PEDIATRICS Vol. 117 No. 2 February 2006, pp. 304-308 (doi:10.1542/peds.2005-0759)
Risk of Intracranial Pathologic Conditions Requiring Emergency Intervention After a First Complex Febrile Seizure Episode Among Children
a Department of Pediatrics, Morgan Stanley Children's Hospital of New York-Presbyterian, Columbia University College of Physicians and Surgeons, New York, New York
b Duke University School of Medicine, Durham, North Carolina
c Department of Neurology, Columbia University College of Physicians and Surgeons, New York, New York
d Gertrude H. Sergievsky Center, Columbia University, New York, New York
e Department of Epidemiology, Joseph L. Mailman School of Public Health, Columbia University, New York, New York
f Department of Radiology, Columbia University College of Physicians and Surgeons, New York, New York
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONREFERENCES |
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OBJECTIVE. To determine the likelihood of intracranial pathologic conditions requiring emergency neurosurgical or medical intervention among children without meningitis who presented to the pediatric emergency department after a first complex febrile seizure.
METHODS. We performed a retrospective review of prospectively collected data for children in neurologically normal condition who presented to a single pediatric emergency department after a first complex febrile seizure (focal, multiple, or prolonged). The complex febrile seizure classification was determined independently by 2 epileptologists. The presence of intracranial pathologic conditions was determined through review of neuroimaging results, telephone interviews, or medical record review.
RESULTS. Data for 71 children with first complex febrile seizures were analyzed. Fifty-one (72%) had a single complex feature (20 focal, 22 multiple, and 9 prolonged), and 20 (28%) had multiple complex features. None of the 71 patients (1-sided 95% confidence interval: 4%) had intracranial pathologic conditions that required emergency neurosurgical or medical intervention.
CONCLUSIONS. For children with first complex febrile seizures, the risk of intracranial pathologic conditions that require emergency neurosurgical or medical intervention is low, which suggests that routine emergency neuroimaging for this population is unnecessary.
Key Words: complex febrile seizures • neuroimaging • emergency intracranial pathology
Abbreviations: CT—computed tomographic • ED—emergency department
ebrile seizures are common, occurring in 2% to 5% of all children.1–4 Most febrile seizures are benign, self-limited, and simple in nature. However, approximately one third of febrile seizures are classified as complex.5 Complex features (multiple seizures, prolonged duration, or focality) have been associated with an increased risk of recurrent febrile seizures and epilepsy but have not been associated with space-occupying, intracranial, pathologic lesions that require emergency intervention.6–10
Previous studies suggested that intracranial abnormalities are rare among children who sustain a simple febrile seizure.3,11 Therefore, an American Academy of Pediatrics practice guideline recommends against the use of emergency neuroimaging for pediatric patients with simple febrile seizures.12 However, there are no practice parameters to guide the evaluation and treatment of patients with complex febrile seizures, and the use of emergency neuroimaging for this population remains controversial. Previous studies evaluating the likelihood of intracranial pathologic conditions among patients with complex febrile seizures were small, lacked rigorous determination of the type of febrile seizure, and did not evaluate complex febrile seizures independently of other febrile seizure types. However, those studies suggested that abnormal neuroimaging findings, primarily on computed tomographic (CT) scans, are uncommon for patients with complex febrile seizures.9,13–17 The objective of this study was to determine the likelihood of significant, space-occupying, intracranial, pathologic conditions requiring emergency intervention in a well-defined, large group of pediatric patients presenting to the emergency department (ED) with a first complex febrile seizure.
