Abstracts

Rationale: Wada test before anterior temporal lobectomy (ATL) is helpful in lateralizing seizure origin and in predicting postoperative memory change. Both degree and direction of Wada memory asymmetry have been associated with surgical outcome and memory decline in temporal lobe epilepsy (TLE). Previous studies evaluated the change by neuropsychological tests focusing on memory. Intelligence changes with respect to degree of Wada asymmetry have not been examined yet. In this study we investigated the relationship of IQ changes and Wada asymmetry after ATL. Methods: Database consisted of 192 patients who underwent ATL (96L, 96R) between July, 1987 and Jan, 2006 at Taipei Veteran General Hospital. Presurgical evaluation included Video-EEG monitoring, brain MRI, SPECT, PET, Wada test and WAIS IQ test in all patients. Patients were followed up at epilepsy clinics and postoperative IQ tests were obtained in 118 cases at 6-9 months after ATL. Wada memory test asymmetry was categorized into “expected asymmetry” (EA) group or “unexpected asymmetry”(UA) group. The former indicated that Wada scores are less in the ipsilateral side of ATL than contralateral side and the latter indicated a reverse result. Wada asymmetry index (WAI) was calculated as side difference divided by baseline score for evaluating the relation between degree of asymmetry and postoperative IQ score. Logistic regression, student’s t-test, ANOVA and chi-square tests were used for statistic analysis. A p value < 0.05 is considered significant. Results: Among 192 patients 69.8% exhibited good seizure outcome (Engel’s I) at 2 years after ATL. The outcome was not influenced by sex, duration of epilepsy, side of operation or normal brain MRI. UA occurred in 17.7% of 192 Wada test. Twenty-seven (28.1%) of L-ATL and 7(7.3%) of R-ATL patients had UA. Seizure outcome are good both in the EA group (67.7 %) (Engel’s I) and UA group (79.4%) (Engel’s I). VIQ improved less in L-ATL than R-ATL among all cases. Postoperative FSIQ, PIQ and VIQ increases were not different between EA and UA groups. The improvement was less in VIQ than in FSIQ and PIQ but it was not statistically significant. The degree of Wada asymmetry was correlated to the VIQ improvement. Twelve of 25 (46.2%) cases of WAI less than 0.2 and only 14 of 93 (15.1 % ) of WAI greater than 0.2 showed a marked decrease in postoperative VIQ Conclusions: In our cases UA are more commonly seen in L-TLE than in R-TLE. UA is not a predictor of poor seizure outcome or postoperative intelligence in this study. UA in Wada test is not supposed to be contraindication for ATL. The less degree of asymmetry in Wada test does have influence on the postoperative verbal intelligence improvement. Comparable to other studies, the less asymmetry of Wada memory score predicts less improvement of postoperative verbal cognitive function.