Global dynamical analysis of the EEG in Alzheimer's disease: frequency-specific changes of functional interactions.

Objective: EEG coherence is decreased in Alzheimer's disease (AD), suggesting decreased interaction between brain areas. Nonlinear EEG analysis in AD points to decreased complexity of brain dynamics, implicating increased interaction. To clarify these apparently paradoxical findings from linear and nonlinear analysis, we calculated global coherence and global correlation dimension (D2), a nonlinear measure, in the EEG of patients with probable AD and controls.

At the heart of primary progressive multiple sclerosis: three cases with diffuse MRI abnormalities only.

We present three patients with a clinical course and cerebrospinal fluid findings consistent with a diagnosis of primary progressive multiple sclerosis (PPMS). Extensive and repeated magnetic resonance imaging (MRI) examinations showed only diffuse abnormality in brain and spinal cord, but no focal lesions. We propose that these cases represent the most pure form of PPMS, even though according to currently applied criteria this diagnosis can not be made in the absence of focal lesions on MRI.

Multiple sclerosis patients show a highly significant decrease in alpha band interhemispheric synchronization measured using MEG.

MEG data were acquired from a group of relapsing-remitting multiple sclerosis (MS) patients and a group of healthy controls, using an eyes-closed no-task condition. An interhemispheric coherence measure (IHCM), reflecting the synchronization between the left and right hemispheres, showed a decrease in the patients, particularly in the alpha band. No comparable differences were seen in the alpha band power or its distribution over the head.

Multiple Sclerosis Impact Scale (MSIS-29): relation to established measures of impairment and disability.

Objective: To validate the newly developed Multiple Sclerosis Impact Scale (MSIS-29) in a large, well characterized, independent group of MS patients by investigating the relation between the MSIS-29 and the Guy's Neurological Disability Scale (GNDS), the Expanded Disability Status Scale (EDSS) and the MS Functional Composite (MSFC).

Methods: Two hundred MS patients were recruited at our outpatient department. At the same visit GNDS, EDSS, MSFC and MSIS-29 were assessed.

The INTERMED: a screening instrument to identify multiple sclerosis patients in need of multidisciplinary treatment.

Objective: To analyse the value of the INTERMED, a screening instrument to assess case complexity, compared with the Expanded Disability Status Scale (EDSS) and the Guy's Neurological Disability Scale (GNDS) to identify multiple sclerosis (MS) patients in need of multidisciplinary treatment.

Methods: One hundred MS patients underwent INTERMED, EDSS, and GNDS examinations. Patient care needs were assessed by a multidisciplinary team and a goal oriented treatment plan was defined.

Quality of life during the first 6 months of interferon-beta treatment in patients with MS.

Objectives: To determine the quality of life (QoL) of MS patients during the initial 6 months of treatment with interferon-beta (IFN-beta). Furthermore, to determine whether changes in QoL relate to disability, emotional state, therapeutic expectations or side effect profile.

Background: IFN-beta has been shown to have beneficial effects on the course of MS.

Nonlinear EEG analysis in early Alzheimer's disease.

Nonlinear EEG analysis attempts to characterize the dynamics of neural networks in the brain. Abnormalities in nonlinear EEG measures have been found repeatedly in Alzheimer's disease (AD). The present study was undertaken to investigate whether these abnormalities could already be found in the early stage of AD.

Decrease of non-linear structure in the EEG of Alzheimer patients compared to healthy controls.

Objective: Non-linear EEG analysis can provide information about the functioning of neural networks that cannot be obtained with linear analysis. The correlation dimension (D2) is considered to be a reflection of the complexity of the cortical dynamics underlying the EEG signal. The presence of non-linear dynamics can be determined by comparing the D2 calculated from original EEG data with the D2 from phase-randomized surrogate data.

Diagnostic usefulness of linear and nonlinear quantitative EEG analysis in Alzheimer's disease.

The sensitivity of the EEG in early AD is somewhat limited. In this respect spectral analysis is little better than visual assessment. In this study we address the question whether a new type of EEG analysis derived from chaos theory can improve the sensitivity of the EEG.

Investigation of EEG non-linearity in dementia and Parkinson's disease.

Many recent studies based on the surrogate data method failed to identify significant non-linearity in the EEG. In this study we examine whether the use of a different embedding method (spatial instead of time delay), and calculation of Kolmogorov entropy (K2) and the largest Lyapunov exponent (L1) in addition to the correlation dimension (D2), can distinguish the EEG form linearly filtered noise. We have calculated D2, L1 and K2 of original EEG epochs and surrogate (phase randomized) data in 9 control subjects, 9 demented patients and 13 Parkinson patients.

Specific patterns of cortical dysfunction in dementia and Parkinson's disease demonstrated by the acceleration spectrum entropy of the EEG.

Acceleration spectrum entropy (ASE) was used to quantify EEG desynchronization, which is related to cortical activation. We investigated the ASE in control and patient groups with dementia (AD) and Parkinson's disease (PD). Both patient groups had significantly lower ASE scores corresponding with less desynchronization in all cortical regions.

Non-linear dynamical analysis of multichannel EEG: clinical applications in dementia and Parkinson's disease.

The irregular, aperiodic character of the EEG is usually explained by a stochastic model. In this view the EEG is linearly filtered noise. According to chaos theory such irregular signals can also result from low dimensional deterministic chaos.