Distribution of febrile seizure duration and associations with development

• Published in: Annals of neurology Vol. 70; no. 1; pp. 93 - 100
• Main Authors: Hesdorffer, Dale C., Benn, Emma K. T., Bagiella, Emilia, Nordli, Douglas, Pellock, John, Hinton, Veronica, Shinnar, Shlomo
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.07.2011; Wiley-Liss; Wiley Subscription Services, Inc
• Subjects: Biological and medical sciences; Child Development - physiology; Child, Preschool; Children & youth; Cohort Studies; Developmental Disabilities - epidemiology; Developmental Disabilities - etiology; Developmental Disabilities - physiopathology; Female; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Humans; Infant; Male; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Prospective Studies; Seizures, Febrile - complications; Seizures, Febrile - epidemiology; Seizures, Febrile - physiopathology; Time Factors; Neurological disorder; Febrile convulsion; Nervous system diseases
• ISSN: 0364-5134; 1531-8249
• DOI: 10.1002/ana.22368

Objective: In prior studies of febrile seizures (FSs), prolonged FSs were defined, absent empirical evidence, as lasting 10 or 15 minutes or more. We assessed the distribution of FS duration in a cohort with first FSs, and the association between FS duration and baseline characteristics of the children. Methods: We calculated the observed cumulative probability, S(t), that a FS would last at least t minutes, S(t) = exp(−t/τ). Data were also fit using a model obtained as the sum of 2 exponential distributions (S[t] = αexp[−t/τ1] + [1 − α]exp[−t/τ2]). After assessing the best fit, the cutoff defining long FS was determined. Logistic regression was used to examine associations between long FSs and baseline characteristics, behavior, and development. Results: In 158 children with a first FS, median duration was 4.0 minutes. Duration of FS was best fit by a 2‐component mixture exponential model. Using this model, we identified 1 population that accounts for 82.3% of FSs and has a mean duration of 3.8 minutes (short FS) and a second population that accounts for 17.7% of FSs and has a mean duration of 39.8 minutes (long FS). Long FSs were significantly associated with developmental delay (p = 0.010) and delays and younger age at first FS (p = 0.048). Interpretation: Like the distribution of afebrile seizure duration in children, the distribution of first FS duration is best modeled by assuming 2 populations. Developmental delay and younger age are associated with prolonged FSs. Our data lend further support to defining 10 minutes as the upper limit for a simple FS. ANN NEUROL 2011