Intrahemispheric reorganization of language in children with medically intractable epilepsy of the left hemisphere.
We investigated language representation in nine children (six male, three female; 5.6-17.7 years of age) who underwent surgical treatment of medically intractable epilepsy of the left hemisphere. Although interhemispheric reorganization has been previously documented in similar groups, this is the first study to systematically evaluate possible intrahemispheric effects of early insult. All cases had left hemisphere seizure foci and underwent extraoperative stimulation mapping (ESM) for language localization prior to receiving cortical resections. To compare ESM findings across subjects and to assess intrahemispheric reorganization, we developed a novel coregistration technique whereby independent raters plotted two-dimensional (2D) ESM findings in 3D standard space. Expressive language sites identified with ESM were compared with a structural probability map of pars opercularis, or Broca's area. The average difference between independent raters' estimates of 28 language sites was 3.9 mm (SD = 2.0), indicating excellent agreement; the coregistration procedure permitted assessment of 2D ESM findings in 3D standard space. We observed language sites in regions substantially anterior and superior to canonical Broca's area, possibly reflecting intrahemispheric reorganization. Findings suggest that left hemisphere insult in young children may result in anterior displacement of language within the frontal cortex.
Kadis
Darren S
DS
Department of Psychology, University of Toronto, Toronto, Ontario, CanadaDepartment of Psychology, Hospital for Sick Children, Toronto, Ontario, Canada.
Iida
Koji
K
Kerr
Elizabeth N
EN
Logan
William J
WJ
McAndrews
Mary Pat
MP
Ochi
Ayako
A
Otsubo
Hiroshi
H
Rutka
James T
JT
Snead
O Carter
OC
Weiss
Shelly K
SK
Smith
Mary Lou
ML
D000293:Adolescent; D001931:Brain Mapping; D002648:Child; D004558:Electric Stimulation; D004566:Electrodes; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007802:Language; D007807:Language Tests; D008297:Male; D009473:Neuronal Plasticity; D016896:Treatment Outcome