Self-Insulating Nerve Electrode for Non-Lifting NAP Recording
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Solution Overview
Problem
Current methods for intraoperative nerve action potential (NAP) recording are technically challenging due to the need to lift nerves, leading to limited recording lengths and significant stimulus artifacts caused by the 'loop effect', which complicates surgical nerve repairs.
Innovation Solution
A system and method using self-insulating and self-holding electrodes with multiple prongs and an elastic base that allow nerves to be sandwiched between the prongs, eliminating the need to lift the nerve and reducing stimulus artifacts through 'bridge grounding' and impedance monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the nerve is lifted out of the surgical field during testing, then the nerve can be isolated and accessed by electrodes, but the nerve segment length is limited and stimulus artifacts increase
Solution Approach 1:
The electrode is divided into multiple insulated prongs (typically three) that can be independently positioned along the nerve. This segmentation allows the electrode to contact different segments of the nerve simultaneously, effectively extending the functional recording length without requiring the nerve to be lifted or extensively dissected.
Solution Approach 2:
The insulated prongs are nested within a common electrode body or handle, allowing compact storage and easy application. When applied, the prongs can be spread to contact the nerve at multiple points, providing both compact handling and extended functional reach along the nerve trajectory.
2Ease of operation
If the nerve is lifted out of the surgical field during testing, then the nerve can be isolated and accessed by electrodes, but large stimulus artifacts are generated due to the loop effect
Solution Approach 1:
The harmful loop effect is eliminated by extracting the nerve from the loop configuration. The electrode design allows current to flow directly between adjacent prongs along the nerve surface, bypassing the need for current to travel through the lifting loop path, thereby removing the source of stimulus artifacts.
Solution Approach 2:
The insulated prongs act as intermediaries that conduct current directly between contact points on the nerve. This intermediary structure provides a controlled current path that prevents the formation of large current loops, thereby reducing stimulus artifacts while maintaining effective nerve stimulation and recording.
3Ease of operation
If multiple electrodes are used to lift and suspend the nerve, then the nerve can be accessed for recording, but the complexity of the device and procedure increases
Solution Approach 1:
Multiple electrode functions are merged into a single integrated electrode assembly. The multiple prongs are combined into one device that can simultaneously perform stimulation, recording, and nerve positioning functions, eliminating the need for separate electrodes and simplifying the overall procedure.
Solution Approach 2:
The electrode assembly is designed with multi-functionality, where the same set of prongs can be used for both stimulation and recording depending on their configuration and connection. This universal design reduces the number of different device types needed and simplifies the procedural steps.
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
Enables high-quality, non-lifting NAP recordings with reduced stimulus artifacts, allowing for more accurate nerve repair surgeries by maintaining nerve contact with the tissue and minimizing loop effects, thus improving surgical outcomes.
Implementation Method 1
The base is formed from a plastic or silicone and has elastic properties. The elastic base or body with a minimum of two projections on one side and one on the opposing side of the nerve... The electrode is self-insulated and self-holding
Data Source
AI summary
The present invention is directed to an electrode system for recording nerve action potential (NAP) from surgically exposed nerve and methods for using such an electrode system. Electrophysiological methods are used during repair surgery of peripheral nerve trauma (PNT). PNT is a major medical problem with an annual incidence similar to that of epilepsy. Surgical intervention is provided based on the severity of nerve injury which is determined preoperatively and intraoperatively mainly by electrophysiological assessments. Among those, intraoperative nerve action potential (NAP) or compound action potential (CNAP) recording is preferred for direct assessment of functional continuity of the nerve.