Recurrence rate of febrile convulsion related to the degree of pyrexia during the first attack

Best practices for the management of febrile seizures in children

Febrile seizures (FS) are commonly perceived by healthcare professionals as a self-limited condition with a generally 'benign' nature. Nonetheless, they frequently lead to pediatric consultations, and their management can vary depending on the clinical context. For parents and caregivers, witnessing a seizure can be a distressing experience, significantly impacting their quality of life. In this review, we offer an in-depth exploration of FS management, therapeutic interventions, and prognostic factors, with the aim of providing support for physicians and enhancing communication with families. We conducted a comprehensive literature search using the PubMed and Web of Science databases, spanning the past 50 years. The search terms utilized included "febrile seizure," "complex febrile seizure," "simple febrile seizure," in conjunction with "children" or "infant." Only studies published in English or those presenting evidence-based data were included in our assessment. Additionally, we conducted a cross-reference search to identify any additional relevant data sources. Our thorough literature search resulted in a compilation of references, with carefully selected papers thoughtfully integrated into this review.

Febrile seizures: an epidemiological and outcome study of 482 cases

INTRODUCTION

Febrile seizures (FSs) are the most common type of seizures seen in children. After the first FS, 3 to 12% of children develop epilepsy, and 30% of these patients present with recurrent FS. The purpose of this study was to describe the epidemiological aspects of FS in order to better define the long-term outcomes in children with first FS and to identify the risk factors associated with the recurrence of FS as well as the development of epilepsy.

METHODS

A retrospective study of 482 children with FS was conducted from January of 2004 to December of 2009 in the pediatric department of Hedi Chaker University Hospital in Sfax, Tunisia. The medical records for each patient were first collected and then analyzed at a later time.

RESULTS

The study included 482 children. Simple FSs were found in 55.2% of children, and complex FSs were observed in 44.8%. The mean duration for follow-up examinations was 2 years and 4 months, and ranged from 1 to 5 years. No deaths or permanent neurological deficits due to FSs were observed, and only six children (1%) developed epilepsy. A total of 57 children (11.7%) developed recurrent seizures. Our findings suggest that a family history of FS, young age at onset, and a low degree of fever were predictive of recurrent FSs.

CONCLUSION

Children with FSs encounter a minor risk of mortality and morbidity. While recurrent seizures are observed in these children, only a minority of these patients develop epilepsy.

Epileptogenesis provoked by prolonged experimental febrile seizures: mechanisms and biomarkers

Whether long febrile seizures (FSs) can cause epilepsy in the absence of genetic or acquired predisposing factors is unclear. Having established causality between long FSs and limbic epilepsy in an animal model, we studied here if the duration of the inciting FSs influenced the probability of developing subsequent epilepsy and the severity of the spontaneous seizures. We evaluated if interictal epileptifom activity and/or elevation of hippocampal T2 signal on magnetic resonance image (MRI) provided predictive biomarkers for epileptogenesis, and if the inflammatory mediator interleukin-1beta (IL-1beta), an intrinsic element of FS generation, contributed also to subsequent epileptogenesis. We found that febrile status epilepticus, lasting an average of 64 min, increased the severity and duration of subsequent spontaneous seizures compared with FSs averaging 24 min. Interictal activity in rats sustaining febrile status epilepticus was also significantly longer and more robust, and correlated with the presence of hippocampal T2 changes in individual rats. Neither T2 changes nor interictal activity predicted epileptogenesis. Hippocampal levels of IL-1beta were significantly higher for >24 h after prolonged FSs. Chronically, IL-1beta levels were elevated only in rats developing spontaneous limbic seizures after febrile status epilepticus, consistent with a role for this inflammatory mediator in epileptogenesis. Establishing seizure duration as an important determinant in epileptogenesis and defining the predictive roles of interictal activity, MRI, and inflammatory processes are of paramount importance to the clinical understanding of the outcome of FSs, the most common neurological insult in infants and children.

