Spinal Cord Stimulation (SCS)

What is SCS?

Spinal Cord Stimulation (SCS) is a minimally invasive procedure that involves implanting a device that applies low currents of electrical stimulation to the spinal cord and/or its exiting nerves.

Spinal cord stimulation is referred to by some pain experts as a “pacemaker for pain”. It works by sending small electrical impulses created by a compact generator through thin leads, or electrical cables, to the spinal cord, where they block pain signals traveling to the brain. Pain is replaced with a mild tingling or a massaging sensation, called paresthesias. A wireless remote control is used to adjust the location and degree of stimulation by selecting pre-programmed settings.

Spinal Cord Stimulation

The core technology that is used in today’s SCS systems was developed in the mid-1960s. Melzack and Wall developed the original theory for the mechanism of spinal cord stimulation in 1965 ⁽¹⁾. This “gate-control theory” for pain proposes that simultaneously triggered touch and vibratory sensation inhibits pain stimuli sensation due to their shared location in the spinal cord, the dorsal horn nucleus. In essence this theory is the foundation for spinal cord stimulation. An everyday example of this theory is seen when one has a headache. Many people will rub their temples or another area of their head, stimulating the muscles of the head or sensory fibers of the skin. When these areas are stimulated, to some degree they block the sharp pain perceived from an active headache. This is also commonly seen when you accidently bump your knee, elbow, or finger and you rub the associated area inhibiting the acute painful stimuli to the brain.

The Anatomy:

The spinal cord is a bundle of nervous tissue and supporting material that extends from the brain to innervate the rest of the body. The brain and the spinal cord together form the central nervous system (CNS), which sends and receives messages from the body through the peripheral nervous system (PNS).

anatomy The spinal cord is contained in the spinal canal formed by the vertebral column. The meninges are a covering consisting of three layers that continues from the cranium to the sacrum and protects the spinal cord and its nerves. The innermost layer, or pia mater, wraps around the brain and spinal cord. The middle layer, or arachnoid mater, is a spider web-like layer. The outermost layer is called the tough dura mater. Between the arachnoid mater and the pia mater is ones cerebral spinal fluid (CSF) which protects and buffers the brain and spinal cord. Outside of the three-layered meninges is the epidural space.

The epidural space is a potential space that lies outside of the dura and typically houses protective fatty tissue and blood vessels. The epidural space is where medications are placed for epidural blocks and where the leads are placed for spinal cord stimulation.

Pain

In general, SCS is much more effective in treating radicular pain, or pain that radiates down one’s arm or leg, than it is at treating axial pain, or pain that is only in the neck or back. One of the first and most frequent uses of SCS has been for the treatment of post-laminectomy syndrome (PLS) which is also called failed back surgery syndrome (FBSS). Post-laminectomy syndrome is recurrent pain, usually involving the lower back and/or legs, following spinal surgery. Imaging must first prove that surgically correctable lesions are absent since PLS is considered a diagnosis of exclusion. A multicenter study confirmed that majority of patients with PLS reported fair to excellent pain relief in both the low back (68.8%) and legs (88.2%) with a spinal cord stimulator device ⁽¹⁾. When compared to repeat spine surgery for PLS, spinal cord stimulation was found to be superior for pain relief ⁽²⁾. Spinal cord stimulation is also more effective in providing leg and back pain relief in the setting of neuropathic pain secondary to PLS when compared to conservative medical treatment ⁽³⁾.

lowerbackpain Complex regional pain syndrome (CRPS), which is also called reflex sympathetic dystrophy (RSD), is a neuropathic pain syndrome that involves severe pain, swelling, and skin changes. CRPS can be a severe disabling condition and is difficult to treat with most conservative care. CRPS is the second most common indication for spinal cord stimulation in the U.S. Research has shown that SCS provides pain relief in over 73% of CRPS patients, as well as significantly reducing the associated edema ^{(4, 5)}. In addition, a European study found that, "the functional status and the quality of life could be significantly improved in sympathetically maintained CRPS I" when SCS was combined with physiotherapy ⁽⁶⁾.

What is SCS?

The Anatomy:

Pain

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