IEEE-EMBS Benelux Chapter Symposium November 9-10, 2009
TRIPLE LEADS WITH LONGITUDINAL GUARDED CATHODES
IN SPINAL CORD STIMULATION-EFFECT OF TRANSVERSAL
LEAD SEPARATION
V.Sankarasubramanian 1, J.R.Buitenweg1, J.Holsheimer1
1
MIRA, Institute of Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
1 Introduction
In spinal cord stimulation (SCS) clinical practice, longitudinal guarded cathode (+-+) stimulation by a single lead, placed on the spinal cord midline provides the broadest paresthesia coverage [1, 3]. Suboptimal lead placements and lead migrations result in changes in paresthesia locations with the inability to be corrected postoperatively. Dual-lead longitudinal tripoles and triple lead transverse tripoles (TTS) provide the necessary mediolateral control over the dorsal column (DC) activated area by steering the cathodal and lateral anodal currents respectively. Dual lead longitudinal tripoles placed symmetrical to the spinal cord midline however recruit a smaller width of DC area [2] and with the transverse tripoles the area of activation remains limited [4]. This study uses a triple lead longitudinal tripole with the center lead placed on the midline. The transversal spacing between the leads is varied to study its effect on the usage range (UR) and the recruited area (both depth and width) of dorsal column activation.
2 Methods
Triple aligned leads were modeled with longitudinal guarded cathode configurations (center lead placed on the SC midline) for various transversal lead separations (1.0, 1.5, 2.0 and 2.5 mm). Medio-lateral field steering was performed with the left and the midline lead for various variable anodal current ratios (VAS). Usage range (UR) and the maximum recruited DC area (SRA) were determined for all
cathodal current ratios (CCRs).
3 Results
A smaller transversal lead separation recruited a larger depth (D) and width (W) of DC area. The triple lead configuration with 1mm transversal separation had the maximum and least varying SRA and UR for
the whole range of CCRs.
4 Conclusions
Triple leads with longitudinal guarded cathodes provide more post-operative flexibility in covering a larger W of the DCs. The transversal separation between the leads is a major determinant in the area
and distribution of paresthesia. Leads with a smaller transversal separation activate a larger DC area.
References
[1] Holsheimer, J., J. J. Struijk, et al. (1995). "Effects of electrode geometry and combination on nerve fibre selectivity in spinal cord stimulation." Medical and Biological Engineering and Computing 33(5): 676-682.
[2] Manola, L., J. Holsheimer, et al. (2005). "Technical performance of percutaneous leads for spinal cord stimulation: A modeling study." Neuromodulation 8(2): 88-99.
[3] North, R. B., D. H. Kidd, et al. (2007). "Spinal cord stimulation with interleaved pulses: A randomized, controlled trial." Neuromodulation 10(4): 349-357.
[4] Struijk, J. J. and J. Holsheimer (1996). "Transverse tripolar spinal cord stimulation: Theoretical performance of a dual channel system." Medical and Biological Engineering and Computing 34(4): 273-279.
