When does an EEG contribute to the management of febrile seizures?

Clinical Predictive Factors of Pathological EEG in Children with Febrile Seizures and Their Association with Subsequent Epileptic Seizures

The objective of this study was to identify clinical parameters predicting either a pathological EEG or a subsequent epileptic seizure (SES), based on the relation between paroxysmal EEG abnormalities and clinical features in children who presented at least one febrile seizure (FS). We collected data of children who presented to our department during the period 2013 to 2018 for EEG recording as part of their febrile seizure assessment. Only children aged between 1 month to 5 years were included. Both the clinical and EEG data were retrospectively collected and statistically studied. We performed a detailed analysis of the EEG recordings. SES was identified for patients with sufficient follow-up. A total of 120 children were included in the study, of whom 48% had EEG abnormalities. Psychomotor retardation (p = 0.002), completion of an EEG within 7 days of the last FS (p = 0.046), and late age (> 3 years) of the first FS onset (p = 0.021) were significantly associated with a pathological EEG. In multivariate analysis, performing early EEG (< 7 days from the last FS) (odds ratio [OR]: 2.35; p = 0.043; confidence interval [CI]: 1.028–5.375) and psychomotor retardation (OR: 4.19; p = 0.008; CI: 1.46–12) were independent predictors of a pathological EEG. Of 120 patients, 45 had a follow-up. However, only 10 (22.22%) had SES. Children with SES tended more to have a psychomotor delay, compared with children without SES (50% vs. 14.28%, p = 0.029). Moreover, the percentage of initial abnormal EEG in patients with SES was significantly higher than those without SES (70% vs. 34.28%, p = 0.05). Even though some FS characteristics predict EEG abnormalities, they are not always associated with SES. We highlight the importance of performing an EEG in the group of children who had both FS and psychomotor retardation. This is most likely the group at the highest risk of developing epilepsy.

Early postictal electroencephalography and correlation with clinical findings in children with febrile seizures

PURPOSE

Electroencephalography (EEG) is frequently ordered for patients with febrile seizures despite its unclear diagnostic value. We evaluated the prevalence of abnormal EEGs, the association between clinical findings and abnormal EEGs, and the predictive value of EEG for the recurrence of febrile seizures.

METHODS

Data were collected on 230 children who were treated for febrile seizures at Kyung Hee University Medical Center from 2005 to 2009. EEGs were recorded after 1-2 days of hospitalization when children became afebrile. EEG patterns were categorized as normal, epileptiform, or nonspecific relative to abnormalities. The patients' medical records were reviewed, and telephone interviews with the families of the children were conducted to inquire about seizure recurrence. The relationships between clinical variables, including seizure recurrence, and EEG abnormalities were evaluated.

RESULTS

Of the 131 children included, 103 had simple and 28 had complex febrile seizures. EEG abnormalities were found in 41 children (31%). EEG abnormalities were more common in children with complex than simple febrile seizures (43% vs. 28%), but the difference was not statistically significant. Logistical regression analysis showed that having multiple seizures in a 24-hour period was significantly predictive of abnormal EEG (odds ratio, 2.98; 95% confidence interval, 1.0 to 88; P=0.048). The frequency of recurrence did not differ significantly in the normal (31%) and abnormal (23%) EEG groups.

CONCLUSION

Multiple seizures within 24 hours were predictive of abnormal EEG in children with febrile seizures. Abnormal EEG was not predictive of febrile seizure recurrence.

