Paroxysmal Seizure-Like Activities Caused by Unrecognized Acute Myocarditis Masquerading as Febrile Seizures in Children

Purpose: Recognition of cardiogenic syncope caused by acute myocarditis masquerading as febrile seizures (FS) in children can be difficult in the emergency department (ED) before a cardiac work-up. We aimed to identify clinical and laboratory characteristics of children with seizure-like activity and fever caused by myocarditis that would enable their condition to be distinguished from benign FS. Methods: We identified seven children who visited the ED for paroxysmal seizure-like activity with fever and were diagnosed with acute myocarditis between 2012 and 2015, as well as 204 children who were diagnosed with benign FS during the same period. A detailed retrospective review of the medical charts of both groups was conducted. Results: Age at onset of seizure-like activity was much higher in the myocarditis group than in the FS group (4.41.9 years vs. 2.41.1 years, P=0.033). Body temperature at seizure-like activity onset was significantly lower in the myocarditis group than in the FS group (37.9C0.2C vs. 38.7C0.6C, P<0.001). Prodromal symptoms were significantly different, with nausea/vomiting (85.7% vs. 1.5%, P<0.001), abdominal pain (42.9% vs. 0.0%, P=0.021), and lethargic mentality (57.10% vs. 0.0%, P=0.015) being more frequent in the myocarditis group. The initial laboratory findings significantly differed between the two groups, with higher levels of liver enzymes, lactate dehydrogenase, creatinine, uric acid, creatine kinase, and potassium in the myocarditis group. Conclusion: Prodromal symptoms and initial laboratory results were significantly different between the myocarditis and FS groups. A good clinical history and laboratory findings can be helpful for differentiating cardiogenic syncope from benign FS.