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Seizures and Epilepsy: Epidemiology and Seizure Classification

INTRODUCTION

The earliest known description of epilepsy is from a Mesopotamian text from around 2000 BCE; it describes a patient with focal head deviation, loss of consciousness, and frothing at the mouth, and the prescription appears to have been exorcism. A neurophysiologic, rather than divine, underpinning of epilepsy was proposed and discussed extensively by Hippocrates in 400 BCE, although the Indian author Atreya may have speculated a similar cause nearly 200 years prior. However, despite Hippocrates’ renown and thorough treatise on the topic, and perhaps due to its dramatic manifestations and behavioral associations, the “sacred disease” remained one of the last to succumb to the rationality of the Enlightenment, with consensus in the medical community accepting its natural pathophysiology only late in the 18th century.

Seizures and epilepsy remain much misunderstood by the general public even today, and this misunderstanding engenders fear and confusion, particularly after the occurrence of a first seizure. As the point of initial contact for patients and families in outpatient, inpatient, and urgent care contexts, the general practitioner has the first opportunity to inform and guide families through this difficult time. Thus, although any child with an unprovoked seizure or suspicion of epilepsy should be referred for evaluation and counseling by a specialist, a basic understanding of the etiology, evaluation, and classification of seizures and epilepsy is essential to the practice of the general pediatrician. Chapter 552 further describes the initial approach to evaluating a child with new-onset seizures.

EPIDEMIOLOGY OF SEIZURES

The lifetime incidence for a single unprovoked seizure is between 8 and 10 in 100 persons, making seizures second in number only to headaches among neurologic conditions. After a first unprovoked seizure, however, the overall risk for recurrence is between 40% and 50%. Measures of the prevalence of epilepsy, on the other hand, have ranged from 4 to 10 active cases per 1000 persons in developed countries. Prevalence in children is similar at 3.2 to 5.5 per 1000 in developed countries. An inverse correlation with economic development and prevalence of epilepsy is well described, with rates in children ranging from 3.6 to 44 (and most typically exceeding 10) per 1000 population in resource-poor countries; rates are especially higher in Latin American and African countries and in remote or rural areas.

Epilepsy presents most frequently at the extremes of age. Although in Western Europe and the United States, incidence rates have consistently fallen in infants during the past 3 decades, the infant period remains the highest risk time period for the presentation of epilepsy. Febrile seizures (a particular form of acute symptomatic seizure; see Chapter 551) are most common during this time period; in patients presenting with epilepsy, epileptic spasms are most common. Through the rest of childhood and adolescence, the incidence progressively decreases, reaching a nadir by early adulthood that begins rising ...

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