For a further discussion of this issue, see Chapter 13. Unquestionably, intractable temporal lobe epilepsy with mesial temporal sclerosis, identified by pathologic studies or magnetic resonance imaging (MRI), has later developed in some children with prolonged febrile seizures.^20,26 These patients are rare,¹⁴ and fortunately febrile status epilepticus is a benign phenomenon in most cases.⁴⁸ The cause-and-effect relationship between prolonged febrile seizures and mesial temporal sclerosis in humans is still debated, and the minimum length of febrile seizure that might cause mesial temporal sclerosis is unknown. Some animal experiments suggest that status epilepticus can damage mesial temporal structures in the immature brain,^51,53 but other studies do not.⁷⁶ Nevertheless, it seems prudent to stop prolonged febrile seizures promptly. It is important to keep in mind that an estimated 75% of prolonged febrile seizures are the first febrile seizure.⁵⁴ Therefore, the effort to eliminate febrile status should not determine the treatment for the vast majority of children with febrile seizures who have an excellent outcome.

Short febrile seizures do not appear to damage the brain. The National Institute of Neurological Disorders and Stroke (NINDS) Collaborative Perinatal Project included 431 sibling pairs in which only one child had febrile seizures.²⁴ Testing included the Wechsler Intelligence Scale for Children (WISC) as a measure of overall intelligence and the Wide Range Achievement Test (WRAT) as a measure of academic achievement. No difference was found between children with and without febrile seizures in psychometric test scores at the age of 7 years. Even those 27 children with a febrile seizure lasting 30 minutes or more had a mean full-scale IQ no different from that of their siblings. The only exceptions occurred in sibling pairs in which the child with the febrile seizures was known to be neurologically abnormal before the first febrile seizure.

The British febrile seizure study documented intellectual, behavioral, and achievement function in a national sample of children followed to age 10 years.⁷⁴ There was no penalty for having one or more febrile seizures.

In the opinion of these authors, these studies are so robust that the issue of short febrile seizures and brain damage can be put to rest.

About 40% of children with a first febrile seizure have at least one recurrence.^1,54 Multiple recurrences are rare, with fewer than 10% having more than three recurrences.⁵⁴ There are several statistically valid predictors of recurrent febrile seizures, although for the individual child in a clinical setting, these predictors are often not very powerful.

Age is the most powerful predictor of a febrile seizure recurrence. If a child has a first febrile seizure at an age of <1 year,⁵⁴ <15 months,⁷ or <18 months,⁴⁰ the risk for recurrence is increased severalfold. The risk for recurrence is also increased if the first seizure occurred at a low body temperature or after a short illness, or if there is a close family history of epilepsy.⁷ Some authors have noted that atypical features of the first febrile seizure (focal, clustered, or prolonged) may predict recurrence,⁵⁷ although the largest studies did not find such a relationship.^1,7 One experienced investigator noted that increased exposure to infectious illness by attendance at a daycare facility increased recurrences.⁴⁰

A typical child with a first febrile seizure who has the highest risk for recurrence (>60%) would be <14 months of age, have a marginally elevated temperature within the first day of being ill, and have a close family relative with febrile seizures. A typical child with a minimal risk for recurrence (<15%) would be >3 years at the first febrile seizure, have a temperature above 39°C at the time of the seizure after an illness of several days, and have no family history of febrile seizures.

If treatment for prevention of recurrent febrile seizures is contemplated, these two extremes of risk should be taken into account. However, the ability to predict recurrence does not mean that preventive treatment is indicated.

Because fever (usually a high fever) is an essential element in the genesis of febrile seizures, it would seem intuitively correct that antipyretics would prevent febrile seizures. Empiric studies suggest the opposite. A meta-analysis concluded that there is no evidence that antipyretic medications reduce the risk of febrile seizure recurrence.²⁵ A British study found that many children with an initial febrile seizure had received an appropriate dose of antipyretics within an hour or two of a febrile seizure.⁶⁵ A Canadian study found no clear benefit in regard to recurrence risk from intensive antipyretic instructions to parents.¹⁷

A Finnish study randomized children to receive placebo or acetaminophen (10 mg/kg) at the time of illness for 2 years following a febrile seizure.⁷⁰ Again, there was no effect on febrile seizure recurrences. Those receiving placebo had recurrent febrile seizures during 8.2% of febrile illnesses, compared with 5.2% for those receiving acetaminophen.

A Dutch study randomized 230 children with at least one risk factor for a recurrent febrile seizure to either receive ibuprofen or placebo during subsequent febrile illnesses. The recurrence risk was identical in treatment and placebo groups.⁷¹

At present, the only apparent effect of antipyretics on febrile seizure treatment may be to increase “fever phobia.”⁶⁷ This may be contrasted with the increasing evidence of the beneficial effects of fever during recovery from infections.⁶⁶ The compulsive use of antipyretic drugs cannot be recommended, other than to make the child more comfortable. Because sponging the child is ineffective in reducing body temperature and is uncomfortable, it should be abandoned.⁵⁵ Despite the strong evidence that antipyretics are ineffective, many health care providers remain attached to their use; more education is needed.⁷⁵

Another obvious approach to reducing febrile seizures would be to reduce the frequency of febrile illness in childhood. Vaccination against common childhood infectious illness is to be supported. Whole-cell pertussis vaccines frequently cause fever, which in turn may provoke a febrile seizure.³⁴ Acellular pertussis vaccine causes fewer febrile reactions, and now is in widespread use for routine immunization. In Canada and Japan there is good evidence that acellular pertussis vaccine is associated with many fewer febrile seizures.^42,44

Day care attendance appears to increase the number of febrile illnesses in children in the febrile seizure age range²² and is associated with first febrile seizures⁹ and recurrences.⁴⁰ The effect of the size of the day care on rates of febrile illness has not been reported. As the risks associated with a febrile seizure are exceedingly low and the benefits of day care may be large, the issue of febrile seizures should rarely have an effect on the choice of setting for a child’s daily care.

Physicians and emergency department personnel should promptly treat any child admitted with an ongoing febrile seizure. Intravenous or rectal liquid diazepam is well studied and demonstrated to be effective.³⁹ Intranasal midazolam was found equally effective to intravenous diazepam to stop seizures in a randomized study of 47 children presenting to an emergency room with a febrile seizure of at least 10 minutes’ duration.⁴³ From the time of administration, intravenous diazepam had a shorter response time; however, it takes time to achieve intravenous access. The time from arrival in the emergency room to seizure cessation averaged 2 minutes less for the midazolam group. A larger study is needed to confirm these results before intranasal midazolam can be recommended to replace diazepam.⁴¹