Trajectories of health-related quality of life and their predictors in adult COVID-19 survivors: A longitudinal analysis of the Biobanque Québécoise de la COVID-19 (BQC-19).

PURPOSE: A significant number of people will experience prolonged symptoms after COVID-19 infection that will greatly impact functional capacity and quality of life. The aim of this study was to identify trajectories of health-related quality of life (HRQOL) and their predictors among adults diagnosed with COVID-19. METHODS: This is a retrospective analysis of an ongoing prospective cohort study (BQC-19) including adults (≥18y) recruited from April 2020 to March 2022. Our primary outcome is HRQOL using the EQ-5D-5L scale. Sociodemographic, acute disease severity, vaccination status, fatigue, and functional status at onset of the disease were considered as potential predictors. The latent class mixed model was used to identify the trajectories over an 18-month period in the cohort as a whole, as well as in the inpatient and outpatient subgroups. Multivariable and univariable regressions models were undertaken to detect predictors of decline. RESULTS: 2163 participants were included. Thirteen percent of the outpatient subgroup (2 classes) and 28% in the inpatient subgroup (3 classes) experienced a more significant decline in HRQOL over time than the rest of the participants. Among all patients, age, sex, disease severity and fatigue, measured on the first assessment visit or on the first day after hospital admission (multivariable models), were identified as the most important predictors of HRQOL decline. Each unit increase in the SARC-F and CFS scores increase the likelihood of belonging to the declining trajectory (univariable models). CONCLUSION: Although to different degrees, similar factors explain the decline in HRQOL over time among the overall population, people who have been hospitalized or not. Clinical functional capacity scales could help to determine the risk of HRQOL decline.

Which has more influence on a family's assessment of the quality of dying of their long-term care resident with dementia: Frequency of symptoms or quality of communication with healthcare team?

OBJECTIVE: Symptoms present at the end of life and the quality of communication with the healthcare team have both been shown to impact family assessments of the quality of dying of their loved one with dementia. However, the relative contributions of these two factors to family assessments have not yet been investigated. To address this knowledge gap, we explored which of these two factors has more influence on family assessments of the quality of dying of long-term care (LTC) residents with dementia. METHOD: This is a secondary analysis of a mortality follow-back study. Ninety-four family members of LTC residents who had died with dementia assessed the quality of dying (very good or not very good), the frequency of symptoms, and the quality of communication with the healthcare team using a self-administered questionnaire mailed 1 month after the resident's death. Logistic regression analyses were performed to determine the relative contributions of the two independent variables of primary interest (frequency of symptoms and quality of communication) to the families' assessments of the quality of dying. RESULTS: Multivariate analyses revealed that the quality of communication with the healthcare team was closely linked to the quality of dying (p = 0.009, OR = 1.34, 95% CI = 1.09-1.65), whereas the frequency of symptoms was not (p = 0.142, OR = 1.05, 95% CI = 0.98-1.11) after controlling for potential confounders. SIGNIFICANCE OF RESULTS: Our findings show that healthcare providers' ability to engage in the end-of-life conversations with families outweighs the frequency of symptoms in family assessments of the quality of dying of their relative with dementia. Enhancing healthcare providers' ability to communicate with families about the end-of-life care could improve families' perceptions of the quality of dying of their relative with dementia and, consequently, ease their grieving process.

Non-Linear Measures of Postural Control in Response to Painful and Non-Painful Visual Stimuli.

Over the past decade, researchers have focused on studying the functional context of perceiving painful stimuli, particularly concerning the posturographic correlates of emotional processing. The aim of this study was to investigate the differential modulation of non-linear measures characterizing postural control in the context of perceiving painful stimuli. The study involved 36 healthy young participants who, while standing, viewed images depicting feet and hands in painful or non-painful situations, both actively (by imagining themselves affected by the situation) and passively. For Center of Pressure (COP) displacement, three non-linear measures (Sample Entropy, Fractal Dimension, and Lyapunov exponent) were calculated. The results suggest lower values of FD and LyE in response to active stimulation compared to those recorded for passive stimulation. Above all, our results pledge for the usefulness of the Lyapunov exponent for assessing postural modulation dynamics in response to painful stimuli perception. The feasibility of this calculation could provide an interesting insight in the collection of biomarkers related to postural correlates of emotional processes and their modulation in neurological disease where socio-affective functions can be often impaired before cognitive ones.

