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Three Part Question

In [children <5 years old presenting to the Emergency Department with a febrile convulsion] does [duration of seizure] correspond to [recurrent febrile convulsions]?

Clinical Scenario

A 4-year-old girl has been brought into the Emergency Department having had a febrile convulsion lasting 25 minutes. She has not had a febrile convulsion before. Her parents are extremely worried and are asking if this will cause her any problems in the future. You wonder what advice to give them.

Search Strategy

OVID Medline <1966 – June Week 3 2005>
EMBASE <1980 – 2005 Week 26>
CINAHL <1982 – June Week 3 2005>
The Cochrane Library 2005 Issue 2.
Medline
(exp Seizures, Febrile/ OR [seizure$.mp. AND {exp FEVER/ OR fever$.mp. OR febrile.mp. OR pyrexia$.mp.}] OR [convulsion$.mp. AND {exp FEVER/ OR fever$.mp. OR febrile.mp. OR pyrexia$.mp.}] OR [fit$.mp. AND {exp FEVER/ OR fever$.mp. OR febrile.mp. OR pyrexia$.mp.}]) AND (length.mp. OR duration.mp. OR prolonged.mp.) AND(recurren$.mp. OR complication$.mp.) Limit to (humans and English language and ("infant (1 to 23 months)" or "preschool child (2 to 5 years)"))
Embase
(exp Febrile Convulsion/ OR [exp SEIZURE/ AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [exp "SEIZURE, EPILEPSY AND CONVULSION"/ AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [seizure$.mp. AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [convulsion$.mp. AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [exp CONVULSION/ AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [fit$.mp. AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}]) AND (length.mp. OR duration.mp. OR prolonged.mp.) AND (recurren$.mp. OR complication$.mp. OR exp NEUROLOGICAL COMPLICATION/ OR exp COMPLICATION/) Limit to (human and English language and (infant or preschool child <1 to 6 years>))
CINAHL
(exp Convulsions, Febrile/ OR [exp Seizures/ AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [seizure$.mp. AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [exp Convulsions/ AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [convulsion$.mp. AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}] OR [fit$ AND {febrile.mp. OR pyrexia$.mp. OR exp FEVER/ OR fever$.mp.}]) AND (length.mp. OR duration.mp. OR prolonged.mp.) AND (exp Recurrence/ OR recurrent.mp. OR complication$.mp.) Limit to (English and (infant <1 to 23 months> or preschool child <2 to 5 years>))

Search Outcome

Medline: 33 papers found, 2 relevant.
Embase: 59 papers found, none new or relevant.
CINAHL: 2 papers found, none relevant.
Cochrane Library: no relevant papers found.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Berg AT, Shinnar S, Hauser WA and Leventhal JM. 1990. USA.	Studies were included if they reported the recurrence risk for children with a first febrile seizure who had no history of a prior seizure disorder. 14 studies were included.	Meta-analysis.	Pooled estimate of overall risk of a recurrent febrile convulsion.	34.3% (95%CI 32.9%-35.7%)	Only 2 of the 14 studies looked at the role duration of febrile convulsions play in risk of recurrence.
			Overall pooled estimate of recurrence risk.	Simple-30.1% (95%CI 26.9%-33.3%), Complex-37.4% (95%CI 31.3%-43.5%)
			Risk difference.	7.3% (95%CI 0.4%-14.2%)
			Knudsen-Recurrence risk.	Simple-33%, Complex-55%, (p<0.05)
			Verity et al-Recurrence risk.	Simple-33.5%, Complex-43.9% (not significant)
			Shirts et al-Recurrence risk.	Simple-28.0%, Complex-33.0% (not significant).
			Nelson and Ellenberg-Recurrence risk.	Same for simple and complex.
			Van den Berg-Recurrence risk.	Simple-38.5%, Complex-33.3%.
			Wallace-Recurrence risk.	Uncomplicated seizures-33.9%, Multiple seizures/>30 minutes duration-60%.
			Shirts et al-Recurrence risk relating to duration.	10 minutes or less duration-28.7%, >10 minutes duration-39.7%
			Thorn-Recurrence risk relating to duration of first febrile convulsion.	<5 minutes duration-46.5%, 5 minutes or longer duration-21.6% (p<0.05).
Habib Z, Akram S, Ibrahim S and Hasan B. 2003. Pakistan.	352 children aged between 3 and 84 months presenting to an emergency department with febrile convulsion between January 1998 and August 2000.	Retrospective cohort study.	Number of seizures lasting 5 minutes or less.	231/352 (65.6%).	Numbers of children in each group do not add up (5 missing children). Only studied recurrences occurring in the emergency department. No details of how long the children stayed in the emergency department. No follow up.
			Number of seizures lasting >5 minutes.	116/352 (33.0%)
			Number of recurrences after a seizure lasting 5 minutes or less.	21/231 (9.1%)
			Number of recurrences after a seizure lasting >5 minutes.	34/116 (29.3%, p<0.001)

Comment(s)

A good quality meta-analysis was found which included many studies that compared the risk of recurrence after simple and complex febrile convulsions. However, only 2 of the 14 studies included investigated the effect of the duration of the febrile convulsion has on increasing the risk of recurrence. The cohort study also stated that children with a febrile convulsion lasting more than 5 minutes are significantly more likely to have a recurrence.

Clinical Bottom Line

The limited amount of evidence regarding the effect of duration of febrile convulsion on the risk of recurrence suggests that there is a significant risk of recurrence if the child suffers a prolonged febrile convulsion (more than 5-10 minutes).

References

1. Berg AT, Shinnar S, Hauser WA and Leventhal JM. Predictors of recurrent febrile seizures:a metaanalytical review. Journal of Pediatrics. 1990; 116(3):329-37.
2. Habib Z, Akram S, Ibrahim S and Hasan B. Febrile seizures:factors affecting risk of recurrence in Pakistani children presenting at the Aga Khan University Hospital. Journal of the Pakistan Medical Association. 2003; 53(1):11-17.