Abstracts

Patients with left temporal lobe epilepsy (TLE) often complain of word finding difficulties. However, results of standardized testing of naming functions frequently fail to detect suspected naming dysfunction. Most traditional naming tests employ visual confrontation naming. This visual modality may not be sensitive to naming deficits in TLE. We evaluated naming in TLE patients and normal controls using both visual and auditory stimulus modalities.
Thirty-two epilepsy patients and eight normal control subjects were recruited. The epilepsy patients were grouped by side (left vs. right) of epileptic focus and onset of epilepsy (before or after age five), with eight patients enrolled in each group. All subjects were required to have normal language functioning as measured by the Western Aphasia Battery (WAB). Groups were matched for age, education, IQ estimated by Nelson Adult Reading Test , and memory performance based on the Wechsler Memory Scale. Naming and word finding were evaluated using the Controlled Word Association Test (COWAT), the Test of Adult Word Finding (TAWF), the Boston Naming Test (BNT), and an additional task using both visual and auditory stimulus modalities. In addition, the time needed to complete each test was recorded. All assessments were made by an investigator (RAK) who was blinded to the lateralization of seizure foci. The blinded investigator also attempted patient classification into left and right groups based on observed behavior during language testing.
The blinded investigator correctly lateralized 28 of 32 TLE patients. The main features that distinguished the left TLE patients were a slight hesitation in initiating responses and an increased level of frustration during instances of word finding difficulty. Formal testing indicated that the late LTLE group performed significantly worse than other groups on the WAB test. All groups including late LTLE group demonstrated normal naming and word retrieval. The late LTLE group took a significantly longer time to complete the WAB than the other groups, but there was no difference between the groups in the time needed to complete other tests. No significant group differences were seen on analysis of the visual versus the auditory stimulus modality.
Standardized measures failed to identify TLE group differences, and were not sufficiently sensitive in detecting word finding difficulties in epilepsy patients. Future investigations should include a measure of latency to first response and should also analyze subject reaction to word finding difficulty.