A case of myocarditis following neonatal meningitis caused by coxsackievirus B1 in spite of intravenous immunoglobulin treatment.

Enteroviral infection is one of the most common neonatal infections, and most patients recover without complications. This report describes a neonate who experienced meningitis followed by myocarditis. A 4-day-old boy was admitted with fever, diagnosed with enteroviral meningitis and treated with intravenous immunoglobulin (IVIG). However, myocarditis was subsequently diagnosed in spite of IVIG treatment, and coxsackievirus B1 (CXB1) was revealed as a cause. A left ventricular aneurysm persisted even though the patient recovered with repeated high-dose IVIG treatment and cardiac supportive care. This report describes a rare case where myocarditis developed several days after a diagnosis of CXB1 meningitis in spite of IVIG treatment. It is important to pay attention to the patient's clinical condition until the end of the second viremia of enterovirus and to consider high-dose IVIG treatment when treating enteroviral infections for neonates.