Practice Parameters for the Use of Spinal Cord Stimulation in the Treatment of Chronic Neuropathic Pain
Spinal Cord Stimulation
Pain has been treated with the application of electrical current since ancient times, when electricity was known only as a mysterious force generated by some lightning and types of fish and conducted through water. After the development of the Leyden jar in 1745 made it possible for physicians to control electrical current, the therapeutic use of electrical stimulation spread throughout the Western World. With the advent of modern, empirical medicine in the 20th century, however, electrotherapy fell out of favor for most indications until it was revived following the 1965 publication of Melzack and Wall’s gate control theory of pain (Melzack & Wall, 1965).
By 1967, advances in implantable cardiac pacemaker technology enabled investigators to deliver electrical current directly to the spinal cord with surgically implanted electrodes and externally powered stimulators (Shealy et al., 1967). Today, spinal cord stimulation (SCS) is a reversible pain therapy applied with sophisticated techniques that include multi-output implanted pulse generators and a choice of electrodes, some of which can be placed percutaneously.
The technical goal of SCS is to achieve stimulation paresthesia at a subjectively tolerable (comfortable) level, overlapping (covering) a patient’s topography of pain (North et al., 1991). This is a necessary condition for pain relief and can be lost if an electrode migrates, equipment fails, or the pain moves or expands to a new area. Noninvasive system adjustment might recapture pain/paresthesia overlap; however, surgical revision is sometimes necessary.
Technical success is not sufficient to ensure clinical success. Some patients with complete coverage of the topography of pain report little or no pain relief. This lack of relief might be evident during the screening trial, or the relief might be lost over time in the absence of a discernible technical problem. In rare instances, a patient will dislike the sensation of paresthesia and decide not to proceed with the therapy.
The reversibility of SCS is one of its most important features; unlike the surgical procedures that are commonly performed to relieve pain, SCS does not ablate pain pathways or change a patient’s anatomy.
SCS offers patients an additional advantage in that its routine screening trial emulates the definitive procedure before a patient undergoes implantation of a pulse generator. Thus, each patient provides “individually based observational evidence,” which, when combined with the broader evidence, “should be used to demonstrate effectiveness and determine appropriate subsequent treatment" (Official Disability Guidelines).
The most common indication for SCS in North America is chronic neuropathic pain, the subject of this document. Neuropathic pain results from injury to the nervous system. Many patients experience neuropathic pain as a component of pain with a mixed nature and origin; that is, neuropathic pain commonly coexists with nociceptive and/or ischemic pain. In Europe, SCS is used most often to treat ischemic pain arising from intractable angina pectoris and to counteract the effects of peripheral vascular disease.
When the use of SCS achieves the clinical goal of relieving neuropathic pain, we can expect an attendant positive impact on quality of life, health-related quality of life, ability to perform activities of daily living, and (when possible and appropriate) return to work. In some circumstances, reduction in the use of medication will also occur.
Shealy CN, Mortimer JT, Reswick JB. Electrical inhibition of pain by stimulation of the dorsal columns: preliminary clinical report. Anest Analg 46(4):489-491, 1967.Abstract | Wikistim Entry North RB, Ewend ME, Lawton MA, Piantadosi S. Spinal cord stimulation for chronic, intractable pain: superiority of "multi-channel" devices. Pain 44(2):119-130, 1991.
Abstract | Wikistim Entry Melzack R, Wall PD. Pain mechanisms: a new theory. Science 150(699):971-979, 1965.
Abstract