Conditioned pain modulation (CPM) predicts efficacy of duloxetine in painful diabetic neuropathy; patients with less efficient CPM are more likely to benefit from the drug.
This study aims to ...individualize the selection of drugs for neuropathic pain by examining the potential coupling of a given drug’s mechanism of action with the patient’s pain modulation pattern. The latter is assessed by the conditioned pain modulation (CPM) and temporal summation (TS) protocols. We hypothesized that patients with a malfunctioning pain modulation pattern, such as less efficient CPM, would benefit more from drugs augmenting descending inhibitory pain control than would patients with a normal modulation pattern of efficient CPM. Thirty patients with painful diabetic neuropathy received 1week of placebo, 1week of 30mg/d duloxetine, and 4weeks of 60mg/d duloxetine. Pain modulation was assessed psychophysically, both before and at the end of treatment. Patient assessment of drug efficacy, assessed weekly, was the study’s primary outcome. Baseline CPM was found to be correlated with duloxetine efficacy (r=0.628, P<.001, efficient CPM is marked negative), such that less efficient CPM predicted efficacious use of duloxetine. Regression analysis (R2=0.673; P=.012) showed that drug efficacy was predicted only by CPM (P=.001) and not by pretreatment pain levels, neuropathy severity, depression level, or patient assessment of improvement by placebo. Furthermore, beyond its predictive value, the treatment-induced improvement in CPM was correlated with drug efficacy (r=−0.411, P=.033). However, this improvement occurred only in patients with less efficient CPM (16.8±16.0 to −1.1±15.5, P<.050). No predictive role was found for TS. In conclusion, the coupling of CPM and duloxetine efficacy highlights the importance of pain pathophysiology in the clinical decision-making process. This evaluative approach promotes personalized pain therapy.
Pain variability can be partially attributed to psycho-cognitive features involved in its processing. However, accumulating research suggests that simple linear correlation between situational and ...dispositional factors may not be sufficiently explanatory, with some positing a role for mediating influences. In addition, acute pain processing studies generally focus on a post-operative model with less attention provided to post-traumatic injury. As such, this study aimed to investigate a more comprehensive pain processing model that included direct and indirect associations between acute pain intensity in the head and neck, pain catastrophizing (using pain catastrophizing scale (PCS)), and pain sensitivity (using the pain sensitivity questionnaire (PSQ)), among 239 patients with post-motor vehicle collision pain. The effect of personality traits (using Ten Items Personality Inventory (TIPI)) and emotional status (using Hospital Anxiety and Depression Scale (HADS) and Perceived Stress Scale (PSS)) on that model was examined as well. To this end, three Structural Equation Modeling (SEM) analyses were conducted. Overall, the data had good fit to all the models, with only PSQ found to have a direct correlation with acute pain intensity. The SEM analyses conversely revealed several mediations. Specifically, that: first, PSQ fully mediated the relationship between PCS and pain intensity; second, PCS and PSQ together fully mediated the relationship between conscientiousness (personality trait) and pain intensity; and finally, emotional status had direct and indirect links with PSQ and pain intensity. In conclusion, these models suggest that during the acute post-collision phase, pain sensitivity intermediates between emotional states and personality traits, partially via elevated pain catastrophizing thoughts.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Surgical and medical procedures, mainly those associated with nerve injuries, may lead to chronic persistent pain. Currently, one cannot predict which patients undergoing such procedures are ‘at ...risk’ to develop chronic pain. We hypothesized that the endogenous analgesia system is key to determining the pattern of handling noxious events, and therefore testing diffuse noxious inhibitory control (DNIC) will predict susceptibility to develop chronic post-thoracotomy pain (CPTP). Pre-operative psychophysical tests, including DNIC assessment (pain reduction during exposure to another noxious stimulus at remote body area), were conducted in 62 patients, who were followed 29.0
±
16.9 weeks after thoracotomy. Logistic regression revealed that pre-operatively assessed DNIC efficiency and acute post-operative pain intensity were two independent predictors for CPTP. Efficient DNIC predicted lower risk of CPTP, with OR 0.52 (0.33–0.77 95% CI,
p
=
0.0024), i.e., a 10-point numerical pain scale (NPS) reduction halves the chance to develop chronic pain. Higher acute pain intensity indicated OR of 1.80 (1.28–2.77,
p
=
0.0024) predicting nearly a double chance to develop chronic pain for each 10-point increase. The other psychophysical measures, pain thresholds and supra-threshold pain magnitudes, did not predict CPTP. For prediction of acute post-operative pain intensity, DNIC efficiency was not found significant. Effectiveness of the endogenous analgesia system obtained at a pain-free state, therefore, seems to reflect the individual’s ability to tackle noxious events, identifying patients ‘at risk’ to develop post-intervention chronic pain. Applying this diagnostic approach before procedures that might generate pain may allow individually tailored pain prevention and management, which may substantially reduce suffering.
Ability to predict which chronic itch patients will benefit from particular treatments is a challenge. Common features in itch and pain in respect to sensory elicitation, and mechanisms of processing ...including sensitization and inhibition at the peripheral and central levels, may serve to understand variability in treatment outcomes. As such this study aimed to explore whether phototherapy outcomes can be predicted by psychophysical parameters of pain and itch modulatory processing.
