Fibromyalgia

Chronic, widespread, non-inflammatory pain syndrome.

• Demographics: women twice as likely as men to be diagnosed; onset typically age 29–37, diagnosed 44–53.
• History:
  • widespread, ongoing pain
  • fatigue (similar to chronic fatigue syndrome), unrefreshing sleep, cognitive fibro fog
  • commonly coexists with depression/anxiety and IBS.
• Examination: tenderness at multiple points (see diagnostic criteria below).
• Investigations: ESR/CRP to screen for an inflammatory component — if raised, look for organic disease (e.g. polymyositis, or the polymyalgic onset phase of RA).
• Management:
  • reassurance — not a sinister or progressive disease
  • attention to sleep and stressors; relaxation program; graded exercise
  • antidepressant therapy (e.g. duloxetine) or pregabalin commonly used first-line
  • referral to a pain specialist for refractory cases.

Diagnostic criteria — moved on from tender-point counting

The older 1990 ACR criteria (widespread pain + tenderness at ≥11 of 18 defined tender points) have been superseded by the 2010/2016 ACR criteria, which drop tender-point examination (poorly reproducible) in favour of a Widespread Pain Index (WPI) and Symptom Severity Scale (SSS) — covering fatigue, unrefreshing sleep, cognitive symptoms and somatic symptom count. This reflects recognition that fatigue/cognitive/sleep symptoms are as central to the diagnosis as the pain distribution itself.

Emerging option: low-dose naltrexone (LDN)

An opioid-receptor antagonist used off-label at 1–5 mg (well below the 50 mg addiction-treatment dose). A 2023 AJGP systematic review found promising but underpowered evidence (5 small prospective controlled trials) — LDN may be an effective, well-tolerated option, but current evidence lacks the power and multi-site reproduction needed to recommend it routinely. Worth knowing about as a low-risk option to discuss for patients who haven’t responded to standard therapy, pending stronger trial data.