Prolonged Febrile Seizures Are Associated with Hippocampal Vasogenic Edema and Developmental Changes

Authors

  • Rod C. Scott,

    1. Neurosciences Unit
    2. Radiology and Physics Unit, Institute of Child Health, University College London, and Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
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  • Martin D. King,

    1. Radiology and Physics Unit, Institute of Child Health, University College London, and Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
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  • David G. Gadian,

    1. Radiology and Physics Unit, Institute of Child Health, University College London, and Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
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  • Brian G. R. Neville,

    1. Neurosciences Unit
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  • Alan Connelly

    1. Radiology and Physics Unit, Institute of Child Health, University College London, and Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
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Address correspondence and reprint requests to Rod C. Scott, The Wolfson Centre, Mecklenburgh Square, London WC1N 2AP, U.K. E-mail: rscott@ich.ucl.ac.uk

Abstract

Summary: Purpose: There is mounting evidence that a prolonged febrile seizure (PFS) can cause acute hippocampal edema although the nature of that edema remains uncertain. The principal aims of the current study were: (1) to use apparent diffusion coefficient (ADC) measurements to further characterize the hippocampal edema previously identified within 5 days of a PFS, and (2) to determine whether the age dependency of ADC in the hippocampus is different in patients when compared to a control population following a PFS.

Methods: Diffusion weighted imaging was acquired in 23 children within 5 days of a PFS, and in 14 of these children a mean of 5.5 months later. Twenty-four control children were enrolled.

Results: There was a reduction in ADC between the acute and follow-up investigations [mean reduction = 0.0072 mm2/s/month since PFS (95% confidence interval; 0.0001–0.014 mm2/s/month since PFS), p = 0.048] consistent with early vasogenic edema, followed by recovery in children investigated within 2 days of a PFS. In addition, the behavior of ADC with respect to age was different in patients when compared to control subjects [mean difference in slope =−0.155 mm2/s/log10 age (95% confidence interval; −0.290–0.0203 mm2/s/log10 age), p = 0.029], in that the expected age dependence was observed only in the control subjects.

Conclusion: We suggest that these latter findings are most consistent with a preexisting developmental hippocampal abnormality that may predispose individuals to having a PFS.

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