Computer model of kilohertz frequency spinal cord stimulation (KHFSCS). (A) A finite element model (FEM) was created of the lower thoracic spinal cord and surrounding anatomy along with a KHFSCS lead implanted in the epidural space. The figure in the upper right corner shows the voltage distribution generated by bipolar stimulation with a +1 A current applied at the contact shown in blue (anode) and −1 A current applied at the contact shown in red (cathode). (B) Multicompartment cable models of the dorsal column (DC) and dorsal root (DR) fibers were included in this analysis and were based on a previously published model of a mammalian myelinated axon.²⁹  DR fibers consisted of a mother fiber and a bifurcated daughter fiber running along the DC.²²  The three-dimensional trajectory of the DR mother fiber approximated the anatomy of dorsal rootlets in the lower thoracic spinal cord.^20,30