Fibromyalgia symptoms can overlap with autoimmune diseases and other arthritis conditions making it difficult to diagnose. The defining symptoms of fibromyalgia are often associated with other subjective and objective symptoms which occur in combination. The cause of fibromyalgia is considered as complex as its clinical presentation. The exact cause of fibromyalgia is still not well understood but mechanisms which have been suggested include:

Abnormal pain perception

Sleep disorders

Abnormal circulating levels of central neurochemical substances

It has also been suggested that joint hypermobility (JH) may be associated with the pathology of fibromyalgia.

Joint Hypermobility

Joint hypermobility is defined as "abnormally increased mobility of small and large joints beyond the limits of their physiological movement." Joint hypermobility is common among in young females and is seen in about 5% of the healthy adult population. When musculoskeletal symptoms occur in hypermobile people in the absence of any other systemic rheumatological disorder, it is called "hypermobility syndrome." Joint hypermobility is also a feature of a medical condition called Ehlers-Danlos syndrome (EDS) that is characterized by weakness of the connective tissues of the body.

The Study

In a study reported in the Journal of Rheumatology, the association between joint hypermobility and primary fibromyalgia was investigated. The study group was comprised of 88 patients (all female, median age 34 years old) with widespread pain clinically diagnosed as fibromyalgia and 90 healthy controls (all female, median age 36 years old). Excluded from the study were:

Patients with any other rheumatological or systemic disorder.

Patients with any other inflammatory process or degenerative arthritis.

Anyone who had been receiving medications.

The patients had not been diagnosed with having fibromyalgia by a rheumatologist prior to the study and had not been treated for fibromyalgia.

Study Process

All patients were admitted based on widespread pain lasting longer than 3 months. Patients and controls were then initially evaluated by a rheumatologist. The patients underwent further and more specific evaluation by two other clinicians (who were blinded to the initial evaluation) for the determination of fibromyalgia and joint hypermobility.

Fibromyalgia was assessed in all patients by questioning about common complaints associated with the disease. They were diagnosed with fibromyalgia if they met the American College of Rheumatology (ACR) criteria for the classification and diagnosis of fibromyalgia. Joint hypermobility was considered present in patients based on the Beighton modification of Carter and Wilkinson criteria for joint hypermobility.

Study Results

Fifty-six of the 88 patients with widespread pain initially resembling fibromyalgia met the ACR criteria for fibromyalgia, while 6 of the 90 healthy controls also met the ACR criteria. Patients with or without fibromyalgia were also compared for the frequency of joint hypermobility. The frequency of joint hypermobility was:

8% in patients with fibromyalgia.

6% in patients without fibromyalgia.

Joint hypermobility was also recognized in 10 of the 32 patients with fibromyalgia who did not exactly meet the ACR criteria. The presence of joint hypermobility was more common in this group than in the controls. Isolated joint hypermobility affects 10-20% of individuals in the general population to some degree, either in isolated joints or more generalized throughout the body.

Conclusions

The association between fibromyalgia and joint hypermobility is not totally understood. Joint hypermobility may cause widespread arthralgia in patients due to misuse or overuse of hypermobile joints.

Data from this particular study indicated:

That the typical complaints of fibromyalgia were primarily observed in the patients that did meet the ACR criteria.

Some patients who exhibit fibromyalgia symptoms clinically but do not meet the ACR criteria could actually have joint hypermobility misdiagnosed as fibromyalgia.

Joint hypermobility was first featured in rheumatology literature in 1967. Today, joint hypermobility is better understood and more widely recognized. However, further investigation and research are still needed to learn even more about the interaction between joint hypermobility and fibromyalgia.