Putative mechanisms behind effects of spinal cord stimulation on vascular diseases: A review of experimental studies

Abstract

Spinal cord stimulation (SCS) is a widely used clinical technique to treat ischemic pain in peripheral, cardiac and cerebral vascular diseases. The use of this treatment advanced rapidly during the late 80's and 90's, particularly in Europe. Although the clinical benefits of SCS are clear and the success rate remains high, the mechanisms are not yet completely understood. SCS at lumbar spinal segments (L2-L3) produces vasodilation in the lower limbs and feet which is mediated by antidromic activation of sensory fibers and decreased sympathetic outflow. SCS at thoracic spinal segments (T1-T2) induces several benefits including pain relief, reduction in both frequency and severity of angina attacks, and reduced short-acting nitrate intake. The benefits to the heart are not likely due to an increase, or redistribution of local blood flow, rather, they are associated with SCS-induced myocardial protection and normalization of the intrinsic cardiac nervous system. At somewhat lower cervical levels (C3-C6), SCS induces increased blood flow in the upper extremities. SCS at the upper cervical spinal segments (C1-C2) increased cerebral blood flow, which is associated with a decrease in sympathetic activity, an increase in vasomotor center activity and a release of neurohumoral factors. This review will summarize the basic science studies that have contributed to our understanding about mechanisms through which SCS produces beneficial effects when used in the treatment of vascular diseases. Furthermore, this review will particularly focus on the antidromic mechanisms of SCS-induced vasodilation in the lower limbs and feet.

Myocardial Sympathetic Innervation in Patients with Symptomatic Coronary Artery Disease: Follow-up After 1 Year with Neurostimulation

“…The question is whether our results can be applied to other CAD patients, in whom SCS is not performed. The answer to this question is not obvious, mainly because the mechanisms behind the effects of SCS are not completely understood (7,26). The effect of SCS might be due to improvement in myocardial blood flow (8,9,27).…”

“…Our data do not support this thesis, as blood flow under rest and stress conditions, as well as CFR, did not change significantly (Table 2). Another hypothesis is that SCS reduces sympathetic tone, decreasing myocardial oxygen consumption and improving myocardial microcirculatory blood flow (26,28). We cannot rule out the possibility that the assumed reduction in sympathetic tone leads to a protective effect on the sympathetic neurons themselves, causing the neurons to be less susceptible to ischemic damage.…”

Spinal Cord Stimulation for Chronic Limb Ischemia

“…These effects lead to a decrease in vascular resistance and an increase in local blood flow ( Figure 1). 7,8,15,16 In addition, SCS suppresses sympathetic vasoconstriction through inhibition of sympathetic nicotine transmission at the ganglionar and postganglionar level. 3,4,7 Pain relief is mediated by the suppression of pain or nociceptive transmission and the release of opioid peptides such as met-enkephalin.…”

Managing Chronic Pain With Spinal Cord Stimulation

“…8,9 GENERAL CONCEPTS Modern SCS systems are made up of 3 components: leads/electrodes, a generator/power source, and a programmer/controller. Leads/electrodes can be divided into percutaneous or ''wire'' leads and paddle or ''laminotomy'' leads.…”