Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Publication date: Available online 20 September 2021
Source: Archives of Physical Medicine and Rehabilitation
Author(s): Patrick J. Knox, Ryan T. Pohlig, Jenifer M. Pugliese, Peter C. Coyle, Jaclyn M. Sions, Gregory E. Hicks
Mechanical hyperalgesia and allodynia incidence varies considerably amongst neuropathic pain patients. This study explored whether sensory or psychological factors associate with mechanical hyperalgesia and brush allodynia in a human experimental model.
Sixty-six healthy volunteers (29 male) completed psychological questionnaires and participated in two quantitative sensory testing (QST) sessions. Warmth detection threshold (WDT), heat pain threshold (HPT) and suprathreshold mechanical pain (STMP) ratings were measured before exposure to a capsaicin-heat pain model (C-HP). After C-HP exposure, brush allodynia and STMP were measured in one session, whilst mechanical hyperalgesia was measured in another session.
WDT and HPT measured in sessions separated by 1 month demonstrated significant but moderate levels of reliability (WDT: ICC = 0.5, 95%CI [0.28, 0.77]; HPT: ICC = 0.62, 95%CI [0.40, 0.77]). Brush allodynia associated with lower WDT (z = −3.06, p = 0.002; Ï• = 0.27). Those with allodynia showed greater hyperalgesia intensity (F = 7.044, p = 0.010, ηp 2 = 0.107) and area (F = 9.319, p = 0.004, ηp 2 = 0.163) than those without allodynia. No psychological self-report measures were significantly different between allodynic and nonallodynic groups. Intensity of hyperalgesia in response to lighter mechanical stimuli was associated with lower HPT, higher STMP ratings and higher Pain Sensitivity Questionnaire scores at baseline. Hyperalgesia to heavier probe stimuli associated with state anxiety and to a lesser extent somatic awareness. Hyperalgesic area associated with lower baseline HPT and higher STMP ratings. Hyperalgesic area was not correlated with allodynic area across individuals.
These findings support research in neuropathic pain patients and human experimental models that peripheral sensory input and individual sensibility are related to development of mechanical allodynia and hyperalgesia during central sensitization, whilst psychological factors play a lesser role.
We evaluated differential relationships of psychological and perceptual sensitivity to the development of capsaicin-induced mechanical allodynia and hyperalgesia. Fifty percent of healthy volunteers failed to develop mechanical allodynia. Baseline pain sensitivity was greater in those developing allodynia and was related to the magnitude and area of hyperalgesia. State psychological factors, whilst unrelated to allodynia, were related to mechanical hyperalgesia. This supports that the intensity of peripheral sensory input and individual sensibility are related to development of mechanical allodynia and hyperalgesia during central sensitization, whilst psychological factors play a lesser role.
Assessing pain in mechanically ventilated infants is challenging. The assessment of skin conductance (SC) is based on the sympathetic nervous system response to stress. This study purpose was to evaluate the validity of SC for assessing pain in mechanically ventilated infants.
A prospective cross-sectional observational design was used to study SC and its relation to: the category of procedure (i.e., painful or non-painful); the phase of procedure (i.e., before, during and after), and referent pain measurements (i.e., Premature Infant Pain Profile-Revised (PIPP-R) and Neonatal Facial Coding System (NFCS)). Eligible infants were those up to 12 months of age, in intensive care units, who were mechanically ventilated, and required painful and non-painful procedures.
From October 2017 to November 2018, 130 eligible infants were identified, and 55 infants were studied. SC (number of waves per second) during painful procedures (median 0.27, interquartile range 0.2–0.4) was statistically significantly higher than those during non-painful procedures (0, 0–0.09). SC during painful procedures was statistically significantly higher than those before (0, 0–0.07) and after painful procedures (0, 0–0.07). SC showed moderate statistically significant positive correlations with PIPP-R (Spearman's rho = 0.4–0.62) and the four-item NFCS (Spearman's rho = 0.31–0.67) before, during and after painful or non-painful procedures respectively. SC had excellent performance (area under the receiver operator curve = 0.979) with excellent sensitivity (92.31%), specificity (95.42%) and negative predictive value (99.21%) but only sufficient positive predictive value (66.67%) when used to discriminate moderate-to-severe pain.
SC showed good validity for assessing pain in critically ill infants requiring mechanical ventilation.
Pain assessment in mechanically ventilated infants is challenging. In this study, the validity of skin conductance (SC) for pain assessment is evaluated in the same population of infants during painful and nonpainful procedures. SC showed good validity for assessing acute pain in relation to category of procedure, phase of procedure, and referent pain measurements. SC is a promising method, especially with other pain assessment methods and other determinants of pain, in a multimodal pain assessment approach to understand the complexity of pain in mechanically ventilated infants.
