RF Probes for Selective Small Nerve Fiber Assessment
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Solution Overview
Problem
Current methods for assessing small nerve fiber function, such as thermal and electrical stimulation, are either expensive, invasive, or non-selective, limiting their clinical applicability and effectiveness in diagnosing small fiber neuropathy.
Innovation Solution
A system utilizing a radiofrequency (RF) generator to deliver RF currents to the skin via small-area RF probes, with a monitoring module to record responses and a microprocessor for analysis, allowing for non-invasive, selective stimulation and assessment of small nerve fiber function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser devices are used for thermal stimulation, then selective activation of small nerve fibers is achieved, but device cost and complexity increase due to required safety equipment
Solution Approach 1:
The patent replaces laser-based thermal stimulation with electrical stimulation using surface electrodes. This substitution eliminates the need for complex laser safety equipment while maintaining the ability to selectively activate small nerve fibers through appropriate stimulation parameters (current intensity, pulse duration, frequency). The electrical stimulation system achieves comparable selectivity without the mechanical and safety complexities of laser systems.
2Device complexity
If Peltier-based thermodes are used for thermal stimulation, then safety equipment is not required, but contact area is large and temperature ramp is slow causing jitter in evoked potential responses
Solution Approach 1:
The patent replaces Peltier-based thermal stimulation with electrical stimulation. This substitution eliminates the inherent limitations of thermal methods (large contact area, slow temperature ramp) while avoiding the need for safety equipment. Electrical stimulation provides precise temporal control and can be delivered through small-area electrodes, achieving both safety and precision without the trade-offs of thermal systems.
3Reliability
If intraepidermal needle electrodes are used for electrical stimulation, then selective activation of small nerve fibers is achieved, but the method becomes invasive and electrodes are not reusable
Solution Approach 1:
The patent applies local quality by using surface electrodes with selectively designed contact areas and impedance characteristics. By optimizing the electrode-skin interface properties (contact area, impedance, geometry), the system achieves selective activation of small nerve fibers without requiring invasive needle penetration. This localized optimization of electrode properties enables non-invasive selective stimulation.
4Ease of operation
If surface electrical stimulation is used, then the method is non-invasive and reusable, but it is not selective for small nerve fibers and coactivates large myelinated Aβ fibers
Solution Approach 1:
The patent achieves selective activation of small nerve fibers through precise control of stimulation parameters: current intensity (micro- to milliamps), pulse duration (milliseconds to seconds), and frequency. By optimizing these parameters, the system exploits the different activation thresholds and rheobase values of small unmyelinated C fibers versus large myelinated Aβ fibers, enabling selective stimulation while maintaining non-invasive surface electrode application.
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 RF system provides a non-invasive, selective, and cost-effective means to assess small nerve fiber function, capable of eliciting brain radiofrequency-evoked potentials for diagnosing small fiber neuropathy without the limitations of existing technologies, including reduced habituation and broad clinical applicability.
Implementation Method 1
a radiofrequency (RF) generator configured to deliver radiofrequency (RF) currents
Data Source
AI summary
The system disclosed herein provides selective Aδ and C small fiber stimulation by means of RF currents applied to the skin using small-area RF probes. The system also records body responses to said stimulation, for example, radiofrequency evoked potentials from the electroencephalogram, reaction times from a push-button and subjective pain ratings from a visual analog scale. These responses are analysed by an algorithm to provide an assessment of the small nerve fiber function. The device and methods may provide for selective small nerve fiber stimulation, followed by objective or subjective quantification of body responses to said stimulation. The device and methods might be used for several purposes, including determination of sensory detection thresholds and pain thresholds to thermal stimuli, objective characterization of pathological conditions involving nociceptive pathways, assistance in the diagnosis and prognosis of small fiber neuropathy, and assessment of efficacy and dose-response relationships of drugs for pain management.