Diferencia entre revisiones de «Myalgia»
(Expanded with EM-focused content: rhabdomyolysis red flags, localized vs diffuse DDx, CK-based evaluation, management, disposition) |
(Add verified PubMed references (PMIDs 31590993)) |
||
| (No se muestra una edición intermedia del mismo usuario) | |||
| Línea 1: | Línea 1: | ||
==Background== | ==Background== | ||
*Myalgia refers to muscle pain, which may be localized or diffuse | *Myalgia refers to muscle pain, which may be localized or diffuse<ref>Glaubitz S, et al. Myalgia in myositis and myopathies. Best Pract Res Clin Rheumatol. 2019 Jun;33(3):101433. PMID 31590993</ref> | ||
*Extremely common complaint — most cases are benign (viral illness, overexertion, medication side effect) | *Extremely common complaint — most cases are benign (viral illness, overexertion, medication side effect) | ||
*Key EM concern: differentiate benign myalgia from | *Key EM concern: differentiate benign myalgia from [[rhabdomyolysis]], myositis, and [[necrotizing fasciitis]] | ||
*Diffuse myalgias may indicate systemic disease (viral infection, autoimmune, endocrine, toxicologic) | *Diffuse myalgias may indicate systemic disease (viral infection, autoimmune, endocrine, toxicologic) | ||
*Statin-induced myopathy is one of the most common medication-related causes | *Statin-induced myopathy is one of the most common medication-related causes | ||
| Línea 46: | Línea 46: | ||
===Diffuse=== | ===Diffuse=== | ||
* | *Viral illness (influenza, COVID-19, EBV, dengue, enterovirus — most common cause) | ||
* | *[[Rhabdomyolysis]] (exertional, traumatic, drug-induced) | ||
*'''Medication-induced''': statins, fibrates, ACE inhibitors, colchicine | *'''Medication-induced''': statins, fibrates, ACE inhibitors, colchicine | ||
* | *Inflammatory myopathy: dermatomyositis, polymyositis, inclusion body myositis | ||
* | *Endocrine: [[hypothyroidism]], [[adrenal insufficiency]], vitamin D deficiency | ||
* | *Electrolyte abnormality: [[hypokalemia]], [[hypocalcemia]], [[hypomagnesemia]], [[hypophosphatemia]] | ||
* | *Autoimmune/rheumatologic: [[SLE]], [[polymyalgia rheumatica]], [[vasculitis]] | ||
* | *Toxicologic: [[alcohol]], [[cocaine]], [[serotonin syndrome]], [[neuroleptic malignant syndrome]] | ||
*Fibromyalgia (diagnosis of exclusion) | *Fibromyalgia (diagnosis of exclusion) | ||
| Línea 63: | Línea 63: | ||
===Laboratory=== | ===Laboratory=== | ||
* | *[[CK]] (creatine kinase): key test — markedly elevated in rhabdomyolysis (>5x normal), moderately elevated in myositis | ||
* | *[[BMP]]: renal function (rhabdomyolysis can cause AKI), potassium, calcium, phosphate | ||
* | *[[Urinalysis]]: positive for blood on dipstick with no RBCs on microscopy = myoglobinuria | ||
*[[CBC]]: infection, leukemia | *[[CBC]]: infection, leukemia | ||
*[[TSH]] if chronic or unexplained myalgias | *[[TSH]] if chronic or unexplained myalgias | ||
Revisión actual - 10:55 22 mar 2026
Background
- Myalgia refers to muscle pain, which may be localized or diffuse[1]
- Extremely common complaint — most cases are benign (viral illness, overexertion, medication side effect)
- Key EM concern: differentiate benign myalgia from rhabdomyolysis, myositis, and necrotizing fasciitis
- Diffuse myalgias may indicate systemic disease (viral infection, autoimmune, endocrine, toxicologic)
- Statin-induced myopathy is one of the most common medication-related causes
Clinical Features
History
- Localized vs. diffuse
- Onset: acute (trauma, overexertion, infection) vs. chronic (fibromyalgia, hypothyroidism, statin use)
- Recent exercise or immobility (rhabdomyolysis)
- Recent illness (viral myalgia)
- Medications: statins, fibrates, colchicine, zidovudine, corticosteroids (chronic)
- Drug/toxin exposure: alcohol, cocaine, amphetamines (rhabdomyolysis)
- Weakness (true weakness suggests myositis or myopathy vs. pain-limited weakness)
- Dark urine (myoglobinuria from rhabdomyolysis)
- Fever, rash, arthralgias (systemic inflammatory/infectious process)
- Weight changes, fatigue, cold intolerance (hypothyroidism)
Physical Exam
- Localized tenderness, swelling, induration
- Muscle strength testing (distinguish weakness from pain)
- Skin: rash (dermatomyositis — heliotrope rash, Gottron papules), erythema, crepitus (necrotizing fasciitis)
- Compartment assessment if concern for compartment syndrome (tense compartment, pain with passive stretch)
- Joint exam (distinguish articular from muscular pain)
- Thyroid exam
Red Flags
- Dark (tea/cola-colored) urine → rhabdomyolysis
