Abstracts

Rationale: To investigate the correlation of Wada test and hippocampal resection with postsurgical outcome of memory and cognition in patients with mesial temporal lobe epilepsy (mTLE). Methods: We included 74 patients with unilateral mTLE who had pre- and post-operative neuropsychological (NP) tests and have been seizure free postsurgically. There were 38 males and 36 females (mean age 29.7±9.4 years). We calculated Wada asymmetry index (WAI) [[(normal hemisphere Wada score (NHWS)-epileptogenic hemisphere Wada score (EHWS)]/ (NHWS + EHWS)])x2 and NP asymmetry index (NPAI) [(pre-surgical scores (SS) - post-SS) / (pre-SS +post-SS)] x2. The length of pre- and post-operative hippocampi were measured. The significances of postoperative NP changes were investigated. Correlations of postoperative NP changes with WAI and the length of hippocampal resection were tested. Results: Forty patients (24 males and 16 females, mean age 31.4±10.4 years) underwent right ATL. The remaining 34 patients (14 males and 20 females, mean age 27.8±7.9 years) underwent left ATL. Age, education, IQ and duration of epilepsy history were not significantly different between right and left ATL groups. There was no significant difference of NP tests between right and left ATL groups. Right ATL group showed significant postoperative improvement in verbal memory [California verbal learning task (CVLT) 1-5 total raw score (TRS), p= 0.000; CVLT long delay free recall, p = 0.000; CVLT recognition hits, p = 0.008; logical memory (LM) immediate recall, p =0.002; LM delayed recall, p= 0.002] whereas left ATL group revealed significant decrease in verbal memory score [CVLT TRS (p = 0.015), CVLT short delay free recall (P = 0.012) and CVLT long delay free recall (p = 0.008)]. Visual memory was not significantly changed postsurgically in both left and right TLE groups. In left TLE group, NPAIs of verbal memory were significantly correlated with WAI (CVLT TRS, r = -0.41, p = 0.015; CVLT short delay free recall, r = -0.39, p = -.022; CVLT long delay free recall, r = -0.52, p = 0.002; LM delayed recall, r = -0.40, p = 0.019) whereas in right ATL group, NPAI of visual memory was significantly correlated with WAI (Rey recognition total score index; r = 0.352, p = 0.026). However, the extent of hippocampal resection or remained hippocampal length was not related to the postsurgical memory outcome. Conclusions: Verbal memory was improved postsurgically in right mTLE patients but decreased in left mTLE patient. WAIs were significantly correlated with NPAI of verbal memory in left TLE and with NPAI of visual memory in right TLE. However, the extent of hippocampal resection was not significantly correlated with postoperative NP outcomes.