The influence of experimental low back pain on neural networks involved in the control of lumbar erector spinae muscles.

Low back pain (LBP) often modifies spine motor control, but the neural origin of these motor control changes remains largely unexplored. This study aimed to determine the impact of experimental low back pain on the excitability of cortical, subcortical, and spinal networks involved in the control of back muscles. Thirty healthy subjects were recruited and allocated to pain (capsaicin and heat) or control (heat) groups. Corticospinal excitability (motor-evoked potential; MEP) and intracortical networks were assessed by single- and paired-pulse transcranial magnetic stimulation, respectively. Electrical vestibular stimulation was applied to assess vestibulospinal excitability (vestibular MEP; VMEP) and the stretch reflex for excitability of the spinal or supraspinal loop (R1 and R2, respectively). Evoked back motor responses were measured before, during, and after pain induction. Nonparametric rank-based ANOVA determined if pain modulated motor neural networks. A decrease of R1 amplitude was present after the pain disappearance (P = 0.01) whereas an increase was observed in the control group (P = 0.03) compared with the R1 amplitude measured at prepain and preheat period, respectively (group × time interaction, P < 0.001). No difference in MEP and VMEP amplitude was present during and after pain (P > 0.05). During experimental LBP, no change in cortical, subcortical, or spinal networks was observed. After pain disappearance, the reduction of the R1 amplitude without modification of MEP and VMEP amplitude suggests a reduction in spinal excitability potentially combined with an increase in descending drives. The absence of effect during pain needs to be further explored.NEW & NOTEWORTHY In the presence of experimental low back pain, spinal, subcortical, and cortical motor networks involved in the control of back muscles were not modified. However, once the pain disappeared, a reduction in motoneuronal excitability was observed without change in corticospinal and vestibulospinal excitability, suggesting a reduction in descending drive. Experimental low back pain may elicit long-term plasticity even after pain extinction.

The Process of Rehabilitation, Return and Stay at Work of Aging Workers Who Suffered an Occupational Injury: A Portrait Based on the Experience of Canadian Stakeholders.

PURPOSE: This study aims to paint a picture of the factors that influence the process of rehabilitation, return, and stay at work, for aging workers who have suffered an occupational injury. METHODS: Based on a descriptive interpretative research design, the authors conducted interviews with 23 participants (i.e., aging workers, workers' representatives, employers, insurers, and rehabilitation professionals) to gather their perspectives. Qualitative data was analyzed through thematic analysis. RESULTS: Fifteen factors related to the worker, health system, workplace, or compensation system were identified. These factors prevail during rehabilitation, return to work, stay at work, or the entire process. CONCLUSIONS: This study contributes to the advancement of knowledge regarding three main ideas: (1) the importance of not placing the responsibility on the worker in this complex process, (2) the key role of the compensation system, and (3) the necessity of transforming work to reduce ageism.

Transcranial direct current stimulation (a-tCDS) after subacromial injections in patients with subacromial pain syndrome: a randomized controlled pilot study.

BACKGROUND: Subacromial pain syndrome (SAPS) is a common complaint in orthopaedics. Subacromial corticosteroid injections (CSI) can relieve pain in the short term. Anodal transcranial direct current stimulation (a-tDCS) has been used for symptomatic pain relief in a variety of chronic pain conditions. The aim of this pilot study was to assess whether the application a-tDCS could enhance the symptomatic relief provided by CSI in patients affected by SAPS. METHODS: Thirty-eight participants (18 to 65-year-old) suffering from SAPS were recruited to have a CSI and randomly allocated to receive, 1 weeks post CSI, real a-tDCS (r-tDCS), sham tDCS (s-tDCS) or no intervention (Control). Upper limb function was measured 1 week prior to the CSI, at the 2- and 4-week follow-ups using self-administered questionnaires and physical measures. Self-reported pain and activity during each day were logged by the participants using visual analog scales (VAS). Differences between groups were tested using repeated-measures ANOVAs. RESULTS: Pain VAS and the Single Assessment Numeric Evaluation scale (SANE) showed significant improvement from baseline 2 weeks and 4 weeks after CSI in all groups (p < 0.05). There were no significant group X time interaction 2 weeks following tDCS treatment in any of the variables. CONCLUSION: All groups showed significant improvement in pain VAS and SANE scores following the CSI. One session of a-tDCS treatment 2 weeks following CSI did not result in any additive or potentializing effects when compared to a s-tDCS or a control group. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03967574 . Registered 30 May 2019 - Retrospectively registered.

