Abstracts

Rationale: About a third of epilepsy patients develop drug-resistant seizures. In refractory temporal lobe epilepsy (TLE), surgery targets the hippocampus, one component of the limbic system (LS) which controls emotion and memory. The LS also includes cingulate, parahippocampal, and dentate gyri, subicular complex, amygdala, septal area and hypothalamus. Resection of LS structures can result in cognitive deficits, e.g. seen in 30-60% after dominant hippocampal resections. Seizures persist after 20-50% of temporal lobe (TL) surgeries, and some patients undergo repeat surgery in the same region. Thus, there is a concern that cognitive impairment could be worsened. There is little data looking at cognitive outcome following repeat resections. This study aimed to explore whether repeat resection of TL or other LS structures was associated with memory decline. Methods: Electronic medical records (EMR) at the University of Colorado were queried from January 2014 through April 2018 for all patients who had repeat surgery of LS structures and neuropsychological testing before and after procedures. Neuropsychological data before and after resections were analyzed for any changes. Abstracted data included age, gender, duration of epilepsy, etiology of epilepsy, presence of a lesion, site of resection, time between first and second surgery, neuropsychological testing data pre- and post-procedure after first and second surgery, medications and post surgical seizure control. Descriptive statistics were used for analysis. Results: Eleven patients with repeat LS resections were identified.  Nine patients had neuropsychological testing (NPT) after the second surgery, however, only 7 had a full set of NPT before and after each procedure.  One additional patient had NPT before his first and after the second surgery with unchanged results.  Consequently, 8 patients were used for analysis of NPT scores. Of the total of 11 patients, mean age was 41 years [range 29-50] at time of repeat surgery, 8 were male. Nine of 11 patients had lesional epilepsy (5 hippocampal sclerosis, 1 cortical dysplasia, 3 malignancies). Resection site was TL in 9 patients and cingulate gyrus in 2.  Mean duration of epilepsy prior to first surgery was 14 years [1-43]. Mean duration to second surgery was 9 years [2 months-16 years], with a mean period of seizure freedom of 1 year in 10 of 11 patients [2 weeks-6 years] after the initial procedure. Following the first surgery, 2 of 8 patients (25%) experienced memory decline, none had improvement. After the second procedure, 1 of 8 patients (12.5%) had memory decline (not a patient who had memory decline previously). The mean number of drugs after the second surgery was 2, unchanged from before. After the second procedure, 2 of 11 patients (18%) were seizure free, 6 (55%) were improved, and 3 (27%) had no change in seizure frequency. Conclusions: Patients who underwent repeat TL or LS procedures for recurrent seizures were not at high risk for further memory decline. A second procedure at our institution, however, was also not likely to lead to seizure freedom. Our data should inform providers counseling patients considered for repeat surgery on cognitive risks regarding the procedure.  Funding: None