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.
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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?
ATender point injections
BLow-dose prednisone
COral duloxetine
DTizanidine at bedtime
EAerobic exercise
Reveal answer & full explanation
Correct answer: E — Aerobic exercise
ATender point injections
BLow-dose prednisone
COral duloxetine
DTizanidine at bedtime
EAerobic exercise✓
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
Low-dose prednisone — widespread aching with fatigue can suggest an inflammatory condition such as polymyalgia rheumatica, but fibromyalgia reflects central sensitization without inflammation (no synovitis, normal ESR); glucocorticoids provide no benefit and EULAR recommends against them
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?
ANormal erythrocyte sedimentation rate and CRP level
BAntinuclear antibody titer of 1:1280 with anti-dsDNA
CThyroid-stimulating hormone elevated at 14 mIU/L
DCreatine kinase elevated at three times normal limit
EErythrocyte sedimentation rate elevated at 55 mm/hr
Reveal answer & full explanation
Correct answer: A — Normal erythrocyte sedimentation rate and CRP level
ANormal erythrocyte sedimentation rate and CRP level✓
BAntinuclear antibody titer of 1:1280 with anti-dsDNA
CThyroid-stimulating hormone elevated at 14 mIU/L
DCreatine kinase elevated at three times normal limit
EErythrocyte sedimentation rate elevated at 55 mm/hr
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 the 2016 revised criteria, diagnosis rests on the widespread pain index and symptom severity scale and remains valid even when another condition coexists; labs are still used to screen for mimics, so a normal inflammatory panel is the expected supportive 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.
Thyroid-stimulating hormone elevated at 14 mIU/L — hypothyroidism is a classic fibromyalgia mimic, causing fatigue, diffuse myalgias, and slowed thinking, which is why TSH belongs in the exclusion workup, but an elevated TSH points to a treatable alternative explanation for her symptoms rather than supporting fibromyalgia.
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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
2016 revised fibromyalgia criteria (Wolfe et al.): 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); the diagnosis is valid irrespective of other diagnoses, so coexisting RA, SLE, or OA does not exclude it.
Labs
Goal is to exclude alternative explanations — not to confirm fibromyalgia
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 plus a limited screen for mimics — 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
Wolfe 2016 — 2016 Revisions to the 2010/2011 Fibromyalgia Diagnostic Criteria (Wolfe et al., Semin Arthritis Rheum 2016;46(3):319-329)
EULAR 2017 — EULAR Revised Recommendations for the Management of Fibromyalgia (Macfarlane et al., Ann Rheum Dis 2017)
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