Abstracts

Approximately 2% of the population is diagnosed with epilepsy and about one third of those diagnosed will develop intractable epilepsy (Snyder, 1998). Thus, surgical intervention, particularly anterior temporal lobectomy (ATL), has become a widely used form of treatment for those with medically uncontrolled seizures (Engel, 1996) and has a success rate of about 80% (Janszky et al., 2005; Olivier, 1988). Previous studies have found unilateral hippocampal atrophy, side of surgery, and duration of seizures to be significantly predictive of seizure control after ATL (Jeong et al., 1999; Olivier, 1988). Additionally, studies have shown that patients with higher preoperative IQ and language scores and lower preoperative verbal memory scores have good seizure control post ATL (Chelune et al., 1991; Chelune et al., 1998; Hennessey et al., 2001).
The primary goal of this study was to determine changes in cognitive functioning after ATL and to identify predictors of favorable seizure and cognitive outcome post-surgically. For seizure outcome, the predictors included hippocampal integrity, seizure laterality and duration, and pre-surgical cognitive functioning. For cognitive outcome, the predictors examined were hippocampal integrity, seizure laterality and duration, and seizure outcome. Data from a convenience sample of 36 patients who underwent ATL for relief from medically intractable seizures were included in this study. Surgery was performed at University Hospital in Cincinnati, Ohio. All participants underwent prolonged video/EEG monitoring and pre- and post-surgical neuropsychological evaluations. Seizure outcome was determined according to Engel[apos]s classification system. Approximately 60% of patients[apos] overall IQ and verbal memory scores improved or remained the same following ATL. The majority of these patients were seizure free post surgery, and those who improved on verbal memory tasks had undergone right ATL. Additionally, patients who were seizure free following ATL significantly improved on an executive functioning task. Interestingly, more than half of the patients declined on nonverbal memory and confrontation naming post right ATL. Multiple regression analyses demonstrated that only pre-surgical cognitive scores were significantly predictive of seizure outcome [italic]F[/italic](8,15)=2.713, [italic]p[/italic][lt].05), accounting for 59% of the variance. Futher, regression analyses yielded statistically significant main effects for nonverbal memory and confrontation naming ([italic]t[/italic](29)=-2.43, [italic]p[/italic][lt].05 and [italic]t[/italic](29)=2.27, [italic]p[/italic][lt].05, respectively). The results demonstrate that patients improved on most measures of cognitive functioning. Further, cognitive improvement appeared to be greatest in patients who were seizure free following ATL. Higher pre-surgical cognitive scores were predictive of seizure relief post surgery.