DO DICHOTIC WORD LISTENING ASYMMETRIES PREDICT SIDE OF TEMPORAL-LOBE SEIZURE ONSET

Dichotic word listening asymmetries are thought to be useful in predic ting side of temporal lobe dysfunction. However, little direct evidenc e exists to support this assumption in practice, especially in patient s with subtle epileptogenic lesions. To determine if word listening ea r asymmetries are valid predictors of side of temporal lobe seizure on set, we examined the preoperative dichotic word listening performance of 80 patients with either left (N = 41) or right (N = 39) temporal lo be (TL) seizure foci. On a group level, patients showed a statisticall y significant 'lesion effect' as evidenced by a relative deficit in th e ear contralateral to the side of lesion. Prediction of side of seizu re focus in individual cases, however, was poor: depending upon the cr iteria used, 61% to 80% of epileptics with unilateral temporal lobe fo ci did not show the expected contralateral ear deficit. Results sugges t that caution be exercised when inferring side of temporal lobe seizu re focus through dichotic word listening asymmetries in individual tem poral lobe epilepsy cases.