Differences in visual naming performance between patients with temporal lobe epilepsy associated with temporopolar lesions versus hippocampal sclerosis.

OBJECTIVE

Naming difficulties are frequently observed in patients with temporal lobe epilepsy (TLE). Although damage/removal of regions of the anterior temporal neocortex including the temporal pole is considered critical for those difficulties, 1 relevant hypothesis proposes that hippocampal damage also has a role. Our aim was to better understand the specific involvement of temporal pole and hippocampus in visual object naming.

METHOD

We assessed 2 types of patients with TLE on a visual confrontation-naming task: patients with hippocampal sclerosis (HS; n = 16) and patients with a lesion on the tip of the temporal pole that spared the hippocampus entirely (n = 18). A common battery of verbal and nonverbal semantic tasks was administered and used as a semantic memory background. Control group were 20 matched healthy participants.

RESULTS

Patients with lesions on their temporal poles differed from patients with HS and control group on naming ability, proportion and rate of error type, and influence of concept familiarity. Of note, naming performance was not affected by hippocampal damage. Using a Bayesian model averaging approach, we found that the number of omission errors distinguished patients with temporal pole damage from patients with HS and controls. This differential pattern occurred despite similar impairment on the semantic memory background in both clinical groups.

CONCLUSION

Current findings provide evidence that temporal pole damage produces or contributes to naming impairment in TLE, while also suggesting that the hippocampus is not critical for naming. They also highlight the importance of error-type analysis when evaluating visual naming in TLE. (PsycINFO Database Record