Clinical Study of Influenza B-Associated Myositis / 소아알레르기및호흡기학회지

ABSTRACT

PURPOSE: Influenza B-associated myositis is an infrequent and poorly known complication of influenza B virus infection in children. The aim of this study was to describe the clinical and laboratory manifestations, diagnosis, and outcomes of influenza B-associated myositis in Korean children. METHODS: A retrospective analysis was conducted in patients aged <16 years who had been diagnosed with influenza B-associated myositis at the Catholic University Bucheon Saint Mary's Hospital between April 2010 and May 2010. RESULTS: Overall, 16 cases were analyzed. Influenza B-associated myositis typically occurred in preschool-aged children with a 31 male predominance. The mean age was 4.6 years (range, 3 to 7 years). The median interval between onset of influenza infection and onset of influenza B-associated myositis was 3 days (range, 1 to 7 days). Only the calf muscles were involved in all patients. Blood creatine phosphokinase concentration was elevated in most patients. Median duration to clinical recovery was 3 days (range, 1 to 4 days). No patient had rhabdomyolysis, renal failure, or related sequelae. All patients had a favorable outcome without administration of antiviral drugs. CONCLUSION: Clinical and laboratory findings of influenza B-associated myositis are very characteristic and allow a rapid diagnosis during the influenza season. Outcomes of influenza B-associated myositis are good with only proper supportive treatment.