Chronic Pain: Old Treatment Offers New Hope Electrical Spine Stimulation Relieves Pain Even When Cause Is Unknown

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By Laurie Barclay

Pain can be, uh ... a real pain. Especially for those people whose pain simply won't go away, who can't just pop a Tylenol and await relief. In fact, to ensure that doctors pay more attention to this important aspect of patient care, the national organization that accredits hospitals recently decided to classify
pain as one of the vital signs meaning that patients being admitted to hospitals must now have their level of pain assessed along with other vital signs like breathing, temperature, and heart rate. If that's not done and not documented the hospital can lose its license.

As part of the ongoing scientific effort to find the best possible treatments for pain, researchers are constantly on the lookout for new techniques or for new ways to use older techniques. The latter is the case in a study published in the May issue of Neurosurgery, which shows that electricity can work to short-circuit pain, even when its cause is unknown.

Using electricity to treat pain dates back as far as 600 B.C., when electric eels were applied to painful areas of the body. In colonial America, inventor Benjamin Franklin, known for his lightning rod as well as his lightning wit, experimented with different types of electrical treatments for pain.

Pain and other sensory information travels from the body to the brain through the spinal cord, a bundle of nerves protected by the bony spinal column. Since the 1960s, doctors have treated pain by spinal cord stimulation, surgically implanting fine electrodes to deliver a mild electric current to the spinal cord.

How does it work? The theory is that information reaching the brain has to pass through a "gate" in the spinal cord that can only let a limited amount of information pass through at once.

Electrical stimulation of the spinal cord causes a mild tingling sensation, which seems to pass through that gate first, protecting the brain from experiencing pain. To test this theory, researchers from Yeungam University in Korea, the University of Toronto in Canada, and Allegheny General Hospital in Pittsburgh, gave 122
patients with persistent pain a brief trial of spinal cord stimulation, using an external device.

The trial was effective in 74 of the patients, who then had surgery for permanent placement of an electrode and stimulator. Pain relief lasted for at least one year in 80% of these patients. Although the equipment sometimes malfunctioned after that, almost half of patients still had sufficient pain relief four years later to continue using the device.

As expected, success rate was highest almost 90% in those patients whose pain was caused by a damaged nerve. Success rate was 74% in patients with pain caused by nerve injury, and 72% in patients with pain caused by spinal cord damage.

Surprisingly, of the patients who had no obvious cause for their pain, 83% responded well to the stimulation. "As most patients with persistent back pain after multiple surgeries for slipped discs or arthritis have no clear reason for pain, spinal cord stimulation may offer new hope to them.

More good news was that outcome was no worse in patients who were receiving workers' compensation payments. Psychological factors such as an unconscious desire to avoid work or to collect benefits sometimes interferes with treatment of these individuals.

"We are in need of more studies like this one, looking at outcome predictors of our treatments for pain," says Milan Stojanovic, MD director of the interventional pain program at Massachusetts General Hospital and Harvard Medical School. By selecting patients most likely to respond to treatment, doctors can improve the chances of success, Stojanovic tells WebMD.