Background: Hemiparetic cerebral palsy (HCP) is described as having twomain forms: arm-dominant, associated with large cortical/subcortical lesions and leg-dominant, associatedwith central white matter lesions. Material/Methods: Twelve children with HCP underwent clinical assessmentand imaging studies. For each child, 20 artifact-free EEG epochs, each of 2s duration, were selectedfor spectral analysis and coherence functions. The objective of this research was to estimate EEG spectralpower, interhemispheric coherence (ICoh), and intrahemispheric (Hcoh) coherence in children with HCPas compared to healthy children. Results: Significant differences between the HCP and control childrenwere detected in the distribution of alpha, theta, delta and beta rhythms over the left and right hemispheres.The ICoh values in the alpha band in the temporal, parietal and occipital regions were significantlylower in the HCP patients than in the controls. There was a significant ICoh increase in the HCP in thetheta and delta band, involving frontal and temporal derivations. The significantly lower ICoh valuesin the HCP children in the beta band involved the frontal, central, parietal and occipital derivations.A higher HCoh value in the HCP children in the alpha band was detected at the right hemisphere. Conclusions:The lower ICoh at the temporal, parietal and occipital derivations in the alpha band implies hypoconnectivitybetween the right and left hemispheres. HCoh asymmetry, which implies relative hypoconnectivity withinthe left hemisphere as compared with the right, suggests that functional hemispheric differentiationmay be diminished.

Keywords: Adolescent, Brain - physiopathology, Case-Control Studies, Cerebral Palsy - physiopathology, Child, Electroencephalography - statistics & numerical data, Paresis - physiopathology