Musculoskeletal · PANCE / PANRE

Fibromyalgia

Written & clinically reviewed by Ryan Busch, PA-C · Updated August 2026 · Report an error

Centralized pain syndrome with widespread tenderness, fatigue, and sleep and cognitive disturbance; normal labs and imaging.

Also known as: fibromyalgia, fibro, fibromyalgia syndrome, FMS

Overview

Chronic centralized pain disorder characterized by widespread musculoskeletal pain, fatigue, nonrestorative sleep, cognitive dysfunction ('fibro fog'), and somatic symptoms without inflammation or structural tissue damage.

Epidemiology

Affects 2-4% of adults; female-to-male ratio ~3:1 (closer to 2:1 with newer criteria). Peak onset 30-50. Frequently coexists with other functional somatic syndromes (IBS, chronic headache, interstitial cystitis, TMJ disorder) and with mood and anxiety disorders.

Try two board-style Fibromyalgia questions

Real questions from the FirstPassPA bank, with the full explanation. Pick an answer — no signup, no email.

Question 1MusculoskeletalMedium
A 45-year-old woman presents with 6 months of widespread musculoskeletal pain that is bilateral and both above and below the waist, along with marked fatigue, non-restorative sleep, and difficulty concentrating. Examination reveals diffuse soft-tissue tenderness without synovitis, and 16 of 18 tender points are positive. CBC, comprehensive metabolic panel, TSH, ANA, and ESR are all within normal limits. Which intervention is the most appropriate initial therapy?
  • AAerobic exercise
  • BOral duloxetine
  • CTender point injections
  • DTizanidine at bedtime
Reveal answer & full explanation
Correct answer: A — Aerobic exercise
  • AAerobic exercise✓
  • BOral duloxetine
  • CTender point injections
  • DTizanidine at bedtime

Why Aerobic exercise is correct

  • This patient meets criteria for fibromyalgia: chronic (>3 months) widespread pain in all quadrants with fatigue, non-restorative sleep, cognitive symptoms (fibro fog), and 16 of 18 tender points positive
  • Normal inflammatory and metabolic workup (CBC, CMP, TSH, ANA, ESR) excludes inflammatory and endocrine mimics
  • The cornerstone of initial management is non-pharmacologic and patient-centered: education, graded aerobic exercise (strongest and most consistent evidence for improving pain, function, and global well-being), and cognitive behavioral therapy to address sleep, mood, and pain coping
  • EULAR and U.S. guidelines recommend these as first-line before drug therapy

Why the others are wrong

  • Oral duloxetine — an SNRI that is FDA-approved for fibromyalgia and a reasonable add-on if symptoms persist despite non-pharmacologic measures, but it is not the initial step; pregabalin and milnacipran fill the same second-line role
  • Tender point injections — local anesthetic injection targets focal myofascial trigger points and has no established role in diffuse fibromyalgia; it does not address deconditioning, sleep, or central sensitization, and repeated injections are not recommended
  • Tizanidine at bedtime — a central alpha-2 agonist borrowed for muscle spasm and sleep, but it lacks guideline support in fibromyalgia and adds sedation, hypotension, and hepatotoxicity risk
Question 2MusculoskeletalMedium
A 38-year-old woman reports 8 months of diffuse, migratory musculoskeletal pain, profound morning fatigue, nonrestorative sleep, and difficulty concentrating. She has a history of irritable bowel syndrome and tension headaches. On examination there is diffuse tenderness to soft-tissue palpation, but no joint synovitis, effusion, or erythema; muscle strength, sensation, and reflexes are normal. Initial laboratory studies are obtained as part of an exclusion workup. Which of the following findings best supports the diagnosis of fibromyalgia?
  • AErythrocyte sedimentation rate elevated at 55 mm/hr
  • BNormal erythrocyte sedimentation rate and CRP level
  • CCreatine kinase elevated at three times normal limit
  • DAntinuclear antibody titer of 1:1280 with anti-dsDNA
Reveal answer & full explanation
Correct answer: B — Normal erythrocyte sedimentation rate and CRP level
  • AErythrocyte sedimentation rate elevated at 55 mm/hr
  • BNormal erythrocyte sedimentation rate and CRP level✓
  • CCreatine kinase elevated at three times normal limit
  • DAntinuclear antibody titer of 1:1280 with anti-dsDNA

