Prolonged febrile seizures are associated with hippocampal vasogenic edema and developmental changes.
OBJECTIVE
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.


CONCLUSIONS
We suggest that these latter findings are most consistent with a preexisting developmental hippocampal abnormality that may predispose individuals to having a PFS.
Scott
Rod C
RC
Neurosciences Unit, Institute of Child Health, University College London, London, UK. rscott@ich.ucl.ac.uk
King
Martin D
MD
Gadian
David G
DG
Neville
Brian G R
BG
Connelly
Alan
A
D000367:Age Factors; D001812:Blood-Brain Barrier / Q000473:pathology; D001929:Brain Edema / Q000175:diagnosis* / Q000473:pathology; D001931:Brain Mapping; D002657:Child Development; D002675:Child, Preschool; D038524:Diffusion Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality; D006624:Hippocampus / Q000098:blood supply / Q000473:pathology*; D006801:Humans; D007223:Infant; D008297:Male; D003294:Seizures, Febrile / Q000175:diagnosis* / Q000473:pathology