From the Guidelines
Viral myositis should be diagnosed and treated based on the severity of symptoms, with mild cases managed with supportive care and severe cases requiring hospitalization and immunosuppressive therapy. The diagnosis of viral myositis involves a comprehensive diagnostic work-up, including a complete rheumatologic and neurologic history, blood testing to evaluate muscle inflammation, and examination of the skin for findings suggestive of dermatomyositis 1. The treatment approach varies depending on the severity of symptoms, with mild cases (G1) managed with continuation of immune checkpoint inhibitor therapy, oral corticosteroids, and analgesia with acetaminophen or NSAIDs 1.
Key Considerations
- For moderate weakness (G2), immune checkpoint inhibitor therapy should be held temporarily, and prednisone or equivalent should be initiated at 0.5-1 mg/kg/d, with referral to a rheumatologist or neurologist 1.
- Severe cases (G3-4) require hospitalization, urgent referral to a rheumatologist and/or neurologist, and initiation of prednisone 1 mg/kg/d or equivalent, with consideration of plasmapheresis, IVIG therapy, and other immunosuppressant therapy 1.
Treatment Approach
- Supportive care with rest, adequate hydration, and pain management using NSAIDs like ibuprofen (400-600mg every 6-8 hours) or acetaminophen (500-1000mg every 6 hours) is essential for all cases.
- Immunocompromised patients may require targeted antiviral medications, and physical therapy can help with recovery in prolonged cases.
- Patients should seek medical care if experiencing severe muscle pain, significant weakness, dark urine, or if symptoms persist beyond two weeks.
Monitoring and Follow-up
- Regular monitoring of CK, ESR, and CRP levels is crucial to assess the severity of muscle inflammation and response to treatment 1.
- Patients with severe symptoms or those who do not respond to initial treatment should be referred to a specialist for further evaluation and management.
From the Research
Diagnosis of Viral Myositis
- The diagnosis of viral myositis is primarily based on clinical presentation, including symptoms such as muscle pain or weakness, fever, and poor general state 2.
- Physical examination and elevated creatine kinase (CK) levels can confirm the diagnosis 3, 4.
- Imaging tests, such as computed tomography or magnetic resonance imaging, can be useful in detecting which muscle is affected 2.
- Blood tests, including screening for viral infections and muscle enzymes, can help identify the causative organism and rule out complications 4, 5.
Treatment of Viral Myositis
- The treatment of viral myositis is mainly supportive, including rehydration, mitigation of fever, and analgesic medication 3, 4, 5.
- Antiviral therapy is not typically required for viral myositis 3.
- Rest and avoidance of strenuous activities can help alleviate symptoms and promote recovery 4.
- In severe cases, hospitalization may be necessary to monitor for complications, such as rhabdomyolysis and kidney damage 4, 5.
Key Features and Complications
- Benign acute childhood myositis (BACM) is a self-limited condition characterized by sudden onset of lower extremity pain during or following recovery from a viral illness 4, 5.
- The prognosis for viral myositis is excellent, with most cases resolving quickly, usually within 3-7 days 4, 5.
- Complications, such as rhabdomyolysis and kidney damage, are rare but can occur, especially in cases with highly elevated creatine phosphokinase levels 4, 5.
- Screening tests for muscular and metabolic disorders may be recommended in recurrent myositis or cases with marked CPK elevation 5.