Cognitive features of adult focal epilepsy with unknown etiology revealed by the trail making test.

Purpose: The purpose of this study was to investigate whether the Trail Making Test (TMT) can clarify cognitive dysfunction in focal epilepsy with unknown etiology.

Methods: Trail Making Test data were obtained from patients with focal epilepsy with no structural abnormalities on magnetic resonance imaging, history or coexistence of central nerve system diseases, intellectual disability, psychiatric disorders, or medications that might interfere with cognitive function. We performed multiple regression analyses with TMT scores as dependent variables and clinical features as independent variables.

Results: We enrolled 125 patients in the study. The statistical analyses revealed that taking fewer antiseizure medications, having a longer duration of education, exhibiting left non-temporal epileptic discharge, and exhibiting right temporal epileptic discharge were associated with shorter time to complete the TMT-A and TMT-B. Older age at the time of last seizure was associated with longer time to complete the TMT-B. In addition, a longer active seizure period was associated with longer time to complete the TMT-A subtracted from time to complete the TMT-B.

Conclusions: This study indicated that the TMT can be used for assessing the cumulative effects of seizures and the effects of polypharmacy on cognitive function in patients with focal epilepsy. Furthermore, our results indicated that the visuospatial cognitive ability associated with the TMT may depend on the site of epileptic focus of non-lesional focal epilepsy.