Neurologic and muscular manifestations associated with influenza B infection in children

BACKGROUND: Influenza viruses have been associated with various neurological and muscular symptoms. The aim of this study was to evaluate the pediatric neurological and muscular manifestations of influenza B during a 5-month epidemic at a single center. METHODS: We retrospectively reviewed the medical records of 355 pediatric patients with laboratory-confirmed influenza B infection. RESULTS: Neurological and muscular symptoms were exhibited by 28 patients (7.9%). The mean age was 48.7 +/- 25.2 months. The mean time between respiratory symptoms and neurological symptoms was 2.2 +/- 1.5 days. The most common symptom was seizure (19/28, 67.9%), followed by myositis (5/28, 17.9%), increased intracerebral pressure (1/28, 3.6%), delirium (1/28, 3.6%), and severe headache (1/28, 3.6%). There was one severe case of meningitis with myocarditis (1/28,3.6%). All seizures were febrile: 15 simple febrile seizures (78.9%), three complex febrile seizures (15.8%), and one febrile status epilepticus (5.3%). The mean age of nine patients with their first seizures was 37.9 +/- 22.2 months, which was older than the typical age of onset for febrile seizure. All the patients, except one, were treated with oseltamivir. There were no deaths or chronic debilitating sequelae. CONCLUSIONS: The neurological and muscular complications of influenza B infection in children are relatively mild, and febrile seizure is the most common. However, clinicians should be alert to the possibility of rare severe complications during influenza B outbreaks