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S Egner

Publications and source records attributed to S Egner.

6 recordsLinked to original sources

Automated EEG preprocessing during anaesthesia: new aspects using artificial neural networks.

The computer-aided detection of artefacts became an essential task with increasing automation of quantitative electroencephalogram (EEG) analysis during anaesthesiological applications. The different algorithms published so far required individual manual adjustment or have been based on limited decision criteria. In this study, we developed an artificial neural networks-(ANN-)aided method for automated detection of artefacts and EEG suppression periods. 72 hr EEG recorded before, during and after anaesthesia with propofol have been evaluated. Selected parameterized patterns of 0.25 s length were used to train the ANN (22 input, 8 hidden and 4 output neurons) with error back propagation. The detection performance of the ANN-aided method was tested with processing epochs between 1 to10 s. Related to examiner EEG evaluation, the average detection performance of the method was 72% sensitivity and 80% specificity for artefacts and 90% sensitivity and 92% specificity for EEG suppression. The improvement in signal-to-noise ratio with automated artefact processing was 1.39 times for the spectral edge frequency 95 (SEF95) and 1.89 times for the approximate entropy (ApEn). We conclude that ANN-aided preprocessing provide an useful tool for automated EEG evaluation in anaesthesiological applications.

Algorithms↗

Musculo-tendinous junction of the flexor carpi ulnaris muscle. An anatomical study.

The aim of the study was to evaluate the occurrence of the anatomical variations of the musculotendinous junction of the flexor carpi ulnaris (FCU) muscle and the variations of its insertion onto the pisiform. One hundred cadaver specimens preserved according to Thiel's method were assessed. Following careful dissection, the distance between the musculotendinous junction and the pisiform and the width of the muscle belly were determined. Three typical anatomical variations were found: 1) a large muscle belly running distally almost to the insertion onto the pisiform; 2) the muscle belly ending more proximally, with some large fibres running parallel to the tendon and almost reaching the pisiform; 3) the musculotendinous junction ending more proximally, with only single fibres continuing distally. The length of the tendon was greater than 10 mm. A number of variations of the distal region of FCU were observed. The presence of muscle fibres almost reaching the insertion point onto the pisiform have to be considered when interpreting MRI or ultrasound findings of this region.

Aged↗

Influence of age on the parasympatholytic property of tricyclic antidepressants.

Clinical evidence indicates that parasympatholytic effects of tricyclic antidepressants increase with age. The aim of the present study was to determine the possible physiological reason for this phenomenon. Subjects included 23 patients (14 female) with major depression, melancholic type, and 23 age- and sex-matched healthy control subjects. Cardiac vagal tone was measured at rest using both spectral analysis and a time domain beat-to-beat method. Results of the spectral and time domain methods for the estimation of vagal tone used in this study were highly correlated in control subjects as well as in medicated depressed subjects. Both patients and control subjects showed an age-related decline in cardiac vagal tone. Tricyclic antidepressants decreased vagal tone significantly by 25-49% depending on age (20-60 years), although the age difference was not significant. The greater effect of tricyclic antidepressants on parasympathetic activity typically seen in older age groups may reflect the fact that predrug levels of vagal tone are already low in older patients. Measurement of vagal tone prior to drug administration may therefore be of prognostic value for anticholinergic side effects.

Adult↗

Major depression and cardiac autonomic control.

We investigated autonomic control of heart rate in patients with major depression, melancholic type. Twenty-three depressed inpatients who were being treated with tricyclic antidepressants and 23 depressed patients who were taking no medications were compared with age- and sex-matched control groups on resting cardiac vagal tone and heart rate. In unmedicated depressed patients, cardiac vagal tone was comparable to that of control subjects, but heart rate was significantly higher. This increase in heart rate may have been due to sympathetic activation caused by anxiety, since the depressed patients were significantly more anxious than the control subjects. Medicated patients exhibited diminished cardiac vagal tone and higher heart rate than unmedicated patients and controls. This was probably due to the anticholinergic effects of the antidepressants. Our findings suggest that cardiac vagal tone is not lower than normal in patients with depression, melancholic type.

Adult↗

Long-term imprisonment leads to cognitive impairment.

The effects of long-term imprisonment on cognitive functions are investigated in a longitudinal study. Twenty-four serious offenders in an Austrian penitentiary underwent concentration and memory performance measurements via a questionnaire presented to them under controlled conditions in two sessions at a 42 month interval. The difference in the parameters indicated cognitive impairment after this period that was highly significant (P < 0.01); this can be interpreted as a direct consequence of imprisonment.

Adult↗