Abstracts

Rationale: Due to its low prevalence parietal lobe epilepsy (PLE) has rarely been investigated in regard to associated cognitive deficits. Therefore this study is one of the first systematic approaches to evaluate the preoperative neuropsychological profile and the postoperative change in adult patients undergoing epilepsy surgery in the parietal cortex. Methods: Standardized neuropsychological assessment in 39 consecutive patients with parietal lobe epilepsy (20 left-, 19 right-sided, 17-58 years, 36% female) was conducted prior to and 12 months after epilepsy surgery. Histology indicated 41% brain tumors, 26% dysplasias, 20% vascular malformations and other pathologies in 13%. The majority of patients (53%) had less than ten years of education. Results: Preoperatively the normalized cognitive profile of patients with PLE revealed sub-average performance in a broad range of cognitive domains: attention (43-76%), executive functions (44-92%), verbal and nonverbal declarative memory (62-67%), and visuoconstruction (81%). Phonematic verbal fluency appeared the most impaired performance (92%). Considering the side of the epileptic focus left hemispheric epilepsies were associated with worse performance in nonverbal memory function (p < 0.01). After surgery 46% of the patients became seizure-free, i.e. they had neither one single seizure nor any aura within the last 12 months. Figural memory performance significantly improved in patients operated within the left hemisphere. Seizure control had a positive effect on verbal fluency. No further significant changes in cognitive functions could be observed after surgery. Conclusions: Patients with PLE displayed deficits in all cognitive domains and particularly also in functions normally associated with the frontal and temporal lobes. Contrary to the excellent seizure outcome observed in pediatric patients with PLE (Gleissner et al., 2008) only 46% of the adult patients became seizure-free indicating the advantage of early surgical treatment in PLE. In line with data of pediatric patients (Gleissner et al., 2008) and patients operated in the posterior cortex (Luerding et al., 2004), surgery in the parietal lobes seems to bear no risk for additional postoperative declines in the evaluated domains. Since a release effect due to postoperative seizure freedom was observed only with regard to verbal fluency, impairments appear more static and rather the result of a retardation due to an early impairment of input systems than that these impairments are dynamic in terms of an acute and reversible secondary epileptogenic involvement of temporal and frontal lobe functions due to irradiating epileptic activity along the axis of the long fiber tracts.