Relationship between language lateralization and handedness in left-hemispheric partial epilepsy.
OBJECTIVE
To investigate the relationship between language lateralization and handedness in patients with epilepsy and a left-sided seizure focus and in healthy control subjects.


METHODS
We recruited a consecutive series of 74 patients and 70 control subjects. Functional MRI, using a noun-verb generation task, was performed to establish the language laterality index (LI). Handedness was quantified using the Edinburgh Handedness Inventory.


RESULTS
Patients showed a shift toward atypical language lateralization (0.43 +/- 0.47; controls 0.57 +/- 034; p < or = 0.05) and left-handedness (55 +/- 57; controls 74 +/- 39; p < or = 0.05). The LI and handedness were correlated in patients (r = 0.54; F = 25.9; p < 0.001) but not in control subjects (r = 0.1; F = 0.64; NS). A combination of left-handedness and atypical LI was more frequent in patients (12%) than control subjects (0%; p < or = 0.05). Crossed hemispheric specialization (e.g., right-handedness associated with atypical LI) was equally frequent in patients (20%) and control subjects (16%; NS).


CONCLUSIONS
In epilepsy patients with a left-sided seizure focus, language lateralization is correlated to handedness. The increased frequency of left-handedness and associated atypical language lateralization is most likely related to the left-hemispheric seizure focus, influencing hemispheric specialization for both domains.
Sveller
C
C
Brain Research Institute, Neurosciences Bldg., Austin Health, Heidelberg West, Victoria, 3081, Australia.
Briellmann
R S
RS
Saling
M M
MM
Lillywhite
L
L
Abbott
D F
DF
Masterton
R A J
RA
Jackson
G D
GD
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D003337:Corpus Callosum / Q000502:physiology; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D049268:Positron-Emission Tomography; D015899:Tomography, Emission-Computed, Single-Photon; D014705:Verbal Behavior / Q000502:physiology*