Atypical speech activations: PET results of 92 patients  with left-hemispheric epilepsy.
OBJECTIVE
Language lateralization and factors that may influence language lateralization were investigated using positron emission tomography.


METHODS
Ninety-two right-handed patients who had left-sided lesions (tumors, focal cortical dysplasia, and vascular lesions) and 19 right-handed normal subjects were included and synonym generation task was used for evaluation of language lateralization.


RESULTS
As expected, the majority of individuals in both groups showed left hemisphere dominance. Lesions in the vicinity of language-related areas did not alter patterns of activation responses. However, atypical inferior frontal gyrus (IFG) activations (33.6%) were more commonly observed in the patient group than in the control group (21%). There were no clear right-sided IFG activations in the control group but almost 28% of the patients showed clear right-sided IFG activations. Atypical language lateralization was strongly correlated with duration of seizure (p = 0.01) and early age at onset (p = 0.03).


CONCLUSIONS
Our data provide evidence for inter-hemispheric plasticity related to language function as a response to lesions involving the left hemisphere. A better understanding of the dynamic organization of the brain and about the interaction between the lesion and reactional plasticity will lead to changes in surgical strategy, which will enable us to perform a total removal of the lesion involving eloquent brain areas with improved functional outcome.
Tanriverdi
Taner
T
Department of Neurosurgery, Montreal Neurological Institute and Hospital, McGill University, 3801 rue University, Suite 109, Montreal, QC H3A-2B4, Canada. tanerato2000@yahoo.com
Klein
Denise
D
Mok
Kelvin
K
Milot
Sylvain
S
Al-Hashel
Jasem
J
Poulin
Nicole
N
Olivier
Andre
A
D000328:Adult; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology*; D004827:Epilepsy / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D009415:Nerve Net; D009473:Neuronal Plasticity / Q000502:physiology*; D049268:Positron-Emission Tomography; D013060:Speech / Q000502:physiology*; D014705:Verbal Behavior / Q000502:physiology*; D055815:Young Adult