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

Q: How do I know if I have fibromyalgia?

A: Fibromyalgia is a hodgepodge of symptoms characterized by mild to extreme discomfort emanating from skeletal muscles and soft tissue throughout the body. It is also referred to as myofascial pain and can encompass other disorders, including temporomandibular joint pain (TMJ).

Over the years, fibromyalgia has had a number of medical labels: muscle hardening, muscular rheumatism, fibrositis, myofascitis, myogelosis, and interstitial myofibrositis. The terms fibromyalgia and myofascial pain often are used interchangeably, but they are not identical twins. Myofascial pain is the umbrella term, and fibromyalgia is a specific kind of pain that encompasses widespread symptoms in muscles throughout the body.

The centerpiece of this disorder involves tender areas of muscle and trigger points (small areas of muscle that cause pain in a distant area when they are pressed). Trigger points are often associated with tender, hard knots within muscle tissue but are not always tender themselves. Trigger points and tender points often are confused, but they are not the same thing.

As with many pain conditions, there are no laboratory tests to diagnose this pain. For years, patients have been complaining to their doctors about achy pain in their muscles that comes and goes, moves around their bodies, and produces fatigue. Yet the shifting character of the condition, seemingly vague symptoms that come and go, and undetectable causes have confounded successful treatment.

In 1990, doctors with the American College of Rheumatology developed specific criteria for diagnosing fibromyalgia. To be diagnosed with it, a patient must have widespread pain and clear signs of muscle tenderness at eleven of eighteen identified spots on the body. The scientist who first spotted these clumps within muscle described them as feeling like "rubbery Rice Krispies."

Lodged within a taut band of muscle or neighboring tissue, they are tight knots. When pressed, they are unusually tender. When pressed hard, they may cause the whole muscle to twitch or a person to flinch, which is known as a jump sign. They frequently congregate in one area of the body, such as in the neck, shoulder, or back, and radiate discomfort to neighboring muscles. If you have had occasional knots in your muscles, like a kink in the neck, you may have had what is called latent trigger points because they can radiate pain but quickly disappear.

The underlying cause of trigger points is frequently a mystery. They can crop up after an injury or disease, from repetitive motion (like lots of lifting or a repeated sports motion), or for no apparent reason.