What are the key components of a physical exam for myositis and what are the typical treatment options?

Physical Examination for Myositis and Treatment Options

The key components of a physical examination for myositis include comprehensive muscle strength testing focusing on proximal muscle groups, skin examination for characteristic rashes, and joint assessment, with treatment primarily involving corticosteroids and immunosuppressive agents based on disease severity.

Physical Examination Components

Muscle Strength Assessment

• Perform manual muscle testing (MMT) of proximal, distal, and axial muscle groups bilaterally, with special attention to proximal muscles where weakness is most common 1
• Test key muscle groups including neck flexors/extensors, deltoids, biceps, wrist extensors, gluteus maximus/medius, quadriceps, and ankle dorsiflexors 2
• Assess for difficulty in standing up, lifting arms, and moving around, which are characteristic of inflammatory myositis 1
• Distinguish true muscle weakness (characteristic of myositis) from pain-limited movement (seen in polymyalgia-like syndromes) 1

Skin Examination

• Examine for cutaneous manifestations suggestive of dermatomyositis, including Gottron papules, heliotrope rash, and shawl sign 1
• Check for skin ulcerations, atrophy, or pigmentation changes that may indicate disease activity or damage 1

Joint and Spine Assessment

• Complete examination of all peripheral joints for tenderness, swelling, and range of motion 1
• Perform spine examination to assess for involvement or differential diagnoses 1

Functional Assessment

• Evaluate activities of daily living (ADLs) using standardized tools such as the Health Assessment Questionnaire 1
• Assess physical function using validated measures like the Manual Muscle Test (MMT8) or Functional Index-2 1, 3

Laboratory and Diagnostic Testing

• Measure muscle enzymes including creatine kinase (CK), aldolase, transaminases (AST/ALT), and lactate dehydrogenase (LDH) 1
• Check inflammatory markers (ESR, CRP) which are typically elevated in inflammatory myositis 1
• Consider autoantibody panels for myositis-specific antibodies (e.g., anti-TIF1γ, anti-NXP2) 1
• Evaluate for cardiac involvement with troponin, ECG, and echocardiogram 1
• Consider EMG, MRI imaging, and/or muscle biopsy when diagnosis is uncertain 1

Treatment Options Based on Severity

Mild Disease (Grade 1)

• Continue immunotherapy if applicable (in immune checkpoint inhibitor-related myositis) 1
• Initiate oral corticosteroids (prednisone 0.5 mg/kg/day) if muscle enzymes are elevated and weakness is present 1, 4
• Provide analgesia with acetaminophen or NSAIDs for myalgia if no contraindications exist 1
• Consider holding statins if the patient is taking them 1

Moderate Disease (Grade 2)

• Hold immunotherapy temporarily if applicable 1
• Initiate prednisone 0.5-1 mg/kg/day if CK is elevated (≥3× upper limit of normal) 1, 4
• Refer to rheumatology or neurology for specialized management 1
• Consider NSAIDs for symptomatic relief 1
• May require permanent discontinuation of immunotherapy if there are objective findings of severe muscle involvement 1

Severe Disease (Grade 3-4)

• Hold immunotherapy and consider hospitalization for patients with severe weakness 1
• Initiate high-dose corticosteroids (prednisone 1 mg/kg/day orally or methylprednisolone 1-2 mg/kg IV) 1, 4
• Consider plasmapheresis or IVIG therapy for acute or severe disease 1
• Consider additional immunosuppressants if no improvement after 2 weeks:
  • Biologics (rituximab, TNFα or IL-6 antagonists) 1
  • Synthetic immunosuppressants (methotrexate, azathioprine, mycophenolate mofetil) 1, 5
• Urgent referral to rheumatology and/or neurology 1

Important Considerations and Pitfalls

• Early recognition and treatment are critical to prevent irreversible muscle damage and complications 5
• Distinguish myositis from other conditions with similar presentations (polymyalgia rheumatica, fibromyalgia, statin-induced myopathy) 1
• Monitor for potential cardiac involvement, which can be fatal if not detected early 5
• Be vigilant for concomitant myocarditis and/or myasthenia gravis, which carry an ominous prognosis 1
• Implement physical therapy early to prevent joint contractures and muscle atrophy 1
• Regular monitoring with serial muscle enzyme measurements and strength assessments is essential 1
• Rapid corticosteroid tapering may lead to disease flare and should be avoided 5