Previous studies have indicated a negative correlation between GRK2 expression and pain development and transmission. Here, we investigated whether G-protein-coupled receptor kinase 2 (GRK2) was involved in regulating diabetic mechanical hyperalgesia (DMH).
The adeno-associated viral vectors containing the GRK2 gene (AAV-GRK2) were used to up-regulate GRK2 protein expression. The expression of GRK2 and exchange protein directly activated by cyclic adenosine monophosphate 1 (Epac1) in the dorsal root ganglion (DRG) of lumbar 4–6 was detected via immunoblotting and immunohistochemistry, and the transfection of the GRK2 gene was detected by immunofluorescence.
Low levels of GRK2 were able to sustain STZ-induced pain in DMH rats. Intrathecal injection of AAV-GRK2 vector up-regulated GRK2 expression, providing pain rain to rats with DMH. With an increase in DMH duration, there was a decrease in paw withdrawal threshold (PWT) value, aggravating the pain, resulting in a decreasing pattern in GRK2 protein expression over time, whereas Epac1 protein expression showed an opposite trend.
GRK2 expression regulated DMH progression and is expected to play a role in the development of targeted therapy for DMH. GRK2 and Epac1 expressions play a vital role in maintaining pain in DMH rats.
Pain assessment and pain care are influenced by the characteristics of both the patient and the caregiver. Some studies suggest that the pain of older persons and of females may be underestimated to a greater extent than the pain of younger and male individuals.
This study investigated the effect of age and sex on prosocial behavior and pain evaluation.
40 young (18–30 y/o; 20 women) and 40 older adults (55–82 y/o; 20 women) acted as healthcare professionals rating the pain and offering help to patients of both age groups. Trait empathy and social desirability were measured with questionnaires.
Linear mixed models showed that older and male patients were offered more help and were perceived as being in more intense pain than younger and female patients.
The characteristics of the patients seem to have a greater impact on prosocial behavior and pain assessment compared to those of the observers, which bears significant implications for the treatment of pain in clinical contexts.
There is a lack of evidence of the relative effects of different exercise modes on pain sensitization and pain intensity in individuals with knee osteoarthritis (KOA).
Ninety individuals with radiographic and symptomatic KOA, ineligible for knee replacement surgery, were randomized to 12 weeks of twice-weekly strength training in addition to neuromuscular exercise and education (ST+NEMEX-EDU) or neuromuscular exercise and education alone (NEMEX-EDU). Outcomes were bilateral, lower-leg, cuff pressure pain- and tolerance thresholds (PPT, PTT), temporal summation (TS), conditioned pain modulation (CPM), self-reported knee pain intensity and number of painful body sites.
After 12 weeks of exercise, we found significant differences in increases in PPT (−5.01 kPa (−8.29 to −1.73, p = .0028)) and PTT (−8.02 kPa (−12.22 to −3.82, p = .0002)) in the KOA leg in favour of ST+NEMEX-EDU. We found no difference in effects between groups on TS, CPM or number of painful body sites. In contrast, there were significantly greater pain-relieving effects on VAS mean knee pain during the last week (−8.4 mm (−16.2 to −0.5, p = .0364) and during function (−16.0 mm (−24.8 to −7.3, p = .0004)) in favour of NEMEX-EDU after 12 weeks of exercise.
Additional strength training reduced pain sensitization compared to neuromuscular exercise and education alone, but also attenuated the reduction in pain intensity compared to neuromuscular exercise and education alone. The study provides the first dose- and type-specific insight into the effects of a sustained exercise period on pain sensitization in KOA. Future studies are needed to elucidate the role of different exercise modes.
This study is an important step towards better understanding the effects of exercise in pain management of chronic musculoskeletal conditions. We found that strength training in addition to neuromuscular exercise and education compared with neuromuscular exercise and education only had a differential impact on pain sensitization and pain intensity, but also that regardless of the exercise mode, the positive effects on pain sensitization and pain intensity were comparable to the effects of other therapeutic interventions for individuals with knee osteoarthritis.
Fibromyalgia is a centralized multidimensional chronic pain syndrome, but its pathophysiology is not fully understood.
We applied 3D magnetic resonance spectroscopic imaging (MRSI), covering multiple cortical and subcortical brain regions, to investigate the association between neuro-metabolite (e.g. combined glutamate and glutamine, Glx; myo-inositol, mIno; and combined (total) N-acetylaspartate and N-acetylaspartylglutamate, tNAA) levels and multidimensional clinical/behavioural variables (e.g. pain catastrophizing, clinical pain severity and evoked pain sensitivity) in women with fibromyalgia (N = 87).
