Comparison of EEG topography at resting state between controls and epilepsy patients. - In: Epilepsia, ISSN 0013-9580, Bd. 46.2005, Suppl. 6, S. 224-225
Purpose: To analyse the topographical distribution of electroencephalogram (EEG) frequency bands in a group of epilepsy patients and in a group of healthy controls at resting state. Methods: 28-channel EEG recordings (10-20 System) were obtained from 12 patients (7 males, 5 females; age 40.25±11.18; focal, and focal secondary generalised epilepsy) and 12 healthy controls (8 males, 4 females; age 39.33±10.39) at open- and closed-eyes resting conditions. From each subject, one minute of data was taken per condition. The EEG was analysed by calculation of band power in 9 Standard EEG bands after ocular artefact correction. Mediän values were used for reducing the impact of outliers, and the topographical distribution was statistically investigated. - Results: Not only the theta band power at fronto-central midline electrodes was higher in patients than in controls in both conditions, but also there was a generalized increase in theta power in patients after eyes-closing, whereas in controls it remains either constant or decreases. The power in the 12-15 Hz band at frontal and central areas was significantly (p<0.05) higher in patients in both conditions. In the p.224 10-12 Hz ränge, the power ratio (closed-to-open eyes) showed significant differences at occipital areas. - Conclusion: The lower Synchronisation in theta band in patients during an odd-ball task reported in our previous study (Perez D et al. Epilepsia 2003;44(8):141.) can be explained through the increased theta power at resting state. The differences observed in other frequency bands shall be further investigated in order to determine their physiological significance.
Cognitive study in epilepsy: analysis of amnestic features. - In: Epilepsia, ISSN 0013-9580, Bd. 46.2005, Suppl. 6, S. 313
Purpose: Recent surveys show that nearly 50% of the epileptic patients are likely to be aware of problems with cognitive function (International Bureau for Epilepsy. Patients in Mind Survey of Cognitive Function, 2004). The current contribution is a part of a study aiming at investigating the correspondence between objective psychological and electrophysiological features characterising such impairments. - Methods: Two different test batteries of diagnostic methods were designed: a combination of neuropsychological tests and a combination of electrophysiological cognitive stimulation paradigms. Both were applied in a group of patients with focal, and focal secondary generalized epilepsy (n=10, age=39.9±11.7) and a group of neurologically healthy controls (n=15, age=37.3±11.4). Here, the statistical parametric (t-Test, (TT)) and nonparametric (Wilcoxon-Test, (WT)) analysis of selected amnestic features from the Berlin Amnesia Test (BAT) and the Diagnostic Cerebral Damage Test (DCS) are focused on. - Results: The comparison between the groups shows that firstly, there is no difference between the features recall unstructuredъ (RU) and recall associative patternъ (RA); secondly, the feature recall semantic structureъ (RS) (=0.05,TT), recall and destructorъ (RD) (=0.10,TT), short time memoryspanъ(SM) (=0.05,WT), semantic interferenceъ (SI) (=0.05,TT) are significantly different and the DCS index of labilityъ (LI) (=0.05,WT) is significantly higher in the patient group. - Conclusions: The results entail that there are no differences between verbal and figural working memory. The conspicuousness in the RD, ST and SI as well as the higher LI, point out a presumably weak memory trace. The lower value of RS indicates possible deficits in strategies of the storage process.
Synchronization during cognitive and self-regulative processes containing slow cortical potentials. - In: Journal of the neurological sciences, ISSN 0022-510X, Bd. 238.2005, Suppl. 1, S. S457
Background: Both, the slow cortical potentials (SCP), acquired during self-regulative processes (SRP) and the contingent negative variations (CNV) originate with strong attendance of information processing, and contain components which are closed to 0 Hz. Despite different existing hypotheses, both generation mechanisms have not been proven yet. In this study, the interest was focused on the topological synchronization within the common EEG bands. - Method: After appropriate preprocessing, single- and multi-trial classical and dynamical coherence analyses were applied to data acquired during a self-regulative procedure, based on SCP and such acquired by modified S1-S2 paradigm. All possible electrode (28 channels) combinations were computed. A comparison based on the consideration of the time, the frequency, and the localization was carried out. - Results: The highest synchronization of the SRP based on SCP can be observed in the central and front-central areas in theta and alpha band. There is no difference in the coherences between task positivation and task negativation in the SRP. Depending on the applied feedback strategy (visual-, musicfeedback and association) additional areas, e.g. right front-temporal, could show higher coherences temporary. Very high theta coupling occur independently on the time interval within the trigger sequences. There is no significant difference between the SRP and CNV process regarding the localizations, the frequencies, and the highness of the coherences. - Conclusion: Both the SRP based on SCP and the CNV-processes evince similar coupling behavior. These facts indicate related or common neurological and psycho-physiological generation mechanisms and will be explored in further detail in future studies.