Why Normal erythrocyte sedimentation rate and CRP level is correct

  • Fibromyalgia is a clinical diagnosis of central sensitization; peripheral tissues are histologically normal, so labs serve to exclude inflammatory and metabolic mimics rather than to confirm the disease.
  • Normal inflammatory markers in a patient with widespread pain, fatigue, nonrestorative sleep, and cognitive symptoms argue against inflammatory arthritis, polymyalgia rheumatica, and connective tissue disease, which is exactly the supportive pattern.
  • Per 2016 ACR criteria, diagnosis rests on the widespread pain index and symptom severity scale with no better alternative explanation, so a normal inflammatory panel is the expected confirmatory-by-exclusion finding.

Why the others are wrong

  • Antinuclear antibody titer of 1:1280 with anti-dsDNA: a high-titer ANA with anti-dsDNA points to systemic lupus erythematosus, not fibromyalgia; ANA should not be ordered as a screen here given its high false-positive rate.
  • Erythrocyte sedimentation rate elevated at 55 mm/hr: an elevated ESR suggests an inflammatory process such as polymyalgia rheumatica or inflammatory arthritis, whereas fibromyalgia characteristically has normal markers.
  • Creatine kinase elevated at three times normal limit: an elevated CK indicates true myopathy such as inflammatory or statin-induced myopathy, which produces objective weakness; fibromyalgia has normal CK and no true weakness on exam.
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Risk factors

  • Female sex
  • Family history (genetic predisposition)
  • Adverse childhood experiences, prior trauma or PTSD
  • Depression and anxiety
  • Other chronic pain conditions (osteoarthritis, RA, lupus — fibromyalgia coexists in 15-30%)
  • Sleep disorders, including OSA
  • Physical or emotional triggering event (motor vehicle accident, infection, surgery)

Pathophysiology

Central sensitization with augmented central nervous system pain processing — reduced descending inhibition, elevated substance P and glutamate, and altered functional connectivity in pain-processing regions. Peripheral tissues are histologically normal.

Clinical presentation

Symptoms

  • Diffuse musculoskeletal pain >3 months in multiple body regions, often migratory
  • Profound fatigue, especially morning fatigue and after exertion
  • Nonrestorative sleep, frequent awakenings
  • Cognitive symptoms — word-finding difficulty, decreased concentration ('fibro fog')
  • Headache, paresthesias, dizziness
  • GI symptoms (IBS overlap), bladder symptoms, dysmenorrhea
  • Mood disturbance — depression and anxiety common

Signs / physical exam

  • Tenderness to palpation at multiple soft-tissue sites (no longer required for diagnosis but commonly observed)
  • Joint exam normal — no synovitis, erythema, or effusion
  • Neurologic exam normal — no objective weakness, sensory loss, or reflex changes
  • Skin and muscle exam unremarkable

Differential diagnosis

  • Hypothyroidism — Fatigue, cold intolerance, weight gain; elevated TSH
  • Polymyalgia rheumatica — Age >50, proximal stiffness, ESR >40 — fibromyalgia has normal markers
  • Inflammatory arthritis (RA, SpA) — Synovitis, elevated CRP/ESR, joint imaging changes
  • SLE / connective tissue disease — Positive ANA with organ involvement; fibromyalgia frequently coexists
  • Inflammatory myopathy — True weakness, elevated CK
  • Obstructive sleep apnea / restless legs — Nonrestorative sleep — treat to improve fibromyalgia outcomes
  • Major depressive disorder — Anhedonia, hopelessness; high comorbidity and overlapping treatment
  • Statin myopathy — Drug exposure, elevated CK
  • Chronic fatigue syndrome (ME/CFS) — Post-exertional malaise dominates; significant overlap

Diagnostic workup

Diagnostic criteria

2016 ACR criteria: widespread pain index (WPI) and symptom severity scale (SSS) — pain in 4 of 5 body regions for ≥3 months with WPI ≥7 and SSS ≥5 (or WPI 4-6 and SSS ≥9), and no alternative diagnosis.

