ELSEVIER Epilepsy Research 19 (1994) 153-160 EPILEPSY RESEAI H Do dichotic word listening asymmetries predict side of temporal lobe seizure onset? Gregory P. Lee a,b,*, David W. Loring c, Nils R. Varney d, Richard J. Roberts d, Jason R. Newell b James A. Martin b, Joseph R. Smith a Don W. King c Kimford J. Meador c A.M. Murro c a Department of Surgery (Neurosurgery), Medical College of Georgia, Augusta, Georgia, USA b Department of Psychiatry and Health Behavior, Medical College of Georgia, Augusta, Georgia, USA c Department of Neurology, Medical College of Georgia, Augusta, Georgia, USA d Iowa City VA Medical Center, Iowa City, USA Received 26 May 1994; accepted 1 June 1994 Abstract Dichotic word listening asymmetries are thought to be useful in predicting side of temporal lobe dysfunction. However, little direct evidence exists to support this assumption in practice, especially in patients with subtle epileptogenic lesions. To determine if word listening ear asymmetries are valid predictors of side of temporal lobe seizure onset, we examined the preoperative dichotic word listening performance of 80 patients with either left (N = 41) or right (N = 39) temporal lobe (TL) seizure loci. On a group level, patients showed a statistically significant 'lesion effect' as evidenced by a relative deficit in the ear contralateral to the side of lesion. Prediction of side of seizure focus in individual cases, however, was poor: depending upon the criteria used, 61% to 80% of epileptics with unilateral temporal lobe loci did not show the expected contralateral ear deficit. Results suggest that caution be exercised when inferring side of temporal lobe seizure focus through dichotic word listening asymmetries in individual temporal lobe epilepsy cases. Keywords: Dichotic listening; Hemispheric asymmetries; Temporal lobe epilepsy; Epilepsy surgery 1. Introduction Neuropsychological assessment is routinely used to aid in the localization of focal epilepsies at most epilepsy surgery centers [6]. Due to its sensitivity to side of hemispheric lesion, and particularly to side of temporal lobectomy, dichotic listening techniques * Corresponding author. Section of Neurosurgery, Medical Col- lege of Georgia, Augusta, GA 30912-4010, USA. Tel.: (706) 721-7883; Fax: (706) 721-7256. have captured a prominent role in the preoperative neuropsychological examination of epilepsy surgery patients [1,5,7,9,16,18,19,22]. Although dichotic lis- tening asymmetries may be useful in detecting later- ality of conspicuous lesions such as lobectomy, hemispherectomy, stroke, or corpus callosotomy [21], there is little evidence to support this clinical prac- tice, especially in patients with subtle epileptogenic lesions. Several investigations have examined the efficacy of verbal dichotic stimuli to detect side of temporal lobe dysfunction in epilepsy surgery populations. 0920-1211/94/$07.00 © 1994 Elsevier Science B.V. All rights reserved SSDI 0920-1211(94)00047-Z