannot provide feedback on stimulation effectiveness
Solution Approach 1:
The system performs self-assessment of lead placement quality through automated ECAP signal detection and analysis. The IMD independently evaluates whether the lead is properly positioned by monitoring ECAP signals, eliminating the need for patient participation in the assessment process
Solution Approach 2:
The system provides continuous feedback about lead placement quality through ECAP signal monitoring, allowing the surgical team to verify proper positioning without requiring patient awareness or response
3Measurement precision
If ECAP signals are measured at multiple locations, then the desired lead placement location can be identified, but the placement time increases
Solution Approach 1:
The system measures ECAP signals at multiple locations (excessive action) to ensure accurate identification of the optimal lead placement site. By sampling more locations than the absolute minimum, the system guarantees precise localization of the dorsal midline and identifies the best position for therapeutic effectiveness
Solution Approach 2:
The system varies stimulation parameters (amplitude, pulse width, frequency) and measurement locations to optimize ECAP signal detection. By changing these parameters, the system can reliably identify placement quality and locate the optimal position despite the increased time required for multiple measurements
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 method provides a higher degree of confidence in lead placement, ensuring effective therapeutic outcomes even when the patient is under general anesthesia and cannot provide feedback on stimulation effectiveness.
Implementation Method 1
stimulation circuitry configured to generate electrical stimulation deliverable via an electrode combination of an electrode array
Implementation Method 2
sensing circuitry configured to sense an evoked compound action potential (ECAP) signal
Data Source
AI summary
Systems, devices, methods, and techniques are described for using evoked compound action potential (ECAP) signals to determine an implant location for a lead. An example method includes receiving first information representative of a first evoked compound action potential (ECAP) signal sensed in response to a first control stimulus delivered to a first location adjacent to a spinal cord of a patient. The method also includes receiving, second information representative of a second ECAP signal in response to a second control stimulus delivered to a second location adjacent to the spinal cord of the patient. Additionally, the method includes outputting a first indication of the first information representative of the first ECAP signal and a second indication of the second information representative of the second ECAP signal.