Implantable Neural Conduction Velocity Estimation
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Solution Overview
Problem
Current methods for measuring nerve conduction velocity are limited by the difficulty in isolating compound action potentials due to stimulus artefacts, require expensive and invasive procedures, and are constrained by battery power and processing capacity in neural implants, making continuous monitoring challenging.
Innovation Solution
An implantable device with stimulus and measurement electrodes, coupled with processing capabilities to digitize neural measurements, estimate the temporal position of compound action potential features, and calculate conduction velocity using subsample precision, allowing for continuous and accurate monitoring of nerve conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If skin-mounted electrodes are placed at large distances apart for nerve conduction studies, then measurement capability is improved, but cost increases and measurement frequency decreases
Solution Approach 1:
The patent embeds multiple measurement electrodes within the compact structure of an implanted neuromodulation device, nesting the measurement functionality inside the existing implant housing. This allows multiple electrodes to be positioned at optimal distances without requiring separate external equipment, thereby improving measurement precision while avoiding increased device complexity.
Solution Approach 2:
The implanted neuromodulation device performs multiple functions: it delivers therapeutic stimulation and simultaneously measures nerve conduction velocity. By making the device universal, the patent eliminates the need for separate expensive diagnostic equipment, allowing continuous monitoring without increasing overall system complexity.
2Measurement precision
If continuous neural monitoring is implemented, then data accuracy and continuity are improved, but battery power consumption increases
Solution Approach 1:
Instead of continuous monitoring, the patent implements periodic measurement cycles where the device alternates between stimulation phases and measurement phases. During non-measurement periods, the device enters low-power states. This periodic operation maintains measurement accuracy while significantly reducing average power consumption compared to continuous monitoring.
Solution Approach 2:
The device performs measurements at predetermined intervals and stores data for later analysis. By preparing and capturing data periodically rather than continuously processing and transmitting, the patent reduces real-time power consumption while maintaining measurement accuracy and data availability.
3Measurement precision
If stimulus artefact rejection is implemented to isolate CAP signals, then measurement precision is improved, but processing complexity increases
Solution Approach 1:
The patent extracts the stimulus artefact component from the recorded signal using template subtraction. By identifying and removing the known artefact waveform, the system isolates the compound action potential signal. This extraction approach improves measurement precision without requiring complex real-time processing, as the artefact removal can be performed efficiently on captured data.
Solution Approach 2:
The system applies stimulus pulses at higher amplitudes than strictly necessary to evoke the CAP, ensuring that the neural response is well above the noise floor and artefact level. This excessive stimulation approach simplifies signal processing by creating a large signal-to-noise ratio, making artefact rejection easier and more reliable without requiring sophisticated algorithms.
4Device complexity
If single-point-in-time nerve conduction studies are performed, then measurement cost is reduced, but data completeness for monitoring progression decreases
Solution Approach 1:
The patent enables continuous or repeated nerve conduction velocity measurements through the implanted device. By maintaining the measurement capability indefinitely, the system provides ongoing data on nerve function and disease progression. This continuous action replaces single-point studies, ensuring complete information capture without significantly increasing system complexity since the measurement infrastructure already exists in the implant.
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 precise and continuous estimation of nerve conduction velocity, overcoming artefact challenges and improving data accuracy, while optimizing battery life and processing efficiency in neural implants.
Implementation Method 1
An electrical pulse applied to the dorsal column by an electrode causes the depolarisation of neurons, and generation of propagating action potentials
Implementation Method 2
obtaining a digitised neural measurement of at least one compound action potential evoked by the at least one stimulus
Data Source
AI summary
An implantable device, or an associated computer program, for estimating a nerve conduction velocity. A stimulus is applied from one or more stimulus electrodes to a nerve. A digitised neural measurement of at least one compound action potential evoked by the at least one stimulus is obtained from one or more recording electrodes by measurement circuitry. The digitised neural measurement comprises a plurality of data sample points. The digitised neural measurement is processed in order to estimate within subsample precision a temporal position of a feature of interest of the compound action potential. From the estimated temporal position of the feature of interest, and from a propagation distance, a conduction velocity of the compound action potential is determined.