Effects of progressive muscle relaxation training on nociceptive flexion reflex threshold in healthy young adults: A randomized trial

The variability in nociceptive flexion reflex threshold measurement is mostly caused by probabilistic effects of the estimation algorithms: a simulation study

OBJECTIVES

The nociceptive flexion reflex (NFR) and its threshold are frequently used to investigate spinal nociception in humans. Since this threshold (NFRT) is a probabilistic measure, specific algorithms are used for NFRT estimation based on the stochastic occurrence of reflexes at different stimulus intensities. We used a validated simulation model of the NFR to investigate the amount of NFRT measurement variability induced by different estimation algorithms in a steady setting of reduced external influences.

METHODS

We simulated the behavior of different estimation algorithms in subjects with an artificially steady baseline NFRT variability (standard deviation: 0 mA) or low baseline NFRT variability (standard deviation: 0.156 mA), equaling a quiet experimental setting. The obtained data were analyzed for NFRT measurement variability caused by the algorithms compared to the baseline variability reflecting other physiological influences.

RESULTS

The standard deviation of the NFRT estimated by the different algorithms ranged between 0.381 and 3.464 mA with 96.8% to 99.6% of the measurement variability attributed to the algorithm used. Out of the investigated algorithms the dynamic staircase algorithm was most precise.

CONCLUSION

The NFRT measurement variability observed during quiet and steady experimental sessions is mostly caused by the properties of the estimation algorithms, due to the probabilistic nature of the reflex occurrence. Our results give reference for choosing the optimal estimation algorithm to improve measurement precision.

Modulation of the nociceptive flexion reflex by conservative therapy in patients and healthy people: a systematic review and meta-analysis

ABSTRACT

The nociceptive flexion reflex (NFR) is a spinally mediated withdrawal response and is used as an electrophysiological marker of descending modulation of spinal nociception. Chemical and pharmacological modulation of nociceptive neurotransmission at the spinal level has been evidenced by direct effects of neurotransmitters and pharmacological agents on the NFR. Largely unexplored are, however, the effects of nonpharmacological noninvasive conservative interventions on the NFR. Therefore, a systematic review and meta-analysis was performed and reported following the PRISMA guidelines to determine whether and to what extent spinal nociception measured through the assessment of the NFR is modulated by conservative therapy in patients and healthy individuals. Five electronic databases were searched to identify relevant articles. Retrieved articles were screened on eligibility using the predefined inclusion criteria. Risk of bias was investigated according to Version 2 of the Cochrane risk-of-bias assessment tool for randomized trials. The evidence synthesis for this review was conducted in accordance with the Grading of Recommendations Assessment, Development and Evaluation. Thirty-six articles were included. Meta-analyses provided low-quality evidence showing that conservative therapy decreases NFR area and NFR magnitude and moderate-quality evidence for increases in NFR latency. This suggests that conservative interventions can exert immediate central effects by activating descending inhibitory pathways to reduce spinal nociception. Such interventions may help prevent and treat chronic pain characterized by enhanced spinal nociception. Furthermore, given the responsiveness of the NFR to conservative interventions, the NFR assessment seems to be an appropriate tool in empirical evaluations of treatment strategies.PROSPERO registration number: CRD42020164495.

Are Cardiometabolic Markers of Allostatic Load Associated With Pronociceptive Processes in Native Americans?: A Structural Equation Modeling Analysis From the Oklahoma Study of Native American Pain Risk

Native Americans (NAs) experience higher rates of chronic pain than the general U.S. population, but the risk factors for this pain disparity are unknown. NAs also experience high rates of stressors and cardiovascular and metabolic health disparities (eg, diabetes, cardiovascular disease) consistent with allostatic load (stress-related wear-and-tear on homeostatic systems). Given that allostatic load is associated with chronic pain, then allostatic load may contribute to their pain disparity. Data from 302 healthy, pain-free men and women (153 NAs, 149 non-Hispanic Whites [NHW]) were analyzed using structural equation modeling to determine whether cardiometabolic allostatic load (body mass index, blood pressure, heart rate variability) mediated the relationship between NA ethnicity and experimental measures of pronociceptive processes: temporal summation of pain (TS-pain) and the nociceptive flexion reflex (TS-NFR), conditioned pain modulation of pain (CPM-pain) and NFR (CPM-NFR), and pain tolerance. Results indicated that NAs experienced greater cardiometabolic allostatic load that was related to enhanced TS-NFR and impaired CPM-NFR. Cardiometabolic allostatic load was unrelated to measures of pain perception (CPM-pain, TS-pain, pain sensitivity). This suggests cardiometabolic allostatic load may promote spinal sensitization in healthy NAs, that is not concomitant with pain sensitization, perhaps representing a unique pain risk phenotype in NAs. PERSPECTIVE: Healthy, pain-free Native Americans experienced greater cardiometabolic allostatic load that was associated with a pronociceptive pain phenotype indicative of latent spinal sensitization (ie, spinal sensitization not associated with hyperalgesia). This latent spinal sensitization could represent a pain risk phenotype for this population.

