Papers of the Week

Since 1967, spinal cord stimulation (SCS) has been used to manage chronic intractable pain of the trunk and limbs. Compared to traditional high-intensity, low-frequency (<100 Hz) SCS that is thought to produce paresthesia and pain relief by stimulating large myelinated fibers in the dorsal column (DC), low-intensity, high-frequency (10 kHz) SCS has demonstrated long-term pain relief without generation of paresthesia. To understand this paresthesia-free analgesic mechanism of 10 kHz SCS, we examined whether 10 kHz SCS at intensities below sensory thresholds would modulate spinal dorsal horn (DH) neuronal function in a neuron type-dependent manner. By using in vivo and ex vivo electrophysiological approaches, we found that low-intensity (sub-sensory threshold) 10 kHz SCS, but not 1 kHz or 5 kHz SCS, selectively activates inhibitory interneurons in the spinal DH. This study suggests that low-intensity 10 kHz SCS may inhibit pain sensory processing in the spinal DH by activating inhibitory interneurons without activating DC fibers, resulting in paresthesia-free pain relief.