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Comparative Study
. 2011 Jul;70(1):93-100.
doi: 10.1002/ana.22368. Epub 2011 Mar 17.

Distribution of febrile seizure duration and associations with development

Dale C Hesdorffer  1 , Emma K T Benn, Emilia Bagiella, Douglas Nordli, John Pellock, Veronica Hinton, Shlomo Shinnar; FEBSTAT Study Team
Collaborators, Affiliations
Comparative Study

Distribution of febrile seizure duration and associations with development

Dale C Hesdorffer et al. Ann Neurol. 2011 Jul.

Abstract

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/τ(1) ] + [1 - α]exp[-t/τ(2) ]). 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.

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Figures

FIGURE 1
FIGURE 1
Semilogarithmic plot of the observed cumulative probability (red dots), estimated cumulative probability assuming one population (green dashed line), and estimated cumulative probability assuming two populations (black line) of FS duration > t among those with an FS duration ≤ 60 minutes.
FIGURE 2
FIGURE 2
Scatter plot of Log Second FS Duration versus Log First FS Duration
FIGURE 3
FIGURE 3
Comparison of the percentage of children with delayed completion of developmental milestones between children with short seizures and those with long seizures
See this image and copyright information in PMC

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