Myositis Lecture Notes

Introduction

• Presenter: Tom from zerofinals.com
• Topics Covered: Polymyositis and Dermatomyositis
• Resources:
  • Written notes at zerofinals.com/myositis
  • Rheumatology section in Zero to Finals Medicine book
  • Flashcards and questions available at members.zerofinals.com

Overview of Myositis

• Definitions:
  • Myositis: Muscle inflammation
  • Polymyositis & Dermatomyositis: Autoimmune conditions causing myositis
• Symptoms: Proximal muscle weakness in arms and legs
• Dermatomyositis Specific Symptoms:
  • Gottron papules on hands
  • Heliotrope rash on eyelids

Causes

• Paraneoplastic Syndromes:
  • Can be caused by underlying cancer
• Viral Infections: Possible triggers like Coxsackie virus, HIV
• Genetic Factors: Certain HLA genes increase risk

Clinical Presentation

• Key Symptom:
  • Gradual onset symmetrical proximal muscle weakness
  • Difficulty with standing, climbing stairs, lifting
• Other Symptoms:
  • Muscle pain or myalgia (not always present)
• Dermatomyositis Skin Changes:
  • Gottron lesions (scaly patches on knuckles, elbows, knees)
  • Heliotrope rash (purple rash on face and eyelids)
  • Periorbital edema (swelling around eyes)
  • Photosensitive erythematous rash

Diagnosis

• Key Test: Creatine kinase blood test
  • Normal: < 300 IU/L
  • Myositis: Can be thousands
• Other Causes of Raised Creatine Kinase:
  • Rhabdomyolysis, acute kidney injury, myocardial infarction, statin use, strenuous exercise
• Diagnosis Methods:
  • Clinical evaluation by rheumatologist
  • Elevated creatine kinase
  • Auto antibodies
  • Electromyography (EMG)
  • MRI scans
  • Muscle biopsy
• Myositis Specific Antibodies:
  • Most notable: Anti-Jo-1 antibodies (linked with polymyositis)

Management

• Initial Assessment: Check for underlying cancer
• Therapies:
  • Physiotherapy and occupational therapy
  • Corticosteroids (e.g., prednisolone) as first-line treatment
  • Other options if steroids are inadequate:
    • Immunosuppressants (e.g., methotrexate)
    • IV immunoglobulins
    • Biologic therapies (e.g., infliximab)

Study Techniques

• Testing Effect:
  • Testing yourself after learning improves long-term recall
• Study Resources:
  • Flashcards, short answer, multiple choice, and extended matching questions at members.zerofinals.com

Conclusion

• Zero to Finals Resources: Books, videos, podcasts, and member site for enhanced learning

Note: Utilize available resources and study techniques mentioned to enhance learning and retention of information related to myositis.