Abstracts

Rationale: Medically refractory temporal lobe epilepsy (TLE) is one of the more common forms of epilepsy, and these patients are at high risk for cognitive deficits. Many patients with refractory TLE show deficits in a wide range of cognitive domains, including memory and executive functioning. While the etiology of executive dysfunction in these patients remains uncertain, the nociferous cortex hypothesis posits that hippocampal sclerosis is associated with dysfunction in other areas of the brain, as well as concomitant secondary cognitive deficits. The purpose of this study, the first part of a larger project, was to investigate the nociferous cortex hypothesis, and specifically whether hippocampal sclerosis was associated with decreased prefrontal volume. Based on previous research showing simultaneous, progressive atrophy in sclerotic hippocampi and extratemporal regions (Dabbs, Jones, Seidenberg, & Hermann, 2009; Coan, Appenzeller, & Bonilha, 2009) including the prefrontal cortex (Keller, Baker, Downes, & Roberts, 2009), it was hypothesized that hippocampal volume would be positively correlated with prefrontal volume in patients with medically refractory TLE. Methods: Data from patients with history of early onset, medically refractory medial TLE and hippocampal sclerosis were analyzed. Selection criteria and sample characteristics have been described elsewhere (e.g., Fuerst, Shah, Shah, & Watson, 2003). MRI-based volumetric measurements of both hippocampi and bilateral prefrontal cortex were performed using a three-dimensional SPGR sequence on a GE 1.5T, Signa 5.4 unit. Volumes of the two hippocampi were correlated with left and right prefrontal volume, after both were normalized by total intracranial volume Results: Two-tailed Pearson correlation coefficients were calculated between the absolute volume of the two hippocampi and the absolute volume of left and right prefrontal areas. Preliminary analyses showed significant positive correlations among hippocampal and prefrontal volumes. All correlations were significant at p ? .05. Conclusions: Consistent with previous research, preliminary analyses showed significant correlations among hippocampal and prefrontal volumes in patients with refractory TLE. As hippocampal volume decreased, so did bilateral prefrontal volume. Results provide on-going support for the nociferous cortex hypothesis. Future analyses will examine executive dysfunction in light of prefrontal and hippocampal volumes.