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Dermatomyositis/Polymyositis, Emergency Medicine

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Dermatomyositis/Polymyositis, Emergency Medicine

Basics

Description

Consultation with a rheumatologist should be made when the diagnosis is suspected for assistance with definitive diagnosis and further treatment.

  • Dermatomyositis (DM) and polymyositis (PM) are systemic inflammatory myopathies, which represent the largest group of acquired and potentially treatable causes of skeletal muscle weakness
  • Patients experience a marked progression of muscle weakness over weeks to months
  • Can lead to respiratory insufficiency from respiratory muscle weakness
  • Aspiration pneumonia can occur owing to a weak cough mechanism, pharyngeal muscle dysfunction, and esophageal dysmotility
  • Cardiac manifestations include myocarditis, conduction defects, cardiomyopathy, and congestive heart failure (CHF)
  • Arthralgias of the hands, wrists, knees, and shoulders
  • Ocular muscles are not involved but facial muscle weakness may be seen in advanced cases

Etiology

  • The exact cause is unknown, although autoimmune mechanisms are thought to be largely responsible
  • Incidence ~1:100,000 with a female preponderance
  • Association with HLA-B8 and HLA-DR3
  • There may be an association between PM and certain viral, bacterial, and parasitic infections
  • DM/PM occurs with collagen vascular disease about 20% of the time
  • In DM, humoral immune mechanisms are implicated, resulting in a microangiopathy and muscle ischemia
  • In PM, a mechanism of T-cell-mediated cytotoxicity is posited. CD8 T cells, along with macrophages surround and destroy healthy, non-necrotic muscle fibers that aberrantly express class I major histocompatibility complex (MHC) molecules
  • Deposition of complement is the earliest and most specific lesion, followed by inflammation, ischemia, microinfarcts, necrosis, and destruction of the muscle fibers
  • Although DM is seen in both children and adults, PM is rare in children
  • Similar to adult DM, juvenile DM (JDM) primarily affects the skin and skeletal muscles
  • Juvenile form may include vasculitis, ectopic calcifications (calcinosis cutis), and lipodystrophy
  • The juvenile form may be associated with coxsackievirus

Diagnosis

Signs and Symptoms

  • PM is distinguished from DM by the absence of rash
  • Patients with PM present with muscle pain and proximal muscle weakness
  • DM presents with skin rash, muscle pain, and weakness
  • Constitutional symptoms include weight loss, fever, anorexia, morning stiffness, myalgias, and arthralgias
  • Patients often note fatigue doing customary tasks:Brushing hair, climbing stairs, reaching above the head, rising from a chairMay also complain of dysphagia, dyspnea, and cough
  • Progressive weakness of the proximal limb and girdle muscles is seen early; distal muscle weakness can occur late in the disease
  • Brushing hair, climbing stairs, reaching above the head, rising from a chair
  • May also complain of dysphagia, dyspnea, and cough
  • General:FatigueFeverWeight loss
  • Dysphagia
  • Progressive muscle weakness:Involves proximal muscles primarilySymmetrical
  • Skin findings of DM:Skin rash occurs with or precedes muscle weaknessHeliotrope rash (lilac discoloration) on the upper eyelids associated with edemaGottron sign: Violaceous or erythematous papules over the extensor surfaces of the joints, particularly knuckles, knees, and elbowsShawl sign: A V-shaped erythematous rash occurring on the back and shouldersPeriungual telangiectasias: Nail-bed capillary changes that include thickened irregular and distorted cuticles"Machinist hands": Darkened horizontal lines across the lateral and palmar aspects of the fingers
  • Fatigue
  • Fever
  • Weight loss
  • Involves proximal muscles primarily
  • Symmetrical
  • Skin rash occurs with or precedes muscle weakness
  • Heliotrope rash (lilac discoloration) on the upper eyelids associated with edema
  • Gottron sign: Violaceous or erythematous papules over the extensor surfaces of the joints, particularly knuckles, knees, and elbows
  • Shawl sign: A V-shaped erythematous rash occurring on the back and shoulders
  • Periungual telangiectasias: Nail-bed capillary changes that include thickened irregular and distorted cuticles
  • "Machinist hands": Darkened horizontal lines across the lateral and palmar aspects of the fingers

Essential Workup

  • Assess airway and breathing for any signs of aspiration or compromise
  • Assess for any signs of cardiac involvement and complications

