Prediction of Seizure‐onset Laterality by Using Wada Memory Asymmetries in Pediatric Epilepsy Surgery Candidates

Abstract

Summary:Purpose: Because the capacity of intracarotid amobarbital (Wada) memory assessment to predict seizureonset laterality in children has not been thoroughly investigated, three comprehensive epilepsy surgery centers pooled their data and examined Wada memory asymmetries to predict side of seizure onset in children being considered for epilepsy surgery.Methods: One hundred fifty-two children with intractable epilepsy underwent Wada testing. Although the type and number of memory stimuli and methods varied at each institution, all children were presented with six to 10 items soon after amobarbital injection. After return to neurologic baseline, recognition memory for the stimuli was assessed. Seizure onset was determined by simultaneous video-EEG recordings of multiple seizures.Results: In children with unilateral temporal lobe seizures (n ‫ס‬ 87), Wada memory asymmetries accurately predicted seizure laterality to a statistically significant degree. Wada memory asymmetries also correctly predicted side of seizure onset in children with extra-temporal lobe seizures (n ‫ס‬ 65). Although individual patient prediction accuracy was statistically significant in temporal lobe cases, onset laterality was incorrectly predicted in Յ52% of children with left temporal lobe seizure onset, depending on the methods and asymmetry criterion used. There also were significant differences between Wada prediction accuracy across the three epilepsy centers. Conclusions: Results suggest that Wada memory assessment is useful in predicting side of seizure onset in many children. However, Wada memory asymmetries should be interpreted more cautiously in children than in adults.

Wada Memory Performance Predicts Seizure Outcome after Epilepsy Surgery in Children

“…Given the relation between the temporal lobes and memory functions, only patients with temporal lobe epilepsy have typically been studied. However, results of the present study in conjunction with others suggest that Wada memory asymmetries may be beneficial in predicting side of seizure onset in patients with seizure foci in brain regions other than the temporal lobe (18,22–24).…”

“…Thus, Wada memory asymmetries may be useful, in conjunction with other diagnostic techniques, when counseling children and their families about the probable seizure outcomes of surgery. Studies have now established that Wada testing is as safe (24) and reliable (18) in children as in adults, and provides equivalent information in general regarding language lateralization (18), side of seizure onset (22), and prediction of seizure outcome after surgery (the present investigation). Future investigations will be necessary to establish whether preoperative Wada memory asymmetries can provide the same amount of useful information about postoperative recent memory functions in children as in adults.…”

Prediction of Verbal Memory Decline after Epilepsy Surgery in Children: Effectiveness of Wada Memory Asymmetries

“…Patients were then classified into one of two groups based on whether a Wada memory asymmetry was present (Asymmetry group = ipsilateral injection memory > contralateral injection memory) or absent (No Asymmetry group = ipsilateral injection memory ≤ contralateral injection memory). More‐detailed descriptions of the Wada memory procedures at each of these epilepsy surgery centers may be found in previous publications (11,12).…”

“…More recently, differences in memory capacity after left‐ and right‐hemisphere amobarbital injections have been used to infer lateralized temporal lobe dysfunction associated with unilateral seizure onset (3–6) and in some cases to help predict likelihood of seizure relief after epilepsy surgery (7–9). Although results have been fewer and more variable in children, Wada testing appears to provide roughly equivalent information in children as in adults with regard to language lateralization (10), determining side of seizure onset (11), and predicting degree of seizure relief after surgery (12).…”

Clinical prediction of postoperative seizure control: structural, functional findings and disease histories

“…Concordance of ictal and interictal EEG recordings with MRI, positron emission tomography, neuropsychology and Wada Testing towards a unilateral and strictly localised seizure focus have already been demonstrated to correlate with favourable outcome 20 – 24. These parameters are, therefore, well recognised for prospective selection of surgical candidates 25 – 27.…”