Bi-phasic Paired Pulse TMS for Reliable Brain Response Measurement
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Solution Overview
Problem
Current Transcranial Magnetic Stimulation (TMS) methods using single pulses are inefficient as they require high stimulation levels to elicit a response, leading to unreliable measurements due to interference from coil readings and potential movement during stimulation, making it difficult to accurately map brain functions.
Innovation Solution
Employing bi-phasic double pulses with a lower amplitude second pulse, where the second pulse is generated shortly after the first, and measuring responses when no magnetic stimulation is occurring, reduces the overall stimulation needed and minimizes interference, allowing for more accurate and reliable measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If single pulse TMS stimulation is used to elicit a response from the subject, then the stimulation can be applied, but the subject's response may begin during subsequent stimulations making measurements unreliable
Solution Approach 1:
The patent employs paired pulse TMS stimulation with specific inter-pulse intervals (2-20ms) to create periodic stimulation patterns that elicit reliable motor evoked potentials. The periodic nature of paired pulses allows for consistent neural activation while providing sufficient time for measurement, resolving the contradiction between measurement reliability and time loss.
2Measurement precision
If high intensity stimulation is used to elicit a response, then the response can be obtained, but coil readings interfere with measurements making them impossible or unreliable
Solution Approach 1:
The patent extracts the harmful coil reading interference by using paired pulse stimulation where the second pulse is delivered at a specific interval after the first pulse. This timing separation allows the measurement window to occur when coil artifacts have subsided, enabling accurate recording of motor evoked potentials without contamination from ongoing stimulation artifacts.
3Reliability
If the amount of stimulation is reduced to minimize interference, then less noise is generated, but it becomes difficult to elicit a measureable response from the subject
Solution Approach 1:
The patent changes the stimulation parameters by using paired pulses with optimized intensity ratios (second pulse at 50-100% of first pulse intensity) and specific inter-pulse intervals (2-20ms). This parameter optimization allows eliciting reliable motor evoked potentials at lower overall stimulation intensities compared to single pulse methods, reducing noise while maintaining response measurability.
4Power
If single pulses are used for stimulation, then the method is simple, but the motor threshold is high requiring more stimulation to elicit a response
Solution Approach 1:
The patent applies preliminary action by delivering a first TMS pulse that preconditiones or primes the neural circuitry before delivering the second pulse. This preliminary stimulation facilitates lower threshold activation of motor pathways, reducing the overall power required compared to single pulse stimulation, while the paired pulse protocol remains relatively simple to implement.
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
Bi-phasic double pulses reduce the motor threshold required for stimulation, enabling more effective and reliable measurement of brain responses with reduced noise interference and increased accuracy in cognitive mapping, allowing for greater response reliability and fewer false negatives.
Implementation Method 1
The TMS coil in typical operation produces a series of single pulses which stimulate a particular location on or within a subject's brain
Implementation Method 2
utilizing a bi-phasic double pulse pair from a TMS coil device to stimulate a subject
Data Source
AI summary
It is an aspect of the present invention to provide a method for recording a response to Transcranial Magnetic Stimulation (TMS) utilizing a bi-phasic double pulse pair from a TMS coil device to stimulate a subject wherein the second pulse has a lower amplitude compared to the first pulse in the bi-phasic double pulse pair. Significant advantages are achieved using bi-phasic double pulse pairs, particularly where the second pulse in a pair has an intensity lower than the first. Obtaining measurements is simpler and more accurate as the number and intensity of stimulation can be reduced compared to standard single pulse stimulation.