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Biomedical subjects

H Künkel

Publications and source records attributed to H Künkel.

At least 19 recordsLinked to original sources
PubMed1992

[Automatic (computer-assisted) EEG analysis in comparison with visual EEG analysis in patients following minor cranio-cerebral trauma (a follow-up study)].

The study was designed to examine the clinical applicability and use of computer-assisted EEG-analysis in comparison to visual EEG-analysis in patients with minor head injuries. For this in 31 patients the following examinations were performed within the first 24 hours, one, three and eight weeks after traumatization: EEG, neurological examination and standardized evaluation of subjective complaints. The EEG was analysed visually as well as computer-assisted. The results were compared to the neurological findings and subjective complaints. Reversible posttraumatic EEG-changes were observed in 50% of all patients. The results of computer-analysis and visual analysis were equivalent in respect to baseline-activity (as one of the main characteristic EEG-features). Furthermore, based on computer-assisted analysis a discriminant function is provided, which is of diagnostic and prognostic value in the single patient. We conclude that the computer-assisted EEG-analysis can be a useful alternative in EEG-routine diagnosis after minor head injuries.

Adolescent↗
PubMed1990

Neurophysiological assessment of early hepatic encephalopathy.

The spontaneous EEG, pattern reversal VEPs, and the P300 wave were studied in patients with liver cirrhosis and early stages of hepatic encephalopathy (HE). The sensitivities of the different neurophysiological methods in the early stages of hepatic encephalopathy were compared with each other and with several neuropsychological tests. P300 latency was shown to be the most appropriate neurophysiological method for detection of early HE. The diagnostic sensitivity of the P300 latency resembled that of the number connection test (NCT). These results are discussed with regard to methodological considerations and the clinical use of both methods.

Adult↗
PubMed1990

Positron emission tomography in neuropsychiatric lupus erythematosus.

We performed positron emission tomography (PET) using 18F-labeled 2-F-2-deoxyglucose in 13 patients with systemic lupus erythematosus (SLE). Ten of them had clinical signs of central nervous system involvement (NP-SLE). All patients with neurologic symptoms showed pathologic changes on PET, always in accordance with the clinical state. Three patients without neuropsychiatric manifestations had normal PETs. Computed tomography of the brain and magnetic resonance imaging proved to be less sensitive to both presence and localization of CNS lesions. We conclude that the combination of PET and MRI constitutes the most useful diagnostic procedure for NP-SLE.

Adolescent↗
PubMed1990

[Event-related potentials in psychiatry--methodologic principles].

The methodological requirements for the use of event-related brain potentials (ERPs) in psychiatry are critically reviewed. In particular the development of psychophysiological models is considered as essential for a functional interpretation of ERP-experiments. In addition problems of signal-analysis and clinical diagnosis relevant to ERP-research in psychiatry are briefly discussed. The logic of ERP-research in psychiatry is illustrated by a series of dichotic listening experiments.

Arousal↗
PubMed1988

Effects of a cholinergic nootropic (WEB 1881 FU) on event-related potentials recorded in incidental and intentional memory tasks.

In a double-blind placebo-controlled randomized study the influence of a cholinergic nootropic (WEB 1881 FU) on event-related brain potentials (ERPs) related to memory performance was investigated. Two different encoding modes were imposed on the subjects, who had to memorize word lists. No significant drug effects were obtained on memory performance and the ERP-concomitant of encoding, the Dm, while ERP effects related to memory were clearly present. However, the two dosages of the drug significantly influenced the overall amplitude of the late cognitive ERP components, suggesting its effect on cognitive processes.

Adult↗
PubMed1987

Human event-related potentials and circadian variations in arousal level.

Contingent negative variation (CNV) potentials were recorded from ten male subjects during a single session in divided- and focussed-attention conditions. Beside a strong dependency of CNV and N1 amplitudes and reaction time on task difficulty, the results of the present study show an effect of the subject types, classified by their peak performance times. The slight increase of CNV amplitude form morning to afternoon recording in evening-type subjects contrasted with a substantial decline in the morning-type subjects. Unexpectedly, both task conditions showed remarkably similar time courses of amplitudes. The attempt to model the individual amplitude curves from arousal levels led to inconclusive results. No final conclusions about the relationship of CNV and arousal levels over the course of a day can be drawn.

Adult↗
PubMed1986

Use of endogenous event-related potentials (ERP) in the evaluation of psychotropic substances: towards an ERP profile of drug effects.

Although endogenous event-related potentials (ERPs) have been successfully used in psychology, they have largely been neglected in the study of psychotropic substances. In the present paper an overview is given of the diversified concepts of ERP research and useful adaptations of these approaches to psychopharmacological questions are shown. In particular, the influence of drugs on the various stages of information processing and the description of individual differences in drug reactions seem suitable for the use of endogenous ERPs. Other possible uses of ERPs in psychopharmacological research are briefly discussed and the problems of the technique are pointed out. It is concluded that future research should aim at the recording of 'ERP profiles' of a drug, monitoring pharmacological effects on the different levels of cognitive functions by a set of selected paradigms.

Brain↗
PubMed1985

[Methodological aspects of the analysis of the effects of drugs (diazepam and caffeine) on contingent negative variation].

The paper discusses the importance and implications of the event-related-potentials in the analysis of effects of centrally acting drugs. This is illustrated using a study on the influence of diazepam and caffeine on the contingent-negative-variation (CNV) as an example. Special emphasis is placed on methodological problems and their possible solutions. A linear robust fitting technique was used for quantification of the slow-rising, ramp-like CNV potentials as an alternative to conventional baseline-to-peak measures. Results obtained by this method were validated by a second analysis taking slow superimposed DC-shifts into account. This was achieved by defining a reference line from the data for CNV-development and -resolution. The possibilities of single-trial potential evaluation were explored by using a pattern recognition algorithm. The average CNV-waveform was used as a reference-signal to which the single-trial potentials were correlated. Since pattern recognition techniques are sensitive to morphological changes of the potentials they are adding a new aspect to event-related-potential analysis.

Adult↗
PubMed1979

The significance of personality traits in EEG evaluation of drug effects.

The relatively clear and compact picture of an electroencephalographic classification of psychotropic substances becomes extremely more complex if the influence of personality traits and topographic differentiations in the EEG are taken into account. Using the example of EEG alterations under diazepam, amitriptyline, pyritinol, EMD 21-657 and caffeine, the complex structure of substance effects, personality factors, topographical differentiations, placebo reactivity and spontaneous circadian variability of the EEG is demonstrated.

Amitriptyline↗
PubMed1978

[Annual rhythms in frequency of electroencephalographic patterns (author's transl)].

A series of electroencephalographic features were measured for about 11,500 patients from a clinical population, over a period of five years (1972 to 1976) and were documented using a standarized procedure. It could be shown that for males a definite yearly rhythm was present for the relative frequencies of alpha-type, partial beta-type, and low voltage EEGs, as well as for continuous and grouped dysrhythmias, the amplitudes of which were in the main 20--30% of the average. For females on the other hand, apart from grouped dysrhythmias, no such yearly rhythms could be proven, at the most such with a periodicity of between 14 and 16 months. The data often display trends that are more distinct than the rhythmicity and as such these should be taken into consideration when deciding upon the model used for statistical regression.

Alpha Rhythm↗