Neurostimulation System Using Non-Rectangular Pulses to Reduce Paresthesia
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Solution Overview
Problem
Current spinal cord stimulation (SCS) therapies often require paresthesia sensations to provide pain relief, but a paresthesia-free method using high-frequency stimulation has shown efficacy, and there is a need to recruit deeper and smaller diameter nerve fibers to enhance therapy efficacy without causing perception.
Innovation Solution
A neurostimulation system with multiple electrodes delivering therapeutic and charge-balancing pulses of non-rectangular shape, where each therapeutic pulse is accompanied by multiple charge-balancing pulses of opposite polarity, allowing for efficient recruitment of smaller diameter fibers and minimizing paresthesia by controlling the recruitment order of axonal diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rectangular stimulation pulses are used to recruit deeper and smaller diameter nerve fibers, then therapy efficacy is improved, but large diameter fibers are preferentially activated causing paresthesia
Solution Approach 1:
The patent inverts the conventional rectangular pulse shape to use a non-rectangular waveform with a gradual rising phase. This inversion of the pulse shape prevents preferential activation of large diameter fibers by avoiding the abrupt onset that triggers them, thereby reducing paresthesia while maintaining therapeutic efficacy through sustained stimulation of smaller diameter fibers.
Solution Approach 2:
The patent changes the temporal parameters of the stimulation pulse by using a non-rectangular waveform with a prolonged rising phase rather than an abrupt onset. This parameter change in the pulse shape modifies the recruitment order of nerve fibers, allowing deeper and smaller diameter fibers to be activated without triggering the large diameter fibers that cause paresthesia.
2Reliability
If high-frequency stimulation is used to achieve paresthesia-free pain relief, then pain relief efficacy is improved, but charge consumption increases
Solution Approach 1:
The patent employs periodic charge-balancing pulses interspersed with therapeutic stimulation pulses. This periodic action allows the system to deliver high-frequency therapeutic stimulation while periodically resetting the charge balance, preventing charge accumulation and enabling sustained high-frequency operation without excessive charge consumption.
Solution Approach 2:
The patent uses charge-balancing pulses that discard excess charge buildup during therapeutic stimulation and recover charge efficiency by maintaining electrochemical balance. This approach allows sustained high-frequency stimulation by periodically eliminating charge accumulation that would otherwise limit the duration and efficiency of therapy delivery.
3Reliability
If multiple charge-balancing pulses are delivered with each therapeutic pulse, then charge balance is improved, but device complexity increases
Solution Approach 1:
The patent segments the charge-balancing function into multiple discrete pulses that are delivered sequentially after each therapeutic pulse. This segmentation of the charge-balancing process into distinct temporal phases simplifies the control logic compared to continuous balancing, as each pulse can be independently controlled and timed to achieve cumulative charge balance.
Solution Approach 2:
The patent maintains continuous charge balance through a series of follow-up pulses that collectively neutralize the charge from each therapeutic pulse. This continuous balancing action, distributed across multiple pulses rather than a single complex operation, maintains electrochemical safety while using straightforward pulse delivery sequences that simplify device architecture.
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
This approach enhances the therapeutic efficacy of SCS by reducing paresthesia and improving pain relief while minimizing power consumption, allowing for more efficient charge utilization and distributed neuron recruitment.
Implementation Method 1
deliver via each electrode of a group of N electrodes (N≤Z and if Z=3 then N=Z) a set of pulses including one therapeutic electric pulse having an amplitude I1, I2, . . . . IN and a number of (N−1) charge balancing electric pulses
Data Source
AI summary
A system and method for neurostimulation of a patient's body includes a device to provide a unique combination of multiphase therapy modes that minimize the recruitment of large diameter nerve fibers and provides distributed neuron recruiting compounding effect thus reducing paresthesia. The system includes a plurality of Z electrodes. For the number of the plurality of electrodes, Z≥3 applies. The delivers, via each electrode of a group of N electrodes (N≤Z and if Z=3 then N=Z), a set of electric pulses including one therapeutic electric pulse having an amplitude I1, I2, . . . . IN and a number of (N−1) charge balancing electric pulses during one cycle. The charge balancing electric pulses each have a polarity being opposite a polarity of the therapeutic electric pulse. Each therapeutic electric pulse and each charge balancing electric pulse have a non-rectangular shape.