Pain expert Dr. Scott Fishman answers questions about back pain:

Q: Will a nerve block relieve my back pain, even if the doctor cannot find the exact nerve that is causing it?

A: A nerve block is a general term for a variety of injections used to treat pain. While originally developed for surgery and often used to make diagnoses, their widest use today is to relieve pain emanating from an identifiable nerve.

Most blocks are very precise, targeting specific nerves. Some are less specific, targeting broad areas where nerves are often irritated. One of the most common non-specific blocks is called an epidural steroid injection.

Most nerve blocks include an injection of medication, typically a local anesthetic or anti-inflammatory drug, to halt the signal traveling along the affected nerves or cool off inflammation in the area. When the block contains a local anesthetic, it is usually at a low concentration so that only pain is reduced, while other functions such as movement are preserved. In other words, the dose is kept low to avoid temporary paralysis.

With either a local anesthetic or anti-inflammatory drug, the chemical washes through the body within hours to weeks, and the pain relieving effects may be equally short-lived. However, the effect of turning off the nervous barrage of pain signals or decreasing inflammation can last longer.

The workhorse of nerve blocks in many pain management centers is the traditional epidural steroid injection. It delivers medication to the space around the spinal cord that may have become inflamed or irritated.

One of the most accurate blocks for back pain is the facet block, which homes in on a minute nerve fiber that may be the source of the suffering. Although the word "facet" (accent on the second syllable) may not sound familiar, the sensation is well known to many back pain sufferers. It is possible that you have felt a bum facet joint if you ever have had pain radiating from the low back into the buttock and thigh.

Although pain medicine offers many types of blocks, keep in mind that they are not a universal treatment for all pain. Blocks are best for reining in pain from an identifiable place in the body, whether it is the back, legs, arms, or face. While sometimes they work like a one-shot cure, blocks often give only short-term relief. However, they are tolerated well by most patients, are over with quickly, and are very safe when specially trained doctors perform them in the right environment.