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METHODS |
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Study Design and Patients
We performed a retrospective review of data gathered from a prospective cohort study of children with a first febrile seizure. Patients 6 months to 5 years of age who presented to the pediatric ED of an urban, tertiary care, university hospital after a first complex febrile seizure between March 1999 and July 2002 were eligible for our review. A febrile seizure was defined as a convulsion that occurred at the time of an oral or rectal temperature of at least 38.3°C for a child who had not experienced a prior afebrile seizure and did not have concurrent meningitis or encephalitis.18 Children who were later diagnosed as having a central nervous system abscess were eligible for this review, to assess the likelihood of this finding among children who sustained a first seizure with complex features in the setting of fever. A complex febrile seizure was defined as a febrile seizure with
1 of the following complex features: prolonged duration (15 minutes), multiple episodes (occurring more than once during the same febrile illness), or focality (including any brief period of transient motor, speech, or vision deficits after the seizure). Patients were excluded if they had undergone any prior neurosurgical intervention or demonstrated any significant neurologic disorder or chronic medical illness. Patients were also excluded if the presenting seizure was associated with head trauma or if the patient was diagnosed as having meningitis or encephalitis. As part of the prospective study, patients were identified either by physicians in the pediatric ED or by trained research assistants who performed twice-daily surveillance of ED logbooks and medical records. At the time of the ED visit, pediatric emergency medicine attending physicians and postgraduate fellows were asked to complete a detailed neurologic evaluation. After obtaining the permission of the child's pediatrician to contact the family, trained research assistants called the family to explain the study and offer participation. Children needed to be enrolled within 1 week after the ED visit. A standardized questionnaire was administered at the time of enrollment, to obtain specific details about the child’s seizure, including duration, focality, and number of seizures. Two epileptologists (W.A.H. and L.L.) independently reviewed the patient's medical record, the guardian questionnaire, and the ED neurologic examination data collection form (when available), to classify the seizure as simple or complex. In the case of disagreements, the 2 evaluators conferred and reached a common classification. For seizures classified as complex, the features of the complex seizure were recorded.
Outcome Assessment
The principal outcome for our review was defined as a clinically important, intracranial, pathologic condition requiring emergency neurosurgical or medical intervention. Clinically important emergency diagnoses included but were not limited to mass lesion, hemorrhage, hydrocephalus, abscess, and cerebral edema. Nonemergency neuroimaging findings, including acute hippocampal injury, were not included despite a potential association with later epilepsy.19 Emergency neurosurgical intervention was defined as the performance of a craniotomy or biopsy or the placement of an intracranial pressure monitor or ventriculoperitoneal shunt.
The presence of clinically important intracranial pathologic conditions was assessed with neuroimaging studies and, when such studies were not performed, with patient follow-up assessments. Emergency cranial CT scans were obtained at the discretion of the treating emergency medicine physician and were read by attending pediatric radiologists. Cranial MRI studies were completed within 1 week after the febrile seizure if the patient was enrolled in the prospective febrile seizure study and were read by a neuroradiologist with expertise in epilepsy. If the patient did not undergo a neuroimaging study, then standardized telephone surveys were administered during November and December 2002, with questions regarding the diagnosis of intracranial disease. Finally, if the patient could not be contacted, then a review of the institutional computerized information system, the medical records, and continuous quality-improvement data were performed to ascertain whether the patient returned to the hospital with a diagnosis of intracranial disease in the 2 months after the initial ED presentation.
Ethics
This retrospective review was approved by the institutional review board at Columbia University.
Statistical Analyses
Data entry and statistical analyses were performed with SPSS, version 11.0 (SPSS, Chicago, IL). Categorical data were summarized as proportions with 95% confidence intervals. Means of normally distributed data were calculated and are reported with SDs.
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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During the study period, 293 children presented to the ED after experiencing a first febrile seizure. Of these, 79 (27%) of 293 seizures were complex in nature. The 2 epileptologists agreed independently on the complex febrile seizure classification of 78 (98.7%) of these 79 seizures. After discussion, all 79 seizures received a consensus classification of complex. Six patients (8%) were excluded, 4 because of a history of developmental delay and 2 because of a history of unprovoked seizure. Two additional patients were not analyzed because follow-up data could not be obtained. The mean age of the remaining 71 patients was 1.64 ± 0.67 years, and 36 patients (51%) were male. Forty (56%) were Hispanic, 10 (14%) black, and 21 (30%) other race/ethnicity. ED forms were completed for 62 (87%) of 71 patients; 49 (79%) were described as well appearing in the ED, 2 (3%) were described as ill appearing (lethargic or inconsolable), and the status of 11 (18%) was described as unclear (increased sleep or crying).
The characteristics of the 71 complex febrile seizures are detailed in Table 1. The majority of patients (72%) experienced seizures with a single complex feature. Emergency management included anticonvulsants administered by emergency medical services or in the ED for 7 patients (10%). Of the 10 patients (14%) for whom a lumbar puncture was performed in the ED, none had meningitis (10 white blood cells per mm3 or positive culture findings). Two patients (3%) were intubated in the ED. Emergency cranial CT scans were obtained in the ED for 10 patients (14%), and 13 patients (18%) were admitted.
