Pain amplification, juvenile fibromyalgia and complex regional pain syndrome: SAQ

This girl has the classic juvenile fibromyalgia by the 2010 American College of Rheumatology criteria, and her sister has the classic complex regional pain syndrome by the Budapest clinical criteria, together illustrating the two phenotypes of the amplified musculoskeletal pain driven by the central sensitization. [7]

Question 1 (10 marks)

Outline the diagnosis and classification of juvenile fibromyalgia in this girl using the 2010 American College of Rheumatology preliminary diagnostic criteria, and explain the central sensitization mechanism that underpins the syndrome. [1]

A full-mark answer reproduces the 2010 criteria, applies them to this girl, and explains the central sensitization mechanism. [3]

The 2010 American College of Rheumatology criteria (4 marks). The diagnosis is made when the symptoms have been present for at least three months and no other disorder explains the pain, plus one of the following: a Widespread Pain Index of seven or more and a Symptom Severity Scale of five or more, or a Widespread Pain Index of three to six and a Symptom Severity Scale of nine or more. The Widespread Pain Index counts the number of the body regions with the pain out of nineteen, and the Symptom Severity Scale scores the fatigue, the unrefreshing sleep, the cognitive symptoms and the somatic symptoms. These criteria replaced the tender-point examination of the original Yunus and Masi criteria because the tender points were operator-dependent. Ting and colleagues validated the 2010 criteria in the adolescent female population in 2016. [1][3]

Application to this girl (2 marks). This girl meets the criteria with the widespread pain for nine months, the Widespread Pain Index of nine and the Symptom Severity Scale of seven. The first alternative is met because the Widespread Pain Index of nine is over seven and the Symptom Severity Scale of seven is over five. The fatigue, the unrefreshing sleep and the school absence are the accompanying features, and the normal blood tests confirm that no other disorder explains the pain. [1]

The central sensitization mechanism (4 marks). Amplified musculoskeletal pain is driven by the central sensitization, the amplified processing of the nociceptive signals in the central nervous system with the reduced descending inhibition. The ordinary sensory input is felt as pain, the allodynia, and the noxious input is magnified, the hyperalgesia. The vicious cycle of the pain, the fear, the avoidance and the deconditioning sustains the syndrome, and the disrupted sleep and the mood symptoms lower the threshold further. The diagnosis is made after the inflammatory, the infectious and the malignant disease are excluded, and the explanation of the central sensitization is the first treatment. [3][7]