DETERMINATION OF COGNITIVE HEMISPHERIC DOMINANCE BY STEREO TRANSCRANIAL DOPPLER SONOGRAPHY

Background and Purpose Transcranial Doppler sonography (TCD) can asses s blood flow velocity changes induced by focal brain activation. There fore, 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 (MC As) of 14 healthy right-handed volunteers while they performed cogniti ve tasks. The averaged blood Row velocity ratio of the two MCAs and th e 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 Bilat eral simultaneous MCA blood flow velocity onitoring and averaging duri ng cognitive tasks can help to identify hemispheric dominance for cogn itive tasks in individuals.