Effect of Material-specificity on the Wada Memory Test in Medial Temporal Lobe Epilepsy with Hippocampal Sclerosis

ABSTRACT

BACKGROUNDS The Wada test is a useful method in predicting the laterality of a epileptogenic zone. However, past research reveals that material specificity has an influence on the lateralization We examined the material-specificity of memory and its change in epileptic patients to discover reasonable items on the Wada test for the proper lateralization of the epileptogenic zone. METHODS: We analyzed 45 patients with video-EEG-confirmed medial temporal lobe epilepsy (mTLE) and definite hippocampal atrophy by an MRI. Eight items were presented during the Wada test including 3 common objects, 1 geometric object, 1 color, 1 word, 1 phrase, and 1 math expression. We checked recognition memo-ry after recovery of hemiparesis and normalization of EEG. RESULTS: For the right mTLE group, recognition memory following a right hemisphere injection was significantly better than a left hemisphere injection for all categories. For the left mTLE group, a significant difference of scores was found for the left versus right hemisphere injection for common objects. When injected to the left hemisphere, all the items helped lateralization, but when injected to the right hemisphere, a phrase did not help with lateralization. CONCLUSIONS: Items with strong unilateral encodings do not help lateralizing the epileptogenic zone.