Distribution of auditory and visual naming sites in nonlesional temporal lobe epilepsy patients and patients with space-occupying temporal lobe lesions

Abstract

Purpose: Current knowledge regarding the topography of essential language cortex is based primarily on stimulation mapping studies of nonlesional epilepsy patients. We sought to determine whether space-occupying temporal lobe lesions are associated with a similar topography of language sites, as this information would be useful in surgical planning. Methods: We retrospectively compared the topography of auditory and visual naming sites in 25 nonlesional temporal lobe epilepsy patients ("nonlesional") and 18 patients with space-occupying lesions ("lesional") who underwent cortical language mapping before left temporal resection. Results: Both groups exhibited a similar pattern of auditory naming sites anterior to visual and dual (auditory-visual) naming sites; no group differences were specific to auditory or visual naming sites. However, significantly fewer lesional (10 of 20) compared with nonlesional patients (21 of 25) exhibited any naming sites in the temporal region (p = 0.04). Although the proportion of naming sites on the superior temporal gyrus was similar between groups, naming sites were found on the middle temporal gyrus in 13 of 25 nonlesional patients, yet in only one of 18 lesional patients (p = 0.002). Across groups, patients with visual naming sites were older than patients without visual naming sites identified (p = 0.02). Conclusions: The precise location of essential language cortex cannot be reliably inferred from anatomic landmarks or patient-related variables. As time constraints are a common quandary in stimulation mapping, the different patterns reported here for patients with and without space-occupying lesions can be used to guide mapping strategies, thereby increasing the efficiency by which positive naming sites are identified. © 2007 International League Against Epilepsy.