Working Memory Integration Processes in Benign Childhood Epilepsy with Centrotemporal Spikes.

OBJECTIVE AND BACKGROUND: Benign epilepsy of childhood with centrotemporal spikes (BECTS) is the most frequent focal epilepsy in children; however, the pattern of affected memory processes remains controversial. Previous studies in BECTS imply deficits in complex working memory tasks, but not in simple modality-specific tasks. We studied working memory processes in children with BECTS by comparing performance in memory binding tasks of different complexities. METHODS: We compared 17 children with BECTS (aged 6 to 13 years) to 17 healthy children matched for age, sex, and intelligence quotient. We measured spatial and verbal memory components separately and jointly on three single-binding tasks (binding of what and where; what and when; and where and when) and a combined-binding task (integration of what, where, and when). We also evaluated basic visuospatial memory functions with subtests of the Children's Memory Scale, and intellectual abilities with verbal tasks of the Wechsler Intelligence Scale for Children-Fourth Edition and the Raven Progressive Matrices. RESULTS: We found no difference between the BECTS and control groups in single-binding tasks; however, the children with BECTS performed significantly worse on the combined task, which included integration of spatial, verbal, and temporal information. We found no deficits in their intellectual abilities or basic visuospatial memory functions. CONCLUSIONS: Children with BECTS may have intact simple maintenance processes of working memory, but difficulty with high-level functions requiring attentional and executive resources. Our findings imply no specific memory dysfunction in BECTS, but suggest difficulties in integrating information within working memory, and possible frontal lobe disturbances.

Speech activation of language dominant hemisphere: a single-photon emission computed tomography study.

We tested the prediction that single photon emission computed tomography (SPECT) of the blood flow distribution in speech-activated brain identifies the language-dominant hemisphere. We based the prediction on the hypothesis that language activation leads to focally increased regional cerebral blood flow (rCBF), which is reflected in the uptake of a flow tracer recorded by SPECT. We compared the results of speech activation to the results of functional transcranial Doppler (fTCD) monitoring in the same subjects. Preoperatively, 17 patients (10 women and 7 men with a mean age of 36 +/- 15 years) with diagnoses of epilepsy (n = 14) or arteriovenous malformation (AVM) (n = 3) had two SPECT and two stereo-TCD monitoring studies in each case, one at rest, and one during 3 min of speech activation. Except for two left-handed patients with right-hemisphere dominance, the subjects had the highest changes of rCBF from baseline to activation in the left posterior inferior frontal cortex and in contralateral cerebellum. The results show that changes of the level of neuronal activity reflected by the measurement of rCBF variations might be detected by SPECT. Additionally, the evaluation of hemispheric language dominance based on SPECT showed a complete agreement with the evaluation based on fTCD results (yielding a kappa coefficient equal to 1), and therefore, speech-activation SPECT mapping might be helpful in the evaluation of hemispheric language dominance, especially when fMRI and PET are not available or they are contraindicated for some reason.