Tuesday, September 22, 2009

Febrile Seizure: Role of Antipyretics

The 1993 International League Against Epilepsy defined a febrile seizure as "an epileptic seizure occurring in childhood associated with fever, but without evidence of intracranial infection or defined cause. Seizures with fever in children who have experienced a previous nonfebrile seizure are excluded."
In other words, febrile seizures are seizures that occur in febrile children between the ages of 6 and 60 months (6-60) who do not have an intracranial infection, metabolic disturbance, or history of afebrile seizures.

Febrile seizures are subdivided into:
- simple and
- complex.

Simple febrile seizures last for less than 15 minutes, are generalized (without a focal component), and occur once in a 24-hour period, whereas complex febrile seizures are prolonged (>15 minutes), are focal, or occur more than once in 24 hours.

The way I remember it would be:
A Simple Febrile seizure is defined as a seizure in a FEBRILE child aged 6 months to 60 months and without:

S = Seizure of focal type
I = Intracranial infection or other insults such as metabolic disturbances
M = Multiple times a day
P = Past history of afebrile seizure
L = Last longer than 15 minutes
E = Examination abnormalities

* if there is evidence of the above criteria. then it is a complex febrile seizure
(Click here for more mnemonics and study aids that I am compiling)

Risk Factors for Recurrent Febrile Seizures
  • Younger than 18 months
  • Duration of fever (i.e., shorter duration of fever before seizure equals higher risk of recurrence)
  • Family history of epilepsy (possible, not definitive)
  • Family history of febrile seizures
  • Height of fever (i.e., the lower the peak fever, the higher the rate of recurrence)
(Ref: Shinnar S, Glauser TA. Febrile seizures. J Child Neurol 2002;17(suppl 1):S44-52)

Click here to download an article on Evaluation and Treatment of the Child with Febrile Seizure by American Family Physician. Click here for another free good review article.

Click here to download a Clinical Practice Guidelines on Long-term Management of the Child With Simple Febrile Seizures by the American Academy of Pediatrics.

Does antipyretics prevent seizures and prevent recurrences of febrile seizures in a child with fever?

Since fever is the key factor in the initiation of a febrile seizure, does the administration of antipyretic agents during febrile episodes prevent seizures and their recurrences by the lowering of the temperature?

In this recent randomized, placebo-controlled, double-blind trial by Strengell et al, a total of 231 children (95 girls and 136 boys; mean age, 1.7 years) who experienced their first febrile seizure were treated first with either rectal diclofenac or placebo.

After 8 hours, treatment was continued with oral ibuprofen, acetaminophen, or placebo up to 4 times a day for as long as the temperature remained greater than 38°C.

The main outcome measure was recurrence of febrile seizures in the children allocated to the 3 oral treatment groups.

There were no significant differences between the groups in the main measure of effect, and the effect estimates were similar, as the rate of recurrence was 23.4% (46/197) in those receiving antipyretic agents and 23.5% (8/34) in those receiving placebo (difference, 0.2; 95% CI, −12.8 to 17.6; P = .99).

Fever was significantly higher during the episodes with seizure vs episodes without seizure (39.7°C vs 38.9°C; difference, 0.7°C; 95% CI, −0.9°C to −0.6°C; P < .001), and this phenomenon was independent of the medication given. What does this mean?

1. Antipyretic agents are ineffective for the prevention of recurrences of febrile seizures.

2. All of the antipyretic drugs were also ineffective in the lowering of temperature during an episode that led to a febrile seizure, and there were no significant differences between the treatment groups.

3. However, all antipyretic agents were effective in the lowering of the fever in episodes that did not lead to a febrile seizure.

Strengell T, Uhari M, Tarkka R et al. Antipyretic agents for preventing recurrences of febrile seizures: randomized controlled trial. Arch Pediatr Adolesc Med 2009; 163 (9):799-804.

Other issues:
Ongoing seizure on arrival in the emergency department is an indication for initiating therapy. Intravenous diazepam is effective in most cases.
How about the use of rectal diazepam?

Rectal diazepam during the first 24 hours of the febrile illness is safe and effective in preventing a recurrence of a febrile seizure as well as effective in terminating prolonged or repetitive febrile seizures
(Ref: Dreifuss FE, et al: A comparison of rectal diazepam gel and placebo for acute repetitive seizures. N Engl J Med 1998; 338:1869.)

Rectal diazepam would be appropriate for use in a prehospital setting such as an ambulance and in cases for which intravenous access is difficult.

If the child continues to convulse after first dose of anticonvulsant........

For a child who continues to convulse, a second dose of intravenous diazepam (or midazolam) should be repeated after 15 min. And if the seizure continues after an adequate dose of a benzodiazepine, a full status epilepticus treatment protocol should be initiated.

Ref: Appleton R, Choonara I, Martland T, Phillips B, Scott R, Whitehouse W. The treatment of convulsive status epilepticus in children. The Status Epilepticus Working Party, Members of the Status Epilepticus Working Party. Arch Dis Child 2000;83:415-9. (Download a free copy of this article on the treatment of convulsive status epilepticus in children here or here)

But how about long-term anti-convulsant therapy?
Treatment with long-term anticonvulsants may reduce the risk of recurrence while on medication, but it does not affect the later risk of epilepsy.

Therefore, in most cases of simple febrile seizures, the risks of long-term anticonvulsant therapy outweigh its benefits.

Current guidelines do not recommend the use of continuous or intermittent therapy with anti-convulsants after a simple febrile seizure.
Ref: Shinnar S, Glauser TA: Febrile seizures. J Child Neurol 2002; 17S:S44. Download the article here

1 comment:

Peter29 said...

Febrile Seizures is very common in children during high fever.Thanks for useful post


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