The different faces of pain in rheumatology: fibromyalgia and rheumatoid arthritis

Rheumatic diseases present very controversial pain processes, as is the case with fibromyalgia . Regarding this disease, the position of rheumatologists has traditionally been distant, in general, but they must learn to manage it. Similarly, in both inflammatory and degenerative rheumatic diseases , the effects of pain may have a delayed effect beyond the injury.

To shed some light, the XLVII National Congress of the Spanish Society of Rheumatology ( SER ) hosted a table on “The faces of pain in rheumatology”, in which two diseases with different perspectives (fibromyalgia and rheumatoid arthritis) were exposed, but with the complexity of pain as a common link.

Evolution of the concept of fibromyalgia

Javier Rivera , from the Rheumatology Service of the Hospital General Universitario Gregorio Marañón (Madrid), addressed the novelties in the diagnosis and conceptualization of fibromyalgia over the years.

To explain the evolution of this disease, we went back to the 70s, when fibromyalgia was a “psychogenic rheumatism” , that is, it had a psychological origin. “That began to change in the 1980s, when it began to be considered a disease of widespread chronic pain ,” said Rivera.

In 1990, the researcher Frederick Wolfe established the first classification criteria for fibromyalgia: widespread pain, lasting more than 3 months and with the presence of 11 of 18 painful points. These criteria served to “name fibromyalgia and make room for rheumatic pathology.”

In 2010, Wolf develops new criteria in which pain points disappear due to lack of sensitivity . The new criteria are: generalized pain, an index of pain and symptoms (tiredness, sleep and assesses the presence of other somatic symptoms).

Later, Wolfe modified those criteria again to improve them and introduce new concepts. Among the novelties, the symptoms are reduced to three fundamental ones: headache, pain in the lower abdomen and depression. “Here an index is created, the fibromyalgia symptom scale (symptom scale of fibromyalgia), which is used for epidemiological studies”, commented the doctor.

In 2016 Frederic Wolfe makes a new review and establishes a different pain scale. The most interesting fact that he adds is that there may be the presence of other comorbidities , that is, that fibromyalgia may be associated with other diseases.

Subsequent to these criteria, others have appeared, such as the AAPT criteria , which “are the same with minor modifications” and where the areas of pain are defined differently.

Pain In Fibromyalgia

Although fibromyalgia is considered a chronic pain disease, it differentiates several types of chronic pain : facial pain problems, such as headaches, visceral pain, irritable bowel syndrome, primary abdominal pain, pelvic floor pain, etc. “These chronic pains actually intermingle with fibromyalgia. Many patients with fibromyalgia have many of these other symptoms,” explained Rivera.  

And it is that the disease is much more complex than just chronic pain . “It is true that it is a chronic pain disease, but there are other symptoms that show a more complex process than simply a chronic pain process,” he said. In fact, there is a list of the 41 most frequent symptoms , but others may occur.

Delay In Diagnosis

“Despite all existing criteria, there is still a delay in diagnosis,” Rivera lamented. For this, he explained, a series of questionnaires were created, especially in Primary Care (PC), to make an adequate screening of what fibromyalgia is. “The problem is that all primary care physicians cannot control all the questionnaires, all the criteria and all the diseases of all the patients, so they end up not being useful either.”

Rivera mentioned a study on physician confidence in fibromyalgia that looked at a number of variables: recognizing fibromyalgia symptoms, differentiating fibromyalgia symptoms from other illnesses, and developing a treatment plan. “The study shows that rheumatologists are the most specialized in these areas ,” he asserted.

However, Rivera wanted to emphasize that the role of PC doctors in fibromyalgia is “quite small”, and that psychiatrists have never considered it a psychiatric illness and “do not consider themselves qualified to treat these patients”. For this reason, he insisted that the diagnosis continues to be difficult, especially in PC , the first line to which a patient with fibromyalgia comes. This, he pointed out, leads to two problems: underdiagnosis and also overdiagnosis. “In the latter case, it happens because there are pains that are not fibromyalgia and sometimes a proper diagnosis is not made.”

Likewise, he listed some of the diseases that have most frequently been diagnosed as fibromyalgia and are not : degenerative mechanical astralgia, tendinitis problems, contractures, astralgia associated with menopausal situations and those related to metabolic syndrome. “All this is not fibromyalgia and we have to know how to differentiate it , both PC doctors and rheumatologists themselves,” he declared.

Rheumatoid arthritis, the most common cause of chronic pain

For his part, Enrique J. Cobos del Moral , from the Department of Pharmacology at the Faculty of Medicine of the University of Granada, focused on rheumatoid arthritis , an autoimmune, systemic and progressive disease that consists of a chronic inflammatory disorder.

It is a very prevalent disease. “In Spain there are about a quarter of a million people and 20,000 new cases are diagnosed each year. And the percentage increases as the population ages. In addition, it is one of the most common causes of chronic pain among the world population , “said the expert.

It also revealed that, in rheumatoid arthritis, pain is the most “prevalent and disabling” symptom from the patient’s perspective. And pain is closely related to cytokines.

The role of cytokines

“One of the reasons why inflammation hurts is due to a purely physical issue. Inside the joints there are many nerve endings and some of them produce mechanical stimuli, which contributes to pain”, explained Enrique J. Cobos.

Apart from that, there are cytokines , small proteins that are crucial in controlling the growth and activity of other cells of the immune system and blood cells. Cytokines have, on the one hand, an indirect effect, that is, they “can promote the production of certain inflammatory redness.” But they also have a direct effect on peripheral nociceptors (terminations that detect pain and transmit it to other areas of the central nervous system).

“Peripheral sensory neurons are sensors of inflammation and have certain molecular machinery, receptors for many of the cytokines that are very important in chronic inflammatory pain disorders ,” he concluded.


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