Abstracts

Rationale: Patients with frontal lobe epilepsy (FLE) often show reduced performance on neuropsychological measures assessing attention, working memory, processing speed, fluency, and concept formation. However, there is limited research examining cognitive outcomes following frontal lobe resection for treatment of pharmacoresistant seizures, and we are aware of only one study that has specifically examined cognitive outcomes following resection of the supplementary motor area (SMA). This study aims to examine declines in cognitive measures following SMA resection in adults with FLE using reliable change indices (RCI).Methods: Fifty-three adults (16-59 years, mean age = 29) completed neuropsychological evaluations before and approximately 7 months after frontal lobe resection (FLR; 26 right, 27 left). Patients were divided into two groups based on whether or not the SMA region was resected (26 resected, 27 spared). There were no significant differences between the two groups on demographic factors, seizure variables, or baseline cognitive performance. We calculated change scores for cognitive measures assessing attention, working memory, executive functioning, and fine motor speed/dexterity and then categorized them as “decline” or “no decline” based on published RCIs (80% confidence interval). We utilized chi-squares to determine whether the proportion of observed changes differed significantly as a function of surgery group. We then conducted analyses to determine the base rate of cognitive decline among patients with resections limited to the SMA region (n=8).Results: The overall base rate of decline following FLR was similar across cognitive measures (ranging from 4 to 17%), with the exception of patients with focal SMA resections who demonstrated greater decline (25%) on fine motor speed/dexterity and visuomotor processing speed. Based on the RCIs, declines in dominant-hand fine motor speed/dexterity occurred much more following SMA resection (33%) than patients with SMA spared (4%). This decline was still demonstrated after controlling for surgeries in which resection was on the same side as the dominant hand (27% decline SMA resected vs. 8% decline SMA spared). Similarly, decline in visuomotor processing speed occurred more in the resected SMA (19%) than the spared SMA (4%). There was no significant difference between patients with amongst resected or spared SMA patients on measures of attention, working memory, verbal fluency, mental flexibility or problem solving (p value range = .199-.978).Conclusions: While patients with SMA resection demonstrated greater declines than expected by chance after FLR, most did not show a meaningful change across neurocognitive measures. Findings with respect to fine motor speed/dexterity and visuomotor processing speed are consistent with the one study examining SMA resection. However, the results largely demonstrate no meaningful change following FLR. Reliable change methods indicate that that frontal lobectomy is generally well-tolerated from a cognitive standpoint.