Language lateralization correlates with verbal memory performance in children with focal epilepsy.
OBJECTIVE
Assessment of language dominance with functional magnetic resonance imaging (fMRI) and neuropsychological evaluation is often used prior to epilepsy surgery. This study explores whether language lateralization and cognitive performance are systematically related in young patients with focal epilepsy.


METHODS
Language fMRI and neuropsychological data (language, visuospatial functions, and memory) of 40 patients (7-18 years of age) with unilateral, refractory focal epilepsy in temporal and/or frontal areas of the left (n = 23) or right hemisphere (n = 17) were analyzed. fMRI data of 18 healthy controls (7-18 years) served as a normative sample. A laterality index was computed to determine the lateralization of activation in three regions of interest (frontal, parietal, and temporal).


RESULTS
Atypical language lateralization was demonstrated in 12 (30%) of 40 patients. A correlation between language lateralization and verbal memory performance occurred in patients with left-sided epilepsy over all three regions of interest, with bilateral or right-sided language lateralization being correlated with better verbal memory performance (Word Pairs Recall: frontal r = -0.4, p = 0.016; parietal r = -0.4, p = 0.043; temporal r = -0.4, p = 0.041). Verbal memory performance made the largest contribution to language lateralization, whereas handedness and side of seizures did not contribute to the variance in language lateralization.


CONCLUSIONS
This finding reflects the association between neocortical language and hippocampal memory regions in patients with left-sided epilepsy. Atypical language lateralization is advantageous for verbal memory performance, presumably a result of transfer of verbal memory function. In children with focal epilepsy, verbal memory performance provides a better idea of language lateralization than handedness and side of epilepsy and lesion.
Everts
Regula
R
Critical Care and Neuroscience, Murdoch Children's Research Institute, Melbourne, Australia. regula@everts.ch
Harvey
A Simon
AS
Lillywhite
Leasha
L
Wrennall
Jacquie
J
Abbott
David F
DF
Gonzalez
Linda
L
Kean
Michael
M
Jackson
Graeme D
GD
Anderson
Vicki
V
D000293:Adolescent; D001931:Brain Mapping; D002648:Child; D004292:Dominance, Cerebral / Q000502:physiology*; D017034:Epilepsy, Frontal Lobe / Q000503:physiopathology* / Q000601:surgery; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D019579:Neocortex / Q000503:physiopathology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011594:Psychometrics; D013223:Statistics as Topic; D014706:Verbal Learning / Q000502:physiology*