Abstracts

This is a Late Breaking abstract

Rationale: Pre-surgical functional and structural whole brain characteristics associated with successful versus unsuccessful temporal lobe (TL) surgery for drug-resistant epilepsy remain incompletely defined. This is an important knowledge gap given that seizure freedom rates after TL surgery may drop as low as 50% after several years. Considerable data has emerged on the ability of key clinical variables (e.g., pathology/lesion status, resection size, side of surgery, seizure frequency, age of seizure onset, illness duration, age, etc.) to predict post-surgical seizure control, but a key feature of brain functional integrity prior to surgery remains understudied – neurocognitive (NC) and psychiatric status. Given the building evidence that even focal epilepsy is a broad brain network disorder, it is reasonable to hypothesize that functional integrity/reserve in regions untouched by surgery plays a role in post-operative seizure control and prevention of epileptogenesis. Here, we capture functional reserve through multi-domain neuropsychological testing and use cluster analysis to determine if there are NC phenotypes prior to surgery associated with distinct seizure outcomes. We hypothesized that multivariate NC phenotypes reflecting stronger functional integrity of the whole brain (i.e., better general NC test performance) will predict better seizure control post-operatively (modified Engel Scale: seizure freedom, Class I).¹_x000D_  _x000D_ Methods: Drug-resistant unilateral TLE patients who underwent TL resections or stereotactic laser interstitial thermal therapy from 2005-2021 were included (n=168; 55% M, 45% F; seizure focus: 51%, LTLE, 49% RTLE). Those with other significant neurologic diagnoses were excluded. We utilized K-means cluster analysis to characterize NC phenotypes associated with distinct seizure outcomes with 12 NC tests as input in domains of verbal and visuoperceptual IQ, attention, processing speed, executive functioning, verbal memory, language, visuospatial skills, fine motor speed, and anxiety/depression.  

Results: Participants with data for all NC/psychiatric tests and surgical outcomes one year post-surgery were included in the analyses, yielding a final analytic sample of 120 TLE patients. Two distinct clusters emerged suggesting better performance across NC tests and lower psychiatric symptomatology were associated with post-operative seizure control. All NC/psychiatric measures significantly contributed to cluster membership (ANOVA, p < .03).