31st January 2024

Diagnosis

Fibromyalgia 

Diagnosis can be challenging due to the heterogeneous nature of the condition. Diagnosis is based on symptoms, with the principal feature being widespread pain. However, sleep disturbance, fatigue, cognitive impairment such as memory loss or poor concentration, and bladder and bowel abnormalities can also occur. The American College of Rheumatology have laid out diagnostic criteria for fibromyalgia:

• Widespread pain index of at least 7, defined as the number of areas in which the patient has experienced pain in the last week (out of 19)
• Symptom severity score of 5 or more, based on the sum of severity of fatigue, waking unrefreshed and cognitive symptoms
• Symptoms lasting for at least 3 months 
• No other disorder diagnosed to otherwise explain the pain

On physical examination, there is usually tenderness present without erythema or swelling of soft tissues or joints. The condition is thought to be caused by a central nervous system dysfunction; there are no routine laboratory tests or imaging modalities to diagnose fibromyalgia. 

Investigations should be guided by the history; routine tests such as FBC and CRP/ESR are used to rule out other causes of inflammatory pain. More specialist testing, such as autoimmune or viral screening, should be considered if the history is suggestive. It should be noted that patients with rheumatological diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), ankylosing spondylitis or osteoarthritis are at higher risk for fibromyalgia. 

Chronic Regional Pain Syndrome 

The Budapest criteria is used for diagnosis of CRPS. The patient must have continued pain, which is disproportionate to any inciting event, as well as symptoms and signs in the following categories:

• Sensory: allodynia or hyperalgesia 
• Vasomotor: temperature asymmetry, skin colour changes or skin colour asymmetry
• Sudomotor/oedema: oedema, sweating changes or sweating asymmetry
• Motor/trophic: decreased range of motion, motor dysfunction (weakness, tremor, dystonia) or trophic changes (hair, nail or skin)

There must be at least one sign in at least two of the categories and at least one symptom in at least three of the categories. Lastly, no other diagnosis should explain the symptoms better. There is no specific investigation for this condition; workup with laboratory tests and imaging should be performed to rule out other conditions. 

References

• Wolfe F., Clauw D J., Fitzcharles M,. et al. The American College of Rheumatology Preliminary Diagnostic Criteria for Fibromyalgia and Measurement of Symptom Severity. American College of Rheumatology. Arthritis Care & Research, 2010;62(5), 600-610.
• UpToDate [Internet]. Clinical Manifestations and Diagnosis of Fibromyalgia in Adults. Uptodate.com. 2021 [cited 29 April 2022]. Available from: https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-fibromyalgia-in-adults?search=fibromyalgia&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H104197758
• Dedhia, J. D., & Bone, M. E. (2009). Pain and fibromyalgia. Continuing Education in Anaesthesia Critical Care & Pain, 9(5), 162–166. 
• Goebel A, Barker CH, Turner-Stokes L et al. Complex regional pain syndrome in adults: UK guidelines for diagnosis, referral and management in primary and secondary care. Royal College of Physicians. 2012.
• American College of Rheumtology [Internet]. Fibromyalgia. rheumatology.org. 2021 [cited 29 April 2022]. Available from: https://www.rheumatology.org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Fibromyalgia