Interpreting excessive slowness in the EEG of an 18 month old is a
difficult and often subjective call, because the EEG is typically in the
4-6 HZ range even while awake, and if drowsy or sleepy 1-3 HZ delta and
slow theta appears normally. There's no such thing as "gamma waves"
referable to the EEG--only delta, theta, alpha, and beta. So I wouldn't
put too much weight on the interpretation that the EEG was a bit slow. By
far the most important data is that this was a single, febrile seizure,
that your daughter is and has been otherwise normal, and that the CT scan
showed no evidence of pathology. Chances are very good this was an
isolated event, though there is a possibility of recurrence with
subsequent fever, only a small minority of children with febrile seizures
subsequently develop epilepsy.
