Each clinical practice recommendation is stratified by type of procedure, based on the strength of the evidence. Definitions of the strength of the recommendations (Standards, Guidelines, Practice Options, Practice Parameters) and classification of the evidence (Class I through Class III) are provided at the end of the Major Recommendations field.
Summary
In the child with a first nonfebrile seizure, diagnostic evaluations influence therapeutic decisions, how families are counseled, and the need for hospital admission and/or specific follow-up plans. This practice parameter has reviewed the published literature concerning the usefulness of studies following a first nonfebrile seizure in children, and has classified the strength of the available evidence. There is sufficient Class I evidence, which involves a well-executed prospective study, to provide a recommendation with the highest degree of clinical certainty--i.e., a Standard, that an electroencephalogram be obtained in all children in whom a nonfebrile seizure has been diagnosed--to predict the risk of recurrence and to classify the seizure type and epilepsy syndrome. The decision to perform other studies, including lumbar puncture, laboratory tests, and neuroimaging, for the purpose of determining the cause of the seizure and detecting potentially treatable abnormalities, will depend on the age of the patient and the specific clinical circumstances. Children of different ages may require different management strategies.
Laboratory Studies
The fact that a first nonfebrile seizure occurred in the absence of any suggestive history or symptoms in a child who is older than age 6 months and has returned to baseline has not been shown to be sufficient reason to perform routine laboratory testing in the child with a first nonfebrile seizure. However, the number of children reported is too small to be confident that in rare circumstances, routine laboratory screening such as blood glucose determination might not provide important information, even without specific clinical indications. There were only two reports of positive toxicology screens, but no studies that systematically evaluated the yield from doing routine toxicology screening in children with first seizures. If no cause for the seizure has been identified, it is important to ask questions regarding possible toxic ingestions or exposures.
Recommendations:
- Laboratory tests should be ordered based on individual clinical circumstances that include suggestive historic or clinical findings such as vomiting, diarrhea, dehydration, or failure to return to baseline alertness. (Smith, Martland, & Lowry, 1996; Eisner et al., 1986; Turnbull et al., 1990; Nordli & Pedley, 1995) (Option)
- Toxicology screening should be considered across the entire pediatric age range if there is any question of drug exposure or substance abuse (Option).
Lumbar Puncture
There is no evidence regarding the yield of routine lumbar puncture following a first nonfebrile seizure. The one study available (Class II) is limited in size and age range. Recommendations based on age and clinical symptoms are available for Class III publications. In the very young child (<6 months), in the child of any age with persistent (cause unknown) alteration of mental status or failure to return to baseline, or in any child with meningeal signs, lumbar puncture should be performed. If increased intracranial pressure is suspected, the lumbar puncture should be preceded by an imaging study of the head.
Recommendations:
- In the child with a first nonfebrile seizure, lumbar puncture is of limited value and should be used primarily when there is concern about possible meningitis or encephalitis (Option).
Electroencephalogram
The majority of evidence from Class I and Class II studies confirms that an electroencephalogram helps in determination of seizure type, epilepsy syndrome, and risk for recurrence, and therefore may affect further management decisions. Experts commonly recommend that an electroencephalogram be performed after all first nonfebrile seizures. It is not clear what the optimal timing should be for obtaining an electroencephalogram. Although an electroencephalogram done within 24 hours of the seizure is most likely to show abnormalities, physicians should be aware that some abnormalities such as postictal slowing that can be seen on electroencephalogram done within 24 to 48 hours of a seizure may be transient and must be interpreted with caution.
There is no evidence that the electroencephalogram must be done before discharge from the emergency department; the study may be arranged on an outpatient basis. Epileptiform electroencephalogram abnormalities may be useful in confirming that the event was a seizure; however, an electroencephalogram abnormality by itself is not sufficient to make a diagnosis that an epileptic seizure occurred, nor can its absence rule out a seizure. The electroencephalogram is necessary to determine the epilepsy syndrome and the diagnosis of an epilepsy syndrome may be helpful in determining the need for imaging studies. The electroencephalogram is also useful in predicting the prognosis for recurrences.
It is not clear what the optimal timing should be for obtaining an electroencephalogram. Although an electroencephalogram done within 24 hours of the seizure is most likely to show abnormalities, physicians should be aware that some abnormalities such as postictal slowing that can be seen on electroencephalogram done within 24 to 48 hours of a seizure may be transient and must be interpreted with caution.
