Impairment of memory following prolonged seizure: effect of age

Abstract

One of the most important risk factors for seizure recurrence is the electroencephalogram (EEG) characteristics of children with a first unprovoked seizure. However, the nature of the relationship between the risk factors for subsequent epilepsy and EEG characteristics, especially the localization of EEG paroxysmal abnormalities (PAs), remains unclear. The importance of EEG characteristics, especially the localizations of PAs, as predictors for subsequent epilepsy in children with a first unprovoked seizure was investigated. The participants were recruited from University of Yamanashi Hospital between July 1, 1997 and June 30, 2010 and followed until December 31, 2014. Eligible candidates were children between 1 month and 15 years old who presented with their first unprovoked non-febrile seizure. Awake and sleep EEGs were performed on a 12- or 16-channel machine 7–20 days after a first unprovoked seizure. Agreement regarding the presence of a PA was required for inclusion of the patient in the study. EEG PAs were classified based on the presence of spikes, sharp waves, or spike-wave complexes, whether focal or generalized, that were considered abnormal for age and state. All subjects were followed for more than 4 years. Of 87 subjects, 48 (55.2%) experienced recurrence. On the other hand, of 87 subjects, 52 (59.8%) showed an EEG PA. Of 18 patients with paroxysms in the frontal region, 17 (94.4%) developed epilepsy. Patients with frontal EEG paroxysms had a significantly higher risk of developing epilepsy than those with focal paroxysms in other regions of EEG foci (p < 0.05). Moreover, compared with generalized EEG foci, the odds ratios for patients with frontal, RD, occipital, and mid-temporal EEG foci were 85.0 (95% CI: 4.5–1617.1), 9.3 (0.9–96.0), 2.5 (0.1–62.6), and 7.5 (0.5–122.7), respectively. Children with a first unprovoked seizure presenting with frontal paroxysmal EEG abnormalities may be at risk for the development of epilepsy later in life.