Epidural spinal cord stimulation does not improve microvascular blood flow in neuropathic pain

For many years, spinal cord stimulation (SCS) has been used successfully in various pain syndromes. SCS is also used to treat vascularly-impaired patients since it apparently improves the microcirculation. The exact physiological mechanisms involved are still unclear. There are even some anecdotal reports of a cooling of the legs during SCS. This study investigated the vascular effects of SCS in 15 patients with failed back surgery syndrome, using infrared thermography of the affected foot and capillaroscopy in the nailfold of the big toe. There were no statistically significant differences (Student's t test) in temperature (P = 0.923) or red blood cell velocity (P = 0.819 first day and P = 0.218 second day) in the affected foot with or without stimulation. A physiological difference in relation to neuropathic pain might explain the lack of improvement in skin microcirculation with SCS.