Predictive Values of Four Wada Memory Asymmetry Indices in Postsurgical Memory Outcome

ABSTRACT

BACKGROUND: The interpretation of Wada memory test is various in different epilepsy centers. Four types of Wada memory score (WMS) were defined by four different criteria to determine the best WMS in predicting postsurgical memory outcome. METHODS: Twenty temporal lobe epilepsy patients underwent Wada test before surgery and pre- and post-operative neuropsychological tests. WMS was obtained by four ways; including 1) total stimulating items, 2) items presented between one and two minutes after amobarbital injection, 3) items presented before ipsilateral EEG slowing decreased to 50%, 4) items presented until EEG slowing disappeared. Wada memory asymmetry index (WAI) was determined by [(WMS of normal side ? WMS of epileptic side)/their mean]. Logical and visual memory tests were performed before and after operation. Neuropsychological asymmetry index (NPAI) was defined as [(postsurgical score ? Presurgical score)/their mean]. Spearman correlation coefficients were obtained between WAIs and NPAIs. RESULTS: WAIs obtained by method 2) and 3) showed relatively good correlation with NPAIs. Visual memory outcome was correlated with WMS better than logical memory both in non-dominant and dominant hemisphere epilepsy groups. The lateralizing value of memory dominance in non-dominant hemisphere epilepsy group was greater than that of dominant group. CONCLUSIONS: Early presented stimuli during Wada test had a better predictive value of postoperative memory outcome.