Abstracts

Rationale: Neuropsychological testing is an important component in surgical assessment and treatment planning in patients diagnosed with Drug Resistant Epilepsy (DRE). These tests evaluate the impact of epilepsy and medication usage on brain functioning, help confirm seizure localization in the brain, and most importantly, determine the risk for cognitive declines following surgery.  However, neuropsychological testing can be variable due to many factors including patient effort, patient’s first language, overall intelligence, and chance response to limited questions. Although neuropsychological testing is often used to localize areas of brain dysfunction, it is an imperfect measure given the imprecise nature of cognitive testing. Detecting structural abnormalities, specifically white matter tracts measured with diffusion tensor imaging (DTI), is a potential way to quantify connections in the brain related to cognitive function. Here, as a pilot study, we explored potential links between DTI and neuropsychological testing in patients with epilepsy.

Methods: Seventy-four patients who underwent both diffusion-weighted magnetic resonance imaging as well as up to 39 neuropsychological tests for pre-surgical workup at the University of Kansas Comprehensive Epilepsy Center were included.  Fractional anisotropy values were assessed in 32 candidate white matter tracts for their correlation with the neuropsychological test scores.  Correlations were calculated using a standard Pearson correlation coefficient. As this was a data exploration study, a combination of the magnitude of correlations and corresponding p-values was used to identify potentially significant relationships.

Results: The strongest relationships observed were for executive function assessed with the Modified Wisconsin Card Sorting Test (MWCST) and memory assessed with total recall in the Hopkins Verbal Learning Test (HVLT-R). Executive function showed the strongest correlation with two frontal lobe projecting tracts: the Superior Longitudinal Fasiculus (r=0.38, p=0.001) and Cingulum Parolfactory (r=0.46, p=0.0001) tracts. Memory showed the strongest correlation with the left cingulum frontal parahippocampal tract (r=0.25, p=0.03).

Conclusions: Fractional anisotropy measured with DTI showed several relationships to both memory and executive function. Larger prospective studies will be needed to further confirm these relationships and test their clinical utility for surgical treatment of patients with epilepsy.

Funding: All funding came directly from the AES Summer Internship Program.