Diagnosis Tests & Interpretation

  • Serum muscle enzymes:Creatine phosphokinase (CPK) is elevated, other muscle enzymes such as aldolase, can also be elevated
  • Diagnostic criteria established in 1975 by Bohan and Peter:Symmetric proximal muscle weakness with dysphagia and respiratory muscle weaknessElevation of serum muscle enzymesElectromyographic features of myopathyMuscle biopsy showing features of inflammatory myopathyConfidence limits for diagnosis (typical rash must be seen for diagnosis of DM):Definite diagnosis: 3 or 4 criteriaProbable diagnosis: 2 criteriaPossible diagnosis: 1 criterion
  • Newer diagnostic criteria using autoantibody profiles (Anti-Jo-1, Anti-SRP, Anti-Mi-2) or immunohistologic characterization may prove to be more specific for diagnosis of specific disease subgroups
  • Creatine phosphokinase (CPK) is elevated, other muscle enzymes such as aldolase, can also be elevated
  • Symmetric proximal muscle weakness with dysphagia and respiratory muscle weakness
  • Elevation of serum muscle enzymes
  • Electromyographic features of myopathy
  • Muscle biopsy showing features of inflammatory myopathy
  • Confidence limits for diagnosis (typical rash must be seen for diagnosis of DM):Definite diagnosis: 3 or 4 criteriaProbable diagnosis: 2 criteriaPossible diagnosis: 1 criterion
  • Definite diagnosis: 3 or 4 criteria
  • Probable diagnosis: 2 criteria
  • Possible diagnosis: 1 criterion
  • Chest radiograph may show interstitial lung disease, evidence of aspiration pneumonia, CHF, or cardiomyopathy
  • EMG studies show myopathic potentials that may support the diagnosis but are not specific for DM/PM
  • Increasing role for MRI in determining regions of inflammation best suited for biopsy
  • Muscle biopsy is the definitive test:In PM, inflammatory infiltrates are often endomysial, although they may be perivascularIn DM, inflammatory infiltrates are mostly perivascular and include a high percentage of B cells
  • Renal biopsies of patients may show focal proliferative glomerulonephritis
  • Pulmonary function tests are useful in following the progression of interstitial lung disease
  • In PM, inflammatory infiltrates are often endomysial, although they may be perivascular
  • In DM, inflammatory infiltrates are mostly perivascular and include a high percentage of B cells

Differential Diagnosis

  • Collagen vascular diseases
  • Muscular dystrophies
  • Spinal muscular atrophy
  • Myasthenia gravis
  • Amyotrophic lateral sclerosis
  • Poliomyelitis
  • Guillain-Barr İ syndrome
  • Hypothyroidism
  • Hyperthyroidism
  • Cushing syndrome
  • Drug-induced:ColchicineZidovudine (AZT)PenicillamineIpecacEthanolChloroquineCorticosteroids
  • Infection:ToxoplasmosisTrichinosisCoxsackievirusHIV, influenzaEpstein-Barr virus
  • Electrolyte disturbances:HypokalemiaHypercalcemiaHypomagnesemia
  • Vasculitis
  • Paraneoplastic neuromyopathy
  • Hypereosinophilic myalgia syndrome
  • Colchicine
  • Zidovudine (AZT)
  • Penicillamine
  • Ipecac
  • Ethanol
  • Chloroquine
  • Corticosteroids
  • Toxoplasmosis
  • Trichinosis
  • Coxsackievirus
  • HIV, influenza
  • Epstein-Barr virus
  • Hypokalemia
  • Hypercalcemia
  • Hypomagnesemia

Treatment

Pre-Hospital

  • Assess ABCs
  • Transport with elevation of head of bed

Initial Stabilization/Therapy

  • Intubation and mechanical ventilation as required
  • Nasogastric (NG) suction to prevent aspiration
  • Pneumothorax has been described as a rare occurrence in childhood DM

Ed Treatment/Procedures

  • Elevate head of the bed to prevent aspiration
  • Begin high-dose corticosteroids to suppress inflammation and improve muscle weakness
  • Avoid triamcinolone and dexamethasone because they may cause a drug-associated myopathy
  • Efficacy of prednisone determined by objective increase in muscle strength, not change in CK levels
  • Some clinicians start glucocorticoid sparing immunosuppressive medications at onset, others reserve these agents for failure to respond to corticosteroids
  • Azathioprine and methotrexate are used with limitations based on side-effect profiles
  • Cyclosporine and monoclonal antibody therapies have been used but with limited success
  • Do not base treatment decisions solely upon CPK level

