Approach

The diagnosis of fibromyalgia (FM) is based on symptoms and should be considered when a person presents with chronic multi-focal pain for longer than 3 months, especially if other symptoms such as fatigue, memory problems, and sleep and mood disturbances are noted, together with a normal physical examination.[95][96]​​

History

Primary symptoms

Widespread body pain and stiffness is one of the primary symptoms of fibromyalgia.[96] A diagnosis of fibromyalgia requires the presence of widespread body pain for at least 3 months.[96][97]​​

Pain is usually diffuse/multi-focal, but may begin as localised pain, particularly the neck and shoulders and then spread to other areas. Initial presentation of pain is commonly insidious, it may be intermittent, but become progressively persistent, and is frequently migratory. Variability of location and severity of pain is a defining feature of fibromyalgia.

The pain of fibromyalgia is often described using 'neuropathic' descriptors such as gnawing, lancinating, or accompanied by numbness or tingling. Patients report that musculoskeletal stiffness is most severe during the morning, improving throughout the day. This may be difficult to differentiate from that of rheumatical diseases such as in rheumatoid arthritis or polymyalgia rheumatica.[96] While patients with inflammatory arthritis, polymyalgia rheumatica and fibromyalgia can report stiffness in the morning, this tends to be more severe and prolonged in inflammatory arthritis. In addition, while patients with stiffness secondary to inflammatory arthritis and polymyalgia rheumatica improve with activity (gelling phenomena), stiffness secondary to fibromyalgia can worsen after prolonged activity (such as at the end of the day).

Sleep disturbance/fatigue and cognitive dysfunction are also considered to be core symptoms of FM.[96] Patients may report feeling exhausted even though they have slept for 8 hours or more during the night.[96] Characteristically sleep 'lightly', waking frequently during the early morning and have difficulty getting back to sleep. One systematic review of case control studies concludes that people with fibromyalgia experience lower sleep quality and sleep efficiency; longer wake time after sleep onset, short sleep duration, and light sleep when assessed objectively.[98] Prospective longitudinal data infer a dose-dependent association between the risk of FM and disordered sleep in women with FM, suggesting poor sleep could be a precursor to developing FM.[48] 

There is a high prevalence of obstructive sleep apnoea in patients with FM, particularly when reporting daytime somnolence. Observational studies have suggested a possible relationship between sleep apnoea and pain severity and a potential role of continuous positive pressure therapy to improve symptoms beyond hypersomnolence.[99][100][101][102]

Cognitive difficulties, commonly referred to as 'fibro fog', which impairs the ability to focus, pay attention, and concentrate, is reported by the majority of patients with fibromyalgia.[103] Evidence from meta-analyses suggests that the self-reported cognitive impact of fibromyalgia is supported by objective neuropsychological measures.[104][105]

Brain imaging studies suggest that sleep, mood/emotion, and cognitive disturbances are connected and may correlate with the severity of pain in patients with FM.[37][38][39][40]​​​[41]

Additional symptoms

Patients may present with sensory sensitivity to touch, light clothing, light/visual stimuli, noise, odours, or temperature.[96][106]​​[107][108]​​​​​ Their history may include conditions associated with fibromyalgia, such as:[21][109]​​[110][111][112]​ 

  • Rheumatological conditions including arthritis

  • Systemic lupus erythematosus

  • Axial spondyloarthritis and osteoarthritis

  • Musculoskeletal conditions such as temporomandibular disorders

  • Female sexual dysfunction or pelvic floor disorders/chronic pain

  • Psychiatric conditions, the most common being depression/major depressive disorder

  • Migraine type headache

  • Chronic gastrointestinal symptoms (e.g., nausea, diarrhoea/constipation, abdominal bloating/cramping/pain)

  • Sleep disturbance (e.g., insomnia, obstructive sleep apnoea).

Importantly, the presence of these conditions does not exclude a concomitant diagnosis of fibromyalgia.

It should be noted that current diagnostic criteria are not validated in patients with underlying rheumatological disease making it challenging to make the FM diagnosis in patients with rheumatological conditions.[82]

Physical examination

On physical examination patients may present with allodynia, a type of neuropathic pain, making them extremely sensitive to touch (activities that are not usually painful, e.g., combing hair, can cause severe pain) and/or hyperalgesia, which causes increased pain from a stimulus that provokes pain.[113][114]

There may be tenderness on palpation in multiple soft tissue sites, as defined by the American College of Rheumatology Classification Criteria 1990.[115] Fibromyalgia tender points tend to be symmetrical on the body and can include:

  • Lower neck in front

  • Edge of upper breast

  • Arm near the elbow

  • Knee

  • Base of the skull in the back of the head

  • Hip bone

  • Upper outer buttock

  • Back of the neck

  • Back of the shoulders

Other tender points may be found on physical exam, and it should be noted that counting of tender points on a patient is no longer diagnostic for fibromyalgia.[96][97]​​ ​

Patients should be assessed to exclude comorbid conditions as noted above, but physicians should bear in mind that the presence of these conditions does not exclude a concomitant diagnosis of fibromyalgia.

Diagnostic testing

There is no x-ray or laboratory test for fibromyalgia; the diagnosis is strictly a clinical one.[95][106]​​​

If the patient does not meet clinical criteria for a diagnosis of fibromyalgia, then some tests should be performed to screen for alternative causes of symptoms, including:

  • Full blood count

  • Thyroid function tests

  • Erythrocyte sedimentation rate and CRP

  • Vitamin D levels

  • Screening for obstructive sleep apnoea (e.g., STOP-BANG score, and if elevated, overnight oximetry or polysomnography)

Rheumatoid factor and anti-cyclic citrullinated protein antibody (anti-CCP antibody) should be obtained if patients have a history suggestive of an inflammatory disorder, such as symmetrical small joint pain with associated inflammatory features, and/or synovitis seen on examination.

Antinuclear antibody or anti-DNA antibody levels should be obtained selectively when there is clinical suspicion of systemic lupus erythematosus based on history (uveitis, sicca symptoms, oral ulcers, rash, photosensitivity, pericarditis/pleurisy, Raynaud's syndrome, cytopenias, seizures, thrombotic complications, renal involvement) as positive results have been reported in healthy people; therefore, they have poor predictive value unless there is significant suspicion of systemic rheumatic disease.[116]

If there is evidence of proximal/distal muscular weakness on physical examination, creatinine kinase levels should be assessed to look for evidence of an underlying myopathy/myositis.

Checking ferritin levels should be considered to look for iron deficiency, particularly as a cause of fatigue, but this can be associated with non-specific symptoms, frequently seen in similar populations such as pre-menopausal women.

These tests are not routinely recommended during testing for fibromyalgia. False positives may occur; positive results indicate the presence of another disorder, but they do not rule out fibromyalgia.

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