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Ildikó Vastagh

Publications and source records attributed to Ildikó Vastagh.

6 recordsLinked to original sources
PubMed2006

[Changes in EEG-complexity after subcortical ischemic brain damage].

INTRODUCTION: Complexity analysis of the EEG is a relatively new field in theoretical and clinical electrophysiology. The authors present results of EEG-analysis in a patient with stroke, utilizing the sensitivity of the new procedures with respect to linear and nonlinear synchronization. PARTICIPANTS AND METHODS: The EEG (19 channels) was recorded in a patient with subcortical unilateral ischaemic completed stroke involving the frontoparietal white matter while leaving the cortex intact and in 12 healthy controls in eyes open and in eyes closed conditions. RESULTS: In the patient, increased Omega-complexity was found in slow (delta, theta) and lower alpha frequencies in the side of the stroke and in high frequencies (beta2 in eyes closed, alpha2, beta1 and beta2 in eyes open conditions) in the intact side. Synchronization likelihood was higher in the ischaemic side in the beta2 (eyes closed) and both in the beta1 and beta2 (eyes open) frequencies. Increasing Omega-complexity caused by eyes opening was markedly reduced in the patient in the beta frequencies compared to that seen in the controls. The difference was more conspicuous in the side of the infarct and involved not only the beta but also the alpha frequencies as well. Opening the eyes decreased synchronization likelihood in all frequency bands in the controls and also in the patient except the alpha2, beta1 and beta2 bands in the side of the lesion. CONCLUSIONS: The increased Omega-complexity and decreased synchronization likelihood in the slow frequencies in the infarcted side is probably the result of lesioned interneuronal connections lowering the level of cooperation of neuronal systems involved in this type of activity. The increased Omega-complexity and decreased synchronization likelihood caused by eyes opening could not be observed in the beta and alpha frequencies in the side of the lesion, possibly caused by damaged thalamocortical connections.

Alpha Rhythm↗
PubMed2006

[Spectral EEG-characteristics of subcortical ischemic brain lesion--a case study].

INTRODUCTION: Although the EEG-changes caused by ischemic stroke are well known, data of the literature are rather ambiguous. The EEG-findings recorded in a patient with a unilateral subcortical ischemic lesion are evaluated with special emphasis related to the effect of the dynamics caused by eye opening. PARTICIPANTS AND METHODS: Data recorded from a patient (54 years old male with a completed stroke involving the frontal and parietal subcortical region in the left side) were compared to those of a control group (12 healthy age matched subjects). Absolute and relative frequency spectra, theta/beta quotients, the interaction index characterizing the effect of eyes opening and the symmetry index were calculated from the EEG recorded in eyes closed and eyes open conditions. Data of the patient were compared to those recorded in the control group on the basis of 95% confidence intervals. RESULTS: Irrespective of the recording conditions the predominance of slow activity and the increase of theta/beta quotients were found in the absolute frequency spectra. The increase of beta and beta2 frequency bands following eye opening on the side of the lesion were found to be less obvious than that seen on the intact side and that observed in the control group. With respect to the interaction index related to the side differences caused by eye opening the change of the beta2 frequency band was found to be the most conspicuouS. The symmetry index underscored the predominance of slow (delta, theta, alpha1) frequencies on the lesion side, and that of the fast (beta1, beta2) frequencies on the intact side in both recording conditions. CONCLUSIONS: Localized lesion of the white matter without cortical damage can cause the predominance of slow activity and decrease of the fast frequency bands on the side of the lesion which can be shown by the absolute frequency spectra and is revealed by the symmetry index. The lack of functional reactivity of the fast frequencies in the side of the lesion can clearly be seen in the change of relative spectra following eye opening and on the basis of the calculation of the interaction index reflecting the dynamics of side differences.

Alpha Rhythm↗
PubMed2006

Spectral and complexity features of the EEG changed by visual input in a case of subcortical stroke compared to healthy controls.

OBJECTIVE: To compare spectral and complexity characteristics of the EEG in a unique case of subcortical infarct to those seen in healthy controls. METHODS: Absolute and relative frequency spectra, theta/beta ratio, the brain symmetry index (BSI), Omega-complexity and synchronization likelihood were calculated of the EEG recorded in eyes closed and eyes open conditions. RESULTS: Increased absolute delta, theta, and Omega-complexity in these frequency bands, higher theta/beta ratios, and decreased relative beta activity were found in the side of the infarct. The BSI localized the excess of slow, and decrease of fast frequency activity to the area of ischemia. Following eyes opening the increase of fast and decrease of slow frequencies, the increase of Omega-complexity in the alpha and beta bands, and the decrease of synchronization likelihood for the fast frequency bands were reduced in the side of the infarct. CONCLUSIONS: The subcortical infarct caused ipsilaterally increased slow, and decreased fast frequency activity accompanied by decreased synchronization of slow, increased synchronization of fast frequencies. Reduced reactivity in the ischemic side was particularly apparent for complexity measures. SIGNIFICANCE: Complexity indices of the EEG are sensitive complementary measures of electrophysiological changes caused by local lesions such as subcortical stroke.

Brain Ischemia↗
PubMed2002

Strategic infarcts of the thalamus in vascular dementia.

Strategic infarcts or focal hemorrhages involving the paramedian nuclei of the thalamus may alter consciousness and produce complex neuropsychological symptoms such as impairment of memory, attention and motivation. Lesions disrupting the thalamo-prefrontal circuits lead to severe subcortical dementia. We analysed here the clinical, neuropsychological and neuroimaging data of 19 patients with cerebrovascular lesions in the thalamus. In six patients with bilateral paramedian infarcts, and in two with anterior thalamic infarcts, vascular dementia and severe personality changes developed. SPECT findings did not correlate with the neuropsychological symptoms. Transcortical sensory and motor aphasia was observed in four patients with thalamic hemorrhages and infarcts. In these patients SPECT detected hypoperfusion in adjacent cortical areas. Clinical symptoms and outcome of four patients are reported in detail. The clinico-morphological correlations of the thalamo-cortical circuits are reviewed and the possible causes of multiple cognitive and behavioural consequences of vascular thalamic lesions are discussed.

Adult↗
PubMed2002

Computed tomographic and transcranial Doppler sonographic findings in acute and subacute phases of middle cerebral artery strokes.

PURPOSE: The aim of this study was to compare the sensitivities of visual and densitometric analyses of CT scans and transcranial Doppler sonograms (TCD) in detecting early changes in acute stroke. METHODS: CT and TCD were each performed twice in 12 patients; first in the acute phase (within 28 hours of stroke onset), then in the subacute phase (mean +/- standard deviation, 6 +/- 3 days after onset) of a stroke. Hypodensity on the CT scans was evaluated visually, and the optical density of both the stroke region and the corresponding region on the unaffected side was measured. Measurement of flow parameters in the middle cerebral artery was carried out with TCD before or shortly (within 4 hours) after CT scanning. RESULTS: In the acute phase, blood flow velocities were significantly lower on the affected side than they were on the unaffected side (means, 42 +/- 13 and 55 +/- 25 cm/second, respectively; p = 0.012). Marked asymmetry in flow velocity was found in 3 of the 4 patients who had normal CT scans in the acute phase. The asymmetry in flow velocity disappeared by the sixth day after the stroke. The resistance index did not correlate with the final infarct size. CONCLUSIONS: In some patients, the use of TCD in acute stroke may show alterations that reflect tissue damage that is undetectable on CT. Therefore, CT and TCD should be considered complementary diagnostic tools in the acute phase of stroke.

Acute Disease↗