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Determination of cognitive hemispheric dominance by "stereo" transcranial Doppler sonography
1Department of Neurology, University of Berne, Inselspital, Switzerland.
Background And Purpose:
Transcranial Doppler sonography (TCD) can assess blood flow velocity changes induced by focal brain activation. Therefore, TCD may have the potential to identify hemispheric dominance for cognitive tasks.
Methods:
Using a system with two TCD probes ("stereo" TCD), we monitored simultaneously both middle cerebral arteries (MCAs) of 14 healthy right-handed volunteers while they performed cognitive tasks. The averaged blood flow velocity ratio of the two MCAs and the hemispheric blood flow velocity shift induced by the cognitive task were calculated.
Results:
In every subject, language tasks resulted in blood flow velocity shift to the left compared with visuospatial tasks. Mean MCA blood flow velocity shift to the left was 1.67%, 2.01%, and 2.31% in three language tasks. Mean blood flow velocity shift to the right was 1.67% and 2.31% in two visuospatial tasks.
Conclusions:
Bilateral simultaneous MCA blood flow velocity monitoring and averaging during cognitive tasks can help to identify hemispheric dominance for cognitive tasks in individuals.