Seizures are one of the most common neurologic disorders in childhood. Approximately 25,000 to 40,000 children in the United States experience a new-onset, nonfebrile seizure every year. Based on a careful history and neurologic examination, the presumed etiology may be determined and will guide the ensuing clinical workup. For the purposes of this chapter, febrile seizures and status epilepticus are excluded from the discussion and are discussed elsewhere.
PATHOGENESIS AND EPIDEMIOLOGY
Seizures result from abnormal, excessive, and synchronous electrical discharge of neurons within the cortex. Based on the location and extent of these discharges, they may manifest in a wide variety of clinical symptomatologies, ranging from mild alterations of consciousness to motor manifestations as dramatic as generalized convulsions.
It is important to note that the majority of new-onset seizures in children are single occurrences and do not necessarily implicate a later diagnosis of epilepsy. Between 0.5% and 1% of children experience a single, nonrecurring, unprovoked seizure during childhood. The diagnosis of epilepsy itself necessitates at least 2 unprovoked or reflex seizures (defined as seizures habitually provoked by an external stimulus, such as flashing lights), a single unprovoked or reflex seizure with the likelihood of recurrence greater than 60%, or the identification of an epilepsy syndrome. The overall incidence of epilepsy in childhood and adolescence ranges from 50 to 100/100,000, with the highest incidence in the first year of life.
The clinical manifestations of a seizure may vary depending on the location and extent of the cortex involved with the seizure. At its subtlest, the signs may be as mild as slight cognitive impairment or sensory auras. The range of manifestations may involve many different realms of neurologic function, such as autonomic alterations or frank motor activity, including generalized tonic-clonic convulsions.
The diagnosis of seizures largely remains a clinical one. Often, a careful history and neurologic exam are all that is required for establishing the diagnosis. The history and exam will guide further workup, based on clinical suspicion of etiology. The differential diagnosis in children includes several seizure-like events, including breath-holding spells, syncope, nonepileptic psychogenic events, movement disorders, Sandifer syndrome, sleep disorders, and behavioral events.
An electroencephalogram (EEG) is essential for a first, unprovoked seizure and is recommended by most experts. An EEG helps to determine the risk for recurrence and is important in determining the type of seizure and epilepsy syndrome. There is some controversy regarding the optimal timing of this study. Although an EEG done within 24 hours of the seizure is most likely to show abnormalities, many of those abnormalities may be transient and resolve with time. There does not appear to be compelling evidence to support performing an emergent EEG within the emergency department for a single new-onset seizure that has clearly resolved. An EEG ...