Spinal Cord Stimulator Pulses for Low-Power Sub-Perception Therapy
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Solution Overview
Problem
Spinal Cord Stimulation (SCS) therapy can cause paresthesia, and high-frequency stimulation to achieve sub-perception therapy without paresthesia requires more power, leading to frequent battery replacement or charging, and electrode selection is challenging, especially for sub-perception therapy where patients cannot feel the stimulation.
Innovation Solution
Employing new pulsing techniques that utilize symmetric biphasic pulses at lower frequencies, recruiting different neural targets during each phase to provide effective sub-perception therapy while minimizing power consumption, and using a monopolar configuration with a case electrode as the current return.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high-frequency stimulation is used to achieve sub-perception therapy without paresthesia, then pain relief without paresthesia is achieved, but power consumption increases leading to frequent battery replacement or charging
Solution Approach 1:
The patent employs asymmetric biphasic pulses with specific timing characteristics where the cathodic phase duration is longer than the anodic phase duration. This periodic pulsed stimulation at lower frequencies achieves sub-perception therapy without paresthesia while reducing overall power consumption compared to continuous high-frequency stimulation. The interphase period between cathodic and anodic phases further optimizes energy efficiency.
Solution Approach 2:
The patent changes multiple stimulation parameters simultaneously: using asymmetric biphasic waveforms instead of symmetric ones, adjusting pulse widths where cathodic pulse width exceeds anodic pulse width, setting specific frequency ranges (10-1000 Hz), and configuring monopolar electrode arrangements. These parameter changes collectively enable sub-perception therapy without paresthesia at lower power consumption levels.
2Object-affected harmful factors
If high-frequency stimulation is used to achieve sub-perception therapy, then pain relief without paresthesia is achieved, but battery life decreases requiring frequent replacement or charging
Solution Approach 1:
By using periodic pulsed stimulation with asymmetric biphasic waves at optimized frequencies and duty cycles, the system achieves therapeutic effect while minimizing average power draw. The intermittent nature of pulsed stimulation compared to continuous stimulation extends battery life while maintaining sub-perception therapy efficacy without paresthesia.
Solution Approach 2:
Optimizing stimulation frequency, pulse width, and amplitude parameters within specific ranges enables the system to achieve therapeutic thresholds with lower energy consumption, directly extending battery operational life between replacements or charging cycles.
3Ease of operation
If conventional stimulation is used, then electrode selection is straightforward, but effective sub-perception therapy cannot be achieved without causing paresthesia
Solution Approach 1:
The patent employs monopolar configuration where a single cathode electrode is paired with a distributed anode (case electrode), creating localized current density at the cathode site that preferentially recruits specific neural targets. This localized stimulation approach enables sub-perception therapy without paresthesia while maintaining relatively simple electrode selection compared to complex multipolar configurations.
Solution Approach 2:
The asymmetric biphasic pulse waveform with unequal anodic and cathodic phase durations creates non-symmetric current flow patterns that selectively recruit neural fibers based on their orientation and excitability characteristics. This asymmetry enables differentiation between dorsal column fiber recruitment (therapeutic) and other fiber recruitment (causing paresthesia), achieving sub-perception therapy without paresthesia.
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
Achieves pain relief without paresthesia at lower frequencies, reducing power consumption and simplifying electrode selection by recruiting specific neural targets effectively, thus extending battery life and improving therapy efficiency.
Implementation Method 1
stimulation circuitry to deliver stimulation pulses to a patient
Implementation Method 2
a neural response signal present at the sense electrode is measured by connecting the sense electrode to the measurement circuitry
Data Source
Figure 1~2B
Figure 3
Figure 4~5
AI summary
New waveforms for use in an implantable pulse generator or external trial stimulator are disclosed which mimic actively-driven biphasic pulses, and which are particularly useful for providing sub-perception Spinal Cord Stimulation therapy using low frequency pulses. The waveforms comprise anodic and cathodic pulses which are effectively monophasic in nature, although low-level, non-therapeutic charge recovery can also be used.