Fibromyalgia or pseudo fibromyalgia? – We have to get it right

Abstract

Chronic pain disorders like fibromyalgia, chronic fatigue syndrome, repetitive strain injury and myofascial pain syndromes are no more considered as ‘waste basket diagnosis’, especially because of better biological understanding of these disorders including their immunological and genetic links.1-3 Patients truly suffering from these illnesses, therefore, need to be recognised correctly. Missing these peculiar illnesses and thereby messing them up by misdiagnosing as more serious ailments like Rheumatoid arthritis, other arthritic conditions, connective tissue diseases, psychiatric illnesses or malingering are expensive errors. An equally expensive error is labelling these close mimics and other pseudo fibromyalgia states as fibromyalgia. In both the scenarios, implications can be clinical (progression of an undiagnosed illness), pharmacological (toxicity of an unwarranted drug therapy) economic, emotional, social or even legal. Unfortunately, these errors are made by General practitioners, Physicians, orthopedicians, Psychiatrists and by Rheumatologists alike.4 Syndromic approach to diagnosis of illnesses relies upon physical signs and investigations to a large extent. In pain disorders like fibromyalgia, however, the vague, ‘out of proportion’ tenderness on minor pressure or even a gentle touch may be the only other notable feature apart from the widespread aches complained by the patient. There is no ‘tell-tale’ sign elicitable by inspection, palpation, percussion or auscultation for this spectrum of illnesses. Laboratory investigations always draw a blank. Chronic pain disorders, therefore, cannot be diagnosed by this conventional approach.5 Although chronic wide spread pain, fatigue, sleep disturbance and mental fogging are some of the hallmarks of these illnesses, familiarity with classification criteria is a prerequisite to identify a good number of them. There are patients, however, with these illnesses that do not fulfill any criteria. Neurochemical misbalances, rather than anatomical lesions are more likely to cause these disorders; nor are they straightforward psychiatric illnesses, in spite of many reports of mind-body link in these conditions.6, 7 While rheumatology clinics in the western and developed world are flooded with such patients and rheumatologists in those parts of the world are more familiar with these illnesses, developing world is less familiar with these maladies. Now that the epidemic seems to be reaching the less developed world, many unanswered questions need to be addressed on this subject. Is it globalization that is bringing it to the developing world, where people earlier could tolerate small aches and pains better? Is it much less common amongst the underprivileged section of the society? Do lifestyle, dietary factors and other socioeconomic factors have some influence on pain threshold, if not on causation of these new world diseases? Painful disorders with anatomical lesions like inflammatory arthropathies, connective tissue diseases and osteoarthritis may also cause vicious cycle of ‘pain begetting more pain’, which may be termed as secondary fibromyalgia.8 On the contrary and paradoxically enough, there is a paradigm shift in the understanding of pain disorders; it is now believed widely that pain itself can cause localised inflammation in a significant proportion of cases and thereby induces this novel mechanism to perpetuate the vicious cycle of pain.9 Whether this has a therapeutic implication is arguable, but breaking this cycle is important in arresting the pain process. Mimics of fibromyalgia comprise a wide spectrum. On the one end, there are highly treatable low grade metabolic disorders like hypothyroidism and vitamin D deficiency causing chronic widespread pain. These relatively common disorders need to be excluded or diagnosed and treated, as the case may be, in a chronic pain scenario.10 On the other end of this spectrum, there are more serious organic pathologies like enthesopathic pain of spondyloarthropathies and at times, out of proportion pain and tenderness of leukemic arthropathies, especially in children presenting as vague aches and pains. Attending physician need to be sensitized to avoid misdiagnosing these conditions as fibromyalgia. Last, but not the least, undiagnosed cases of psychiatric illnesses including depression and malin-gering for social, emotional or economic gains can also present as ‘pseudofibromyalgia’.11, 12 The Chinese study in this issue by Rong MU et al. has revealed poor awareness and deficiency in diagnostic skills amongst doctors including rheumatologists and is a must- read article for all. Some of the points discussed in the preceding paragraphs are realised in this paper. Many rheumatologists who considered themselves non-believers of this vague entity in the recent past, have now turned into believers in view of emerging evidences cited above. No rheumatologist can afford to make a mistake today in diagnosing or excluding these modern day illnesses.