Fibromyalgia symptoms can mask the presence of chronic inflammatory disease affecting the joints of the pelvis and spine, according to new research.
The study, titled “Prevalence of Axial Spondyloarthritis Among Patients With Fibromyalgia: A Magnetic Resonance Imaging Study With Application of the Assessment of SpondyloArthritis International Society Classification Criteria,” was published in the journal Arthritis Care & Research. It highlights the importance of vigilant management of fibromyalgia symptoms by doctors and patients, taking into account the possible underlying presence of inflammatory disorders.
Unlike other rheumatologic diseases, fibromyalgia is non-inflammatory in nature, and recent reports suggest that it is caused by uncontrolled hyper-activation of the pain-associated nervous response.
Fibromyalgia patients can present a broad spectrum of symptoms, including chronic nocturnal back pain, morning stiffness, and disturbed sleep. However, these are also symptoms of an inflammatory condition called axial spondyloarthritis (SpA).
SpA is a chronic inflammatory condition involving the spine, pelvis, and surrounding joints. Although SpA and fibromyalgia are very different diseases, they can overlap and share similar symptoms.
Aiming to determine the incidence of SpA among fibromyalgia patients, a total of 99 patients with fibromyalgia underwent magnetic resonance imaging (MRI) evaluation for the identification of structural alterations common in SpA chronic inflammation, such as bone erosion and spine deformations (sclerosis).
About 8% of patients presented symptoms of inflammation in pelvic joints, while 17% and 25% presented bone erosion and sclerosis, respectively. Despite the frequency of these symptoms, only 10% of fibromyalgia patients were positively SpA diagnosed, according to the Assessment of SpondyloArthritis International Society classification criteria.
“When approaching the clinical conundrum of differentiating between ‘pure’ fibromyalgia and those cases with an unsuspected underlying inflammatory disease, the physician must attempt to rely [on] clinical judgment and on available diagnostic tools,” the study’s authors, from medical centers in Tel Aviv, Israel, wrote.
Through blood tests that evaluate levels of a protein associated with inflammation, known as CRP, the authors found that the diagnosis of SpA was positively associated with increased CRP levels and physical function limitation. This result suggests that CRP could be used as diagnostic tool for SpA among fibromyalgia patients.
“These results underscore the importance of recognizing the overlap between inflammatory and centralized pain in each patient and call for increased clinical vigilance in the process of differential diagnosis,” the authors concluded.