The localization and lateralization of memory deficits in children with temporal lobe epilepsy.
OBJECTIVE
It is often reported that children with temporal lobe epilepsy (TLE) experience nonlateralized memory impairments. However, many of these studies have been exploratory and not based on memory theory. Further, differences between mesial and lateral subgroups have not been adequately examined. This study aimed to discern more specific patterns of memory impairment in children with TLE.


METHODS
Forty-three children (5-16 years) with lesional TLE participated. Subjects were categorized in terms of lesion laterality (left, n = 21; right, n = 22) and intratemporal location (mesial, n = 31; lateral, n = 12). Verbal and nonverbal memory tasks were administered that reflected associative, allocentric and recognition paradigms.


RESULTS
Facial recognition was poorer in right TLE (p = 0.03). There were no differences between left and right groups on any other memory task, even when comparisons were restricted to cases with mesial involvement. Irrespective of laterality, clear differences were observed between mesial and lateral lesion subgroups (arbitrary associative learning, p = 0.01; complex figure recall, p = 0.03). The lateral lesion subgroup displayed intact memory function relative to normative standards.


CONCLUSIONS
Memory is more frequently impaired in children with mesial as opposed to lateral TLE. Tasks with an associative component discriminated between these subgroups, supporting an associative model of hippocampal function. With the exception of facial recognition, memory deficits were not lateralized. Therefore, the nature of memory impairment experienced by children with TLE cannot be extrapolated from adult models.
Gonzalez
Linda M
LM
Australian Centre for Child Neuropsychology Studies, Murdoch Children's Research Institute, Melbourne, Australia. linda.gonzalez@rch.org.au
Anderson
Vicki A
VA
Wood
Stephen J
SJ
Mitchell
L Anne
LA
Harvey
A Simon
AS
D000293:Adolescent; D000367:Age Factors; D001245:Association Learning / Q000502:physiology; D001931:Brain Mapping; D002648:Child; D002675:Child, Preschool; D004833:Epilepsy, Temporal Lobe / Q000145:classification / Q000175:diagnosis* / Q000503:physiopathology; D005145:Face; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008569:Memory Disorders / Q000175:diagnosis* / Q000503:physiopathology; D009483:Neuropsychological Tests; D020238:Prosopagnosia / Q000175:diagnosis / Q000503:physiopathology; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000503:physiopathology*