Nonverbal selective reminding test: Efficacy in the assessment of adults with temporal lobe epilepsy

Abstract

Although the relationship of verbal memory tests to left temporal lobe epilepsy (LTLE) has reportedly been well established, research on the relationship of nonverbal memory to right TLE (RTLE) has yielded mixed findings, thus bringing into question the clinical utility of nonverbal memory assessment. In the present study, we used a selective reminding procedure for nonverbal spatial material to control for procedural factors, such as verbal mediation, which may in part be the basis for these mixed findings. A sample of 39 LTLE patients and 33 RTLE patients were given both a test of verbal selective reminding (VSR) and a test of nonverbal selective reminding (NVSR) as part of a presurgical evaluation. Diagnosis of RTLE and LTLE was rendered after an extensive presurgical evaluation including magnetic resonance imaging, video-electroencephalography, the intracarotid sodium amytal procedure, and intracranial electrodes when necessary. Results obtained from the NVSR allowed better classification of patients than did VSR, yielding 40% above chance classification. More important, given impaired performance, the probability that a patient had RTLE was 0.70. VSR performance did not allow for classification significantly above chance levels. Although combining the resultsfrom the VSR and NVSR resulted in the best classification, the gain was minimal (72% vs. 70% for NVSR alone), particularly because 26 patients could not be classified. Our results support previous findings of a relationship between nonverbal memory performance and RTLE epilepsy but bring into question the unequivocal acceptance of an exclusive relationship of verbal memory to LTLE.