Abstracts

RATIONALE: Several studies have suggested Wada memory performance is related to seizure outcome in adult epilepsy surgery patients, but this relationship has not been thoroughly investigated in children. To address this deficiency, we examined Wada memory asymmetries in youngsters from three comprehensive epilepsy surgery centers who subsequently underwent resective epilepsy surgery to determine if Wada memory performance could predict seizure outcome.
METHODS: One hundred and twelve children (mean age: 12.8 yrs., range 7 - 16 yrs.) with intractable epilepsy underwent Wada testing as part of their preoperative evaluation for surgery. Seizure onset was determined by simultaneous video/EEG monitoring of multiple seizures. All patients underwent resective epilepsy surgery (69 = left hemisphere, 43 = right hemisphere). Seventy-seven underwent unilateral temporal lobe resection, and 35 had extratemporal lobe resections. Seventy-six (68%) were seizure-free (Engel Class I), and 36 (32%) were non-seizure-free (Engel Classes II-IV) at follow-up. Mean follow-up interval was 3.7 yrs. (range = 6 mos. - 10.2 yrs.). Memory stimuli were presented soon after intracarotid amobarbital injection, and recognition memory for the items was assessed after return to neurological baseline. Although minor institutional differences existed in procedures for amobarbital administration, there were no statistically significant difference between left (mean=102.0 mg) and right (mean=102.1 mg) hemisphere amobarbital doses.
RESULTS: Mean ipsilateral minus contralateral Wada memory difference scores were 22.9% for all seizure-free, and 1.2% for all non-seizure-free, children (p = .02). When restricting the analysis to youngsters with temporal lobectomies (TL), ipsilateral minus contralateral difference scores increased to 27.4% for seizure free TLs, and 5.1% for non-seizure-free TL children (p =.01). With regard to individual patient prediction, 47 of 63 (75%) children who had memory score asymmetries in the correct direction were seizure-free. In contrast, only 29 of 49 (59%) children whose memory score asymmetries were not in the correct direction were seizure-free.
CONCLUSIONS: These results suggest Wada memory performance asymmetries are related to degree of seizure relief after epilepsy surgery in children and adolescents. Moreover, the association between Wada memory asymmetries and postsurgical seizure relief seen in the present study is similar to results obtained in adult epilepsy surgery patients.