- Severe localized pain + swelling + fever → necrotizing fasciitis or deep abscess
- Progressive proximal weakness → inflammatory myositis (dermatomyositis, polymyositis)
- Diffuse myalgias + fever + rash → consider toxic shock syndrome, viral hemorrhagic fever, vasculitis
- Pain out of proportion to exam + crepitus → necrotizing soft tissue infection
Differential Diagnosis
Myalgia
- Infection:
- Viral infection (e.g. Influenza)
- Bacterial infection
- Spirochete infection (E.g. Dengue fever; Trichinella)
- Drugs:
- Statins
- Bisphosphonates
- Corticosteroids
- Ciprofloxacin
- Clofibrate
- Colchicine
- Chloroquine
- Emetine
- Aminocaproic acid
- Zidovudine
- Bretylium
- Penicillamine
- Drugs causing hypokalemia
- Metabolic disorders:
- Vitamin D deficiency
- Mitochondrial myopathy
- Scurvy
- Osteomalacia
- Fibromyalgia
- Endocrine:
- Polymyalgia rheumatica
- Rhabdomyolysis
- Myositis
- Systemic lupus erythematosus
- Rheumatoid arthritis
- Inclusion body myositis
- Sarcoidosis
- Scleroderma
- Sjögren’s syndrome
- Psychiatric (e.g. somatic manifestations of depression)
- Domestic abuse
- Crush injury
- Lyme disease
- Ehlers-Danlos syndrome(hypermobility syndrome)
- HIV myopathy
- Hypophosphatemia
- Hypokalemia
- Hypothermia
- Prolonged immobility
- Strenuous exercise (overuse) or heat stroke
- Seizure
- Severe volume contraction
- Alcoholism
- Muscular dystrophy
- Duchenne
- Becker
- Limb-girdle
- Facioscapulohumeral
- Myotonic dystrophy
- Myotonia congenita
- Compartment syndrome; Muscle infarction
- Neuropathic
- Chronic fatigue syndrome
- Vasculitis
- Sarcocystosis
- Spinal stenosis
- Diabetic lumbosacral plexopathy
Localized
- Muscle strain/overuse
- Contusion
- Compartment syndrome
- Necrotizing fasciitis
- Abscess/pyomyositis
- Stress fracture
Diffuse
- Viral illness (influenza, COVID-19, EBV, dengue, enterovirus — most common cause)
- Rhabdomyolysis (exertional, traumatic, drug-induced)
- Medication-induced: statins, fibrates, ACE inhibitors, colchicine
- Inflammatory myopathy: dermatomyositis, polymyositis, inclusion body myositis
- Endocrine: hypothyroidism, adrenal insufficiency, vitamin D deficiency
- Electrolyte abnormality: hypokalemia, hypocalcemia, hypomagnesemia, hypophosphatemia
- Autoimmune/rheumatologic: SLE, polymyalgia rheumatica, vasculitis
- Toxicologic: alcohol, cocaine, serotonin syndrome, neuroleptic malignant syndrome
- Fibromyalgia (diagnosis of exclusion)
Evaluation
When Workup is Needed
- Diffuse myalgias with red flags (dark urine, weakness, fever)
- Localized myalgias with signs of infection or compartment syndrome
- Mild myalgias from viral illness or overexertion typically need no workup
Laboratory
- CK (creatine kinase): key test — markedly elevated in rhabdomyolysis (>5x normal), moderately elevated in myositis
- BMP: renal function (rhabdomyolysis can cause AKI), potassium, calcium, phosphate
- Urinalysis: positive for blood on dipstick with no RBCs on microscopy = myoglobinuria
- CBC: infection, leukemia
- TSH if chronic or unexplained myalgias
- LFTs, aldolase if inflammatory myopathy suspected
- ESR/CRP if inflammatory process suspected
- Toxicology screen if drug-related rhabdomyolysis suspected
Imaging
- Not routinely needed for diffuse myalgia
- CT or MRI if abscess, deep space infection, or compartment syndrome suspected
- X-ray if stress fracture or bony pathology considered
Management
General
- Analgesics: NSAIDs, acetaminophen
- Rest, ice for localized strains
- Discontinue offending medication if drug-induced (statins — discuss with PCP)
Rhabdomyolysis
- Aggressive IV fluid resuscitation (NS at 200-300 mL/hr initially)
- Monitor CK, electrolytes, renal function serially
- Correct electrolyte abnormalities (especially hyperkalemia, hypocalcemia)
- See Rhabdomyolysis for detailed management
Myositis/Inflammatory
- Rheumatology consultation
- May require corticosteroids or immunosuppressive therapy
Disposition
Admit
- Rhabdomyolysis with CK >5,000 or renal impairment
- Necrotizing fasciitis or deep space infection
- Compartment syndrome
- Severe electrolyte derangements
- Inflammatory myopathy with respiratory muscle weakness
Discharge
- Viral myalgias with normal labs
- Mild statin myopathy (coordinate medication change with PCP)
- Muscle strain with pain control
- Return precautions: dark urine, severe worsening pain, weakness, fever, decreased urine output
See Also
External Links
References
- ↑ Glaubitz S, et al. Myalgia in myositis and myopathies. Best Pract Res Clin Rheumatol. 2019 Jun;33(3):101433. PMID 31590993
