Viral myositis

Viral myositis is an inflammatory muscle disease (classified under Orphanet code 206991; ICD-10: M60.0) caused by direct viral infection of skeletal muscle tissue or immune-mediated muscle inflammation triggered by a viral infection. It can affect individuals of any age but is particularly well-recognized in children, where it often presents as benign acute childhood myositis (BACM) following influenza or other viral infections. The condition primarily affects the musculoskeletal system, causing muscle pain (myalgia), tenderness, swelling, and weakness, most commonly in the calves and thighs. Patients may have difficulty walking or may refuse to bear weight. Elevated serum creatine kinase (CK) levels reflect muscle damage. Systemic symptoms such as fever, malaise, and upper respiratory symptoms often precede or accompany the muscle involvement. A wide range of viruses have been implicated, including influenza A and B (the most common cause in children), coxsackievirus, echovirus, HIV, HTLV-1, hepatitis B and C, Epstein-Barr virus, cytomegalovirus, and parainfluenza viruses. In most pediatric cases, particularly those associated with influenza, the condition is self-limiting and resolves within days to a week with supportive care including rest, hydration, and analgesics. However, in rare cases, viral myositis can progress to rhabdomyolysis, a severe breakdown of muscle tissue that can lead to acute kidney injury due to myoglobinuria, requiring urgent medical intervention including aggressive intravenous fluid resuscitation. In immunocompromised patients or those with HIV-associated myositis, the course may be more prolonged and require specific antiviral therapy or immunomodulatory treatment. There is no specific curative therapy for most forms of viral myositis; management is primarily supportive with monitoring of renal function and CK levels.

Common questions about Viral myositis