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

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)

Nonlinear Analysis of EEG in Various Mental States of Normal Person

BACKGROUND: In order to compare the differences between various mental activities and to determine the significance of chaotic patterns, we performed a fractal dimension and Lyapunov exponent analysis of digital EEG data which are known to be non linear biological signals. METHODS: During the EEG recordings, different kinds of tasks were performed, including eye closing, eye opening, calculation, listening to music, and remembering a picture. Performance signals were recorded for each test as a digital EEG for more than one minute. We used our own software, CHASIM, to calculate the fractal dimension and Lyapunov exponent. The statistical analysis performed was an ANOVA using SAS 6.12 for Windows (9.0). RESULTS: The fractal dimensions during the "listening to music and noise", and "moving both toes" tasks were increased. During the "eye opening", "calculation", and "moving both fingers" tasks, the fractal dimensions were decreased. CONCLUSIONS: Auditory stimulation generated a higher correlation dimension than visual stimulation. The interpretation of these results is still not totally clear, but we hope to find future applications for non-linear chaotic analysis for the functional evaluation of the central nervous system.

A Case of Primary Lymphoma Presenting as Cauda Equina Syndrome

Primary CNS lymphoma (PCNSL) which is localized in the cauda equina of the spinal cord is very rare. A 75-year-old man had pain in both legs and gait disturbance for the last 45 days. Painful paresthesia and weakness in both legs worsened during a one month period and he was unable to stand up by himself. In a physical examination, lym-phadenopathy nor organomegaly was found. A neurological examination revealed a dominantly proximal muscle weak-ness of the lower extremities. All modalities of sensation were decreased in both legs and a Romberg test was found positive. A CSF cytology demonstrated a large B-cell lymphoma. Following an extensive evaluation of the patient, the lymphoma was found to be limited in the cauda equina. The patient was treated with systemic dexamethasone. After the treatment, his symptoms were improved and a follow up lumbar spine MRI showed shrunken cauda equina lesions.

Usefulness of Diffusion - Weighted Imaging in Acute and Subacute Ischemic Stroke: Comparison with Fast Spin-Echo T2-Weighted Imaging and Fluid Attenuated Inversion Recovery Imaging

BACKGROUND: Diffusion-weighted MR imaging (DWI) was designed to detect the random molecular otion of water in tissue. DWI has gained increasing interest recently because it can demonstrate yperacute stroke earlier than any other imaging methods so far. The purpose of our study was to etermine the clinical usefulness and significance of DWI compared with those of Fast Spin Echo T2-weighted image (SE T2WI) and Fluid Attenuated Inversion Recovery (FLAIR) image in acute and subacute ischemic stroke. METHOD: Twenty-five adult patients with clinical diagnoses of acute or subacute cerebral infarctions were imaged with fast SE T2WI, FLAIR and DWI using a 1.5-T image. RESULTS:All the patients had areas of high signal intensity indicating acute or subacute lesions on DWI and these lesions provide an excellent clinicoanatomic correlation. CONCLUSIONS: DWI is most useful in the diagnosis and localization of acute or subacute lacuna or subcortical infarction in patients with preexisting chronic infarctions or white matter hyperintensity showing high signal intensity similar to acute or subacute infarctions on T2WI or FLAIR image.