Low-Intensity 10 kHz Spinal Cord Stimulation Reduces Behavioral and Neural Hypersensitivity in a Rat Model of Painful Diabetic Neuropathy

Abstract

Background: Low-intensity 10 kHz spinal cord stimulation (SCS) has been shown to provide pain relief in patients with chronic pain resulting from diabetic peripheral neuropathy (DPN). However to date, there have been no studies of 10 kHz SCS in animal models of diabetes. We aimed to establish correlative data of the effects of this therapy on behavioral and electrophysiological measures in a DPN model. Methods: Twenty-five adult male Sprague-Dawley rats were injected once intraperitoneally with 60 mg/kg streptozotocin (STZ) to induce diabetes over a subsequent 4 w period, while 4 naïve control animals were not injected. After approximately 21 d, 12 of STZ-injected rats had mini epidural SCS leads implanted: 8 received continuous low intensity (~30% motor threshold) 10 kHz SCS, and 4 received sham SCS (0 mA) over 7 d. Behavioral assays (von Frey filament probe of hindpaw) were measured in 18 animals and in vivo dorsal horn electrophysiological studies (receptive field; response to afferent brush, von Frey probe, pinch) were performed in 17 animals. Results: Across behavioral assays of mechanical allodynia and electrophysiological assays of receptive field size and mechanosensi-tivity, diabetic animals stimulated with 10 kHz SCS showed statistically significant improvements compared to sham SCS. Conclusion: Low-intensity 10 kHz SCS produced several measures associated with a reduction of pain in diabetic rodent models that may help explain the clinical benefits of 10 kHz SCS in patients with painful diabetic neuropathy.