Pain catastrophizing scores were positively correlated with Glx and tNAA levels in insular cortex, and negatively correlated with mIno levels in posterior cingulate cortex (PCC). Clinical pain severity was positively correlated with Glx levels in insula and PCC, and with tNAA levels in anterior midcingulate cortex (aMCC), but negatively correlated with mIno levels in aMCC and thalamus. Evoked pain sensitivity was negatively correlated with levels of tNAA in insular cortex, MCC, PCC and thalamus.
These findings support single voxel placement targeting nociceptive processing areas in prior 1H-MRS studies, but also highlight other areas not as commonly targeted, such as PCC, as important for chronic pain pathophysiology. Identifying target brain regions linked to multidimensional symptoms of fibromyalgia (e.g. negative cognitive/affective response to pain, clinical pain, evoked pain sensitivity) may aid the development of neuromodulatory and individualized therapies. Furthermore, efficient multi-region sampling with 3D MRSI could reduce the burden of lengthy scan time for clinical research applications of molecular brain-based mechanisms supporting multidimensional aspects of fibromyalgia.
This large N study linked brain metabolites and pain features in fibromyalgia patients, with a better spatial resolution and brain coverage, to understand a molecular mechanism underlying pain catastrophizing and other aspects of pain transmission. Metabolite levels in self-referential cognitive processing area as well as pain-processing regions were associated with pain outcomes. These results could help the understanding of its pathophysiology and treatment strategies for clinicians.
Pain catastrophizing underpins several psychosocial theories of pain, but there is limited evidence to support the proposal that changes in pain catastrophizing cause changes in pain. Results from mediation analyses have conflicting results, and one reason for these might be the timing of the assessment of pain catastrophizing. This study aimed to test the effect of the timing of the assessment of pain catastrophizing on its mediating role on pain intensity.
Causal mediation analysis using data from a randomized controlled trial which included 100 participants with chronic low back pain. The trial found that clinical hypnosis, compared to pain education, reduced worst pain intensity and pain catastrophizing. In model 1, we used data from 2-week follow-up for pain catastrophizing and 3-month follow-up for pain. In model 2, we used data from 3-month follow-up for both pain catastrophizing and pain.
The intervention had a significant average total effect on pain (−1.34 points, 95% CI −2.50 to −0.13). The average causal mediation effect was significant when pain catastrophizing, and pain were measured at the same time (−0.62 points, 95% CI −1.30 to −0.11) but not significant when pain catastrophizing and pain intensity were measured at different times (−0.10 points, 95% CI −0.42 to 0.09).
The timing of the assessment influenced the mediating role of pain catastrophizing on pain intensity. These results raise questions on the casual role that pain catastrophizing has on pain intensity. Psychosocial interventions such as clinical hypnosis can reduce pain intensity even when there has been no change in pain catastrophizing.
Individuals' perceptions of back pain may shape what they do in response to manage their pain, for example, self-care, medication and seeking healthcare. Illness perceptions encompass a variety of beliefs such as how long pain is expected to last and whether treatments are perceived to control pain. Whether these beliefs meaningfully cluster and whether these clusters are associated with how people manage their back pain are currently unknown.
1,343 individuals with back pain from a general population sample completed the brief Illness Perceptions Questionnaire and measures about their pain and illness behaviours. Using a two-stage cluster analysis, we identified four distinct clusters of individuals. Logistic regression was used to investigate relationships between cluster membership and illness behaviours.
After adjustment for socio-demographic characteristics, pain severity, interference and duration, relative to a low threat illness perception cluster, a high threat cluster was more likely to have contacted a general practitioner (OR: 3.03, 95% CI: 1.75, 5.23) and a moderate threat–high treatment control cluster was more likely to have consulted a physical therapist (OR: 2.21, 95% CI: 1.26, 3.87). Both the moderate threat–high treatment control cluster and high threat cluster were also less likely to have reported self-care (OR: 0.64, 95% CI: 0.43, 0.95; OR: 0.53, 95% CI: 0.34, 0.83, respectively).
The cluster analysis provided a meaningful classification of individuals based on their cognitive illness perceptions of their back pain, as these clusters were associated with different illness behaviours. Interventions which modify clusters of illness perceptions may be effective in influencing how individuals respond to back pain.
Within a general population setting, we identified four clearly distinct groups of people based on the perceptions they held about their back pain. These groupings seemed to reflect meaningful characterisations as they differed based on the characteristics of their pain (e.g., severity and duration) and, after adjustment for these characteristics, were associated with different ways of managing pain. Interventions which focus on targeting the sets of illness perceptions that people hold may be effective in influencing how individuals manage back pain.