Perturbing the activity of the superior temporal gyrus during pain encoding prevents the exaggeration of pain memories: A virtual lesion study using single-pulse transcranial magnetic stimulation.

BACKGROUND: Past studies have shown that pain memories are often inaccurate, a phenomenon known as mnemonic pain bias. Pain memories are thought to play an important role on how future pain is felt. Recent evidence from our laboratory suggests that individuals who exaggerate past pain display increased superior temporal gyrus (STG) activity during the encoding of experimental painful stimulations, suggesting that this brain structure plays an important role in pain memories. OBJECTIVE: /hypothesis. To determine whether a virtual lesion paradigm, targeting the STG during pain encoding, can affect long-lasting pain memories. We hypothesized that interfering with the activity of the STG would attenuate mnemonic bias. METHODS: Randomized double-blind study with two parallel groups. Participants received either sham (n = 21) or real (n = 21) transcranial magnetic stimulation (TMS - virtual lesion paradigm) over the STG during pain encoding (milliseconds after the administration of a painful stimuli). Pain intensity and unpleasantness were evaluated using a visual analog scale (VAS; 0 to 10) immediately after the painful event, and at recall, 2 months later. The mnemonic pain bias (calculated by subtracting the pain scores obtained at recall from the pain score obtained during encoding) was compared between the two groups for both pain intensity and unpleasantness. RESULTS: Participants in both groups did not differ in terms of age and gender (real TMS = 27 years ±â€¯9, 43% female; sham TMS = 25 years ±â€¯4, 49% female; p > 0.64). The mnemonic bias related to pain intensity was similar in both groups (p = 0.83). However, the mnemonic bias related to pain unpleasantness was lower in the real TMS group (p = 0.04). CONCLUSIONS: Our results provide the first evidence that the STG, is causally involved in the formation of biased memories of pain unpleasantness.

Low-Back Pain and Knee Position-Related Differences on Postural Control Measures During a One-Legged Stance in Athletes.

CONTEXT: Chronic low-back pain (CLBP) may be associated with changes in postural balance in athletes as poor postural control during sports practice. OBJECTIVE: To compare the postural control of athletes with and without CLBP during 2 one-legged stance tasks and identify the center of pressure (COP) cutoff values to determine the main differences. Designed: A cross-sectional study. SETTING: Laboratory of functional evaluation and human motor performance. PARTICIPANTS: A total of 56 male athletes, 28 with and 28 without CLBP (mean age = 26 y). INTERVENTION: The one-legged stance with knee extension and with the knee at 30° flexion tasks were measured and analyzed on a force platform. The participants completed three 30-second trials (30 s of rest between each trial). MAIN OUTCOME MEASURES: The COP parameters: the area of COP, mean COP sway velocity in both the anteroposterior and mediolateral directions, and total COP displacement were computed, and a receiver operating characteristics curve analysis was applied to determine the group differences. RESULTS: Athletes with CLBP had poorer postural control (P < .01) in both tasks. The 30° knee flexion reported more postural instability than the knee extension for all COP parameters (a large effect size d = 0.80).The knee extension cutoffs identified were >7.1 cm2 for the COP area, >2.6 cm/s for the COP sway velocity in the anterior-posterior direction, and >3.2 cm/s for the mediolateral direction. Whereas, the 30° knee flexion cutoffs were >10.9 cm2 for the COP area, >2.9 cm/s for the COP sway velocity in the anterior-posterior direction, and >4.1 cm/s for the mediolateral direction. Both measures showed enough sensitivity and specificity (ie, area under the curve = 0.88 in and 0.80, respectively) to discriminate both groups. CONCLUSIONS: The athletes with CLBP had poorer postural control than the healthy athletes and obtained specific cutoff scores from the COP values.

