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Seizures

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BACKGROUND

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Approximately 5% of children will have at least one seizure before the age of 20 years.1 A seizure is the manifestation of abnormally synchronized electrical activity in the brain. The initial approach to a patient with a seizure should focus on stabilizing the patient and evaluating for potentially reversible seizure causes. While most unprovoked seizures are brief and resolve spontaneously, seizures secondary to metabolic disturbances, infections, or intracranial hemorrhage may be more prolonged. Timely evaluation and treatment are essential in preventing or minimizing the complications of a prolonged seizure, including hypoventilation, tissue hypoxia, and cerebral edema.

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Most children who experience a single seizure, which is often provoked by fever or acute illness, do not go on to develop epilepsy. Epilepsy is diagnosed by the presence of recurrent unprovoked seizures and has a prevalence in childhood of approximately 0.5%.2

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EPILEPTIC SEIZURES

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CLINICAL PRESENTATION

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The presentation and seizure semiology (symptoms during a seizure) depends on the region of brain involved as well as the underlying etiology. Epilepsy classification systems are clinically useful frameworks and provide diagnostic and therapeutic criteria.

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Previous classification systems (e.g. the 1981 International Classification of Epileptic Seizures and the 1989 International Classification of Epilepsies, Epileptic Syndromes, and Related Disorders), although widely accepted, were based primarily on the phenomenology of the seizure and concepts that predate the era of neuroimaging, genetic technologies, and modern molecular biology. Since 2001, the International League Against Epilepsy (ILAE) has moved toward a classification that allows for neuroscientific advances to be incorporated into clinical practice.3 Additional revisions were made in 2006 and 2010.4

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According to the 2010 ILAE revised terminology, seizures have been classified as either generalized or focal (Table 118-1). Generalized seizures are defined as originating anywhere within, and rapidly involving, bilateral hemispheres. They can be asymmetric. This produces a loss or impairment of consciousness and may produce tonic activity (stiffening), clonic activity (rhythmic jerking), tonic-clonic activity (stiffening followed by or alternating with rhythmic jerking), atonic activity (loss of tone), myoclonic activity (sudden contraction of muscles), or absence seizures (typically with staring, blinking, and automatisms). Focal seizures originate from networks limited to one hemisphere. Simple partial and complex partial terms, while still used in clinical practice, are being replaced by different focal seizure descriptors according to the degree of impairment during seizures (Table 118-2). For example, a focal seizure beginning in or rapidly spreading to the left motor strip (left frontal cortex) would likely involve clonic movements of the right arm, leg, or face without impairment of consciousness. A focal seizure arising from the temporal lobe might result in an abnormal psychic experience such as déjà vu. A focal seizure can spread to involve the entire cortex and produce generalized seizure activity.

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Table Graphic Jump Location
TABLE 118-1Classification of Seizures...

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