Neuropsychological status at seizure onset in children: risk factors for early cognitive deficits

Abstract

Objective: This large, prospective, community-based study characterized neuropsychological functioning and academic achievement at the time of the first recognized seizure and identified risk factors for cognitive deficits.

Methods: We compared 282 children (ages 6-14 years, IQ > or =70) with a first recognized seizure to 147 healthy siblings on a battery of well-standardized and widely used neuropsychological and academic achievement tests and examined relationships with demographic and clinical variables.

Results: In this intellectually normal cohort, 27% with just one seizure and up to 40% of those with risk factors exhibited neuropsychological deficits at or near onset. Risk factors associated with neuropsychological deficits included multiple seizures (i.e., second unprovoked seizure; odds ratio [OR] = 1.96), use of antiepileptic drugs (OR = 2.27), symptomatic/cryptogenic etiology (OR = 2.15), and epileptiform activity on the initial EEG (OR = 1.90); a child with all 4 risks is 3.00 times more likely than healthy siblings to experience neuropsychological deficits by the first clinic visit. Absence epilepsy carried increased odds for neuropsychological impairment (OR = 2.00).

Conclusions: A subgroup of intellectually normal children with seizures showed neuropsychological deficits at onset. Academic achievement was unaffected, suggesting that there is a window early in the disorder for intervention to ameliorate the impact on school performance. Therefore, the risk factors identified here (especially if multiple risks are present) warrant swift referral for neuropsychological evaluation early in the course of the condition.

Figure 1 Neuropsychological factor scores by epileptic syndrome On language, all other syndrome groups scored lower than the localization-related idiopathic group. For attention/executive/construction, both the generalized idiopathic absence and the localization-related cryptogenic groups scored lower than siblings. For verbal memory and learning, the localization-related cryptogenic group scored lower than the siblings. Sibling controls, n = 147; generalized idiopathic/absence, n = 39; generalized idiopathic/tonic-clonic, n = 42; localization-related/idiopathic, n = 53; localization-related/cryptogenic, n = 111; localization-related/symptomatic, n = 17. Although the generalized symptomatic/cryptogenic group (n = 8) was included in the comparisons between etiologies, it was excluded from the analysis comparing specific syndromes because of small sample size.

Figure 2 Neuropsychological factor scores by antiepileptic drug (AED) use, multiple seizures, and epileptiform activity on initial EEG Among children who had a seizure, children who were prescribed AEDs (n = 141) scored lower than those who were unmedicated (n = 140) on processing speed (p = 0.001), language (p = 0.04), and verbal memory and learning (p = 0.05), even in children who had had only one seizure and in children without epileptiform activity on EEG. Children who had 2 or more seizures before baseline interview (n = 187) had lower scores compared to children with only one seizure (n = 95) on attention/executive/construction (p = 0.03), even in children who were unmedicated. Children who exhibited epileptiform activity on the initial EEG (present group, n = 173) scored lower than those without epileptiform activity (absent group, n = 107) on the processing speed factor (p = 0.004, d = 0.31), even in children who were unmedicated.