The Ottawa Panel guidelines on programmes involving therapeutic exercise for the management of hand osteoarthritis.

OBJECTIVE:: To identify programmes involving therapeutic exercise that are effective for the management of hand osteoarthritis and to provide stakeholders with updated, moderate to high-quality recommendations supporting exercises for hand osteoarthritis. METHODS:: A systematic search and adapted selection criteria included comparable trials with exercise programmes for managing hand osteoarthritis. Based on the evaluated evidence, a panel of experts reached consensus through a Delphi approach endorsing the recommendations. A hierarchical alphabetical grading system (A, B, C+, C, C-, D-, D, D+, E, F) was based on clinical importance (≥15%) and statistical significance ( P < 0.05). RESULTS:: Ten moderate- to high-quality studies were included. Eight studies with programmes involving therapeutic exercise (e.g. range of motion (ROM) + isotonic + isometric + functional exercise) seemed to be effective. Forty-six positive grade recommendations (i.e. A, B, C+) were obtained during short-term (<12 weeks) trials for pain, stiffness, physical function, grip strength, pinch strength, range of motion, global assessment, pressure pain threshold, fatigue and abductor pollicis longus moment and during long-term (>12 weeks) trials for physical function and pinch strength. CONCLUSION:: Despite that many programmes involving exercise with positive recommendations for clinical outcomes are available to healthcare professionals and hand osteoarthritis patients that aid in the management of hand osteoarthritis, there is a need for further research to isolate the specific effect of exercise components.

The knitting community-based trial for older women with osteoarthritis of the hands: design and rationale of a randomized controlled trial.

BACKGROUND: The prevalence of hand osteoarthritis (HOA) has been reported to be higher amongst women over 50 years old (66%) compared to men of the same age (34%). Although exercise therapy has been shown effective in reducing symptoms and disability associated with HOA, adherence to treatment programs remains low. The primary objective of this RCT is to examine the effectiveness of a 12-week knitting program for morning stiffness (primary outcome) and pain relief (secondary outcome) 2 h post-wakening in females (aged 50 to 85 years old) with mild to moderate hand osteoarthritis (HOA). METHODS/DESIGN: A single-blind, two-arm randomized controlled trial (RCT) with a parallel group design will be used to reach this objective and compare results to a control group receiving an educational pamphlet on osteoarththritis (OA) designed by the Arthritis Society. The premise behind the knitting program is to use a meaningful occupation as the main component of an exercise program. The knitting program will include two components: 1) bi-weekly 20-min knitting sessions at a senior's club and 2) 20-min home daily knitting sessions for the five remaining weekdays. Participants assigned to the control group will be encouraged to read the educational pamphlet and continue with usual routine. Pain, morning stiffness, hand function, self-efficacy and quality of life will be measured at baseline, six weeks, 12 weeks (end of program) with standardized tools. We hypothesize that participants in the knitting program will have significant improvements in all clinical outcomes compared to the control group. A published case study as well as the preliminary results of a feasibility study as examined through a 6-week pre-post study (n = 5 women with HOA) involving 20-min daily knitting morning sessions led to this proposed randomized controlled trial research protocol. This article describes the intervention, the empirical evidence to support it. DISCUSSION: This knitting RCT has the potential to enhance our understanding of the daily HOA symptoms control and exercise adherence, refine functional exercise recommendations in this prevalent disease, and reduce the burden of disability in older women. TRIAL REGISTRATION: (ACTRN12617000843358) registered on 7/06/2017.

Efficacy of transcranial direct-current stimulation in women with provoked vestibulodynia.

