BACKGROUND: In spinal cord stimulation for low-back pain, the use of electrode arrays with both low-power requirements and selective activation of target dorsal column (DC) fibers is desired. The aligned transverse tripolar lead configuration offers the best DC selectivity. Electrode alignment of the same configuration using 3 parallel percutaneous leads is possible, but compromised by longitudinal migration, resulting in loss of DC selectivity. This loss might be repaired by using the adjacent anodal contacts on the lateral leads.
OBJECTIVE: To investigate if stimulation using adjacent anodal contacts on the lateral percutaneous leads of a staggered transverse tripole can restore DC selectivity.
METHODS: Staggered transverse tripoles with quadripolar lateral anodes were modeled on the low-thoracic vertebral region (T10–T12) of the spinal cord using (a) percutaneous lead with staggered quadripolar lateral anodal configuration (PERC QD) and (b) laminotomy lead with staggered quadripolar lateral anodal configuration (LAM QD), of the same contact dimensions. The commercially available LAM 565 surgical lead with 16 widely spaced contacts was also modeled. For comparison with PERC QD, staggered transverse tripoles with dual lateral anodes were modeled by using percutaneous lead with staggered dual lateral anodal configuration (PERC ST).
RESULTS: The PERC QD improved the depth of DC penetration and enabled selective recruitment of DCs in comparison with PERC ST. Mediolateral selectivity of DCs could not be achieved with the LAM 565.
CONCLUSION: Stimulation using PERC QD improves anodal shielding of dorsal roots and restores DC selectivity. Based on our modeling study, we hypothesize that, in clinical practice, LAM QD can provide an improved performance compared with the PERC QD. Our model also predicts that the same configuration realized on the commercial LAM 565 surgical lead with widely spaced contacts cannot selectively stimulate DCs essential in treating low-back pain.
ABBREVIATIONS: DC, dorsal column
dCSF, dorsomedial cerebrospinal fluid
DM, dura mater
DR, dorsal root
ES, epidural space
LAM QD, laminotomy lead with staggered quadripolar lateral anodal configuration
LAM 565, commercially available laminotomy lead with widely spaced staggered quadripolar lateral anodal configuration
PERC AL, percutaneous lead with aligned dual lateral anodal configuration
PERC QD, percutaneous lead with staggered quadripolar lateral anodal configuration
PERC ST, percutaneous lead with staggered dual lateral anodal configuration
SCS, spinal cord stimulation
UR, usage range