Caudate atrophy and impaired frontostriatal connections are linked to executive dysfunction in temporal lobe epilepsy

This study tested the hypothesis that executive dysfunction, common in temporal lobe epilepsy (TLE), is associated with an abnormal frontostriatal network. Structural and diffusion tensor MR scans, the Wisconsin Card Sorting Test (WCST) targeting cognitive flexibility, and the Trail Making Test B examining parallel sequencing were obtained from 9 patients with left TLE and 17 healthy controls. The five major findings were: (1) Caudate volume is reduced on the left side in TLE. (2) The atrophy involves the dorsal and ventral head of the caudate. (3) These atrophic caudate regions have a corresponding high probability of connections to dorsal prefrontal, anterior cingulate, and orbitofrontal cortex. (4) Smaller caudate volumes are linked to greater numbers of WCST perseverative errors. (5) Reduced connections between caudate and dorsal prefrontal cortex correlated with poorer scores on the Trail Making Test B. The results suggest that atrophy in the dorsal head of the caudate might disrupt frontostriatal networks that are critical for executive functioning in TLE.