Polymyositis: Difference between revisions
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==Background== | ==Background== | ||
Idiopathic inflammatory myopathy causing symmetric proximal muscle weakness, elevated CK,and characteristic EMG findings | *Idiopathic inflammatory myopathy causing symmetric proximal muscle weakness, elevated CK, and characteristic EMG findings | ||
==Clinical Features== | ==Clinical Features== | ||
*Symmetrical proximal muscle weakness with insidious onset | *Symmetrical proximal muscle [[weakness]] with insidious onset | ||
*Generally painless (though 30% have myalgia) | *Generally painless (though 30% have [[myalgia]]) | ||
*Difficulty with kneeling, climbing stairs, combing hair, or rising from a seated position | *Difficulty with kneeling, climbing stairs, combing hair, or rising from a seated position | ||
*Weak neck extensors causing difficulty of holding head up | *Weak neck extensors causing difficulty of holding head up | ||
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==Differential Diagnosis== | ==Differential Diagnosis== | ||
{{Myalgia DDX}} | |||
{{Weakness DDX}} | {{Weakness DDX}} | ||
==Evaluation== | ==Evaluation== | ||
===Workup=== | |||
*CBC | *CBC | ||
*ESR | *ESR | ||
*CRP | *CRP | ||
*CK | *CK: Most sensitive muscle enzyme | ||
*[[Urinalysis]] | *[[Urinalysis]] | ||
*Consider: | *Consider: | ||
**LDH | |||
**AST/ALT | |||
**Aldolase | |||
**RF | **RF | ||
**ANA | **ANA | ||
**Anti-Jo-1 | **Anti-Jo-1 | ||
**Myositis antibody panel | |||
===Diagnosis=== | |||
*Typically requires muscle biopsy | |||
==Management== | ==Management== | ||
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**[[Methotrexate]] as second line for poor response to corticosteroids | **[[Methotrexate]] as second line for poor response to corticosteroids | ||
**Other agents with less evidence: IVIG, TNF Inhibitors | **Other agents with less evidence: IVIG, TNF Inhibitors | ||
*Assess for [[interstitial lung disease]] | |||
**[[CXR]], consider CT chest | |||
* | **Pulmonary function tests (PFTs) | ||
* | *Screen for associated malignancy, especially:<ref>Hill CL et al. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. 2001 Jan 13;357(9250):96-100.</ref> | ||
**Ovarian | **Ovarian | ||
**Lung | **Lung | ||
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**Lymphoma | **Lymphoma | ||
**Bladder | **Bladder | ||
==Disposition== | |||
*Rheumatology or neurology consultation either in ED or as outpatient depending on severity of symptoms | |||
==See Also== | ==See Also== | ||
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==References== | ==References== | ||
<references/> | |||
[[Category:Rheumatology]] | [[Category:Rheumatology]] | ||
[[Category:Neurology]] | [[Category:Neurology]] | ||
Latest revision as of 08:35, 15 December 2022
Background
- Idiopathic inflammatory myopathy causing symmetric proximal muscle weakness, elevated CK, and characteristic EMG findings
Clinical Features
- Symmetrical proximal muscle weakness with insidious onset
- Generally painless (though 30% have myalgia)
- Difficulty with kneeling, climbing stairs, combing hair, or rising from a seated position
- Weak neck extensors causing difficulty of holding head up
- Associated arthralgias
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
Weakness
- Neuromuscular weakness
- Upper motor neuron:
- CVA
- Hemorrhagic stroke
- Multiple sclerosis
- Amyotrophic Lateral Sclerosis (ALS) (upper and lower motor neuron)
- Lower motor neuron:
- Spinal and bulbar muscular atrophy (Kennedy's syndrome)
- Spinal cord disease:
- Infection (Epidural abscess)
- Infarction/ischemia
- Trauma (Spinal Cord Syndromes)
- Inflammation (Transverse Myelitis)
- Degenerative (Spinal muscular atrophy)
- Tumor
- Peripheral nerve disease:
- Neuromuscular junction disease:
- Muscle disease:
- Rhabdomyolysis
- Dermatomyositis
- Polymyositis
- Alcoholic myopathy
- Upper motor neuron:
- Non-neuromuscular weakness
- Can't miss diagnoses:
- ACS
- Arrhythmia/Syncope
- Severe infection/Sepsis
- Hypoglycemia
- Periodic paralysis (electrolyte disturbance, K, Mg, Ca)
- Respiratory failure
- Emergent Diagnoses:
- Symptomatic Anemia
- Severe dehydration
- Hypothyroidism
- Polypharmacy
- Malignancy
- Aortic disease - occlusion, stenosis, dissection
- Other causes of weakness and paralysis
- Acute intermittent porphyria (ascending weakness)
- Can't miss diagnoses:
Evaluation
Workup
- CBC
- ESR
- CRP
- CK: Most sensitive muscle enzyme
- Urinalysis
- Consider:
- LDH
- AST/ALT
- Aldolase
- RF
- ANA
- Anti-Jo-1
- Myositis antibody panel
Diagnosis
- Typically requires muscle biopsy
Management
- Prednisone 1mg/kg/day for 4-8 weeks until CK returns to reference range
- Followed by prednisone taper
- Other treatments that rheum may prescribe:
- Methotrexate as second line for poor response to corticosteroids
- Other agents with less evidence: IVIG, TNF Inhibitors
- Assess for interstitial lung disease
- CXR, consider CT chest
- Pulmonary function tests (PFTs)
- Screen for associated malignancy, especially:[1]
- Ovarian
- Lung
- Pancreatic
- Stomach
- Colorectal
- Lymphoma
- Bladder
Disposition
- Rheumatology or neurology consultation either in ED or as outpatient depending on severity of symptoms
See Also
References
- ↑ Hill CL et al. Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. 2001 Jan 13;357(9250):96-100.