BACKGROUND: Provoked vestibulodynia is a highly prevalent condition characterized by acute recurrent pain located at the vaginal entrance in response to pressure application or attempted vaginal penetration. Despite a wide variety of treatments offered to women with provoked vestibulodynia, a high proportion of women are refractory to conventional treatment. Transcranial direct-current stimulation is a noninvasive brain stimulation technique that has been shown effective for improving various chronic pain conditions. Growing evidence suggests that the central nervous system could play a key role in provoked vestibulodynia. Targeting the central nervous system could therefore be a promising treatment for women with provoked vestibulodynia. OBJECTIVE: The purpose of this study was to evaluate and compare the efficacy of active and sham transcranial direct-current stimulation in reducing pain intensity during intercourse in patients with provoked vestibulodynia. STUDY DESIGN: We conducted a triple-blind, parallel-group, randomized controlled trial. Women aged 17-45 years diagnosed with provoked vestibulodynia by a gynecologist using a validated protocol were randomized to 10 sessions of either active transcranial direct-current stimulation (intensity = 2 mA) or 10 sessions of sham transcranial direct-current stimulation, over a 2-week period. Both active and sham transcranial direct-current stimulation were applied for 20 minutes, with the anode positioned over the primary motor cortex, and the cathode over the contralateral supraorbital area. Outcome measures were collected at baseline, 2 weeks after treatment, and at 3-month follow-up by an evaluator blinded to group assignment. The primary objective was to assess pain intensity during intercourse, using a numerical rating scale. Secondary outcomes focused on sexual function and distress, vestibular sensitivity, psychological distress, treatment satisfaction, and patient impression of change. Statistical analyses were conducted on the intention-to-treat basis, and treatment effects were evaluated using a mixed linear model for repeated measures. RESULTS: A total of 40 patients were randomly assigned to receive either active (n = 20) or sham (n = 20) transcranial direct-current stimulation treatments from November 2014 through February 2016. Baseline characteristics were similar between the active and sham transcranial direct-current stimulation groups. In full compliance with the study protocol, every participant followed all courses of the study treatment, including assessments at 2-week and 3-month follow-up. Pain during sexual intercourse was not significantly different between active and sham treatment groups 2 weeks after treatment (P = .84) and at follow-up (P = .09). Mean baseline and 2-week assessment pain intensity were, respectively, 6.8 (95% confidence interval, 5.9-7.7) and 5.6 (95% confidence interval, 4.7-6.5) for active transcranial direct-current stimulation (P = .03) vs 7.5 (95% confidence interval, 6.6-8.4) and 5.7 (95% confidence interval, 4.8-6.6) for sham transcranial direct-current stimulation (P = .001). Nonsignificant differences between the 2 groups were also found in their sexual function and distress after treatment (P > .20) and at follow-up (P > .10). Overall, at 2-week assessment 68% assigned to active transcranial direct-current stimulation reported being very much, much, or slightly improved compared to 65% assigned to sham transcranial direct-current stimulation (P = .82), and still comparable at follow-up: 42% vs 65%, respectively (P = .15). CONCLUSION: Findings suggest that active transcranial direct-current stimulation is not more effective than sham transcranial direct-current stimulation for reducing pain in women with provoked vestibulodynia. Likewise, no significant effects were found on sexual function, vestibular sensitivity, or psychological distress.

Unravelling the effect of experimental pain on the corticomotor system using transcranial magnetic stimulation and electroencephalography.

The interaction between pain and the motor system is well-known, with past studies showing that pain can alter corticomotor excitability and have deleterious effects on motor learning. The aim of this study was to better understand the cortical mechanisms underlying the interaction between pain and the motor system. Experimental pain was induced on 19 young and healthy participants using capsaicin cream, applied on the middle volar part of the left forearm. The effect of pain on brain activity and on the corticomotor system was assessed with electroencephalography (EEG) and transcranial magnetic stimulation (TMS), respectively. Compared to baseline, resting state brain activity significantly increased after capsaicin application in the central cuneus (theta frequency), left dorsolateral prefrontal cortex (alpha frequency), and left cuneus and right insula (beta frequency). A pain-evoked increase in the right primary motor cortex (M1) activity was also observed (beta frequency), but only among participants who showed a reduction in corticospinal output (as depicted by TMS recruitment curves). These participants further showed greater beta M1-cuneus connectivity than the other participants. These findings indicate that pain-evoked increases in M1 beta power are intimately tied to changes in the corticospinal system, and provide evidence that beta M1-cuneus connectivity is related to the corticomotor alterations induced by pain. The differential pattern of response observed in our participants suggest that the effect of pain on the motor system is variable from on individual to another; an observation that could have important clinical implications for rehabilitation professionals working with pain patients.

