Abstracts

Rationale: Lateralization of language function is an essential prerequisite for epilepsy surgery in potentially eloquent areas. Many children with severe epilepsy, however, are not capable of performing a WADA-test or functional MRI (fMRI) study. Therefore, functional transcranial Doppler sonography (fTCD) has been established as an alternative method, whis is non-frightening and easily applicable, even in severely retarded children. The acid test for language lateralization is the proof of atypical representation. Methods: 12 children (age range 8 - 16 years) were examined for lateralization of language function by fMRI and fTCD by two different investigators, who were blinded for the result of the complementary test. A semantic word generation task was used in both procedures. In fTCD the averaged event related cerebral blood flow velocity (CBFV) increases in the middle cerebral arteries were recorded. The difference between left and right hemispheric blood perfusion provides an index of language lateralization. In fMRI lateralization indices were calculated in a standardized manner (LI = yl-yr / yl+yr). Results: Among 12 children examined to lateralize language function by fMRI and fTCD we identified 3 children with congruent lateralization indices as assessed by fMRI and fTCD. Conclusions: Even in cases of atypical language lateralization, fTCD has proven to be as reliable as fMRI with the advantage of a test situation, that is adapted for children with severe behavioural problems, mental retardation or very young age and allows easily performed re-examination to control results.