Dermatomyositis

Welcome to PT 635 Pathophysiology of Complex Patient Problems This is a wiki created by and for the students in the School of Physical Therapy at Bellarmine University in Louisville KY. Please do not edit unless you are involved in this project, but please come back in the near future to check out new information!!

Original Editors -Megan Saranson from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Lead Editors - Your name will be added here if you are a lead editor on this page.  Read more.

Definition/Description

A systemic connective tissue disease, found in the rheumatoid family, characterized by inflammatory and degenerative changes in the muscles and skin leading to symmetric weakness and some degree of muscle atrophy, principally in the limb girdles, neck and pharynx.  This disease has also shown to effect the esophagus, lungs, and least commonly the heart.

Prevalence

• In the United States, approximately 5-10 in 1 million people are affected and the incidence appears to be increasing.
• May appear at any age but most commonly from age 40-60 in adulthood; in childhood 5-15
• The female to male ratio is 2:1

Characteristics/Clinical Presentation

• Symptom onset maybe acute or insidious
•  Progressive symmetric muscle weakness primarily in muscles of proximal joints and neck and pharynx
•  Dusky or erythematous skin rash, potentially scaly, elevated, or smooth. Typically found on the face resembling the butterfly rash associated with SLE, neck, shoulders, chest and back, forearms, lower legs, medial malleoli, and dorsum of the proximal interphalangeal and metacarpophalangeal joints.

• Gottron's papules 

•  Base and sides of nails maybe hyperemic
•  Muscular pain and tenderness typically associated with the rash
•  Subcutaneous calcifications may occur particularly in childhood
• diffuse alopecia with scaly scalp
  
•  Fatigue, fever, weight loss
•  Difficulty swallowing
•  Cardiopulmonary involvement such as arrhythmias, congestive heart failure, conduction deficits, ventricular hypertrophy, or pericarditis and respiratory muscles in severe cases

 

Associated Co-morbidities

Associated with other diseases and malignancies primarily ovarian, gastric, and colonic 

Medications

Corticosteroids:

• Prednisone

Immunosuppressive or cytotoxic agent: 

• Methotrexate
• Azathioprine
• Cyclophosphamide
• Cyclosporin
• Mycophenolate mofetil
• Chlorambucil

Antimalarial: steroid-sparing agent to treat skin disease

• Hydroxychloroquine and chloroquine

Mainstay adequate antibody levels to improved muscle function and for skin lesions in patients whom corticosteroids and immunosupressives have failed:

• Intravenous immune globulin

Monoclonal antibodies (destruction of B cells):

• Rituximab

Calcium channel blocker: (gradual resolution of calcinosis)

• Diltiazem

Diagnostic Tests/Lab Tests/Lab Values

laboratory studies are helpful but nonspecific:

•  ESR frequently elevated
•  Antinuclear antibodies (ANA) elevated in 60 to 80 percent of patients
•  Elevated creatine kinase (CK) enzyme, transaminases, and lactate dehyrogenase levels
•  EMG to measure the electrical activity of the muscles: typically present as short-wave and fibrillations or myopathic pattern, 10 percent are false-negative
• Rheumatoid factor: elevated in 20 percent of patients, most often in those with overlap syndromes
• Neopterin and factor VIII–related antigen (von Willebrand factor): reported to correlate with juvenile DM
  

Causes

• The etiology of this disease is unknown
• Potential autoimmune mechanism; T cells inappropriately recognize muscle fiber antigens as foreign and attack the    muscle tissues causing muscle breakdown
• Potentially triggered by a virus
• Potentially drug induced

Systemic Involvement

Systemic manifestations:
Common: proximal muscle weakness, dysphonia, dysphagia
Less common: respiratory muscle weakness, visual changes, abdominal pain

Systemic complications/association:

Cardiomyopathy
Cardiac conduction defects

Aspiration pneumonia secondary to respiratory muscle weakness
Diffuse interstitial pneumonitis/fibrosis
Large-bowel infarction secondary to vasculopathy has occurred in juvenile patients with myositis
Muscle atrophy
Muscle calcification
Ocular complications including iritis, nystagmus, cotton-wool spots, optic atrophy, conjunctival edema and pseudopolyposis
Internal malignancy

Medical Management (current best evidence)

There is no cure for this systemic disease but the symptoms can be treated.  Corticosteroids are used initially to reduce the inflammation, shorten the time to normalization of muscle enzymes, and reduce morbidity. Maintenance therapy with Prednisone usually is necessary indefinitely in the adult patient. Immunosuppressive therapies may be used in individuals who do not respond well to the corticosteroids.  The skin disease is primarily treated with sun avoidance, topical corticosteroids, antimalarial agents,methotrexate, mycophenolate mofetil, and/or intravenous immune globulin.

Physical Therapy Management (current best evidence)

•  Patient education on joint preservation
• Strengthening to tolerance
• Range of motion exercises to prevent contractures
  
  

Alternative/Holistic Management (current best evidence)

add text here

Differential Diagnosis

• CREST Syndrome
• Parapsoriasis
• Graft Versus Host Disease
• Pityriasis Rubra Pilaris
• Lichen Myxedematosus
• Polymorphous Light Eruption
• Lichen Planus
• Psoriasis, Plaque
• Lupus Erythematosus, Acute
• Rosacea
• Lupus Erythematosus, Discoid
• Sarcoidosis
• Lupus Erythematosus, Subacute Cutaneous
• Tinea Corporis
• Morphea
• Urticaria, Chronic
• Multicentric Reticulohistiocytosis
  

Case Reports

add links to case studies here (case studies should be added on new pages using the case study template)

http://www.intarchmed.com/content/1/1/25

http://pathhsw5m54.ucsf.edu/case34/case34.html

http://www.amc.edu/amr/archives/200201/case02.html

Resources

http://www.dailystrength.org/c/Polymyositis-and-Dermatomyositis/support-group

http://www.myositissupportgroup.org/

http://www.myositis.org/template/page.cfm?id=189

http://www.ninds.nih.gov/disorders/dermatomyositis/dermatomyositis.htm

Recent Related Research (from Pubmed)

see tutorial on Adding PubMed Feed

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References

see adding references tutorial.