Acute viral myositis and rhabdomyolysis: A descriptive study.

Introduction. Acute viral myositis is an inflammatory condition caused by respiratory viruses, characterized by lower-extremity pain and difficulty walking. It is a benign, self-limiting condition; complications such as rhabdomyolysis or acute kidney injury are rare. The objective of this study is to analyze the clinical course and treatment of patients seen in a pediatric emergency department (PED). Population and methods. Retrospective observational study with exploratory analysis of associations. Patients diagnosed with acute viral myositis between January 2018 and March 2023 at the PED were analyzed. Demographic, clinical, and laboratory data were collected and analyzed using means, standard deviations, and bivariate analysis (Student's t-test or chi-square test), as well as correlations (Pearson or Spearman). Results. Forty patients were included, with a mean age of 6.75 years (SD 2.59). Blood tests were performed in 30 of 40 patients (75.0%; 95% CI: 59.8-85.8). Eleven of 40 patients (27.5%; 95% CI: 16.1-42.8) met the criteria for rhabdomyolysis. No cases of renal failure or other complications were observed. Exploratory analysis revealed that creatine phosphokinase (CPK) levels were higher in males than in females and were associated with age, the AST/ALT ratio, lactate dehydrogenase (LDH), and the need for hospitalization and intravenous fluid therapy. Conclusion. Acute viral myositis in this pediatric series had a favorable clinical course. A proportion of patients presented with markedly elevated CPK levels and criteria for rhabdomyolysis, with no cases of acute renal failure.