What is the incidence of first adult seizure?

Updated: Nov 30, 2017
  • Author: Eissa Ibrahim AlEissa, MD, MBBS; Chief Editor: Selim R Benbadis, MD  more...
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It is estimated that 1 in 26 people will develop epilepsy during his or her lifetime. [20]

The incidence of single unprovoked seizures is 23-61 cases per 100,000 persons-years, while the incidence of acute symptomatic seizures is 29-39 cases per 100,000 population per year. [21, 22, 23]

Beghi et al attributed the variability to differences in methodology and definitions. [19] The rates were similar in different geographic areas despite technical differences in the studies.

Racial differences have not been studied, but there appears to be a small to moderate male preponderance of men studies of first adult seizures in most reports. [14, 18, 24, 25] However, in an early study, Annegers et al found a slight overall preponderance of women. [10] Their etiologic categories were neurologic deficit from birth, remote symptomatic, and no known previous etiology. The investigators identified a preponderance of men in the group with neurologic deficit from birth, no sex preponderance in the group with remote symptomatic seizures, and a slight preponderance of women in the group with no known previous etiology. [10] These authors did not determine if these sexual differences were statistically significant.

Among patients who had an initial generalized tonic-clonic seizure, Bora et al found that only 45.5% were men. [15] Patients with partial seizures and structural lesions proven on computed tomography (CT) scan were excluded from this study.

Age does affect the incidence rate of epilepsy, with the highest incidence in the very young and very old groups. The incidence rate in children younger than 1 year is 100-233 per 100,000. [26] The rate decreases in patients aged 20-60 years to 30-40 cases per 100,000, but the rate increases to 100-170 cases per 100,000 in patients older than 65 years. [26]

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