EMG-Guided RF Ablation Probe Placement and Lesion Confirmation
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Solution Overview
Problem
Current RF ablation procedures face challenges in accurately placing the probe near the target nerve, distinguishing between target and non-target nerves, and confirming successful lesion formation during the procedure.
Innovation Solution
A system and method that utilize nerve stimulation and monitoring of electrical muscle activity in specific muscle fascicles to guide the placement of the RF ablation probe, differentiate between target and non-target nerves, and confirm the formation of a lesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluoroscopic guidance is used for probe placement, then the procedure can be performed in an outpatient setting with standard imaging, but the measurement precision of nerve location is insufficient
Solution Approach 1:
The patent introduces EMG monitoring as an intermediary technique to bridge the gap between simple fluoroscopic imaging and complex nerve localization. By monitoring electrical activity in adjacent muscles, the system provides indirect but precise information about probe proximity to the target nerve, enhancing measurement precision without requiring complex direct nerve imaging
Solution Approach 2:
The patent replaces reliance on mechanical/floroscopic imaging alone with an electrical field-based detection system. By using electrical stimulation and EMG monitoring to detect nerve proximity, the system substitutes mechanical imaging limitations with electrical field interactions that provide more precise neural structure localization
2Reliability
If electrical stimulation is used to verify probe position, then nerve proximity can be assessed, but the ability to distinguish between target and non-target nerves is insufficient
Solution Approach 1:
The patent implements a feedback mechanism where EMG signals from adjacent muscles provide real-time information about probe position relative to specific nerves. By analyzing the pattern, amplitude, and latency of muscle responses to electrical stimulation, the system distinguishes between target and non-target nerves, enhancing reliability of nerve identification
Solution Approach 2:
The patent segments the assessment by monitoring EMG activity in specific adjacent muscles that are selectively innervated by different nerve roots. By dividing the monitoring into muscle-specific channels, the system can differentiate between adjacent nerves based on which specific muscle fascicles are activated, solving the nerve differentiation problem
3Measurement precision
If RF ablation is performed without immediate verification, then the procedure is simpler and faster, but confirmation of successful lesion formation is lacking
Solution Approach 1:
The patent performs preliminary electrical stimulation and EMG monitoring before and during RF ablation to predict and verify lesion formation. By assessing nerve proximity and function before energy delivery, and monitoring changes during ablation, the system confirms successful lesion formation without significantly extending procedure time
Solution Approach 2:
The patent uses the patient's own muscle responses as the verification mechanism. The EMG system monitors the patient's spontaneous muscle activity and responses to stimulation, allowing the procedure to self-verify success through physiological feedback rather than requiring separate imaging confirmation
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 enables precise placement of the RF ablation probe near the target nerve, effectively differentiates between target and non-target nerves, and provides real-time feedback for confirming successful lesion formation, thereby improving the accuracy and effectiveness of the RF ablation procedure.
Implementation Method 1
a signal generator to deliver a nerve stimulation to the first target nerve via the first probe electrode
Implementation Method 2
a first recording electrode to monitor electrical muscle activity in the medial fascicle of the multifidus muscle
Implementation Method 3
heating the tissue surround the tip to temperatures above 45° C., causing protein coagulation and cellular death. Radiofrequency ablation heats tissue by driving an electrical current between the probe's active tip and a cutaneously placed grounding pad
Implementation Method 4
A thermocouple is attached to the probe and positioned within the thermal field. The thermocouple measures the temperatures within the thermal field and uses the temperature measurements to control the amount of electrical power that is delivered to the tissue
Data Source
AI summary
A system and method for locating a target nerve associated with a facet joint via nerve stimulation and monitoring of electrical muscle activity in a multifidus muscle adjacent the target nerve are described. The system includes a probe housed within a cannula and comprising a probe electrode; a recording electrode for monitoring electrical muscle activity in a medial fascicle of the multifidus muscle; a signal generator; and a controller coupled to the probe electrode and recording electrode. The controller delivers a nerve stimulation from the signal generator to the nerve via the probe electrode and monitors electrical muscle activity in the medial fascicle via the recording electrode. The probe's proximity to the nerve is determined by the electrical muscle activity in the medial fascicle elicited as a result of the nerve stimulation, where the controller provides feedback to a user to guide placement of the probe adjacent the nerve.