Determination of cortical language dominance using functional transcranial Doppler sonography in left-handers

Abstract

Objective: Verbal analytical functions are primarily related to the left hemisphere in right-handers, but there is yet no agreement about cortical language dominance in left-handers. Also, there are some contradictory reports about sex differences in cortical language lateralization. The aim of this study is to investigate cortical language dominance in left-handers and to explore gender influence on cortical language representation.

Methods: We performed functional transcranial Doppler sonography (previous validated for determination of cerebral language lateralization) during a word generation task, measuring changes in mean cerebral blood flow velocity (BFVmean) in both middle cerebral arteries (MCA) in 150 healthy subjects (75 left-handers and 75 right-handers). In left-handers we observed significant increase BFVmean in right MCA in 58 (77.3%) subjects. Bilateral increase was observed in 11 (14.7%) subjects and increase in left MCA in 6 (8%) subjects. In right-handed group 93.3% subjects showed left cortical dominance, while 6.7% showed bilateral language representation.

Results: Current results showed significant (P<0.0001) right hemispheric language dominance in healthy left-handed subjects.

Conclusions: Our results showed significant difference in hemispheric dominance for verbal function between righthanders and lefthanders. Also there is statistically insignificant female gender tendency for bilateral hemispheric language representation in both handedness.