Changes in instantaneous heart rate during hyperventilation: possible diagnostic value in epilepsy. - In: Epilepsia, ISSN 0013-9580, Bd. 46.2005, Suppl. 6, S. 218
Purpose: To investigate the changes in the instantaneous heart rate (IHR), as a marker of the activity of autonomous nervous system, during hyperventilation in a group of refractory epilepsy patients and a group of healthy controls. - Methods: The electrocardiogram (ECG) signals were acquired in the patient group (n=6, 4 females, 2 males; focal or multi-focal epilepsy diagnosis, epilepsy history ≥ 21 years) during the clinical electroencephalogram (EEG) measurements of which hyperventilation (3 minutes) was a part. The recording was continued another 3 minutes after the activation method. The procedure was repeated in the control group (n=6, 4 females, 2 males). The IHR values were computed from the pre-processed ECG signals as a function of time. The percentage normalized ratio of the average IHR within the hyperventilation and post-hyperventilation intervals is assigned as an index of changes in the IHR. - Results: None of the patients were observed to have epileptic activity in EEG during the measurements. The results of ECG analysis show that a) the increase and the decrease in the IHR have a non-linear character; b) the index assigned is lower in the epilepsy group (7.5±3.6) than in the control group (22.5±9.4). - Conclusions: In a previous study we had determined differences between patients and controls in the EEG/DC-shifts accompanying hyperventilation [Kirlangic ME et al. Epilepsia 2003; 44: Suppl. 8: 142). Although no epileptic discharges were observed in EEG, a difference was also determined in the changes in the IHR, in this study. These differences can be exploited for epilepsy diagnostics and therapy evaluation.
Regelbasierte Kantenerkennung zur schnellen kantenbasierten Segmentierung der Glottis in Hochgeschwindigkeitsvideos. - In: Bildverarbeitung für die Medizin 2005, (2005), S. 188-192
Statische und dynamische retinale Gefäßanalyse in der augenärztlichen Praxis : ein erster Erfahrungsbericht. - In: Klinische Monatsblätter für Augenheilkunde, ISSN 1439-3999, Bd. 221.2004, Suppl. 5, V25, insges. 1 S.
http://dx.doi.org/10.1055/s-2004-836177
Retinal vessel analysis for the morphological and functional examination of a central microcirculation area - a new clinical method. - In: Klinische Neurophysiologie, ISSN 1439-4081, Bd. 35 (2004), 3, lecture 192
https://doi.org/10.1055/s-2004-832104
Lokale retinale arterielle Gefäßreaktion auf mäßige artifizielle Augeninnendruckerhöhung bei Glaukompatienten und Normalpersonen. - In: Klinische Monatsblätter für Augenheilkunde, ISSN 1439-3999, Bd. 221.2004, Suppl. 3, V25, insges. 1 S.
http://dx.doi.org/10.1055/s-2004-835194
Blickgeführte Perimetrie - eine Möglichkeit zur Objektivierung der Gesichtsfelddiagnostik. - In: Klinische Monatsblätter für Augenheilkunde, ISSN 1439-3999, Bd. 221.2004, Suppl. 5, D55, insges. 1 S.
http://dx.doi.org/10.1055/s-2004-836210
Validierungsergebnisse zur retinalen Gefäßanalyse mit einem Gefäßmodell. - In: Beiträge zur 38. Jahrestagung der Deutschen Gesellschaft für Biomedizinische Technik im VDE - BMT 2004, 22 -24 September 2004, TU Ilmenau, (2004), S. 826-827