Interactive functional Doppler sonography for evaluation of hemispheric dominance of language in infants

As known from patients suffering from central nervous insults, language disturbances often result from left hemispheric brain lesions and usually cannot be compensated after an age of approximately 5 years. Planning intracerebral operations close to areas potentially important for language control requires to determine the dominant hemisphere. For this purpose we tested functional transcranial Doppler sonography (fTCD) in infants.

Probands: 23 right-handed children (m=10, f=13, age 5.1±0.7 years, without pathological findings according to pediatric audiological testing and of appearant normal intelligence; mother tongue German.

Methods: simultaneous transcranial Doppler sonography of cerebral blood flow velocity (CBV) in the left and right medial cerebral artery before and during central nervous language processing.

Paradigm: silent forming of answers to spoken questions.

Testing design: time locked averaging of max.16 trials, each consisting of a baseline phase (10sec) and a phase of activity (20s).

Evaluation: calculation and plotting of the differences in sides of the increase of CBV between baseline and phase of activation online, exclusion of trials not evaluable due to artefacts; averaging of the differences in sides of the increase of CBV, statistical control.

Results: During silent generation of answers, 18 of 22 children had higher increase in CBF in the left, only 1 in the right middle cerebral artery. 3 children showed no significant difference between hemispheres, the data from 1 child could not evaluated due to artefacts.

Conclusion: Using online analysis of hemodynamic data of CBF to control for artefacts from movements and with optimal baseline data, fTCD seems appropriate for determining the hemisphere dominant for language control even in children 5 to 6 years of age. To validate such data, results from WADA tests should be compared.