Abstract
Seventy-seven patients with intractable temporal lobe seizures were subjected to a series of verbal recognition tests during intracarotid amytal test (IAT) or Wada's Test as a part of presurgical evaluation. They included 11 patients whose speech dominant hemisphere was found to be lateralized on the right. In view of the side of speech dominance and of epileptogenic focus in temporal lobe, they were divided into the following 4 groups; 23 patients with left speech dominance and left focus (LL), 43 with left dominance and right focus (LR), 5 with right dominance and left focus (RL), and 6 with right dominance right focus (RR).
The Overall recognition rate in the verbal recognition test was 83.1%(80.2-93.3%) when it was performed without amytal injection. As a result of IAT to the right side, the recognition rate decreased markedly in patients with right speech dominance (RR and RL), and was fairly good only in patients with left speech dominance and right focus (LR). Conversely, IAT to the left brought about a marked decrease of the recognition rate in patients with left speech dominance (LL and LR) while maintaining a fairly good rate only in patients with right speech dominance and left focus (RL).
The present data indicate that 1) preservation of verbal memory function depends primarily on the speech dominant hemisphere regardless of whether it was either on the left or right, 2) there exists an underlying dysfunction in the focus side hemisphere in association with verbal memory impairment in patients with temporal lobe epilepsy, 3) both speech dominant hemisphere and memory circuits including hippocampus are responsible for preservation of verbal memory function.
