From the Guidelines
Viral myositis treatment should prioritize supportive care with rest, hydration, and pain management, with corticosteroids considered for severe cases, as recommended by the most recent guidelines 1.
Overview of Viral Myositis
Viral myositis is a condition characterized by muscle inflammation caused by viral infections, commonly including influenza, HIV, coxsackievirus, and SARS-CoV-2. The management of this condition focuses on alleviating symptoms and supporting the body's recovery from the viral infection.
Diagnostic Approach
The diagnostic work-up for viral myositis, as suggested by guidelines 1, should include a comprehensive rheumatologic and neurologic history, examination for muscle strength and skin findings suggestive of dermatomyositis, and blood tests to evaluate muscle inflammation, including creatine kinase (CK), transaminases, lactate dehydrogenase (LDH), aldolase, and inflammatory markers like ESR and CRP. Additional tests such as electromyography (EMG), MRI, and/or biopsy may be considered on an individual basis when the diagnosis is uncertain.
Management and Treatment
The management of viral myositis primarily involves supportive care, including:
- Rest to reduce muscle strain
- Adequate hydration to help the body recover from the infection
- Pain management using NSAIDs like ibuprofen (400-600mg every 6-8 hours) or acetaminophen (500-1000mg every 6 hours) for symptom relief, as guided by the patient's healthcare provider and considering potential interactions or contraindications 1. For severe cases, short courses of corticosteroids such as prednisone may be necessary, with the dosage and duration determined by the severity of symptoms and the patient's overall health status, as outlined in guidelines for managing immune-related adverse events 1.
Monitoring and Follow-Up
Patients with viral myositis should be monitored for complications such as rhabdomyolysis, which presents with dark urine, severe muscle pain, and weakness. If symptoms worsen or persist beyond two weeks, a medical evaluation is necessary to reassess the treatment plan and consider additional diagnostic tests or interventions.
Considerations for Immune-Related Adverse Events
In the context of immune checkpoint inhibitor therapy, myositis can be a severe and potentially life-threatening adverse event. Guidelines recommend a stepped approach to management, including holding or discontinuing the immune checkpoint inhibitor, initiating high-dose corticosteroids, and considering additional immunosuppressive therapies or plasmapheresis in severe cases, as detailed in the American Society of Clinical Oncology clinical practice guidelines 1.
Given the potential severity of myositis, especially in the context of immune checkpoint inhibitor therapy, it is crucial to prioritize a thorough diagnostic work-up and aggressive management to prevent long-term morbidity and mortality, as emphasized by recent clinical guidelines 1.
From the Research
Definition and Treatment of Myositis
- Myositis, or idiopathic inflammatory myopathy, is an overarching concept that includes dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, and the antisynthetase syndrome 2.
- Glucocorticoids are still considered the mainstay of treatment of myositis, but some patients require add-on immunosuppressive therapy due to insufficient response to glucocorticoids, relapses, or glucocorticoid-related side effects 3, 2.
Acute Viral Myositis
- Acute viral myositis (AVM) may be triggered by influenza A/B, enteroviruses, and other viruses 4.
- Typical symptoms of AVM include localized pain in the calves, limited ambulation, gait abnormality, and muscle weakness in the lower limbs, with a mean duration of 3.6 days 5.
- AVM can lead to severe complications, including rhabdomyolysis, but acute kidney injury (AKI) may be absent in some cases, even with extreme creatine kinase (CK) elevation 4.
Diagnosis and Management
- The diagnosis of AVM is based on clinical and laboratory findings, including increased muscle enzymes, such as creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) 5.
- Management of AVM includes supportive care and monitoring of laboratory parameters, with complete recovery of laboratory parameters typically observed within 30 days 5.
- In some cases, AVM may require differential diagnosis and management of rhabdomyolysis, with potential causes for the clinical phenotype, including viral originators or autoimmune diseases 4.