Polymyositis: Difference between revisions
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==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 | ||
* Associated arthralgias | *Associated arthralgias | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
* Hypokalemia | *Hypokalemia | ||
* Hypophosphatemia | *Hypophosphatemia | ||
* Thyroid disorder (hypothyroidism or hyperthyroidism) | *Thyroid disorder (hypothyroidism or hyperthyroidism) | ||
* Myopathies | *Myopathies | ||
* Inclusion body myositis | *Inclusion body myositis | ||
* Drug Induced myopathies (EtOH, antimalarials, colchicine, antifungals) | *Drug Induced myopathies (EtOH, antimalarials, colchicine, antifungals) | ||
{{Weakness DDX}} | {{Weakness DDX}} | ||
==Diagnosis== | ==Diagnosis== | ||
* CBC, ESR, CRP, CK, UA, RF, ANA, Anti-Jo-1 | *CBC, ESR, CRP, CK, UA, RF, ANA, Anti-Jo-1 | ||
==Management== | ==Management== | ||
* Prednisone 1mg/kg/day for 4-8 weeks until CK returns to reference range | *Prednisone 1mg/kg/day for 4-8 weeks until CK returns to reference range | ||
* Followed by prednisone taper | *Followed by prednisone taper | ||
* 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 | ||
==Disposition== | ==Disposition== | ||
Revision as of 12:46, 4 July 2016
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
- Hypokalemia
- Hypophosphatemia
- Thyroid disorder (hypothyroidism or hyperthyroidism)
- Myopathies
- Inclusion body myositis
- Drug Induced myopathies (EtOH, antimalarials, colchicine, antifungals)
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:
Diagnosis
- CBC, ESR, CRP, CK, UA, RF, ANA, Anti-Jo-1
Management
- Prednisone 1mg/kg/day for 4-8 weeks until CK returns to reference range
- Followed by prednisone taper
- Methotrexate as second line for poor response to corticosteroids
- Other agents with less evidence: IVIG, TNF Inhibitors
Disposition
- Rheumatology or neurology consultation either in ED or as outpatient depending on severity of symptoms
- Very strongly associated with malignancy (~30%), especially:[1]
- Ovarian
- Lung
- Pancreatic
- Stomach
- Colorectal
- Lymphoma
- Bladder
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.