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Functional transcranial Doppler sonography (fTCD) during word generation is well established for language lateralization in adults. In this study, we evaluated an fTCD-paradigm to reliably identify the dominant hemisphere in young, partially illiterate children
Twenty-one healthy right-handed children (6-11 years) were asked to describe pictures from children’s books while the cerebral blood flow velocity (CBFV) was simultaneously measured in both middle cerebral arteries (MCA). Data were analysed offline with the software Average®, which performed a heart-cycle integration and a baseline-correction and calculated a lateralization index (LI) with its standard error of the mean increase in CBFV separately for both MCA. The results were compared to the outcome of 23 healthy right-handed adolescents (12-18 years) who performed the picture-description task in addition to the established word generation task. Non-parametric statistics were applied.
Fourteen of 21 (61%) children showed left lateralization in the picture description paradigm (mean LI: 0.74±4.22). There was no significant difference or correlation between the LI of the children and the adolescents (mean LI: 2.35±4.65; P=0.192). No correlation between LI and age was found.
Twenty of the 21 (95%) adolescents performing the word generation task showed left lateralization in this paradigm, and 14 of 21 (67%) showed left lateralization in the picture description paradigm. No significant correlation between the LI of both paradigms was seen (R=0.338; P=0.144). There was no significant difference between the LI of the word generation (3.72±1.93) and picture description paradigm (2.35±4.65; P=0.60) adolescents.
Frequency of left language lateralization and data quality during picture description was similar in children und adolescents without correlation of age and LI. This suggests that fTCD is equally applicable in both age groups. However, the picture description paradigm appears to activate the dominant hemisphere less selectively than the established word generation task in a third of the subjects, possibly due to the complex stimuli