Association Between Falls and Brain Subvolumes: Results from a Cross-Sectional Analysis in Healthy Older Adults.

Falls are a consequence of gait instability. Cortical and subcortical abnormalities have been associated with gait instability but not yet with falls. This study aims to compare the global and regional brain subvolumes between healthy older fallers and non-fallers. A total of 77 healthy older individuals (23 fallers and 54 non-fallers, 69.8 ± 3.5 years; 45.5 % female) were included in this study using a cross-sectional design. Based on an a priori hypothesis, the following brain subvolumes were quantified from three-dimensional T1-weighted MRI using FreeSurfer software: total white matter abnormalities, total white matter, total cortical and subcortical gray matter, hippocampus, motor cortex, somatosensory cortex, premotor cortex, prefrontal cortex and parietal cortex volumes. Gait performances were also recorded. Age, sex, body mass index, comorbidities, use of psychoactive drugs, far-distance visual acuity, lower-limb proprioception, depressive symptoms and cognitive scores (Mini-Mental State Examination, Frontal Assessment Battery) were used as covariates. Fallers have more frequently depressive symptoms (P = 0.048), a lower far distance visual acuity (P = 0.026) and a higher coefficient of variation of stride time (P = 0.008) compared to non-fallers. There was a trend to greater subvolumes for the somatosensory cortex (P = 0.093) and the hippocampus (P = 0.060) in the falls group. Multiple logistic regressions showed that subvolumes of the somatosensory cortex and the hippocampus (P < 0.042) were increased in fallers compared to non-fallers, even after adjustment for clinical and brain characteristics. The greater subvolumes of the somatosensory cortex and hippocampus reported in fallers compared to non-fallers suggests a possible brain compensatory mechanism involving spatial navigation and integration of sensory information.

Can We Quickly and Thoroughly Assess Pain with the PACSLAC-II? A Convergent Validity Study in Long-Term Care Residents Suffering from Dementia.

A previous study found that the modified version of the Pain Assessment Checklist for Seniors with Limited Ability to Communicate (PACSLAC-II) is a valid tool to assess pain in elderly individuals suffering from dementia and who are unable to communicate verbally. The primary objective of this study was to confirm the convergent validity of the PACSLAC-II using direct evaluation of long-term care residents in real-life situations, using two other well-validated pain assessment scales (i.e., PACSLAC and Pain Assessment in Advanced Dementia [PAINAD]). A secondary objective was to document and compare the time required to complete and score each assessment scale. During two potentially painful procedures (i.e., transfer/mobilization), 46 long-term care residents (mean age = 83 ± 10 years) suffering from dementia were observed by three independent evaluators, each using one of the assessment scales (randomly assigned). Correlational analyses and analysis of variance were used to evaluate the association between each scale and to compare scoring time. The PACSLAC (r = 0.61) and the PAINAD (r = 0.65) were both moderately associated with the PACSLAC-II (all p values < .001). The PAINAD's average scoring time (63 ± 19 seconds) was lower than the PACSLAC-II's (96 ± 2 seconds), which was lower than the PACSLAC's (135 ± 53 seconds) (all p values < .001). These results suggest that the PACSLAC-II is a valid tool for assessing pain in individuals with dementia. The time required to complete and score the PACSLAC-II was reasonable, supporting its usefulness in clinical settings.

Effect of pulsed electromagnetic field therapy on experimental pain: A double-blind, randomized study in healthy young adults.

Previous studies suggested that pulsed electromagnetic field (PEMF) therapy can decrease pain. To date, however, it remains difficult to determine whether the analgesic effect observed in patients are attributable to a direct effect of PEMF on pain or to an indirect effect of PEMF on inflammation and healing. In the present study, we used an experimental pain paradigm to evaluate the direct effect of PEMF on pain intensity, pain unpleasantness, and temporal summation of pain. Twenty-four healthy subjects (mean age 22 ± 2 years; 9 males) participated in the experiment. Both real and sham PEMF were administered to every participant using a randomized, double-blind, cross-over design. For each visit, PEMF was applied for 10 minutes on the right forearm using a portable device. Experimental pain was evoked before (baseline) and after PEMF with a 9 cm(2) Pelletier-type thermode, applied on the right forearm (120 s stimulation; temperature individually adjusted to produce moderate baseline pain). Pain intensity and unpleasantness were evaluated using a 0-100 numerical pain rating scale. Temporal summation was evaluated by comparing pain intensity ratings obtained at the end of tonic nociceptive stimulation (120 s) with pain intensity ratings obtained after 60 s of stimulation. When compared to baseline, there was no change in pain intensity and unpleasantness following the application of real or sham PEMF. PEMF did not affect temporal summation. The present observations suggest that PEMF does not directly influence heat pain perception in healthy individuals.