Medication

  • Prednisone: 60 mg/d PO (peds: 1-2 mg/kg/d PO) (in severe illness consider methylprednisolone pulse 1,000 mg/d for 3 days):Length of treatment and taper individualized to clinical response and normalization of CK
  • Length of treatment and taper individualized to clinical response and normalization of CK
  • Methotrexate: 15-25 mg PO per week (peds: 15 mg/m2/wk PO not >25 mg)
  • Azathioprine: Start at 50 mg/d then in 2 wk, increase by 50 mg until a dose of 1.5 mg/kg/d.After 3 mo, may increase dose to 2.5 mg/kg/d if tolerated
  • Intravenous immunoglobulin (IVIG), plasmapheresis, and cyclosporine are also used by some rheumatologists
  • After 3 mo, may increase dose to 2.5 mg/kg/d if tolerated

Follow-Up

Disposition

  • Respiratory insufficiency
  • Aspiration pneumonia
  • Profound muscle weakness
  • Weakened cough mechanisms
  • Pharyngeal dysfunction
  • CHF
  • Well-appearing patients with no respiratory dysfunction and no risk for aspiration
  • Patients who can take oral corticosteroids and immunosuppressive agents as outpatients

Follow-Up Recommendations

  • Compared to the general population, the incidence of malignant conditions appears to be increased in patients with DM (but not in those with PM)
  • A complete annual physical exam with pelvic, breast, and rectal exams; urinalysis; CBC; blood chemistry tests; and a chest film are often recommended for cancer surveillance in patients with a history of DM

Pearls and Pitfalls

  • The diagnosis of an inflammatory myopathy is largely clinical supported by selected lab testing and muscle biopsy
  • Most patients improve with therapy, and many make a full functional recovery, which is often sustained with maintenance therapy
  • Up to 30% may be left with some residual muscle weakness
  • It is important to keep in mind that relapses may occur at any time despite successful response to therapy

Additional Reading

  • Amato AA, Barohn RJ. Evaluation and treatment of inflammatory myopathies. J Neurol Neurosurg Psychiatry. 2009;80:1060-1068.
  • Casciola-Rosen L, Mammen AL. Myositis autoantibodies. Curr Opin Rheumatol. 2012;24:602-608.
  • Gordon PA, Winer JB, Hoogendijk JE, et al. Immunosuppressant and immunomodulatory treatment for dermatomyositis and polymyositis. Cochrane Database Syst Rev. 2012;8:CD003643.
  • Longo DL, Kasper DL, Jameson JL, et al. Polymyositis, dermatomyositis, and inclusion body myositis: Introduction. In Harrisons Principles of Internal Medicine. 18th ed. New York, FY: McGraw-Hill; 2012:2103-2103.
  • Wedderburn LR, Rider LG. Juvenile dermatomyositis: New developments in pathogenesis, assessment and treatment. Best Pract Res Clin Rheumatol. 2009;23:665-678.

See Also (Topic, Algorithm, Electronic Media Element)

  • Hypokalemia
  • Hypothyroidism
  • Myasthenia Gravis
  • Systemic Lupus Erythematosus

Codes

ICD9

  • 710.3 Dermatomyositis
  • 710.4 Polymyositis

ICD10

  • M33.20 Polymyositis, organ involvement unspecified
  • M33.90 Dermatopolymyositis, unspecified, organ involvement unspecified
  • M33.92 Dermatopolymyositis, unspecified with myopathy
  • M33.22 Polymyositis with myopathy
  • M33.21 Polymyositis with respiratory involvement
  • M33.29 Polymyositis with other organ involvement
  • M33.2 Polymyositis
  • M33.91 Dermatopolymyositis, unsp with respiratory involvement
  • M33.99 Dermatopolymyositis, unsp with other organ involvement
  • M33.9 Dermatopolymyositis, unspecified

SNOMED

  • 396230008 Dermatomyositis (disorder)
  • 31384009 Polymyositis (disorder)
  • 238935002 Dermatomyositis sine myositis
  • 196136009 Lung disease with polymyositis (disorder)
  • 239899000 Polymyositis associated with autoimmune disease (disorder)