Abnormalities of the uncinate fasciculus correlate with executive dysfunction in patients with left temporal lobe epilepsy

Abstract

Objective: To evaluate executive deficits in patients with left temporal lobe epilepsy (TLE) and to analyze the association of executive deficits and diffusion tensor imaging (DTI) parameters of the uncinate fasciculus.

Methods: This study included 14 adult left TLE patients and 15 healthy controls. Executive function was examined using neuropsychological tests, including the Stroop color-word, digit span, digit symbol, trail-making test, and verbal fluency tests. All subjects underwent brain DTI.

Results: Compared with controls, TLE patients needed significantly more time (P=0.036) and had more wrong answers (P<0.001) in the Stroop test, and exhibited significantly lower scores in the digit span (P=0.017), digit symbol (P=0.009), and verbal fluency (P=0.001) tests. Additionally, TLE patients took significantly longer to accomplish the trail-making test (P=0.042). Fractional anisotropy (FA) of the left uncinate fasciculus in TLE patients was significantly lower compared to controls (P<0.001). FA of the left uncinate fasciculus in TLE patients and controls positively correlated with verbal fluency (r=0.565, P=0.035; r=0.561, P=0.031) and digit span (r=0.556, P=0.039; r=0.559, P=0.030) test scores.

Conclusions: Patients with left TLE exhibit wide ranges of executive deficits. Abnormal FA values in the left UF ipsilateral to the epileptogenic zone suggest that disrupted integrity in the left uncinate fasciculus is related to executive deficits in patients with left TLE.

Keywords: Cognition; Diffusion tensor imaging; Temporal lobe epilepsy; Uncinate fasciculus.