Publications by authors named "Karl-Juergen Bär"

4 Publications

  • Page 1 of 1

Understanding Facial Expressions of Pain in Patients With Depression.

J Pain 2017 04 2;18(4):376-384. Epub 2016 Dec 2.

Department of General Practice and Elderly Care Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Although depression is associated with more clinical pain complaints, psychophysical data sometimes point to hypoalgesic alterations. Studying the more reflex-like facial expression of pain in patients with depression may offer a new perspective. Facial and psychophysical responses to nonpainful and painful heat stimuli were studied in 23 patients with major depressive disorder (MDD) and 23 matched control participants. As psychophysical data, pain thresholds, tolerance thresholds, and self-report were assessed. Facial responses were videotaped and subjected offline to Facial Action Coding System analysis. One of the key facial responses of pain, which is a known facial signal of negative affect (contraction of the eyebrows), was significantly increased in MDD patients. Moreover, facial expressions and pain ratings were strongly correlated in MDD patients, whereas these 2 response systems were-in line with established findings-only weakly related in healthy participants. Pain psychophysics was unaltered in MDD patients compared with healthy control participants. In conclusion, the facial expression of pain in MDD patients indicates rather hyper- than hypoalgesia, with enhanced affective pain processing. Moreover, the linkage between subjective and facial responses was much stronger in MDD patients, which may be due to a reduced influence of social display rules, which normally complicate this relationship.

Perspective: The facial expression of pain in patients with depression indicates stronger affective pain processing and stronger association with self-report than in healthy individuals.
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http://dx.doi.org/10.1016/j.jpain.2016.11.011DOI Listing
April 2017

Humans, but not animals, perceive the thermal grill illusion as painful.

Behav Brain Res 2016 10 15;313:172-176. Epub 2016 Jul 15.

Institute of Physiology I, University Hospital, Teichgraben 8, 07743 Jena, Germany.

Simultaneous presentation of alternating innocuous warm and cold stimuli induces in most humans a painful sensation called thermal grill illusion (TGI). Here, pain is elicited although nociceptors are not activated. Upon back-translation of behavioural correlates from humans to animals, we found that neither cats nor rodents show adverse reactions when exposed to TGI stimulation. These results question that a TGI observed as a pain-related change in behaviour can be elicited in animals. While distinct neuronal patterns as previously reported may be measurable in animals upon TGI stimulation, their translational meaning towards the sensation elicited in humans is unclear.
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http://dx.doi.org/10.1016/j.bbr.2016.07.020DOI Listing
October 2016

Exaggerated differences in pulse wave velocity between left and right sides among patients with anxiety disorders and cardiovascular disease.

Psychosom Med 2007 Nov 17;69(8):717-22. Epub 2007 Oct 17.

Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA.

Objective: To compare the left-right differences in pulse wave velocity (PWV) measures in normal controls and patients with anxiety disorders and cardiac disease. Pulses from the right and left sides of normal subjects are highly correlated at each segmental level. However, some evidence suggests that the right hemisphere has a greater effect on parasympathetic activity, as there may be a right hemisphere disadvantage in patients with low cardiac vagal function. Decreased vagal function is associated with vascular dysfunction and hypertension.

Methods: We compared normal controls (n = 22), patients with anxiety (n = 26), and patients with cardiovascular disease (n = 72) using the Vascular Profiler (VP-1000), which enables the measurement of ankle and brachial blood pressure (BP) in both arms (brachial), both legs (ankle) and carotid artery, and lead I electrocardiogram and phonocardiogram. Using these signals, PWV, and arterial stiffness index % were calculated for the comparison of these measures on the right and left sides of the body.

Results: Patients with anxiety and cardiovascular disease had significantly higher left-right differences in heart-ankle pulse wave velocity, brachial-ankle pulse wave velocity, and arterial stiffness index percentage compared with that of normal controls. Our data also showed significant differences between left-right vascular indices in patients with anxiety and cardiovascular disease (p < .00001); there was no such significant difference in normal controls.

Conclusions: These results may implicate an exaggerated vagal withdrawal in the left extremities resulting in higher PWV in patients with anxiety and cardiovascular illness.
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http://dx.doi.org/10.1097/PSY.0b013e3181574272DOI Listing
November 2007

Relationship between beat-to-beat variability of RT-peak and RT-end intervals in normal controls, patients with anxiety, and patients with cardiovascular disease.

Ann Noninvasive Electrocardiol 2007 Jul;12(3):203-9

Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI, USA.

Background: Some studies suggest that it is important to take the end of "T" wave to quantify QT-interval variability, which signifies cardiac repolarization lability, as there is substantial and important information beyond the peak of the T wave on the surface electrocardiogram.

Methods: In this study, we examined the relationship between the variability of beat-to-beat RTe (beginning of R-peak to T-end) and the variability of RTp (R-peak to T-peak) in the following groups: normal controls (n = 26), patients with anxiety (n = 26), and patients with cardiovascular disease with or without diabetes (n = 63). We obtained ECG sampled at 1024 Hz in lead II configuration in supine posture to obtain beat-to-beat interbeat interval (R-R) and RT-interval variability for 256 seconds.

Results: We found significant positive correlations (r = 0.8; P < 0.00001) in normal controls and patients with anxiety between the variability of RTeVI and RTpVI (RTe and RTp variability indices, respectively, corrected for the mean of RTe and RTp and the mean and the variance of R-R). These correlations were also statistically significant in the medically ill group but the r values were much smaller (r = 0.45 in various groups). The slopes were also significantly different between the two groups (P < 0.001). Bland-Altman plots also showed better agreement between the two measures in the controls and patients with anxiety compared to the group with cardiovascular disease.

Conclusions: These findings have methodological implications for studies comparing people with and without overt cardiovascular illness. While RTe or RTp variability index may be used interchangeably in normal controls and some patients with no overt cardiovascular problems, it may be more prudent to use both RTe and RTp variability indices in patients with cardiovascular illness. These indices, especially RTeVI, may provide different information about cardiac repolarization lability. Future studies should address the importance of the relative usefulness of these two measures especially in cardiac patients before and after successful treatment.
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http://dx.doi.org/10.1111/j.1542-474X.2007.00162.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6932619PMC
July 2007