Abstracts

RATIONALE: The objective of this abstract is to highlight the potential importance of auditory naming assessment in temporal lobe epilepsy (TLE). Object naming ability usually is assessed with visual naming (VN) tests that present drawings. Although a significant minority of TLE patients demonstrates VN impairment, recent studies suggest that naming to description (NTD) is a more sensitive and perhaps more ecologically valid approach to the measurement of naming problems in TLE. In addition, dominant temporal lobe sites specifically associated with the ability to name objects based on their definitions have been identified presurgically. In one TLE study, when stimulation of the posterior temporal lobe disturbed naming, both VN and NTD were usually affected, but anterior temporal lobe stimulation disturbed NTD almost exclusively (Hamberger et al., 1999, 2001). These data indicate that NTD merits further analysis in patients with epilepsy.
METHODS: To further explore the nature of dysnomia in TLE, the current study assessed a group of patients with either left or bilateral TLE and a group of healthy controls on computerized, timed (E-Prime software) measures of VN and NTD. Two lists of 63 objects from the Snodgrass & Vanderwart (1980) corpus were compiled. The stimuli in each list were matched on age of word acquisition, familiarity, imageability, word frequency, and other variables. There was a VN and a NTD test for each list, and administration was counterbalanced across test type and list. Line drawings were used as the stimuli for VN. For NTD, a definition was created and audiotaped for each object. The vocabulary in the definitions was kept as basic as possible and each definition included a brief physical description of the object and either a functional attribute or an encyclopedic fact about it. Speed of naming responses was recorded by a voice-activated timer. Accuracy was recorded by the examiner.
RESULTS: Both NTD speed and accuracy scores distinguished patients from controls better than VN scores. NTD speed was the only naming test variable significantly associated with self-reported language problems on the QOLIE-89. It is notable that 1) NTD speed and accuracy correlated more strongly, compared to VN, with numerous neuropsychological test scores, 2) NTD speed correlated significantly with language complaints in general, not with word finding problems specifically, and 3) language complaints showed strong correlations with multiple cognitive and demographic variables.
CONCLUSIONS: It is well established that many individuals with left hemisphere TLE show VN impairment. NTD ability has received little attention in this group, although Hamberger and colleagues reported important differences between NTD and VN performance in both traditional clinical and electrical stimulation studies. Our investigation supports the usefulness of NTD in neuropsychological studies of TLE. NTD classified TLE and controls more accurately than VN. Although NTD has a broad range of verbal demands, this quality might actually make it a good analogue of conversational speech and an appropriate measure of word finding problems.
[Supported by: The Epilepsy Foundation and NIH K23 NS42251 & RO1 NS37738.]