Altered autonomic nervous system reactivity to pain in trigeminal neuralgia.

BACKGROUND: In the past two decades, there has been increasing evidence to suggest that trigeminal neuralgia (TN) may be linked to a dysfunction of the autonomic nervous system (ANS). The aim of the present study was to formally test this hypothesis by comparing the reactivity of the ANS to experimental pain in a population of TN patients and healthy controls. METHODS: Twelve patients diagnosed with classical TN and 12 healthy controls participated in the study. Cardiac activity was assessed while participants were instructed to rest and again during a cold pressor test (CPT). Heart rate variability analyses were performed off-line to obtain parasympathetic (high-frequency) and sympathetic (low-frequency) indices. RESULTS: At baseline, ANS measures did not differ between healthy controls and TN patients, and both groups showed a similar increase in heart rate during the CPT (all p values >0.05). However, TN patients showed a greater increase in cardiac sympathetic activity and a greater decrease in cardiac parasympathetic activity during CPT compared with healthy controls (all p values <0.05). Importantly, changes in sympathetic reactivity, from baseline to CPT, were negatively associated with the number of pain paroxysms experienced each day by TN patients in the preceding week (r=-.58, p<0.05). CONCLUSIONS: These results suggest that TN, like many other short-lasting, unilateral facial pain conditions, is linked to ANS alterations. Future studies are required to determine if the altered ANS response observed in TN patients is a cause or a consequence of TN pain.

Significance of Non-phase Locked Oscillatory Brain Activity in Response to Noxious Stimuli.

BACKGROUND: Although current pain-evoked electroencephalographic (EEG) studies provide valuable information regarding human brain regions involved in pain, they have mostly considered neuronal responses which oscillate in phase following a painful event. In many instances, cortical neurons respond by generating bursts of activity that are slightly out of phase from trial-to-trial. These types of activity bursts are known as induced brain responses. The significance of induced brain responses to pain is still unknown. METHODS: In this study, 23 healthy subjects were given both non-painful and painful transcutaneous electrical stimulations in separate testing blocks (stimulation strength was kept constant within blocks). Subjective intensity was rated using a numerical rating scale, while cerebral activity tied to each stimulation was measured using EEG recordings. Induced brain responses were identified using a time frequency wavelet transform applied to average-removed single trials. RESULTS: Results showed a pain-specific burst of induced theta activity occurring between 180 and 500 ms post-shock onset. Source current density estimations located this activity within the dorsolateral prefrontal cortex (DLPFC, bilaterally), however, only right DLPFC activity predicted a decrease in subjective pain as testing progressed. CONCLUSION: This finding suggests that non-phase locked neuronal responses in the right DLPFC contribute to the endogenous attenuation of pain through time. PERSPECTIVE: This article presents neuroimaging findings demonstrating that, in response to pain, non-phase locked bursts of theta activity located in the right dorsolateral prefrontal cortex are associated with a progressive decrease in subjective pain intensity, which has potentially important implications regarding how humans endogenously control their experiences of pain.

The influence of pain and kinesiophobia on motor control of the upper limb: how pointing task paradigms can point to new avenues of understanding.

