Substance P: Neck and back pain when the damaged disc is not pressing on a nerve.

Posted by Doug LandauOctober 09, 2008 11:15 AM

At a medico-legal program, I participated in the discussion of back and neck pain after an accident. When there is a herniated disc that presses on the spinal cord or nerve root, one can actually see the anatomical cause of the pain on an MRI film. When the disc material or fragment that has escaped from the disc (the “jelly from the doughnut”) is not pressing on the spinal cord or nerve root, there is often pain as well. Evidence tends to suggest that “Substance P” (for "Prostaglandin") escapes from the disc into the root canal. There is no actual, mechanical, anatomical impingement. However, the Substance P may irritate the nerve root and cause localized pain.

When there is a chemical cause of back or neck pain, then surgery may not be the best solution. Some clients have found relief through epidural injections. I have accompanied clients to their appointments and observed these procedures, which are performed under local anaesthesia, with the patient awake. The doctor looks at an x-ray machine that shows the medicine being injected into the back or neck, near the site of the pain so that relief can be had. Because pills are not swallowed, the stomach (and complications from upset) are bypassed and the medicine is injected directly to the spot where the doctor believes the greatest relief of symptoms will be achieved. Recent medical studies have shown that cervical epidural injections can lead to pain relief significant enough to prevent patients from having to undergo surgery. Other researchers have also concluded that lumbar injections reduce the need for lumbar surgical decompression. Investigations into the biochemistry of disc degeneration and herniation indicate that intraspinal inflammation is a major cause of radicular pain. A neurotoxic, inflammatory mediator is contained within the disc nucleus and is released after annular injury. In other words, just like the fibrous, touch car tire that may get a small tear in the fibers may leak, the disc's annular fibers can tear and the material inside can leak into the spinal canal, irritating and inflaming the spinal cord. This can happen even where the bulging or herniated disc is not physically touching the large spinal cord nerve bundle. For more, go to Pain Physician.