Language lateralization in temporal lobe epilepsy: a comparison between fMRI and the Wada Test.
OBJECTIVE
Recent studies have claimed that language functional magnetic resonance imaging (fMRI) can identify language lateralization in patients with temporal lobe epilepsy (TLE) and that fMRI-based findings are highly concordant with the conventional assessment procedure of speech dominance, the intracarotid amobarbital test (IAT).


METHODS
To establish the power of language fMRI to detect language lateralization during presurgical assessment, we compared the findings of a semantic decision paradigm with the results of a standard IAT in 68 patients with chronic intractable right and left temporal lobe epilepsy (rTLE, n=28; lTLE, n=40) who consecutively underwent a presurgical evaluation program. The patient group also included 14 (20.6%) subjects with atypical (bilateral or right hemisphere) speech. Four raters used a visual analysis procedure to determine the laterality of speech-related activation individually for each patient.


RESULTS
Overall congruence between fMRI-based laterality and the laterality quotient of the IAT was 89.3% in rTLE and 72.5% in lTLE patients. Concordance was best in rTLE patients with left speech. In lTLE patients, language fMRI identified atypical, right hemisphere speech dominance in every case, but missed left hemisphere speech dominance in 17.2%. Frontal activations had higher concordance with the IAT than did activations in temporoparietal or combined regions of interest (ROIs). Because of methodologic problems, recognition of bilateral speech was difficult.


CONCLUSIONS
These data provide evidence that language fMRI as used in the present study has limited correlation with the IAT, especially in patients with lTLE and with mixed speech dominance. Further refinements regarding the paradigms and analysis procedures will be needed to improve the contribution of language fMRI for presurgical assessment.
Benke
Thomas
T
Department of Neurology, Innsbruck Medical University, Innsbruck, Austria, and Department of Neurology, University Hospital of the RWTH Aachen University, Germany. thomas.benke@uibk.ac.at
Köylü
Bülent
B
Visani
Pamela
P
Karner
Elfriede
E
Brenneis
Christian
C
Bartha
Lisa
L
Trinka
Eugen
E
Trieb
Thomas
T
Felber
Stephan
S
Bauer
Gerhard
G
Chemelli
Andreas
A
Willmes
Klaus
K
D000293:Adolescent; D000328:Adult; D000654:Amobarbital / Q000008:administration & dosage / Q000494:pharmacology; D001037:Aphasia / Q000139:chemically induced; D001931:Brain Mapping / Q000379:methods; D002343:Carotid Artery, Internal; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000601:surgery; D007839:Functional Laterality / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007269:Injections, Intra-Arterial; D007802:Language; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013060:Speech / Q000187:drug effects / Q000502:physiology
D000654:Amobarbital