Fibromyalgia

What is Fibromyalgia?

Fibromyalgia or Fibromyalgia Syndrome (FMS) is a chronic musculoskeletal pain disorder, characterized by fatigue, widespread aching and stiffness in muscles and soft tissues. Pain is predominantly localized to the upper and lower back, neck, shoulders, elbows, knees and pelvic joints regions. FMS is not an exclusive diagnosis and may be seen with other conditions such as rheumatoid arthritis, irritable bowel syndrome, tension headaches or lupus.

Although the diagnosis of fibromyalgia syndrome can now be made with increasing certainty, it poorly characterized from a diagnostic perspective. The American College of Rheumatology has criteria for assessing fibromyalgia syndrome, to assist in the proper differentiation from maladies similar symptoms such as Lyme disease, lupus, hypothyroidism, Gulf War Syndrome, and Chronic Syndrome. Although the rheumatology guidelines focus on the in-clinic assessment of musculoskeletal pain, they are important in helping to make an accurate diagnosis of such an elusive disorder.

Debate still exists as to the patho-physiology of FMS. Investigation into hypothalamitic function and neuropeptides has resulted in some tantalizing leads to possible abnormalities; however, further research is necessary to confirm these findings.

Pressure points for the assessment of pain associated with FMS

Can Anyone Get FMS?

With what is known of the epidemiology of the syndrome it is impossible to say who may or may not be at risk. FMS is believed to affect about 2% of Americans. Generally FMS afflicts women between the ages of 60- 80 years old who account for 3.5% of the reported cases. Men account for only 0.5% of reported cases. The reasons for these differences are still under scientific investigation. FMS has been known to affect people of every race, age and background.

Guidelines for Assessing FMS Symptoms

The American College of Rheumatology 1990 criteria for the classification of fibromyalgia*

  1. History of widespread pain; pain is considered widespread when all of the following are present:
    • Pain in the left side of the body
    • Pain in the right side of the body
    • Pain above the waist
    • Pain below the waist

    2. In addition, axial skeletal pain (cervical spine or anterior chest or thoracic spine or low back) must be present. In this definition, shoulder and buttock pain is considered as pain for each involved side. “Low back” pain is considered lower segment pain.

  2. Pain in 11 of 18 tender point sites on digital palpation.
    Pain, on digital palpation, must be present in at least 11 of the following 18 tender point sites:
    • Occiput: bilateral, at the suboccipital muscle insertions
    • Low cervical: bilateral, at the anterior aspects of the intertransverse spaces at C5-C7
    • Trapezius: bilateral, at the midpoint of the upper border
    • Supraspinatus: bilateral, at origins, above the scapular spine near the medial border
    • Second rib: bilateral, at the second costochondral junctions, just lateral to the junctions on upper surfaces
    • Lateral epicondyle: bilateral, 2 cm distal to the epicondyles
    • Gluteal: bilateral, in upper outer quadrants of buttocks in anterior fold of muscle
    • Greater tronchanter: bilateral, posterior to the trochanteric prominence
    • Knee: bilateral, the medial fat pad proximal to the joint line

*For classification purposes, patients will be said to have fibromyalgia if both criteria are satisfied. Widespread pain must have been present for at least 3 months. The presence of a second clinical disorder does not exclude the diagnosis of fibromyalgia.

What Causes FMS?

Currently the cause of fibromyalgia remains unclear despite much investigation and speculation. There is speculation of a link between FM disorders in immunopathologic disease, inflammatory disease, or metabolism of the muscle. Sleep disturbance, is common in FMS patients and may be causative or result from neuroendocrine, serotonin or somatomedin-C dysfunction or metabolism disturbance. Altered pain processing is thought to be a possible cause rather than contributor.

Quantitative Measurement of Substance P

The Confirmatory Test to Aid in the Diagnosis of FMS (Test Code: SUBP)

One of the major factors which have hampered the clinical assessment of Fibromyalgia Syndrome (FMS) is the lack of adequate and reliable laboratory diagnostic testing. As the major factor for the diagnosis of FMS is the categorization of pain, the majority of the diagnosis of FMS has been the in clinic examination of the patient. Patient examinations are subjective, and result in a wide disparity of results due to the experience of the administering physician.

In 1994 researchers at the University of Texas Health and Science Center, department of medicine discovered an elevation in the level of the neurotransmitter Substance P in the spinal fluid of patients suffering from FMS. In 1998 researchers with the Karolinska Institute at Huddinge Hospital in Stockholm Sweden discovered that Substance P was not elevated in patients suffering form CFS. These findings have, for the first time, have given a definable quantifiable test for distinguishing between FMS and CFS.

Substance P was first discovered in 1931 by von Euler and Gaddum, and since then has become one of the best understood neuropeptide transmitters. A member of the tachykinin family of neurotransmitters; these amidated neuropeptides share a carboxy terminal sequence, with a variable N-terminal sequence. Extensive research over the past 70 years has lead to an understanding of the function and influence of Substance P.

Substance P is known to be distributed throughout the peripheral and central nervous system. In the peripheral system, Substance P is localized in the primary sensory neurons and the neurons intrinsic to the gastrointestinal tract. Substance P has been found to be involved in a wide variety of processes such as pain, anxiety, depression and inflammation.

Development of a Clinical Assay

Substance P is an 11-amino acid neuropeptide, synthesized as a pro-peptide and enzymatically truncated to the active form. It is involved with the transmission of pain from the periphery to the central nervous system, and has been implicated as an influencing factor in many pathways including pain, vomiting, depression and anxiety.

Substance P has emerged as a potentially reliable diagnostic marker to differentiate between CFS and FMS which share many of the same symptoms, with the exception of pronounced pain. Researchers at VIP Dx have validated a test for cerebral spinal fluid which quantifies the amount of Substance P present in an individual, giving an accurate determination between FMS or CFS.