EEG characteristics predict subsequent epilepsy in children with febrile seizure

The role of electroencephalography (EEG) in the work-up of febrile seizure (FS) remains controversial. We investigated the importance of EEG characteristics, especially the localizations of paroxysmal discharges, as predictors for subsequent epilepsy. Patients were referred from the outpatient department for EEG within 7-20 days after the seizure. EEGs were classified as paroxysmally abnormal based on the presence of spikes, sharp waves, or spike-wave complexes, whether focal or generalized, that were considered abnormal for age and state. Of 119 patients with FS, 26 (21.8%) revealed paroxysmal abnormality on EEG and 9 (7.6%) developed epilepsy. Of nine patients with later epilepsy, 6 (66.7%) revealed paroxysmal EEG abnormality. Of 26 patients with paroxysmal abnormality, 6 (23.1%) developed epilepsy. Of 10 patients with generalized paroxysmal spike and wave activity, one (10%) developed epilepsy. Of seven patients with rolandic discharge (RD), two (28.5%) developed epilepsy. Of four patients with paroxysms in the frontal region, three (75%) developed epilepsy. Of five patients with paroxysms in the occipital region, none developed epilepsy. Compared with generalized EEG foci, the relative risk (RR) for patients with frontal EEG foci was 27.0. Patients with frontal EEG paroxysms had a significantly higher risk of developing epilepsy than those with paroxysms in other regions of EEG foci (p=0.035). These findings suggest that patients with FS presenting with frontal paroxysmal EEG abnormalities may be at risk for epilepsy. In patients with frontal paroxysmal EEG abnormalities, serial EEG should be performed, even though it does not contribute to treatment.

Epileptogenesis after prolonged febrile seizures: mechanisms, biomarkers and therapeutic opportunities

Epidemiological and recent prospective analyses of long febrile seizures (FS) and febrile status epilepticus (FSE) support the idea that in some children, such seizures can provoke temporal lobe epilepsy (TLE). Because of the high prevalence of these seizures, if epilepsy was to arise as their direct consequence, this would constitute a significant clinical problem. Here we discuss these issues, and describe the use of animal models of prolonged FS and of FSE to address the following questions: Are long FS epileptogenic? What governs this epileptogenesis? What are the mechanisms? Are there any predictive biomarkers of the epileptogenic process, and can these be utilized, together with information about the mechanisms of epileptogenesis, for eventual prevention of the TLE that results from long FS and FSE.

Febrile seizures: four steps algorithmic clinical approach

Febrile seizures (FS) are the most common form of convulsive phenomena in human being and affect 2% to 14% of children. It is the most common type of seizures that every pediatrician is dealing with. It is the most benign type of all seizures occurring in childhood. There are many debates on how to approach to febrile seizures in pediatric neurology and there are many possible malpractices in this field. Some of the most common frequent queries areHow could we differentiate FS from seizures and fever associated with serious infections involving the central nervous system?When should we refer the affected child for further investigations such as lumbar puncture, EEG, neuroimaging, and routine biochemical studies?How should we treat FS in its acute phase?How could we assess the risk for further recurrences as well as other risks threatening the child's health in future?How could we select the patients for treatment or prophylaxis?Which medication(s) should be selected for treatment or prophylaxis?Trying to answer the above-mentioned questions, this review article will present a four steps algorithmic clinical approach model to a child with febrile seizures based on the current medical literature.

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.

Do clinical variables predict an abnormal EEG in patients with complex febrile seizures?

PURPOSE

Febrile seizures are the commonest convulsive event in children younger than 5 years of age (incidence of 2-5%). Electroencephalography (EEG) is not indicated in the work up of simple febrile seizures. Information about its role in the assessment of complex febrile seizures (CFSs) is unclear and EEGs are frequently ordered. This study was designed to assess utility of clinical variables at presentation in predicting the likelihood of an abnormal EEG.

METHODS

EEG requisitions, EEG reports, clinic charts and medical records over an 11-year period (1990--2001) were retrospectively reviewed. The relationship between clinical variables like age, timing of the EEG since CFS, family history of seizures, neurological assessment and EEG abnormalities was statistically analyzed.