ABSTRACT: People experiencing kinesiophobia are more likely to develop persistent disabilities and chronic pain. However, the impact of kinesiophobia on the motor system remains poorly understood. We investigated whether kinesiophobia could modulate shoulder pain-induced changes in (1) kinematic parameters and muscle activation during functional movement and (2) corticospinal excitability. Thirty healthy, pain-free subjects took part in the study. Shoulder, elbow, and finger kinematics, as well as electromyographic activity of the upper trapezius and anterior deltoid muscles, were recorded while subjects performed a pointing task before and during pain induced by capsaicin at the shoulder. Anterior deltoid cortical changes in excitability were assessed through the slope of transcranial magnetic stimulation input-output curves obtained before and during pain. Results revealed that pain reduced shoulder electromyographic activity and had a variable effect on finger kinematics, with individuals with higher kinesiophobia showing greater reduction in finger target traveled distance. Kinesiophobia scores were also correlated with the changes in deltoid corticospinal excitability, suggesting that the latter can influence motor activity as soon as the motor signal emerges. Taken together, these results suggest that pain and kinesiophobia interact with motor control adaptation.

Reliability and minimal detectable change of dynamic temporal summation and conditioned pain modulation using a single experimental paradigm.

BACKGROUND: Quantitative sensory tests (QST) are frequently used to explore alterations in somatosensory systems. Static and dynamic QST like pain threshold and temporal summation (TS) and conditioned pain modulation (CPM) are commonly used to evaluate excitatory and inhibitory mechanisms involved in pain processing. The aim of the present study was to document the reliability and the minimal detectable change (MDC) of these dynamic QST measurements using a standardized experimental paradigm. MATERIAL AND METHODS: Forty-six (46) pain-free participants took part in 2 identical sessions to collect TS and CPM outcomes. Mechanical (pressure pain threshold [PPT]) and thermal (constant 2-minute heat pain stimulation [HPS]) nociceptive stimuli were applied as test stimuli, before and after a cold-water bath (conditioning stimulus). TS was interpreted as the change in pain perception scores during HPS. CPM were determined by calculating the difference in pain perception between pre- and post- water bath for both PPT and HPS. Relative and absolute reliability were analyzed with intra-class correlation coefficient (ICC2, k), standard error of the measurements (SEMeas) and MDC. RESULTS: Results revealed a good to excellent relative reliability for static QST (ICC ≥ 0.73). For TS, a poor to moderate relative reliability depending on the calculation methods (ICC = 0.25 ≤ ICC ≤ 0.59), and a poor relative reliability for CPM (ICC = 0.16 ≤ ICC ≤ 0.37), both when measured with mechanical stimulation (PPT) and thermal stimulation (HPS). Absolute reliability varied from 0.73 to 7.74 for static QST, 11 to 22 points for TS and corresponded to 11.42 points and 1.56 points for thermal and mechanical-induced CPM, respectively. MDC analyses revealed that a change of 1.58 to 21.46 point for static QST, 31 to 52 points for TS and 4 to 31 points for CPM is necessary to be interpreted as a real change. CONCLUSION: Our approach seems well-suited to clinical use. Although our method shows equivalent relative and absolute reliability compared to other protocols, we found that the reliability of endogenous pain modulation mechanisms is vulnerable, probably due to its dynamic nature.

Counting your chickens before they hatch: improvements in an untreated chronic pain population, beyond regression to the mean and the placebo effect.

Introduction: Isolating the effect of an intervention from the natural course and fluctuations of a condition is a challenge in any clinical trial, particularly in the field of pain. Regression to the mean (RTM) may explain some of these observed fluctuations. Objectives: In this paper, we describe and quantify the natural trajectory of questionnaire scores over time, based on initial scores. Methods: Twenty-seven untreated chronic low back pain patients and 25 healthy controls took part in this observational study, wherein they were asked to complete an array of questionnaires commonly used in pain studies during each of 3 visits (V1, V2, V3) at the 2-month interval. Scores at V1 were classified into 3 subgroups (extremely high, normal, and extremely low), based on z-scores. The average delta (∆ = V2 - V1) was calculated for each subgroup, for each questionnaire, to describe the evolution of scores over time based on initial scores. This analysis was repeated with the data for V2 and V3. Results: Our results show that high initial scores were widely followed by more average scores, while low initial scores tended to be followed by similar (low) scores. Conclusion: These trajectories cannot be attributable to RTM alone because of their asymmetry, nor to the placebo effect as they occurred in the absence of any intervention. However, they could be the result of an Effect of Care, wherein participants had meaningful improvements simply from taking part in a study. The improvement observed in patients with high initial scores should be carefully taken into account when interpreting results from clinical trials.