Relationship between the Wada test and preoperative/postoperative memory in mesial temporal lobe epilepsy patients

Abstract

Objectives: To study the correlation between Wada memory test and neuropsychometric tests which were applied preoperatively to mesial temporal lobe epilepsy patients associated with hippocampal sclerosis (MTLE-HS) who had undergone selective amygdalohippocampectomy and find out the effects of early onset epileptic seizures on atypical memory dominance. Methods: Drug-resistant 27 patients (16 left, 11 right MTLE-HS) had video EEG, cranial MRI and Wada test preoperatively. Weschler visual subtest and verbal memory processing tests were applied to all patients before surgery and the first year after the operation. Results: The number of left hemisphere memory dominant patients was 6 (22.2%) and the number of atypical memory dominant patients was 21 (77.8%) according to the Wada test. There was a significant difference between the two groups when compared for epileptic seizure onset age; (p=0.042), and also a significant diffference when compared for HS (right/left) side (p=0.002). When we analyzed the correlation between preoperative and postoperative verbal and nonverbal tests and left memory Wada dominance; in verbal memory processing tests ‘delayed recall’ scores between groups were significant (p=0.042), on the other hand in patients with atypical memory dominance ‘total learning’ scores between groups were significant (p<0.001). Conclusion: As a result, we found that the earlier the onset of seizures, the more atypical the memory dominance (right or bilateral). The Wada test was effective for assessing verbal memory; on the other hand, it was inadequate for assessing visual memory dominance. If the scores of ‘delayed recall’ in verbal memory were high in the patients with typical verbal dominance and ‘total learning’ scores in the patients with atypical verbal dominance, the scores also tended to rise after the operation.