Determining Hemispheric Dominance ofCortical Motor Areas in Adolescents with Unilateral Cerebral Palsy Using EEG-source Localization

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2015-07-01
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en
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Abstract
In adolescents with unilateral cerebral palsy (uCP) the cortical representation of the affected hand can be located at the ipsi- or contralateral hemisphere. Whether the affected hand is controlled by the ipsior contralateral hemisphere could have implications for the effectiveness of rehabilitation. To optimize therapeutic outcomes it is therefore relevant to determine hemispheric dominance in advance. This study assesses the possibility of using a source localization approach of Motor Evoked Potentials (MEPs) extracted from the ongoing EEG during a cued-target response task to map hemispheric dominance in controlling the affected hand. This approach would allow for an affordable and child friendly brain imaging alternative compared to fMRI and TMS. In experiment 1, EEC data was obtained from adult controls (n=15) to construct an EEG source model for goal directed hand movements (button presses). Based on data from the control group, we were able to construct a source model containing 4 sources. In experiment 2, EEC data were obtained from adolescents with uCP (n=l 0) and the EEG source model was used to analyze the EEGs of the uCP group during the same task. We used averaged rootmean- square (RMS) values within 3 time windows related to the MEP for statistical analysis. Apart from differences between the two groups, the uCP group failed to show an effect of hemisphere with respect to source activity when using the affected hand but did show an effect of hemisphere when the non affected hand was used. The lack of hemisphere effect for the affected hand might result from inter-individual differences in this group that might have resulted in either contra- or ipsilateral activations when using the affected hand. In experiment 3, both functional and structural MRI data were obtained from adolescents with uCP (n=10) and compared to the EEG data and behavioral measures of hand capacity by means of regression analyses. Data from the MRJ anatomical scans revealed correlations between the EEG source localization and lesion. Data from the fMRI experiment failed to reach a solution in two participants and fMRI solutions mostly revealed bilateral involvement. No correlation between the flVIRI and EEG source-localization was observed. However, a significant correlation was observed between the fMRI and quantified mirror-movements suggesting that fMRI did not just reflect hemispheric control of the affected hand but bilateral activation due to mirror movements. We believe that the EEC has the potential to be used to determine hemispheric dominance and might be more reliable than an fMRI approach.
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Faculteit der Sociale Wetenschappen