What is a Spinal Cord Stimulator?
A spinal cord stimulator is a device used to exert pulsed electrical signals to the spinal cord to control chronic pain. Further applications are in motor disorders. The lumbar spinal cord is a preferred target for the control of spinal spasticity or augmentation of standing and stepping capabilities. Spinal cord stimulation (SCS), in the simplest form, consists of stimulating electrodes, implanted in the epidural space, an electrical pulse generator, implanted in the lower abdominal area or gluteal region, conducting wires connecting the electrodes to the generator, and the generator remote control. SCS has notable analgesicproperties and, at the present, is used mostly in the treatment of failed back surgery syndrome,complex regional pain syndrome and refractory pain due to ischemia.
Mechanism of Action
The neurophysiologic mechanisms of action of spinal cord stimulation are not completely understood yet. Linderoth and others have noted that the mechanism of analgesia when SCS is applied in neuropathic pain states may be very different from that involved in analgesia due to limb ischemia. In neuropathic pain states, experimental evidence show that SCS alters the local neurochemistry in dorsal horn, suppressing the hyperexcitability of the neurons. Specifically, there is some evidence for increased levels of GABArelease, serotonin, and perhaps suppression of levels of some excitatory amino acids, including glutamate and aspartate. In the case of ischemic pain, analgesia seems to derive from restoration of the oxygen demand supply.This effect could be mediated by inhibition of the sympathetic system, although vasodilation is another possibility. It is also probable that a combination of the two mechanisms is involved.