Polymyositis
A 42-year-old female presents to the neurology clinic with a three-month history of progressive muscle weakness. She reports difficulty climbing stairs, rising from a seated position, and lifting objects above her head. Over the past few weeks, she has also noticed mild shortness of breath and occasional swallowing difficulty. She denies joint pain, numbness, or sensory loss.
Medical History & Social Background
• Medical history: Hypertension, hypothyroidism (on levothyroxine).
• Family history: No known neuromuscular disorders or autoimmune diseases.
• Occupation: Office worker, previously active but now struggling with daily tasks.
• Social history: Non-smoker, no alcohol use.
Physical Examination
• Neuromuscular:
√. Proximal muscle weakness in both upper and lower limbs (deltoids, hip flexors).
√. No muscle atrophy or fasciculations.
√. Intact deep tendon reflexes and normal sensation.
• Pulmonary: Mild tachypnea, normal breath sounds.
• Cardiovascular: Normal heart sounds, no murmurs or peripheral edema.
• Skin: No rashes or skin changes suggestive of dermatomyositis.
Laboratory & Diagnostic Findings
• Creatine kinase (CK): Elevated (3,500 U/L, normal <200 U/L).
• Aldolase, AST, ALT: Elevated, consistent with muscle injury.
• Antinuclear antibody (ANA): Positive (1:160, speckled pattern).
• Anti-Jo-1 antibody: Positive.
• Electromyography (EMG): Myopathic changes with fibrillations.
• Muscle biopsy: Endomysial inflammation with CD8+ T-cell infiltration, confirming polymyositis.
• Pulmonary function tests (PFTs): Decreased forced vital capacity (FVC), suggestive of early interstitial lung disease (ILD).
Diagnosis
The patient's progressive proximal muscle weakness, elevated CK, positive anti-Jo-1 antibodies, and muscle biopsy findings confirm a diagnosis of polymyositis.
Management Plan
1. First-line treatment
• High-dose corticosteroids (prednisone 1 mg/kg/day).
• Physical therapy to maintain muscle function.
2. Immunosuppressive therapy (for steroid-sparing effect and lung disease)
• Methotrexate or azathioprine for long-term management.
• Mycophenolate mofetil or cyclophosphamide if interstitial lung disease progresses.
3. Monitoring & Long-Term Care
• Regular CK and muscle strength assessments.
• Lung function tests and high-resolution CT (HRCT) for ILD progression.
• Cardiac evaluation (echocardiogram, MRI) if myocarditis is suspected.
Challenges & Considerations
• Risk of aspiration pneumonia due to dysphagia.
• Monitoring for steroid-induced complications (osteoporosis, diabetes, hypertension).
• Possible overlap syndrome with other connective tissue diseases (e.g., systemic sclerosis, lupus).
Prognosis
With early treatment, many patients regain muscle strength, but some develop chronic weakness and lung complications, requiring long-term immunosuppressive therapy.
A) Myasthenia gravis
B) Guillain-Barré syndrome
C) Polymyositis
D) Multiple sclerosis
A) Elevated creatine kinase (CK)
B) Anti-Jo-1 antibody positivity
C) Positive antinuclear antibody (ANA)
D) Elevated aldolase
A) Nonsteroidal anti-inflammatory drugs (NSAIDs)
B) High-dose corticosteroids
C) Plasmapheresis
D) Acetylcholinesterase inhibitors
A) Myocarditis
B) Gastrointestinal bleeding
C) Interstitial lung disease (ILD)
D) Peripheral neuropathy