Febrile seizures: current views and investigations

Febrile seizures (FSs) are seizures that occur during fever, usually at the time of a cold or flu, and represent the most common cause of seizures in the pediatric population. Up to 5% of children between the ages of six months and five years-of-age will experience a FS. Clinically these seizures are categorized as benign events with little impact on the growth and development of the child. However, studies have linked the occurrence of FSs to an increased risk of developing adult epileptic disorders. There are many unanswered questions about FSs, such as the mechanism of their generation, the long-term effects of these seizures, and their role in epileptogenesis. Answers are beginning to emerge based on results from animal studies. This review summarizes the current literature on animal models of FSs, mechanisms underlying the seizures, and functional, structural, and molecular changes that may result from them.

Which factors determine febrile seizure recurrence? A prospective study

PURPOSE

Many factors have been studied as potential predictors of recurrent febrile seizures (FS), however the available data in literature are inconsistent. The aim of the present paper is to determine which factors are responsible for the first and for multiple recurrences of FS, in a large sample of children with a long-term follow up.

METHODS

Two hundred and sixty children were followed after their first FS. The inclusion criteria were: a history of a first febrile seizure; no personal history of afebrile seizures; no previous anticonvulsant medication and age between three months and six years. The median time of follow up was 4.3 years. We had a contact with the families of the children every 4-6 months and also in every recurrence.

RESULTS

Very significant prognostic markers for the first FS recurrence were low age at onset, recurrence within the same illness, frequent febrile episodes and maternal preponderance. Powerful prognostic factors that may predispose children who already have one recurrence to a second or more are low age at onset and especially positive family history of FS. Additionally, low temperature prior to the initial seizure is a powerful predictor for three or more recurrences.

CONCLUSIONS

Prognostic factors for FS recurrence are a useful tool for the clinician. It is obvious that as many powerful predictors a child has, the greater will be the risk for FS recurrence.

Febrile seizures: an update

This review focuses on the latest knowledge and understanding of febrile seizures and outlines the more important issues in the management of children who present with an apparent "febrile seizure". It is not the remit of this paper to discuss the detailed management of febrile seizures. Throughout this review, the words "partial" and "focal" will be used interchangeably and the term "febrile seizure" (FS) will be used, reflecting the proposed changes in the terminology of seizures and epilepsies.1

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.

Risk of recurrent seizures after a primary human herpesvirus 6-induced febrile seizure

OBJECTIVE

To test the hypothesis that children experiencing first febrile seizures caused by human herpesvirus 6 (HHV-6) have an increased risk for recurrent seizures when compared with children experiencing first febrile seizures attributed to other illnesses.

DESIGN AND PARTICIPANTS

Descriptive prospective study of 36 HHV-6 culture-positive children and a matched subgroup of 86 HHV-6 culture-negative children, all of whom had their first febrile seizures evaluated in a tertiary care emergency department and were followed for at least 12 months, with an average follow-up of 35.7 months.

PRIMARY OUTCOME MEASURE

The recurrence of seizures among HHV-6 culture-positive and HHV-6 culture-negative children with no known previous neurologic deficits.

RESULTS

A decreased incidence of recurrent seizures occurred in children whose first febrile seizures were caused by HHV-6. Twenty percent of HHV-6 culture-positive children and 40% of HHV-6 culture-negative children (P < 0.038) experienced a recurrent seizure within 1 year of their first febrile seizure. The mean time to recurrence within 12 months was 8.6 months for children with HHV-6 infection and 3.8 months (P < 0.001) for children without HHV-6 infection. Most recurrent seizures occurred within 12 months of a first febrile seizure for both HHV-6-positive and HHV-6-negative children (88 and 91%).

CONCLUSIONS

Children who had their first febrile seizures caused by primary HHV-6 infection did not demonstrate an increased risk for recurrent seizures when compared with children whose first febrile seizures were from other etiologies.

Lower degree of fever at the initial febrile convulsion is associated with increased risk of subsequent convulsions

We studied 132 children admitted consecutively with their first febrile convulsion to assess whether the degree of fever at the onset of the convulsion can predict the risk of subsequent convulsions. The children studied were reviewed at least 2 years after the initial febrile convulsion to determine the number of children who had recurrences of febrile convulsions and/or afebrile convulsions. Children with body temperatures below 39 degrees C at the onset of their initial febrile convulsion (Group 1) were two and half times more likely to experience multiple convulsions within the same illness than those with body temperatures above 39 degrees C (Group 2). This occurred when the body temperature rose above that which had triggered the initial febrile convulsion. Children in Group 1 were also over three times more likely to experience recurrent febrile convulsion in subsequent illnesses than those in Group 2. As for subsequent development of afebrile convulsion or epilepsy, although the risk was low, it only occurred in Group 1. It is suggested that the known association between multiple convulsions, recurrent febrile convulsions and epilepsy may be due to the single predisposing factor of a low degree of fever at the onset of febrile convulsion. Each child with febrile convulsion may have his own threshold for eliciting a convulsion with fever; the lower this threshold is, the more likely are subsequent convulsions.

