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Acute stress reduces responses to static evoked pain stimuli (stress-induced analgesia [SIA]). Whether SIA inhibits temporal summation of pain, a dynamic evoked pain measure indexing central sensitization, has been little studied and mechanisms were not evaluated.
Learn More >To analyze cervical tenderness scores (CTS) in patients with various temporomandibular disorders (TMD) and in controls and to examine associations of CTS with demographic and clinical parameters.
Learn More >In this study, we investigated whether illusionary body ownership over artificial hands and non-corporeal objects modulates pain perception. Previous research has yielded to mixed results, but has separated painful stimulation used to test pain perception from the stimulation that was used to induce the illusion. Here, we used a variant of the rubber hand illusion (RHI) paradigm and induced the illusion directly via a combination of visual and painful stimuli. We presented heat pain stimuli at the real hand and visual stimuli beneath a rubber hand (part1), or a glass ball (part2). Illusion ratings were higher and pain ratings were lower in the synchronous compared to the asynchronous condition in both parts of the experiment. This study demonstrated the successful induction of a body illusion using a new visual-thermal method with painful stimuli. We showed that the RHI and interestingly also the glass ball has an analgesic effect on the perception of the heat pain stimuli. Our data suggests that induced ownership over artificial limbs but also over non-corporeal objects can reduce the perceived pain perception. This might be mediated via a partial referral of the perceived location of pain or respectively a distribution of pain over two locations. Perspective: This article presents a new visual-thermal method with painful stimuli for the induction of the Rubber Hand Illusion. An illusionary body ownership over artificial hands and non-corporeal has an analgesic effects on the perception of pain. Similar approaches might be useful to alleviate chronic pain, but needs further testing.
Learn More >Intra-epidermal nerve fibers (IENFs) are presumed to comprise mainly of itch-transmitting nerve fibers, and variations in their density have been studied in itch disorders; epidermal nerve fiber density is also a criterion in diagnosing small fiber neuropathy in clinical neurological practice. IENFs are typically identified with 2-dimensional (2D) histological slides, but 2D sections do not accurately represent nerves, which branch out in three-dimensions (3D).
Learn More >(i) To investigate the prevalence of poor sleep quality and (ii) to explore the associations between clinical, cognitive and emotional factors and quality of sleep in patients with chronic widespread pain (CWP) attending multidisciplinary treatment.
Learn More >To study the impact of anesthesia opioid-related outcomes and acute and chronic postsurgical pain, we organized a multicenter study that comprehensively combined detailed perioperative data elements from multiple institutions. By combining pre- and postoperative patient-reported outcomes with automatically extracted high-resolution intraoperative data obtained through the Multicenter Perioperative Outcomes Group (MPOG), the authors sought to describe the impact of patient characteristics, preoperative psychological factors, surgical procedure, anesthetic course, postoperative pain management, and postdischarge pain management on postdischarge pain profiles and opioid consumption patterns. This study is unique in that it utilized multicenter prospective data collection using a digital case report form integrated with the MPOG framework and database. Therefore, the study serves as a model for future studies using this innovative method. Full results will be reported in future articles; the purpose of this article is to describe the methods of this study.
Learn More >Non-specific chronic low back pain (CLBP) is a multifactorial disorder. Pain-related fear and altered movement preparation are considered to be key factors in the chronification process. Interactions between both have been hypothesized, but studies examining the influence of situational fear on movement preparation in low back pain (LBP) are wanting, as well as studies differentiating between recurrent LBP (RLBP) and CLBP. Therefore, this study examined whether experimentally induced pain-related fear influences movement preparation. In healthy controls (n=32), RLBP (n=31) and CLBP (n=30) patients central and peripheral measures of movement preparation were assessed by concurrently measuring trunk muscle anticipatory postural adjustments (APA) with EMG and Contingent Negative Variation (CNV) with EEG during performance of rapid arm movements (RAM). Two conditions were compared, one without (no fear) and one with (fear) possibility of painful stimulation to the back during RAM. Visual analogue scales were used to assess pain-related expectations/fear in both conditions. The experimentally induced fear of pain during movement performance led to an increase in CNV-amplitude, which was similar in all three groups. Concerning APAs no effects of fear were found, but group differences with generally delayed APAs in CLBP compared to controls and RLBP patients were evident. These results suggest that with fear an attentional redirection towards more conscious central movement preparation strategies occurs. Furthermore, differences in movement preparation in RLBP and CLBP patients exist, which could explain why RLBP patients have more recovery capabilities than CLBP.
Learn More >Measuring altered nociceptive processing involved in chronic pain is difficult due to a lack of objective methods. Potential methods to characterize human nociceptive processing involve measuring neurophysiological activity and psychophysical responses to well-defined stimuli. To reliably measure neurophysiological activity in response to nociceptive stimulation using EEG, synchronized activation of nerve fibers and a large number of stimuli are required. On the other hand, to reliably measure psychophysical detection thresholds, selection of stimulus amplitudes around the detection threshold and many stimulus-response pairs are required. Combining the two techniques helps in quantifying the properties of nociceptive processing related to detected and non-detected stimuli around the detection threshold.The two techniques were combined in an experiment including 20 healthy participants to study the effect of intra-epidermal electrical stimulus properties (i.e. amplitude, single- or double-pulse and trial number) on the detection thresholds and vertex potentials. Generalized mixed regression and linear mixed regression were used to quantify the psychophysical detection probability and neurophysiological EEG responses, respectively.It was shown that the detection probability is significantly modulated by the stimulus amplitude, trial number, and the interaction between stimulus type and amplitude. Furthermore, EEG responses were significantly modulated by stimulus detection and trial number. Hence, we successfully demonstrated the possibility to simultaneously obtain information on psychophysical and neurophysiological properties of nociceptive processing. These results warrant further investigation of the potential of this method to observe altered nociceptive processing.
Learn More >Pain is the vital sense preventing tissue damage by harmful noxious stimuli. The capsaicin receptor TRPV1 is activated by noxious temperatures, however, acute heat pain is only marginally affected in mice after TRPV1 knockout but completely eliminated in mice lacking TRPV1 positive fibers. Exploring contribution of candidate signal transduction mechanisms to heat pain in humans needs translational models.
Learn More >Recent research has shown that placebos can be effective even if they are openly prescribed to participants. Yet, it is unclear how such "open-label placebos" (OLPs) compare to deceptive placebo (DP) and what the mechanisms of actions are. In this study, we therefore compared 2 versions of OLP to DP and no treatment (NT).
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