Executive Function in Adults Following Hemispherectomy

Doctor of Philosophy in Clinical Psychology (PhD)
Hemispherectomy (HE) is an invasive neurosurgical approach used in youth with intractable epilepsy to control seizure frequency and enhance quality of life. Given the relatively rare occurrence of HE, the long-term outcomes are neither well-researched nor well-understood. Particularly unclear are the cognitive outcomes experienced in adulthood by those who underwent HE as children or adolescents, especially in the domain of executive functioning (EF). In the present study, I examined EF as measured by the Delis-Kaplan Executive Function System (D-KEFS) in nine adults who underwent HE in childhood or adolescence. It was hypothesized that participants would perform significantly below the normative population on 11 primary measures of the nine DKEFS tests. Results revealed significantly lower performances across participants on the Trail Making Test (Number-Letter Switching) as well as the Color-Word Interference Test (Inhibition/Switching). Additionally, a significant proportion of performances were at least 1 standard deviation below the normative mean for Design Fluency (Switching Total Correct) and Color-Word Inference (Inhibition/Switching). Secondary analyses showed that found side of HE did not significantly impact performance. These current findings suggest difficulty with response inhibition and cognitive flexibility in this sample, the latter of which may be partially impacted by impaired performances on tasks involving lower-level cognitive abilities (e.g., visual scanning, motor speed). Such aspects of EF may represent targets for intervention and support post-HE, though continued research on the long-term and specific cognitive effects of HE is needed.