The adaptive value of fever

There is overwhelming evidence in favor of fever being an adaptive host response to infection that has persisted throughout the animal kingdom for hundreds of millions of years. As such, it is probable that the use of antipyretic/anti-inflammatory/analgesic drugs, when they lead to suppression of fever, results in increased morbidity and mortality during most infections; this morbidity and mortality may not be apparent to most health care workers because fever is only one of dozens of host defense responses. Furthermore, most infections are not life-threatening and subtle changes in morbidity are not easily detected.

Febrile seizures: rate and risk factors of recurrence

The rate of recurrence of febrile seizures and the factors predictive of a recurrence were prospectively examined in a cohort of 98 Saudi children who presented consecutively with their first febrile seizure at the pediatric emergency department of the King Khalid University Hospital, Riyadh, Saudi Arabia. Children with prior afebrile seizures or evidence of a neurodevelopmental deficit were excluded. The median age was 15 months (range, 4 to 60 months). Of the 98 children, 72 had simple and 26 had complex initial febrile seizures. In a follow-up of 3 to 6 years (mean, 49 months), 26% of the 98 untreated children had at least one recurrence and only 8% had more than three recurrent febrile seizures; 30% of first recurrences took place within 3 months, 60% within 6 months, 72% within 12 months, and 96% within 24 months of the onset. Four major risk factors for recurrent febrile seizures were identified: early age at onset (< 12 months), first-degree consanguinity of parents, epilepsy in a first-degree relative, and complex initial febrile seizure. Gender, family history of febrile seizures, and degree of fever were not related to recurrence.

Seizure recurrence after a first febrile convulsion

In this study, 140 children aged from 6 months to 6 years who presented with a first febrile convulsion at the King Fahad Hofuf Hospital, Al-Hassa, Saudi Arabia were retrospectively identified. Information about these children was obtained from their medical records covering a follow-up period of 3 years from July 1989 to June 1992. Recurrent febrile convulsions occurred in 60 of them (43%). Relevant risk factors that were observed to be significantly associated with seizure recurrence included an age of less than 18 months (odds ratio [OR] = 3.82; 95% confidence interval [CI] = 9.26, 1.58), an initial febrile convulsion that was complex (OR = 4.41; CI = 9.50, 2.05) and a positive family history of febrile convulsions (OR = 4.12; CI = 10.74; 1.58), while a decreased risk of recurrence occurred with a temperature of over 39 degrees C (OR = 4.60; CI = 9.44; 2.24). There was no association between seizure recurrence and the duration of the initial febrile convulsion (OR = 0.93; CI = 2.33; -2.04) or family history of epilepsy (OR = 0.88; CI = 4.22, -3.27). An important observation in the present study is the close association (ORM-H = 2.36; X2M-H = 9.65) between the development of an afebrile convulsion and seizure recurrence among the group of children with CFC. Anticonvulsant prophylaxis should therefore be considered for children whose initial febrile convulsions are complex in nature.

A prospective study of recurrent febrile seizures

BACKGROUND

Febrile seizures occur in about 2 to 4 percent of all children, approximately one third of whom will have recurrent febrile seizures. Little is known about predictors of recurrence.

METHODS

In this prospective study, we identified 347 children (1 month to 10 years of age) who presented with a first febrile seizure at one of four pediatric emergency departments. Information about these children was collected from medical records and interviews with the parents, and the children were followed for a median of 20 months to ascertain whether febrile seizures recurred.

