Hemispheric surgery in children with refractory epilepsy: seizure outcome, complications, and adaptive function.

PURPOSE: To describe seizure control, complications, adaptive function and language skills following hemispheric surgery for epilepsy. METHODS: Retrospective chart review of patients who underwent hemispheric surgery from July 1993 to June 2004 with a minimum follow-up of 12 months. RESULTS: The study population comprised 24 children, median age at seizure onset six months and median age at surgery 41 months. Etiology included malformations of cortical development (7), infarction (7), Sturge-Weber Syndrome (6), and Rasmussen's encephalitis (4). The most frequent complication was intraoperative bleeding (17 transfused). Age <2 yr, weight <11 kg, and hemidecortication were risk factors for transfusion. Postoperative complications included aseptic meningitis (6), and hydrocephalus (3). At median follow-up of 7 yr, 79% of patients are seizure free. Children with malformations of cortical development and Rasmussen's encephalitis were more likely to have ongoing seizures. Overall adaptive function scores were low, but relative strengths in verbal abilities were observed. Shorter duration of epilepsy prior to surgery was related significantly to better adaptive functioning. CONCLUSIONS: Hemispheric surgery is an effective therapy for refractory epilepsy in children. The most common complication was bleeding. Duration of epilepsy prior to surgery is an important factor in determining adaptive outcome.

Frequency of scale elevations and factor structure of the Behavior Rating Inventory of Executive Function (BRIEF) in children and adolescents with intractable epilepsy.

The Behavior Rating Inventory of Executive Function (BRIEF) is a standardized rating scale that provides information about the nature and extent of executive function deficits displayed by children and adolescents in daily life. BRIEF protocols completed by parents of 80 children with intractable epilepsy were evaluated with respect to prevalence and severity of scale elevations in the sample, and also with respect to factor structure. Overall, the sample was rated as having significantly more executive function problems than healthy children in the BRIEF standardization sample; elevations on the Working Memory and Plan/Organize scales were most frequently seen. Fully 36% of the sample had four or more significantly elevated scales. However, 31% of the sample had no clinically elevated scales, indicating that executive difficulties, though frequent, are not necessarily characteristic of all children with severe epilepsy. As in the validation studies reported in the manual, a two-factor solution emerged from a principal factor analysis of BRIEF scales. However, the factor structure as given in the manual was not entirely replicated; specifically, the Monitor scale was found to load equivalently on both factors. The results of this study suggest that a substantial proportion of children with intractable epilepsy display significant executive function deficits in daily life. Research into the relationship of BRIEF scores to other measures of executive functioning in children with epilepsy is needed to further clarify its clinical utility.

The factor structure of the CVLT-C in pediatric epilepsy.

The current study used archival data to evaluate the fit of six latent variable models, originally generated by Donders (1999), for the California Verbal Learning Test-Children's Version (CVLT-C; Delis, Kramer, Kaplan, & Ober, 1994) in a large (N = 289) sample of pediatric epilepsy cases presenting at three tertiary treatment centers. Using confirmatory factor analysis, we found that a model including factors of Attention Span, Learning Efficiency, Free Delayed Recall, Cued Delayed Recall, and Inaccurate Recall demonstrated the best relative fit for our data. These findings are consistent with those reported by Donders (1999) in his reanalysis of the CVLT-C standardization sample data, supporting the validity of this factorial model in pediatric epilepsy populations.

Emotional arousal in agenesis of the corpus callosum.

While the processing of verbal and psychophysiological indices of emotional arousal have been investigated extensively in relation to the left and right cerebral hemispheres, it remains poorly understood how both hemispheres normally function together to generate emotional responses to stimuli. Drawing on a unique sample of nine high-functioning subjects with complete agenesis of the corpus callosum (AgCC), we investigated this issue using standardized emotional visual stimuli. Compared to healthy controls, subjects with AgCC showed a larger variance in their cognitive ratings of valence and arousal, and an insensitivity to the emotion category of the stimuli, especially for negatively-valenced stimuli, and especially for their arousal. Despite their impaired cognitive ratings of arousal, some subjects with AgCC showed large skin-conductance responses, and in general skin-conductance responses discriminated emotion categories and correlated with stimulus arousal ratings. We suggest that largely intact right hemisphere mechanisms can support psychophysiological emotional responses, but that the lack of interhemispheric communication between the hemispheres, perhaps together with dysfunction of the anterior cingulate cortex, interferes with normal verbal ratings of arousal, a mechanism in line with some models of alexithymia.