Polymyositis
Emma Vaitkevicius, Kennedy Klein, Amber
Lister, Madison Chapin, Melissa Takacs
Prevalence, Incidence, and Etiology
● 5-22 per 100,000
● Mean age → 31 - 60 y/o
● Higher prevalence in Females and
African - American populations
Prevalence, Incidence, Etiology
● Idiopathic, meaning no known cause, linked to:
○ Medicine
■ Myotoxic agents
■ Example: cholesterol - lowering drugs
○ Autoimmune diseases
■ lupus, RA, scleroderma, etc.
○ Cancers
■ Hodgkin's lymphoma
● Potential hereditary indication
● No known way to prevent or transmit
Pathology
● Autoimmune disease affecting muscle tissue
● The cells involved
○ Cytotoxic T lymphocytes and macrophages
○ Muscular antigens
● Direct damage to Muscle tissue
○ Autoimmune reaction causes muscle fiber breakdown
○ Breakdown damage causes release of inflammatory mediators
○ Abnormal activation of cytotoxic T cells and macrophages
Pathology
● Secondary problems may include dermatomyositis and inclusion body
myositis (IBM)
● Course of disease:
○ Muscle weakness develops over weeks to months
○ Rare cases- acute muscle weakness
○ No incubation period
● Treatment:
○ Corticosteroids
○ Immunosuppressants
Diagnosis and Treatment
● Diagnosis
○ Blood tests - Increased muscle enzymes
○ Electromyography - Changes in pattern
○ MRI - Detect inflammation
○ Muscle Biopsy - Analyze abnormalities
● Treatment
○ No cure
○ Muscle strengthening (PT)
○ Medication - corticosteroid drug, immunosuppressive agents
○ Thermotherapy
○ Orthotics and assistive devices
Sign and Symptoms
● Bilateral muscle weakness most proximal to the trunk
● If muscle weakness is an extreme case
○ Respiratory failure and pneumonia
● Difficulty swallowing
○ Malnutrition
Prognosis
● Problems
○ Difficulty performing ADLs
○ Increased risk of falling
○ Arthritis
○ Shortness of breath
○ Difficulty swallowing/speaking
○ Heart arrhythmias
● Effect of Treatment
○ Physical therapy can help gain back strength and flexibility
○ Medications prevent symptoms and cause disease to go dormant
Prognosis Cont’d
● Long term disabilities
○ Difficulty swallowing- could lead to malnutrition
■ If throat/neck muscles are affected
○ Aspiration pneumonia
○ Breathing problems
■ If chest muscles are affected
● Physical therapy prognosis
○ PT is a treatment option! Strength and stretching exercises would be utilized to prevent
worsening of symptoms and gain back lost function
○ It has been proven that physical therapy paired with medication has had great impact on
preventing progression of disease
Implications and Disease Management for Physical
Therapists
● Presentations for differential diagnosis
○ Bilateral muscle weakness surrounding trunk muscles
○ Abnormal increase in muscle enzymes in blood tests
○ EMG or MRI performed following blood tests
● Disease management with PT
○ PT can be a significant intervention to maintain and improve muscular strength
○ Earlier treatment better prognosis
○ Muscles that are are affected and not exercised are at increased risk for severe atrophy
● PT implications
○ Studies have shown that aerobic and low-intensity resistance exercise have improved function
○ Focusing on rest days during severe flare ups to prevent further injuries to affected muscles.
Contraindications and Precautions for Physical Therapy
● Contraindications
○ Acute pathology flare ups
○ Severe pain, uncontrolled bp or irregular heartbeat
● Treatment/intervention precautions
○ difficulty swallowing
○ breathing problems
○ aspiration pneumonia
○ Polymyositis linked to other autoimmune disorders and cancers
Clinical Pearls
● Low risk in 18 y/o and younger
● While it can not be cured, it can be managed
● Bilateral muscle weakness mostly proximal to the trunk
○ When experiencing flare ups, as a PT, be cautious for when and how you treat them
● Associated with other conditions
Questions:
1. What are the basic word parts for the term, Polymyositis?
a. Many - muscle - infection
b. one - muscle - infection
c. Many - cell - inflammation
d. Many - muscle - inflammation
2. All of these individuals have a higher risk of developing polymyositis,
except:
a. 50 y/o female
b. 33 y/o african - american male
c. 16 y/o male
d. 59 y/o male with lupus
Sources
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Photo Sources
Polymyositis. osmosis. https://www.osmosis.org/learn/Polymyositis. Accessed September 30, 2022.
Silver N. How does polymyositis affect your muscles? Healthline. https://www.healthline.com/health/polymyositis.
Published April 19, 2022. Accessed September 30, 2022.
William C. Shiel Jr. MD. Polymyositis & dermatomyositis treatment, symptoms & diagnosis. MedicineNet.
https://www.medicinenet.com/polymyositis/article.htm. Published January 4, 2021. Accessed September 30, 2022.
