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; ϕ = 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.
