Febrile seizures and mesial temporal sclerosis: No association in a long-term follow-up study.

OBJECTIVE: To determine whether febrile seizures cause mesial temporal sclerosis (MTS), the occurrence of MTS was evaluated in an unselected series of patients with febrile seizures. METHODS: Twenty-four patients with a prolonged first febrile seizure, 8 with an unprovoked seizure after the first febrile seizure, and 32 age-, sex-, and handedness-matched control subjects with a single simple febrile seizure without later unprovoked seizures were selected from 329 febrile seizure patients followed up prospectively. The occurrence of MTS was evaluated after a mean follow-up time of 12.3 years by MR volumetry of amygdala and hippocampal formation and qualitative analysis of mesial temporal structures. RESULTS: None of the patients had MTS. The mean total volumes of the right and left hippocampal formations and amygdala did not differ significantly between any of the three groups. The qualitative analysis revealed no sclerotic changes in the mesial temporal area. The patients with a prolonged initial febrile seizure had a lower mean right-left volume difference in hippocampal formations than the control subjects, but this had no effect on the outcome. CONCLUSION: The occurrence of MTS following even prolonged febrile seizures is an uncommon event, confirming the good clinical outcome of febrile seizures.

Preventive treatment for recurrent febrile seizures.

Febrile seizures are the most common convulsive events in childhood occurring in 2-5 % of children. 20-30% of these children will have a recurrence during a subsequent febrile infection. Even though the outcome of febrile seizures is benign, the possibility of recurrences keeps most families in fear for years after the first seizure event. Each febrile infection the child experiences increases the risk of recurrence, and there is a positive correlation between the height of the temperature during an infectious disease and the occurrence of febrile seizures. However, prophylactic use of antipyretics does not decrease the recurrence rate. Intermittent use of diazepam during febrile episodes prevents febrile seizures only in selected child populations. The continuous use of antiepileptic drugs is no longer warranted because their side-effects outweigh their benefits. The number of febrile episodes is the only risk factor that can be influenced by preventive measures. The time being, we can reassure parents on the benign nature of febrile seizures.

Risk of recurrence and outcome after the first febrile seizure.

After their first febrile seizure, 180 children were prospectively monitored to provide data for a quantitative and qualitative analysis of the factors affecting the risk of recurrence of febrile seizures and to evaluate the influence of recurrences on the outcome. Of these children, 153 had subsequent febrile episodes and were included in the risk-factor analysis. The outcome was evaluated after a 2-year follow-up in 156 children. Each febrile episode increased the risk of recurrence by 18%. Each degree of increase in temperature (Celsius) during subsequent infections almost doubled the risk of recurrence. Age, sex, the type of initial seizure, the temperature during the initial seizure, or a family history of febrile seizures or epilepsy did not influence the recurrence rate significantly. The results indicate that procedures that minimize the probability of febrile infections would decrease the risk of recurrences of febrile seizures.

A meta-analytic review of the preventive treatment of recurrences of febrile seizures.

OBJECTIVE: To assess the efficacy of various medications in the prevention of recurrent febrile seizures. STUDY DESIGN: A meta-analysis of all published randomized, placebo-controlled trials of the preventive treatment of febrile seizures published in English; 45 articles were found, but only 9 trials were randomized and placebo-controlled--4 using phenobarbital; 3, diazepam; 1, pyridoxine; and 1, phenytoin. In one of the phenobarbital trials, valproate was also compared with placebo. RESULTS: The risk of recurrences was significantly lower in children receiving continuous phenobarbital therapy than placebo (odds ratio 0.54, 95% confidence intervals 0.33 to 0.90, p = 0.017). The odds ratio for recurrences in the valproate group was 0.09, 95% CI 0.01 to 0.78, p = 0.011. No difference in the risk was found for recurrences between children receiving intermittent diazepam and placebo (odds ratio 0.81, 95% CI 0.54 to 1.22, p = 0.31). The risk for recurrences in children receiving pyridoxine or phenytoin did not differ from the risk among children receiving placebo. Four children would have to be treated with valproate (95% CI 2 to 11) or eight children would have to be treated with phenobarbital (95% CI 5 to 27), continuously, to prevent one febrile seizure. CONCLUSIONS: Because both agents found to be effective in prevention of recurrent febrile seizures have known adverse effects, prophylaxis of febrile seizures cannot be recommended.