Abstract

Pain can be divided into two broad categories, nociceptive pain and neuropathic pain. Nociceptive pain is a dull, throbbing pain which results from irritated nerves after physical tissue injury. This is seen commonly in cancer or after a fracture. Nociceptive pain is amenable to treatment with pain medications such as opioids and/or anti-inflammatories. Neuropathic pain is described as burning, shooting, or shocking pain. This type of pain results from nerve damage or abnormal nerve conduction such as pain exhibited with failed back syndrome, post surgical pain, neuromas, shingles, and complex regional pain syndrome (previously called RSD or causalgia). Neuropathic pain tends to be resistant to treatment with pain medications. Neurostimulation has been an effective treatment option for the management of chronic neuropathic pain. It is a reversible therapy which can even be tested before permanent implantation.

Spinal cord stimulation (SCS) is an adjustable, non-destructive, neuromodulatory procedure which delivers therapeutic doses of electrical current to the spinal cord or to a targeted nerve. This low-voltage stimulation can block the transmission of pain. The enthusiasm for SCS began with the introduction of the gate control theory for pain control by Melzack and Wall in 1965 1.They noted that stimulation of large myelinated fibers of peripheral nerves resulted in paresthesias and blocked the activity in small nociceptive projections. In other words, pain receptors compete with each other and with other sensory afferents. Appropriate stimulation of a “rival” afferent can effectively block a pain signal. This is why rubbing your chin after its been hit relieves the pain – the bump is still present, but the rubbing blocks it. The SCS system is implanted in a space surrounding the spinal cord, called the epidural space, where it stimulates the dorsal columns which can mask the sensation of pain by producing a tingling sensation.

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