RESULTS

One hundred and seventy-five children were included in the study. Of these 39.43% had EEG abnormalities. Children with a normal EEG were younger than those with an abnormal EEG (mean age 15.72 months versus 19.75 months, p<0.05). Using multivariate analysis, factors predictive of abnormal EEGs in children with CFS were; age >3 years (p=0.010; 95% CI: 1.5--18.8), EEGs performed within 7 days (p=0.00; 95% CI: 1.78--7.12) and an abnormal neurological exam (p=0.053; 95% CI: 0.98--16.9). A family history of febrile seizures was more likely to be associated with a normal EEG (p=0.01; 95% CI: 0.04--0.60).

CONCLUSIONS

Clinical variables at presentation can be used to screen children with CFS for whom an EEG is considered. This may lead to better use of resources. Whether abnormal EEG translates to future recurrences or epilepsy needs a prospective study.

Treatment and outcome in patients with febrile convulsion associated with epileptiform discharges on electroencephalography

The aim of this study is to determine the efficacy of prophylactic treatment for patients with febrile convulsions (FCs) in whom electroencephalograms (EEGs) revealed epileptiform discharges. We retrospectively investigated 43 patients who met the following criteria: (a) at least one FC during the study period; (b) epileptiform discharges were first recognized; (c) no unevoked seizures before epileptiform discharges were first seen; (d) normal psychomotor development and no neurological abnormality; and (e) follow-up >3 years. The clinical characteristics, treatment, and a later occurrence of FCs or unevoked seizures were studied. EEGs revealed focal epileptiform discharges in 25 patients and generalized ones in 18. There was no significant difference in the rate of recurrence of FC or occurrence of unevoked seizures between those with focal and generalized epileptiform discharges. No prophylaxis was performed in ten patients, 14 patients being treated with intermittent diazepam and 19 with a daily anticonvulsant. The rate of recurrence of FC was not significantly different between patients with and without prophylaxis. Unevoked seizures were only observed in two patients undergoing daily treatment. Intermittent or daily anticonvulsant therapy will not reduce the risk of recurrence of FCs or later development of unevoked seizures in patients with FC with epileptiform discharges.

Evaluation of the child who convulses with fever

Febrile seizures result from age-dependent hyperexcitability of the brain that is induced by fever. Although there are important genetic influences that render a febrile child more likely to develop seizures, it is the fever per se that causes the seizure. Of primary importance in the diagnostic assessment of such children are efforts directed at finding the cause of the fever. Once found, the cause should be treated specifically, e.g. antibacterials for otitis media, and/or symptomatically, e.g. antipyretics for viral pharyngitis. It is essential to exclude underlying meningitis in all children with febrile seizures, either clinically or, if any doubt remains, by lumbar puncture. In as many as one child in six with meningitis, seizures are the presenting sign, and in one-third of these patients, meningeal signs and symptoms may be lacking. The great majority of such cases of meningitis are bacterial in origin, and delay in diagnosis can result in serious neurologic morbidity, and even death.In the child who convulses with fever, it is always important to consider that something in addition to the fever has caused the child to have a seizure. Infection that has gone unnoticed, such as meningitis or encephalitis, as well as a systemic illness, head trauma, intoxication, electrolyte imbalance, low blood sugar, or a phakomatoses, can cause seizures. One must also consider the possibility that the child with a febrile seizure has epilepsy, and that fever has simply triggered a seizure recurrence in a child who also experiences unprovoked seizures.Thus, based on the specifics of each case, the diagnostic evaluation of the child with a febrile seizure can be very limited or moderately comprehensive. Imaging studies are necessary only in selected cases. The electroencephalogram is of limited value. The primary concern is always the need to exclude meningitis. Therefore, a lumbar puncture should be carried out, except in those cases where the possibility of CNS infection seems truly remote.

Febrile seizures

Febrile seizures are the most common form of childhood seizures, occurring in 2 to 5% of children in the United States. Most febrile seizures are considered simple, although those with focal onset, prolonged duration, or that occur more than once within the same febrile illness are considered complex. Risk factors for a first febrile seizure, recurrence of febrile seizures, and development of future epilepsy are identifiable and varied. Children with febrile seizures encounter little risk of mortality and morbidity and have no association with any detectable brain damage. Recurrence is possible, but only a small minority will go on to develop epilepsy. Although antiepileptic drugs can prevent recurrent febrile seizures, they do not alter the risk of subsequent epilepsy. This has led to a changing view of how we approach the treatment of these common and largely benign seizures. This chapter will review the current understanding of the prognosis and management of febrile seizures.

