title: Triple leads programmed to perform as longitudinal guarded cathodes in spinal cord stimulation: a modeling study.
abstract: OBJECTIVE
  In spinal cord stimulation, neurosurgeons increasingly tend to implant dual leads. Dual leads (longitudinal bipole/tripole) provide medio-lateral control over the recruited dorsal column (DC) area by steering the injected cathodal currents. However, the DC recruited area is suboptimal when dual aligned leads straddling the midline programmed as longitudinal guarded cathodes (+-+) are used instead of a single lead placed over the spinal cord midline with the same configuration. As a potential improvement, an additional third lead between the two aligned leads is modeled to maximize the medio-lateral extent of the DCs at the low-thoracic vertebral region (T10-T12).
  
  
  METHODS
  The University of Twente Spinal Cord Stimulation software (UT-SCS) is used in this modeling study. Longitudinal guarded cathodes were modeled on the low-thoracic vertebral region (T10-T12) using percutaneous triple lead configurations. The central lead was modeled over the spinal cord midline and the two lateral leads were modeled at several transverse distances to the midline lead. Medio-lateral field steering was performed with the midline lead and the second lead on each side to achieve constant anodal current ratios and variable anodal current ratios.
  
  
  RESULTS
  Reducing the transverse lead separation resulted in increasing the depths and widths of the recruited DC area. The triple lead configuration with the least transverse separation had the largest DC recruited area and usage range. The maximum DC recruited area (in terms of both depth and width) was always found to be larger under variable anodal current ratio than constant anodal current ratio conditions.
  
  
  CONCLUSIONS
  Triple leads programmed to perform as longitudinal guarded cathodes provide more postoperative flexibility than single and dual leads in covering a larger width of the low-thoracic DCs. The transverse separation between the leads is a major determinant of the area and distribution of paresthesia.
authors.affiliation: MIRA, Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands. v.sankarasubramanian@ewi.utwente.nl
authors.forename: Vishwanath
authors.initials: V
authors.lastname: Sankarasubramanian
authors.forename: Jan R
authors.initials: JR
authors.lastname: Buitenweg
authors.forename: Jan
authors.initials: J
authors.lastname: Holsheimer
authors.forename: Peter
authors.initials: P
authors.lastname: Veltink
mesh_terms: D003198:Computer Simulation; D004599:Electric Stimulation Therapy / Q000295:instrumentation* / Q000379:methods*; D004566:Electrodes; D004567:Electrodes, Implanted; D006801:Humans; D008959:Models, Neurological; D012984:Software; D013116:Spinal Cord / Q000502:physiology*