Abstract

Fibromyalgia syndrome (FMS) is the second most common rheumatologic disorder affecting 2%-8% of the population; it can also occur secondary to many inflammatory conditions, in particular prevalence is estimated at 15%-20% in rheumatoid arthritis (RA). The underlying mechanism for primary and secondary FMS has previously been poorly understood, however evidence in support of central and peripheral sensitization theories alongside impaired pain inhibition are becoming progressively recognised to contribute towards allodynia and hyperalgesia; the abnormal pain responses confirmed to occur in FMS in neuroimaging studies.
A diagnosis of secondary FMS poses many challenges to physicians, hence, alongside the American College of Rheumatology 2010 FMS criteria; a joint count difference scoring methods has been proposed to assist in diagnosing concomitant FMS in RA. However, cognitive and somatic elements of FMS must also be taken into consideration when diagnosing the condition. Literature demonstrates that it is of paramount importance to identifying secondary FMS in RA because unrecognized FMS can result in heightened disease activity scores and thus over treatment of RA or, in some cases, the cessation of therapies due to a perceived lack of efficacy.
Furthermore, it is imperative to diagnose coexisting FMS in patients with RA as treatments for RA alone will not target the symptoms of FMS, additional pharmacological and non-pharmacological treatments such as antidepressants and a graded exercise program respectively, are of proven benefit and should be encouraged for all patients. The intricate relationship between RA and FMS is also entwined with underlying depression; the combination of all three has vast implications for quality of life and is known to impede the chances of obtaining RA disease remission.

Keywords: Hyperalgesia; Fibromyalgia syndrome; Allodynia