Significance of fiber diameter in kilohertz frequency spinal cord stimulation. (A) Dorsal column (DC) fiber activation and conduction block thresholds for fiber diameters of 7.3, 11.5, and 15.0 μm are shown in the left, middle, and right columns, respectively. The top row shows the activation thresholds for each fiber size, whereas the bottom row shows the corresponding conduction block thresholds. (B) Minimum thresholds for DC fiber activation and conduction block for each fiber diameter. The minimum thresholds for dorsal root (DR) fiber activation (DR_AT) and conduction block (DR_BT) are also illustrated with the dashed lines.