The value of early postictal EEG in children with complex febrile seizures

PURPOSE

To assess the usefulness of an early postictal EEG in neurologically normal children with complex febrile seizures.

METHODS

We conducted a retrospective chart review of all neurologically normal children who were hospitalized over a period of 2.5 years after complex febrile seizures, and had an EEG up to 1 week after the seizure.

RESULTS

Thirty-three patients (mean age, 17.8 months) qualified for inclusion into the study. Twenty-four patients were qualified as complex cases based on one factor (prolonged in 9, repetitive in 13, and focal in 2). Nine other patients had two complex factors: in six patients, the seizures were long and repetitive; in two patients, the seizures were focal and repetitive; and in one patient, the seizures were long, focal, and repetitive. Thirteen (39%) patients experienced prior febrile seizures. All 33 patients had a normal postictal sleep EEG. Our results indicate with a 95% probability that the true rate of abnormalities in an early postictal EEG performed on otherwise normal children with complex febrile seizures is 8.6% or less.

CONCLUSIONS

The yield of abnormalities of an early postictal EEG in this population is low and similar to the reported rate of abnormalities in children with simple febrile seizures. The routine practice of obtaining an early EEG in neurologically normal children with complex febrile seizures is not justified.

Febrile seizures: is the EEG a useful predictor of recurrences?

We examined the predictive value of a paroxysmal EEG in children with febrile seizures seen at the University Pediatric Clinic, Skopje, Macedonia, between 1982 and 1984. This was the only facility providing EEG or neurologic consultation for children in Macedonia, and almost all children in the area who experienced a febrile seizure were referred to this facility. EEGs were classified as epileptiform if they contained spikes and sharp waves or spike wave complexes, which were either focal or generalized, and were considered abnormal for age and state. Nonspecifically abnormal was defined as focal or generalized slowing excessive for age and state. Follow-up visits were scheduled at 6-month intervals; mean follow-up time was approximately 23 months. In order to determine whether clearly abnormal EEG features would predict recurrences, we compared the recurrences in 170 children with initial normal-appearing EEGs with 99 children with initial paroxysmal EEGs. There was no significant difference in risk of recurrence of febrile seizures between the two groups; increase in recurrence risk was determined primarily by younger age. The EEG did not add information regarding the likelihood of recurrence of febrile seizures.

Pediatric epilepsy syndromes: an update and critical review

Epilepsy syndromes occupy an important position in the current nosology of the epilepsies, describing and classifying seizure disorders with shared clinical and EEG features. Increasingly, this schema is being refined as new information becomes available and our understanding of etiology and presentation of each syndrome widens. Advances in neuroimaging and neurogenetics have been particularly important and are likely to fundamentally change our concepts of syndrome classification. At present, the International League Against Epilepsy classification of epilepsy syndromes according to presumed localization (partial, generalized, undetermined) and etiology (idiopathic, cryptogenic, symptomatic). In clinical practice, it is often useful to conceptualize epilepsy syndromes according to their usual age at presentation, which greatly facilitates syndrome identification in new patients and recognizes the age-related expression of many childhood epilepsies. Definitional problems exist for many pediatric epilepsy syndromes, particularly the epileptic encephalopathies of early infancy, the benign epilepsies of infancy and childhood, the myoclonic epilepsies of infancy and early childhood, and the idiopathic generalized epilepsies of childhood and adolescence. It is likely that further input from the fields of molecular genetics and neuroimaging will enable the classification of epilepsies to become more etiologically oriented and disease specific.

The place of the EEG and imaging in the management of seizures

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