The Relation of Clinical Scale and Non-Linearity of EEG in Early Parkinson's Disease

ABSTRACT

BACKGROUND: Many recent studies based on non-linearity have been performed to quantify the complex behavior of the brain in order to understand the pathophysiology of Parkinson's disease (PD). METHODS: We calculated the Fractal dimension (FD) and Lyapunov exponent (L1), the non-linear biologic signals, by digital EEG using 'CHASIM' program, non-linear times series signal simulator and then compared the UPDRS score with the degree of atrophy in the substantia nigra upon brain MRI and EEG data respectively. All subjects (N=20) showed definite hemiparkinsonism. RESULTS: Upon EEG analysis, a strong positive correlation was noted between FD of the left hemispheric electrodes (FP1,F3,T3,T5) and the UPDRS scores in left-sided symptomatic patients. Additionally, positive correlations were noted between the ipsilateral MRI index ratio in the right and left-sided symptomatic patients and respective UPDRS scores. CONCLUSIONS: These results suggested that thalamocortical drive is reduced in the contralateral hemisphere to parkinsonian symptoms and thalamocortical or corticothalamic glutaminergic projection in the ipsilateral hemisphere is increased in the early stage of Parkinson's disease. Additionally, hemiparkinsonim may primarilly cause anatomic and functional changes in the contralateral hemisphere and a compensatory effect in the ipsilateral hemisphere at the same time. We suggest that disease duration may be a compensating factor and of which require further investigation. We hope that our results will aid the understanding of the specific patterns of dysfunction and treatment effects by non-linear EEG measures and anatomic changes of the substantia nigra through continuous follow up of the patients. (J Korean Neurol Assoc 19(3)232~238, 2001)