Neuromuscular assessment of the elderly worker, NEW: a multidisciplinary European research project.
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Biomedical subjects
Publications and source records attributed to Hermie Hermens.
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OBJECTIVES: The purpose of this study was to examine the influence of neuroticism (N) and its different subfacets anxiety (N-anx) and depression (N-dep) on cortical pain processing expressed as event-related potentials (ERPs). METHODS: Seventy-five healthy participants received electrical pain stimuli under condition of simultaneous electroencephalogram registration. Multiple regression analyses were conducted to study the amount of pain-ERP variance. ERP variance was explained by N and its subfacets. RESULTS: N moderated the way pain was processed cortically. Higher levels of N were associated with higher pain-ERP amplitudes. Within this association, differential subfacet effects were observed: N-anx reduced, whereas N-dep augmented pain-ERP amplitudes. DISCUSSION: A personality trait reflecting bias toward negative emotions may moderate the way pain is processed cortically, with directionally different effects depending on whether the trait is expressed predominantly in the realm of anxiety or depression.
The objective of this explorative study was to investigate to what extent changes in perceived pain, induced by myofeedback training, are correlated to changes in muscle activation patterns. Thirty subjects with work-related myalgia received myofeedback training. Before (T(0)), directly after (T(1)) and 4 weeks or, in a subset of patients, 3 months after (T(2)) this training, surface electromyography (sEMG) measurements of the upper trapezius muscle were performed during standardized computer tasks; a typing and a stress task. Besides this, visual analogue scales (VAS) were filled in to assess the levels of pain in the neck and shoulders. From the sEMG, root mean square (RMS) and relative rest time (RRT, i.e. the percentage of time RMS is below a certain threshold) were used for data analysis. The relationships between RRT, RMS and VAS at T(0) as well as for the changes between T(1)-T(0) and T(2)-T(0) were investigated using Spearman correlation coefficients. The results revealed no significant correlations between VAS and RMS both at baseline (range R = -0.22 to 0.17) and for the observed changes (range R = -0.33 to 0.32). Also, for VAS and RRT, low correlations were found for baseline (range R = -0.27 to 0.21) and for changes between T(1)-T(0) (range R = -0.02 to 0.38). However, for the changes between T(2)-T(0), correlation coefficients for the VAS for the shoulder and the RRT of the right trapezius during both the typing and stress tasks were significant at the P = 0.05 level, whereas the correlation coefficients for the VAS for the neck and both the left and right trapezii during the stress task approached significance (P = 0.05 and P = 0.1, respectively). These results suggest that decreases in pain observed at long term follow up after myofeedback training might occur as a result of an increased ability to relax but not as a result of decreased muscle activation level. However, the largest correlation found was 0.6. This means that the maximal explained variance (R (2)) is low (36%), and that there are also other processes than the changes in muscle activation that contribute to changes in perceived pain.
This paper presents a new inherently triaxial accelerometer-based system for determining the ability to maintain balance while standing. In this study, the accelerometer was placed at the back of the subject at the approximate height of the centre of mass. The data were processed to obtain five performance parameters. Paired t-tests indicated that the accelerometer measurements were able to distinguish between the different test conditions as well as or better than simultaneous AMTI force platform measurements (P < or = 0.05). The accelerometer system is fully portable, independent of inclination in space, low-cost and allows long term measurements of standing balance.
This article reports preliminary results of pilot studies of a new implantable two channel drop foot stimulator. The stimulator consists of an externally worn transmitter inductively coupled to an implanted receiver unit located in the lower leg, lateral and distal to the knee. The receiver is connected to electrodes located under the epineurium of the deep and the superficial peroneal nerves. Stimulation is triggered by detection of heel lift and terminated at heel strike in a manner similar to surface mounted systems. The location of the electrodes allows for a degree of selectivity over the resultant moment about the ankle joint that is not possible with surface stimulation of the common peroneal nerve. The two subjects used the stimulator on a regular basis and showed increases in walking speed of between 10% and 44% when compared to their baseline measurements. Isometric tests have demonstrated that the stimulator allows selective and repeatable stimulation of ankle joint muscles.
OBJECTIVE: The purpose of the present study was to answer the question whether pain report can be increased and decreased by operant conditioning. We predicted that the conditioned pain effects would remain significant after correction for social desirability and fantasy proneness. Furthermore, we tried to show that the neurophysiologic basis of verbal pain report, defined by pain (event)-related potentials, was affected by the conditioning procedure. Specifically, it was expected that the central recording site N150-P260 pain (event)-related potentials peak-to-peak amplitude would show the largest effect. METHODS: There were 4 groups: an up-conditioning group, a down-conditioning group, an at-random conditioning, and no-feedback control group. Healthy patients received 45 calibrated pain stimuli of equal physical intensity and were asked to rate the pain intensity they experienced. Up-conditioning was established by rewarding the subject if pain report increased compared with the previous trial. Down-conditioning of pain report was achieved by rewarding a decrease in the pain score. RESULTS: Results of the subjective pain reports clearly indicated that both forms of conditioning succeeded. Up-conditioning resulted in the highest pain scores and down-conditioning in the lowest scores with the two control groups in between them. Controlling for level of social desirability and fantasy proneness did not negatively influence these results. The N150-P260 pain (event)-related potentials peak-to-peak central recording site component also showed the predicted effect and reached statistical significance. DISCUSSION: We concluded that the subjective report of pain as well as a specific pain-related potentials component can be operantly conditioned.