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The likelihood of emergency intracranial pathologic conditions and the mode of outcome determination are detailed in Table 2. Of the 71 patients, 46 (65%) underwent neuroimaging (emergency CT scans obtained at the discretion of the ED physician and/or MRI scans obtained within 1 week after the ED visit for the prospective study). For patients for whom telephone follow-up assessments were completed, the median time to interview was 22.4 months (interquartile range: 18.9–30.7 months). None of the 71 patients with a first complex febrile seizure demonstrated a significant intracranial pathologic condition requiring emergency intervention. No patient had an abscess.
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONREFERENCES |
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An American Academy of Pediatrics guideline recommends against performing routine neuroimaging for children who sustain a first simple febrile seizure.12 However, little data are available to determine the need for neuroimaging for children with a first complex febrile seizure. In this study, none of the 71 children who presented to the ED with first complex febrile seizures had space-occupying, intracranial, pathologic lesions that required emergency medical or neurosurgical intervention. This argues against the need for routine emergency neuroimaging for well-appearing children with first complex febrile seizures. This study does not address the role of nonurgent neuroimaging for patients with complex febrile seizures, to detect pathologic conditions that do not require emergency intervention, including acute hippocampal injuries that may increase the risk of future epilepsy or mesial temporal sclerosis.
Our data coincide with findings of previous studies of children with complex febrile seizures, which noted a low likelihood of abnormal neuroimaging findings requiring emergency medical or surgical management. Three previous studies reported data on neuroimaging findings for "neurologically normal" children who experienced a complex febrile seizure. For children admitted because of initial-onset seizures, McAbee et al20 found CT abnormalities for only 1 (5%) of 20 patients with a first complex febrile seizure; the abnormality did not necessitate intervention. al-Qudah13 reported on 13 children with complex febrile seizures, all of whom had normal CT scans. In a retrospective study, Garvey et al14 found CT abnormalities for 3 (18%) of 17 children who presented with first complex febrile seizures, although none required intervention. In 2 additional studies that included all children who presented to the ED with new-onset seizures, regardless of previous neurologic history, all neuroimaging studies performed for children with complex febrile seizures yielded normal results.15,21 Most recently, Yucel et al17 evaluated retrospectively the neuroimaging findings for children with complex febrile seizures who demonstrated postictal deficits, focal seizures, or focal electroencephalographic findings. Seven (16%) of 45 patients exhibited abnormal cranial CT scan or MRI findings; however, none required medical or neurosurgical intervention. In no series of reported patients has an otherwise well-appearing patient with a complex febrile seizure needed an emergency intervention because of an abnormal imaging finding.
This study differs methodologically from prior studies in several ways. Most prior studies have been retrospective, without stringent methods to classify the nature of the seizures. In this study, consecutive patients were enrolled prospectively. They were classified by experienced epileptologists using detailed questionnaires administered systematically to parents/guardians and prospectively collected ED physical examination data. In addition, we were able to obtain follow-up data for patients for whom no neuroimaging was completed.
This study has several limitations. Although the number of patients with first complex febrile seizures in this study is the largest reported to date, the 4% upper boundary of the 95% confidence interval is too high to ensure that uncommon patients would not have serious intracranial pathologic conditions. A case report22 of a patient with a brain abscess that presented as a complex febrile seizure serves as a reminder that, although they are uncommon, serious intracranial pathologic conditions can be responsible for seizures among febrile children and should always be considered for these patients. For that patient with an abscess, the authors noted that the patient experienced a seizure lasting >40 minutes and was mildly lethargic and irritable in the ED once seizure activity ceased.22 The small sample size of our study also limits the ability to determine whether 1 complex feature or a combination of complex features may be more predictive of abnormal intracranial pathologic conditions requiring emergency intervention than the classification of complex febrile seizures in general. In addition, it should be recognized that we excluded patients with meningitis and cannot comment on an association between seizures with complex features and the likelihood of this disease.
We have demonstrated a low risk of intracranial pathologic conditions requiring emergency intervention in a well-defined population of generally well-appearing children who sustain a first complex febrile seizure. This finding is consistent with prior studies. Our results suggest that emergency neuroimaging may be unnecessary for well-appearing children who present to the ED with a first complex febrile seizure.
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ACKNOWLEDGMENTS |
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This work was supported in part by a grant from the National Institute of Child Health and Human Development (grant 5R01 HD 36867).
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FOOTNOTES |
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Accepted May 25, 2005.
Address correspondence to Dale C. Hesdorffer, PhD, Gertrude H. Sergievsky Center, Columbia University, 630 W 168th St, P&S Unit 16, New York, NY 10032. E-mail: dch5{at}columbia.edu
The authors have indicated they have no financial relationships relevant to this article to disclose.
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