Labs

  • Goal is to exclude alternative explanations — not to confirm fibromyalgia
  • CBC, CMP, TSH, CRP, ESR, CK, vitamin D, vitamin B12
  • Consider ANA only if specific connective tissue features (avoid as screen — high false-positive rate)
  • Consider HCV, Lyme, celiac screen only if clinically indicated

Imaging

  • Generally NOT indicated — incidental findings on MRI commonly mislead
  • Image only if focal red-flag findings emerge (true weakness, focal joint signs, neurologic deficits)

Diagnostic algorithm

DomainFirst-line
EducationReassurance: real pain, no tissue damage, not progressive
ExerciseGraded aerobic exercise (walking, swimming, cycling)
SleepSleep hygiene; treat OSA / RLS
PsychologicalCBT, mindfulness-based stress reduction
Medication — pain/sleepAmitriptyline 10-50 mg qhs, cyclobenzaprine qhs
Medication — pain/moodDuloxetine, milnacipran (SNRI)
Medication — pain/sleep alt.Pregabalin, gabapentin
AvoidChronic opioids, repeat imaging without red flags
Fibromyalgia management — non-pharmacologic measures and SNRIs/TCAs/gabapentinoids are the evidence base; opioids are not.

Treatment

First-line

  • Patient education — emphasize that pain is real, reflects altered central pain processing, and is not destructive or progressive
  • Aerobic exercise — graded, low-impact (walking, swimming, cycling); cornerstone of treatment
  • Sleep hygiene and treatment of sleep disorders (OSA, restless legs)
  • Cognitive behavioral therapy and mindfulness-based stress reduction
  • Treat coexisting depression and anxiety

Complications

  • Functional disability, work absence, reduced quality of life
  • Depression, anxiety, suicidality (elevated risk)
  • Polypharmacy and adverse drug effects
  • Missed alternative diagnosis if criteria applied superficially
  • Healthcare overutilization and unnecessary imaging or procedures

PANCE pearls

  • Fibromyalgia is a clinical diagnosis based on symptom criteria and exclusion of alternatives — extensive lab and imaging workup is rarely productive.
  • Aerobic exercise is more effective than any single medication.
  • Combining a low-dose TCA at night with an SNRI or pregabalin in the day is a common, evidence-based strategy.
  • Fibromyalgia frequently coexists with inflammatory arthritis — treating the inflammatory disease alone will not relieve central pain.
  • Opioids are contraindicated as long-term therapy.

References

  • ACR 2016 — 2016 Revisions to the ACR Diagnostic Criteria for Fibromyalgia (Wolfe et al., Semin Arthritis Rheum 2016)
  • EULAR 2017 — EULAR Revised Recommendations for the Management of Fibromyalgia (Macfarlane et al., Ann Rheum Dis 2017)

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Commonly confused with

vs Polymyalgia Rheumaticavs Polymyositis and Dermatomyositis

Related Musculoskeletal diagnoses

Osteoarthritis (OA)Rheumatoid Arthritis (RA)GoutPseudogout (CPPD Disease)Systemic Lupus Erythematosus (SLE)Polymyalgia Rheumatica (PMR)Giant Cell Arteritis (GCA)Ankylosing Spondylitis (Axial Spondyloarthritis)Psoriatic Arthritis (PsA)Septic ArthritisOsteomyelitisOsteoporosisAcute Low Back Pain and Lumbar RadiculopathyLumbar Spinal Stenosis

Differentials & related conditions

Hypothyroidism (Hashimoto Thyroiditis)Polymyositis and DermatomyositisMajor Depressive Disorder (MDD)

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