When it comes to the spine, there are many tissues that have nerve endings for pain. The spinal or facet joints have free nerve endings. So do the discs, ligaments, and muscles.

When a pain signal is started, the spinal cord relays the message to the brain. The brain signals the body part to let it know that it hurts. But the pain we feel is usually diffuse or widespread over an area. It is not pinpointed to one spot. This makes it difficult to isolate the underlying cause of the problem.

Trauma or injury (even microtrauma) often starts a cascade of events that results in inflammation. The chemicals produced during inflammation appear to be the source of the pain. The pain is more likely caused by the inflammatory changes in the joint than caused by actual joint destruction seen on x-rays. That's why it's possible to have a perfectly normal looking spine or joint and still have great pain.

There is a new method for testing the facet joints. Researchers have found that increased nitric oxide (NO) in and around the joints is common when there's inflammation. In fact one study from Sweden showed that patients with chronic back pain had three times the level of NO compared to healthy adults without back pain.

NO is a gas that acts as a messenger in the body. It has many functions but obviously has a role in inflammation as well. For patients with elevated NO, steroid injection has been shown to help reduce pain and improve function.

The hope is that in the future, we will be able to identify molecular markers in the blood to tell us exactly where the pain is coming from. For now, patience is required as doctors try to sort out the complex issues around back pain. Sometimes it's just a matter of trial and error until we find what works for each individual patient.