Fibromyalgia

BASICS

Central sensitization: increased sensitivity to nociceptive, nociplastic, neuropathic pain
Alterations in neuroendocrine, neuromodulation, neurotransmitters, and biochemical pathways
Sleep abnormalities: α-wave intrusion
No systemic inflammation; localized CNS immune processes possible
Genetics: polygenic inheritance; familial aggregation; odds ratio ~8.5 for first-degree relatives
Environmental triggers: trauma, illness, stress, infections

1990 ACR: widespread pain >3 months + ≥11 of 18 tender points
2010/2011 ACR (revised 2016): Widespread Pain Index (WPI) and Symptom Score (SS)
Generalized pain in ≥4/5 regions, WPI ≥7 + SS ≥5 or WPI 4–6 + SS ≥9
Symptoms >3 months
Fibromyalgia can be diagnosed despite other active diseases

Chronic widespread pain in limbs and axial skeleton
Fatigue, sleep disturbance
Mood disorders: depression, anxiety, PTSD
Cognitive impairment ("fibro fog")
Headaches (tension, migraine)
Regional pain syndromes: IBS, chronic pelvic pain, vulvodynia, interstitial cystitis
Exercise intolerance, dyspnea, palpitations
Sexual dysfunction, ocular dryness
Chemical sensitivities and drug reactions
Symptoms wax and wane

≥11 tender points (9 bilateral pairs) sensitive and specific for diagnosis
No synovitis, enthesopathy, or inflammatory signs typical
Neurologic: generalized nonanatomic dysesthesia; focal signs suggest other diagnoses

Labs: CBC, ESR/CRP, CPK, TSH, CMP, vitamin D, Mg, B12, folate, urine drug screen
ANA, RF, Lyme titers only if indicated
Imaging generally to exclude other diagnoses
Sleep studies for OSA/narcolepsy
Psych/neuropsychiatric evaluation for mood, cognition

FDA-approved: duloxetine, milnacipran, pregabalin (partial responders)
First line:
Amitriptyline 10-50 mg PO qhs (or secondary amines: desipramine, nortriptyline)
Duloxetine: start 30 mg/day, increase to 60 mg/day
Milnacipran: titrated to 50 mg BID
Pregabalin: start 75 mg BID, up to 450 mg/day
Cyclobenzaprine 5-10 mg qhs
Second line:
Gabapentin, venlafaxine XR, tramadol (+ acetaminophen), quetiapine
Others: pramipexole, memantine, low-dose naltrexone, medical cannabis, hyperbaric oxygen
Vitamin D supplementation if deficient

Avoid polypharmacy; monitor for drug interactions and stacked sedative/serotonergic/anticholinergic effects

Trigger point injections for regional myofascial pain
Multidisciplinary rehabilitation with physical/occupational therapy and integrated pain management

NSAIDs (except in comorbid conditions)
Full-agonist opioids (except refractory)
Benzodiazepines, SSRIs alone
Magnesium, guaifenesin, thyroxine, corticosteroids, DHEA, interferon, calcitonin, nabilone, most antiepileptics

Evidence-supported: acupuncture, biofeedback, hypnotherapy, balneotherapy, yoga, tai chi, mindfulness meditation, rTMS, tDCS, low-level laser therapy
Limited evidence for S-adenosyl-L-methionine, acetyl-L-carnitine supplementation
Ineffective: chiropractic, multivitamins, homeopathy

Healthy diet encouraged; caloric/carbohydrate restriction may help obese patients
Reduced pain reported with hypocaloric, vegan, and low-FODMAP diets

Chronic, fluctuating course
~50% partial remission after 2-3 years; complete remission uncommon
Poorer outcomes: longer symptoms, depression, obesity, poor treatment adherence, older age, lack of social support

Wolfe F, Clauw DJ, Fitzcharles MA, et al. 2016 Revisions to the 2010/2011 fibromyalgia diagnostic criteria. Semin Arthritis Rheum. 2016;46(3):319-329.
Macfarlane GJ, Kronisch C, Dean LE, et al. EULAR revised recommendations for the management of fibromyalgia. Ann Rheum Dis. 2017;76(2):318-328.

Fibromyalgia is a nociplastic pain disorder involving central sensitization, distinct from somatoform disorders.
Frequently comorbid with mood and anxiety disorders which require assessment and treatment.
Use 1990 or 2010/2016 ACR criteria for diagnosis.
Best outcomes occur with patient understanding and active participation in a multimodal treatment approach including exercise, sleep hygiene, lifestyle changes, pharmacotherapy, and CBT.