Abstracts

Rationale: Frontal lobectomy has been associated with declines in executive functioning, speed/attention, language, and motor coordination in adults with frontal lobe epilepsy. However, most prior studies have been conducted on small samples with limited cognitive batteries. The goal of the current study is to characterize cognitive outcome in a large sample of adult patients who have undergone frontal lobectomies for the treatment of medically intractable epilepsy using objective methods to characterize meaningful cognitive change. Methods: Adult patients who underwent frontal lobe resections at Cleveland Clinic between 1989 and 2011 were included if they had pre and postoperative neuropsychological data available for review. A total of 96 patients were identified (right-sided resection=49, left-sided resection=47; male=52, female=44) ranging in age from 16-59 (M=29.3). Mean age at seizure onset was 13.12 (SD=9.85) and mean epilepsy duration was 16.32 years (10.76). Reliable change indices (90% CI), developed on nonsurgical epilepsy patients, were used to characterize cognitive change following epilepsy surgery. Chi-square analyses were then used to 1) determine whether the base rate of cognitive change following frontal lobe resection was greater than would be expected by chance alone (i.e., 5% improvement, 5% decline) and 2) examine differences in cognitive outcome as a function of surgical side. Results: A larger proportion of patients demonstrated declines in cognitive functioning than expected by chance alone. This was most apparent on measures of intelligence, problem-solving, and confrontation naming. However, there were also more patients than expected with meaningful postoperative improvements on these measures. In addition, a large proportion of patients demonstrated improvements in fine manual dexterity and visuomotor processing speed following surgery. Patients who underwent surgery in the nondominant hemisphere were more likely to show declines in complex visuomotor sequencing than those who had dominant resections. Although they did not reach statistical significance (p=.06-.08), a higher proportion of patients who underwent dominant surgeries showed declines in auditory immediate and delayed memory and confrontation naming. Conclusions: This study presents cognitive outcome data on a large sample of patients who underwent frontal lobectomies for treatment of epilepsy. Although surgery resulted in cognitive declines in some patients, a substantial portion of patients demonstrated cognitive improvements following surgery. Preliminary data on the role of site/extent of surgical resection and seizure outcome are presented, and results are discussed in the context of the existing literature.