Spinal Cord Stimulation Sweet Spot Search for Paresthesia-Free Therapy
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Solution Overview
Problem
Existing spinal cord stimulation (SCS) systems often cause paresthesia, which is the tingling or numbness sensation that patients experience due to electrical stimulation, and there is a need for methods to provide pain relief without inducing these sensations.
Innovation Solution
The method involves programming spinal cord stimulators to generate stimulation pulses with specific frequencies and pulse widths that do not cause paresthesia, using biphasic pulses with equal but opposite polarities, and adjusting current steering to optimize the location and amplitude of stimulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spinal cord stimulation is used to provide pain relief, then pain relief is achieved, but paresthesia (tingling or numbness sensation) is induced
Solution Approach 1:
The patent applies parameter changes by modifying stimulation frequency and pulse width parameters to achieve pain relief without paresthesia. Specifically, it uses low frequency (1-100 Hz) and long pulse width (100-1000 μs) combinations that activate pain-inhibiting neural pathways while avoiding the tingling sensations associated with conventional high-frequency stimulation.
Solution Approach 2:
The patent employs periodic action through rhythmic stimulation patterns where the spinal cord stimulator delivers pulses at controlled intervals. The periodic nature of the stimulation at low frequencies creates natural rhythm that synchronizes with pain-modulating neural oscillations, providing analgesia without overwhelming the sensory system with paresthesia.
2Reliability
If higher frequency stimulation is used to provide pain relief, then pain relief effectiveness increases, but power consumption increases
Solution Approach 1:
The patent applies parameter changes by inverting the conventional wisdom about frequency and power consumption. Instead of using high frequency to improve pain relief effectiveness, it uses low frequency (1-100 Hz) combined with long pulse width to achieve the same analgesic effect while dramatically reducing power consumption. This counterintuitive parameter selection directly addresses the contradiction by showing that lower frequency can be more efficient for pain relief.
Solution Approach 2:
The patent applies partial action by using longer pulse width (100-1000 μs) than conventional brief pulses to maximize neural activation during each stimulation cycle. This extended pulse duration ensures adequate pain inhibition is achieved with fewer, lower-frequency pulses, thereby reducing overall power consumption while maintaining or improving pain relief effectiveness.
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 effectively provides pain relief without causing paresthesia by selecting optimal frequency and pulse width combinations that require minimal power, allowing for precise control of stimulation parameters to minimize discomfort.
Implementation Method 1
The IPG 10 includes a biocompatible device case 12 that holds the circuitry and battery 14 necessary for the IPG to function... The IPG 10 is coupled to electrodes 16 via one or more electrode leads 15... The goal of SCS therapy is to provide electrical stimulation from the electrodes 16 to alleviate a patient's symptoms
Data Source
AI summary
Methods and systems for testing and treating spinal cord stimulation (SCS) patients are disclosed. Patients are eventually treated with sub-perception (paresthesia free) therapy. However, supra-perception stimulation is used during “sweet spot searching” during which active electrodes are selected for the patient. This allows sweet spot searching to occur much more quickly and without the need to wash in the various electrode combinations that are tried. After selecting electrodes using supra-perception therapy, therapy is titrated to sub-perception levels using the selected electrodes. Such sub-perception therapy has been investigated using pulses at or below 10 kHz, and it has been determined that a statistically significant correlation exists between pulse width (PW) and frequency (F) in this frequency range at which SCS patients experience significant reduction in symptoms such as back pain. Beneficially, sub-perception stimulation at such low frequencies significantly lowers power consumption in the patient's neurostimulator.