Abstracts

Rationale. The ability of intracarotid amobarbital (Wada) memory assessment to predict lateralization of seizure onset in children has not been thoroughly investigated. To address this deficiency, three comprehensive epilepsy surgery centers pooled their pediatric Wada memory data and examined the capacity of Wada memory asymmetries to predict side of seizure onset in children being considered for epilepsy surgery. Methods. One hundred and fifty-two children (mean age: 13.37 yrs., range 7 - 16 yrs.) with intractable epilepsy underwent Wada testing as part of their preoperative evaluation for possible epilepsy surgery. Although the type and number of memory stimuli and methods varied at each institution, all children were presented with 6 to 10 items (e.g., pictures, line drawings, real objects, geometric shapes, arithmetic problems, and printed words) soon after amobarbital injection. After return to neurological baseline, recognition memory for the various stimuli was assessed. Seizure onset was determined by simultaneous video/EEG monitoring of multiple seizures. Results. In children with unilateral temporal lobe seizure onset (N = 87), Wada memory asymmetries accurately predicted seizure laterality to a statistically significant degree (p = .0001). Wada memory asymmetries also correctly predicted side of seizure onset in children with extra-temporal lobe seizures (N = 65, p = .0009). Although individual patient prediction was significantly accurate across all temporal lobe cases (p = .002), onset laterality was incorrectly predicted in up to 40% of left temporal lobe seizure onset children depending upon the asymmetry criterion used. There were significant differences between Wada prediction accuracy among the different epilepsy centers. Conclusion. Results suggest Wada memory asymmetries may be useful in predicting side of seizure onset in many children. However, Wada memory asymmetries should be interpreted more cautiously in children than adults, especially among children with left temporal lobe seizure foci. Wada methodology and stimuli type appear critical in determining its success in predicting seizure onset laterality.