Recommendations:
- The electroencephalogram is recommended as part of the neurodiagnostic evaluation of the child with an apparent first unprovoked seizure (Standard)
Neuroimaging Studies
Although abnormalities on neuroimaging are seen in up to one third of children with a first seizure, most of these abnormalities do not influence treatment or management decisions such as the need for hospitalization or further studies. Of available reported imaging results, from
Class I and Class II studies of children, an average of about 2% revealed clinically significant findings that contributed to further clinical management, the majority of which were performed because the seizure was focal or there were specific clinical findings beyond the fact that a seizure had occurred (see the table in the guideline document).
Thus, there is insufficient evidence to support a recommendation at the level of standard or guideline for the use of routine neuroimaging, i.e., imaging performed for which having had a seizure is the sole indication, after a first nonfebrile seizure in children. However, neuroimaging may be indicated under some circumstances either as an emergent or nonurgent procedure.
The purpose of performing an emergent neuroimaging study in the context of a child's first seizure is to detect a serious condition that may require immediate intervention. The possible effects of emergency medication used to treat the seizure must be taken into consideration.
The purpose of performing a nonurgent neuroimaging study, which can be deferred to the next several days or later, is to detect abnormalities that may affect prognosis and therefore have an impact on long-term treatment and management. Factors to be considered include the age of the child, the need for sedation to perform the study, the electroencephalogram results, a history of head trauma, and other clinical circumstances such as a family history of epilepsy.
Recommendations:
- If a neuroimaging study is obtained, magnetic resonance imaging is the preferred modality. (Yang et al., 1979; Resta et al., 1994; O'Dell et al., 1997; Berg et al., 1999; Kuzniecky, 1996; Iannetti et al., 1996; Radue & Scollo-Lavizzari, 1994) (Guideline)
Emergent neuroimaging should be performed in a child of any age who exhibits a postictal focal deficit (Todd's paresis) not quickly resolving, or who has not returned to baseline within several hours after the seizure. (Vining & Freeman, 1986; Ferry, 1992) (Option)
- Nonurgent imaging studies with magnetic resonance imaging should be seriously considered in any child with a significant cognitive or motor impairment of unknown etiology, unexplained abnormalities on neurologic examination, a seizure of partial (focal) onset with or without secondary generalization, an electroencephalogram that does not represent a benign partial epilepsy of childhood or primary generalized epilepsy, or in children under 1 year of age. (Nordli & Pedley, 1995; King et al., 1998) (Option)
Definitions:
Classification of Evidence:
Class I. Must have all (a through d):
- Prospective study of a well defined cohort which includes a description of the nature of the population, the inclusion/exclusion criteria, demographic characteristics such as age and sex, and seizure type.
- The sample size must be adequate with enough statistical power to justify a conclusion or for identification of subgroups for whom testing does or does not yield significant information.
- The interpretation of evaluations performed must be done blinded to outcome.
- There must be a satisfactory description of the
technology used for evaluations (e.g., electroencephalogram, magnetic
resonance imaging).
Class II. Must have a or b:
- A retrospective study of a well-defined cohort which otherwise meets criteria for Class 1a, 1b, and 1d.
- A prospective or retrospective study which lacks any
of the following: adequate sample size, adequate methodology, a description of
inclusion/exclusion criteria, and information such as age, sex, and
characteristics of the seizure.
Class III. Must have a or b:
- A small cohort or case report.
- Relevant expert opinion, consensus, or survey.
A cost-benefit analysis or a meta-analysis may be Class I, II, or III, depending on the strength of the data upon which the analysis is based.
Strength of Recommendations:
Standards. Generally accepted principles for patient management that reflect a high degree of clinical certainty (i.e., based on Class I evidence or, when circumstances preclude randomized clinical trials, overwhelming evidence from Class II evidence that directly addresses the issue, decision analysis that directly addresses the issue, or strong consensus of Class III evidence).
Guidelines. Recommendations for patient management that may identify a particular strategy or range of management strategies and that reflect moderate clinical certainty (i.e., based on Class II evidence that directly addresses the issue, decision analysis that directly addresses the issue, or strong consensus of Class III evidence).
Practice options. Other strategies for patient management for which the clinical utility is uncertain (i.e., based on inconclusive or conflicting evidence or opinion).
Practice parameters. Results, in the form of one or more specific recommendations, from a scientifically based analysis of a specific clinical problem.
