Motor asymmetry and hemisphere interactions in Parkinson's disease

About 90%, of the people in general population are right-handed. Such right-side motor lateralization is presumed to be, at least partially, related to higher brain functions, especially to presentation of speech areas in the left hemisphere. Although lateralization may be predetermined genetically, the investigations into this problem have not yielded the equivocal results. Motor deficit asymmetry is a constant trait of Parkinson's disease (PD). It means that a study of PD patients gives a remarkable possibility for investigation into hemisphere interactions. Using motor potential method, 62 patients with predominantly akinetico-rigid lateralized PD type and relatively preserved social adaptation have been examined. The patients differed from tho controls by all MP components and reduction of hemisphere asymmetry: while using both right and left hands counterlateral hemisphere, as well as ipsilateral one, were insufficiently activated. This indicates pathological process diffusion in PD and hemisphere interaction dysfunction. Even in hemiparkinsonian stage of PD, a rather unusual pattern of hemisphere interaction is formed.