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Abstract:
Abnormal neural activity occurring in the associative cortex
during the critical period of brain maturation may disturb the
structural and/or the functional changes establishing the neural
substrate for the specific cognitive function assigned to the
affected cortical area. To examine this hypothesis, we studied the
cognitive development of eight children affected with an idiopathic
age-related epileptic syndrome characterized by a focus of
paroxystic spike-wave discharges (SWD) on waking EEG generalizing
during sleep. Quantification, localization and extension of
epileptic discharges were obtained from repeated waking and sleep
EEG. Detailed neuropsychological evaluation measured verbal and non
verbal cognitive performances along the course of epilepsy. PET
scan studies were performed in six children who had the most severe
cognitive disorders. While sleep EEG showed continuous SWD,
cognitive performances were disturbed in all eight children. The
features of cognitive disturbances appeared to depend on the
involvement of the associative cortex. In four children, the
impairment concerned specifically the cognitive function normally
sub served by the cortical region concerned with the generation of
epileptic discharges. In the other, the cognitive impairments were
transient and concomitant with the occurrence of SW discharges.
Specific cognitive dysfunction persisted, after recovery of
epilepsy, only in children with epileptic focus localized in the
associative cortex.
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