Clinical findings in patients with febrile seizure after 5 years of age: A retrospective study

Objective: Febrile seizures (FSs) typically occur in infants and children between 6 and 60 months of age. Rarely, FS can occur in late childhood (late FS [LFS]; >5 years of age); however, the clinical features of LFS remain unclear. We aimed to clarify the clinical features of LFS. Methods: We retrospectively analyzed data from patients with LFS who visited Hirakata City Hospital between January 2004 and December 2014. We defined LFS as a seizure accompanied by fever (temperature >= 38 degrees C) occurring after 5 years of age, without a central nervous system infection. Results: A total of 505 patients (349 boys, 156 girls: 5-14 years old) were included. A history of FS before 60 months of age was observed in 319 of 460 patients (69.3%) with sufficient information about previous FS history among the 505 patients enrolled. LFS was more likely to occur in males (69.1%). Seizure duration was <= 15 min in 87.4% of cases. A family history of FS in first-degree relatives was observed in 103/327 cases (31.5%). Among LFS cases, 45% occurred at 5 years of age, and 92.1% experienced only one seizure after 5 years of age. The number of seizure episodes gradually lessened with age, decreasing drastically to 5.6% of cases older than 9 years. Conclusions: Our findings suggest that sex differences, seizure duration, and family history were similar for LFS and FS. Over 90% patients with LFS experienced no recurrence after 5 years of age. Further study is needed to verify the recurrence rate of LFS. (C) 2020 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.