Prospective cohort study on chronic-itch patients (n = 44) assessed before 20 treatments of NB UVB. Level of itch and pain reduction following painful stimulation (reflecting the 'pain inhibits pain' phenomenon) used to assess the top-down modulation response efficacy. Magnitude of Conditioned Pain Modulation (CPM) for itch (CPM-itch) and for pain (CPM-pain) (reflecting inhibition) and magnitude of temporal summation (TS) of pain (reflecting ascending facilitation pathways) assessed to predict treatment effect.
Higher improvement of itch symptoms following phototherapy was correlated with more efficient CPM-itch (r = 0.62, p < .001), but not magnitude of CPM-pain or level of temporal summation.
Findings emphasize the role of descending inhibition pathways in determining phototherapy efficacy in chronic itch patients. Such an evaluation-based approach may contribute to better patient selection for phototherapy improving patients' disease outcomes.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The prevalence of terminally ill patients, who die at home, is increasing. The aim of this study was to address the meaning of being young adults, who were the caregivers of their dying parents. ...In-depth, semistructured interviews were conducted with 14 Israeli Jewish young adults, who had been the primary caregivers for parents who had cancer and eventually died at home. Three themes emerged: (a) “I was Chosen and was led into that situation”: modes of taking on and performing the role of a caregiver, (b) “My life was on hold”: the experience of performing the caregiving role, and (c) “I underwent . . . the real school of life”: caring for the dying parent as an imprint on self-development. Participants integrated compassionate caring into their identity, reflecting an empowering encounter of young carers with their dying parents as a process of growth in the face of harsh, stressful experiences.
This study demonstrates low to moderate temporal stability of conditioned pain modulation over a 7–10month period using an established paradigm.
Conditioned pain modulation (CPM) is a phenomenon that ...may be tested with a dynamic quantitative sensory test that assesses the inhibitory aspect of this pain modulatory network. Although CPM has been adopted as a clinical assessment tool in recent years, the stability of the measure has not been determined over long time intervals. The question of stability over time is crucial to our understanding of pain processing, and critical for the use of this tool as a clinical test. The primary objective of this study was to evaluate the stability of a CPM paradigm over time in healthy women. The secondary objective was to determine the potential influence of menstrual cycle phase on CPM. CPM was assessed 8 times in 22 healthy women during the follicular and luteal phases of 4 different cycles. The CPM effect was evidenced by a reduction in the pain rating of a test stimulus (6.3±0.2) with the introduction of a conditioning stimulus (5.0±0.3; P<0.001). The intraclass correlation coefficient for the CPM effect was modest (0.39; CI=0.23–0.59), suggesting that there is significant variation in CPM over long time intervals. CPM did not vary across phases in the menstrual cycle. Prior to the adoption of CPM as a clinical tool to predict individual risk and aid diagnosis, additional research is needed to establish the measurement properties of CPM paradigms and evaluate factors that influence CPM effects.
Temporal summation (TS) is usually evoked by repetitive mechanical or electrical stimuli, and less commonly by tonic heat pain. The present study aimed to examine the TS induction by ...repetitive-phasic versus tonic heat pain stimuli. Using 27 normal volunteers, we compared the extent of summation by three calculation methods: start-to-end pain rating difference, percent change, and double-logarithmic regression of successive ratings along the stimulation. Subjects were tested twice, and the reliability of each of the paradigms was obtained. In addition, personality factors related to pain catastrophizing and anxiety level were also correlated with the psychophysical results. Both paradigms induced significant TS, with similar increases for the repetitive-phasic and the tonic paradigms, as measured on 0–100 numerical pain scale (from 52.9
±
11.7 to 80.2
±
15.5,
p
<
0.001; and from 38.5
±
13.3 to 75.8
±
18.3,
p
<
0.001, respectively). The extent of summation was significantly correlated between the two paradigms, when calculated by absolute change (
r
=
0.543,
p
=
0.004) and by regression (
r
=
0.438,
p
=
0.025). Session-to-session variability was similar for both paradigms, relatively large, yet not biased. As with other psychophysical parameters, this poses some limitations on TS assessment in individual patients over time. The extent of TS induced by both paradigms was found to be associated with anxiety level and pain catastrophizing. Despite some dissimilarity between the repetitive-phasic and the tonic paradigms, the many similarities suggest that the two represent a similar physiological process, even if not precisely the same. Future clinical applications of these tests will determine the clinical relevance of the TS paradigms presented in this study.
Accommodating a patient's treatment preference has been reported to promote greater responsiveness and better clinical outcomes. The effect of administration route preference (ARP) on the individual ...analgesic response has not been extensively examined to date. This study aimed to investigate whether ARP-matched treatment, i.e., individualized intramuscular (IM) or oral (PO) analgesic administration according to patient choice, would increase the analgesic effect.
In this prospective randomized study, we collected 38 patients with acute low back pain (aLBP) presenting at the emergency room of the Galilee Medical Center (Naharia, Israel) and asked them to report their ARP for analgesics. Regardless of their reported preference, they received either PO or IM diclofenac according to the treating physician's preference. Pain intensity was self-reported using the numeric pain score (NPS) before and during the first hour after drug administration.
Both groups receiving PO or IM administration reported similar initial pain on admission, (NPS 8.63 ± 1.5 and 8.74 ± 1.6, respectively) and the same magnitude of pain reduction. However, patients who received the drug in their desired route (oral or injection) had a significantly greater reduction in pain levels (4.05 ± 2.8) as compared with patients who received the undesired route (2.08 ± 1.8), p < 0.05.
These findings support the hypothesis that individualized ARP-matched treatment in aLBP improves therapeutic outcomes, although further studies with larger cohorts are needed.
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