![]() Technology for SCS has improved over the decades, with more reliable stimulation equipment better designed to stimulate the dorsal columns has evolved. ![]() SCS is the clinical implementation of the Gate Theory, which posits that activation of large myelinated afferent nerves which mediate touch and pressure sensations, can inhibit, or "close the gate" on transmission of pain signals to higher centers in the brain (Melzack & Wall, 1965). Spinal cord stimulation, or SCS, has been clinically applied since 1967, when Dr Norman Shealy first implanted stimulation electrodes over the dorsal columns in an attempt to provide relief for patients with chronic, intractable pain (Shealy et al., 1967). The ability to center stimulation regions in the dorsal column with high resolution may allow for better optimization of paresthesia-pain overlap in patients. 3) and the mean steering step for mediolateral steering is 0.02 mm for multi-source systems vs 1 mm for single source systems, a 50-fold improvement. ![]() The model predicted that the multi-source system can target more central points of stimulation on the dorsal column than a single source system (100 vs. The model compared the field steering results with single source versus dedicated power source systems on dual 8-contact stimulation leads. The volume of activation (VOA) and the central point of the VOA were computed using a predetermined threshold of the activating function. The activating function for 10 um fibers was computed as the second difference of the extracellular potential along the nodes of Ranvier on the nerve fibers in the dorsal column. The volume conductor model of a low-thoracic spinal cord with epidurally-positioned dual parallel (2 mm separation) percutaneous leads was first created, and the electric field was calculated using ANSYS, a finite element modeling tool. Using a mathematical model with an accurate fiber diameter distribution, we studied the ability of dual parallel leads to steer stimulation between adjacent contacts on dual parallel leads using (1) a single source system, and (2) a multi-source system, with a dedicated current source for each contact. This construct provides flexibility in steering stimulation current mediolaterally over the dorsal column to achieve better pain-paresthesia overlap. Since patient pain patterns can be unique, a common stimulation configuration is the placement of two leads in parallel in the dorsal epidural space. In spinal cord stimulation (SCS), concordance of stimulation-induced paresthesia over painful body regions is a necessary condition for therapeutic efficacy.
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