Abstracts

Rationale: The results of preoperative neuropsychological memory test are reported to suggest the laterality of the epileptogenic focus in temporal lobe epilepsy. Wada test is used for identification of language dominant cerebral hemisphere and examination of memory function. We examined the relationship between memory evaluation using the Wada test and postoperative outcomes of drug-resistant temporal lobe epilepsy. Methods: We evaluated postoperative outcome about 38 patients with drug-resistant temporal lobe epilepsy with 2 years or more after surgery; 14 males, 24 females; mean age 32 years (16-54); mean following-up period after surgery 4.2 years (2-9). Using the Wada test, we determined the correct answer rate (%) of the memory evaluation task for language dominant hemisphere (DH) and non-language dominant hemisphere (NDH), and calculated Memory Index (MI; correct answer rate in DH ÷ that in NDH). Results: We were divided the patients into the DH-lowering group (MI <0.9; 9 persons), the NDH-lowering group (MI ≥ 1.1; 20 persons), and the low laterality group (0.9 ≤ MI <1.1; 9 persons). The operation side and the memory reduced hemisphere were concordant with 8/9 persons (89%) in the DH-lowering group and 18/20 persons (90%) in the NDH-lowering group. In DH-lowering group, all patients achieved class 1 (100%) in Engel outcome scale. In NDH-lowering group, 18 and 2 patients had class 1 (90%) and 2 (10%), respectively. Both DH and NDH-lowering group showed good postsurgical outcomes. In low laterality group, postoperative outcome is 4 patients in class 1 (45%), 2 in class 2 (22%), 3 in class 3 (33%), and the outcome was poorer than that in both DH- and NDH-lowering group. In this group, the operation side was concordant with the memory reduced hemisphere in only 3 of 9 patients (33%). In addition, In addition, 7 out of 9 in the low laterality group were accompanied unilateral lesions such as hippocampal sclerosis and cavernous angioma, but only 4 (57%) achieved class 1 in those 7 patients. Preoperative result of Wechsler Adult Intelligence Scale (WAIS)-R/III showed patients whose verbal IQ is 5 or more lower than active IQ accounted for 45% in the DH-lowering group, 55% in the NDH-lowering group, and 40% in the low laterality group, respectively. Preoperative Wecheler Memory Scale-Reviced (WMS-R) presented that about 60% of patients had verbal memory that was reduced 5 or more above visual memory in all groups. Preoperative psychological examination did not show a clear tendency like memory evaluation by Wada memory test performance. Conclusions: Wada test was also useful for predicting focus laterality in addition to estimation of postoperative outcome of drug-resistant temporal lobe epilepsy. Careful postoperative following-up should be required, taking into account the possibility of seizure recurrence in the low-laterality group of MI, even if there are obvious lesions. Funding: No funding