RESULTS

Recurrent febrile seizures occurred in 94 of the 347 children (27 percent) with a cumulative risk of 25 percent at one year and 30 percent at two years. The duration of fever before the initial seizure was associated with the risk of recurrence at one year: for fever lasting less than 1 hour, the risk of recurrence was 44 percent; for fever lasting 1 to 24 hours, 23 percent; and for fever lasting more than 24 hours, 13 percent (P less than 0.001). With each degree of increase in temperature (in degrees Fahrenheit), from 101 degrees F (38.3 degrees C) to greater than or equal to 105 degrees F (40.6 degrees C), the risk of recurrence at one year declined, from 35 percent to 30, 26, 20, and 13 percent (P for trend = 0.024). An age of less than 18 months and a family history of febrile seizures were also associated with an increased risk of recurrence. A family history of epilepsy, complex febrile seizures, and neurodevelopmental abnormalities did not increase the risk of recurrent febrile seizures.

CONCLUSIONS

A shorter duration of fever before the initial febrile seizure and a lower temperature are associated with an increased risk of recurrence in children who have febrile seizures.

Seizure recurrence after a first febrile seizure: a multivariate approach

The results are presented of a follow-up study of 155 Dutch children after the first febrile seizure. Of these initially untreated children 37 per cent had had at least one, 30 per cent at least two and 17 per cent at least three subsequent seizures. The vulnerable period for recurrent seizures after the first febrile seizure was between 12 and 24 months, whereafter the risk was four to five times lower; after any seizure the risk was highest within the first six months, declining steadily after six months without seizures. A first-degree family history of any type of seizure predicted multiple recurrences; an age of at least 30 months and a temperature of greater than or equal to 40 degrees C at initial seizure were associated with reduced risk. Factors in combination influenced the risk of recurrent seizures, sometimes in opposite ways.

Predictors of recurrent febrile seizures: a metaanalytic review

The 1980 National Institutes of Health Consensus Development Conference on Febrile Seizures identified five circumstances in which it might be appropriate to consider anticonvulsant prophylaxis after a first febrile seizure: (1) a focal or prolonged seizure, (2) neurologic abnormalities, (3) afebrile seizures in a first-degree relative, (4) age less than 1 year, and (5) multiple seizures occurring within 24 hours. We performed a metaanalysis of 14 published reports to evaluate the strength of association between each of these indications and recurrent febrile seizures. Young age at onset (less than or equal to 1 year) and a family history of febrile seizures (not listed in the recommendations) each distinguished between groups with approximately a 30% versus a 50% risk of recurrence. Family history of afebrile seizures was not consistently associated with an increased risk. Focal, prolonged, and multiple seizures were associated with only a small increment in risk of recurrence. The data were not adequate to assess the risk associated with neurologic abnormalities. By considering children with combinations of risk factors, some studies were able to distinguish between groups with very low and very high recurrence risks. Only age at onset was consistently predictive of having more than one recurrence. These results suggest that the great majority of children who have a febrile seizure do not need anticonvulsant treatment even if one of the factors listed in the Consensus Statement is present, and that the rationale and indications for treating febrile seizures need to be reconsidered.

Effect of fever on recurrence rate of febrile convulsions

We studied 154 children admitted consecutively with their first febrile convulsion to assess the influence of the temperature on the recurrence rate of convulsions. Those with temperatures of 40 degrees C or more were nine times less likely to have subsequent convulsions than those with temperatures of 38-38.9 degrees C.

Frequent febrile episodes and recurrent febrile convulsions

The relationship between the number of febrile episodes and recurrent febrile convulsions was studied prospectively in 289 children after their first febrile seizure. They were randomized to either short-term diazepam prophylaxis (n = 152) or to no prophylaxis (n = 137), and followed for 18 months. Among untreated children with many subsequent febrile episodes (greater than or equal to 4 per year) 29 of 37 (78%) had a recurrence vs. 17 of 100 (17%) with only few (less than 4 per year) feverish illnesses. The former group had a 4:1 chance of developing further febrile fits, compared with a 1:4 chance in the latter (P less than 0.0001). A similar pattern was observed in the prophylaxis group, but less recurrences were seen (30% vs. 6%, P less than 0.0001). By Cox regression analysis, the subsequent occurrence of many febrile episodes could be identified among several items, including young age at onset, as the adverse factor most highly associated with further febrile fits (P less than 0.0001).