The Relationship Between Adverse Life Events and Endogenous Inhibition of Pain and Spinal Nociception: Findings From the Oklahoma Study of Native American Pain Risk (OK-SNAP)

Adverse life events (ALEs) are a risk factor for chronic pain; however, mechanisms underlying this association are not understood. This study examined whether cumulative ALE exposure impairs endogenous inhibition of pain (assessed from pain report) and spinal nociception (assessed from nociceptive flexion reflex; NFR) in healthy, pain-free Native Americans (n = 124) and non-Hispanic Whites (n = 129) during a conditioned pain modulation (CPM) task. Cumulative ALE exposure was assessed prior to testing by summing the number of potentially traumatic events experienced by each participant across their lifespan. Multilevel modeling found that ALEs were associated with NFR modulation during the CPM task even after controlling for general health, body mass index, sex, age, blood pressure, sleep quality, stimulation intensity, stimulus number, perceived stress, and psychological distress. Low exposure to ALEs was associated with NFR inhibition, whereas high exposure to ALEs was associated with NFR facilitation. By contrast, pain perception was inhibited during the CPM task regardless of the level of ALE exposure. Race/ethnicity did not moderate these results. Thus, ALEs may be pronociceptive for both Native Americans and non-Hispanic Whites by impairing descending inhibition of spinal nociception. This could contribute to a chronic pain risk phenotype involving latent spinal sensitization. PERSPECTIVE: This study found that adverse life events were associated with impaired descending inhibition of spinal nociception in a sample of Native Americans and non-Hispanic Whites. These findings expand on previous research linking adversity to chronic pain risk by identifying a proximate physiological mechanism for this association.

Hypnosis and progressive muscle relaxation for anxiolysis and pain control during extraction procedure in 8-12-year-old children: a randomized control trial

Introduction

Hypnosis (H) and Progressive Muscle Relaxation (PMR) have proven to be effective in a variety of medical settings; there is a paucity of their practical application in paediatric dentistry. The study aimed to comparatively evaluate the role of H and PMR on anxiety, heart rate (HR), oxygen saturation (SPO₂), blood pressure (BP), pain, and analgesic requirement during extraction in children.

Materials and methods

Sixty children aged 8–12 years undergoing primary molar extractions were randomly allocated to three groups—H, PMR, and control (C). The anxiety (proposed Visual Facial Anxiety scale), HR, and SPO₂ were measured pre/post-operatively with/without interventions (H, PMR, C) at 4 intervals. The BP and pain (Wong-Baker faces pain scale) were recorded pre- and post-operatively. Need for analgesic post-operatively was assessed.

Results

Statistically significant reduction in anxiety was noted post-extraction in H (0.30 ± 0.80), PMR (0.50 ± 0.69) (p < 0.001*). HR showed a statistically significant drop after H, PMR application. (p < 0.001*) No significant difference in SPO₂ was noted in the three groups (p > 0.05). Pain control was well achieved using H (85%), PMR (70%); BP was well-regulated in the H, PMR compared to C group (p < 0.001*). Need for analgesics was reduced in H (45%), PMR (50%) versus C (100%). Both techniques H, PMR were comparable in all measures.

Conclusion

Hypnosis and PMR are effective techniques for anxiolysis and pain control in paediatric dental patients.

Does muscular or mental fatigue have an influence on the nociceptive flexion reflex? A randomized cross-over study in healthy people

BACKGROUND

The nociceptive flexion reflex (NFR) is a spinally-mediated withdrawal reflex occurring in response to noxious stimuli and is used as an electrophysiological marker of spinal nociception. Although it is well-documented that the NFR is subject to powerful modulation of several personal factors, the effects of experimentally induced fatigue on the NFR have not yet been examined. Hence, this study aimed to characterize if and how fatigue affects spinal nociception in healthy adults.

METHODS

The NFR of 58 healthy people was measured prior to and following rest and two fatiguing tasks performed in randomized order. The NFR was elicited by transcutaneous electrical stimulation of the sural nerve and objectified by electromyographic recordings from the biceps femoris muscle. An isokinetic fatiguing protocol was used to induce localized muscle fatigue of the hamstrings. The modified incongruent Stroop-word task was used to provoke mental fatigue. A linear mixed model analysis was performed to assess the influence of fatigue on the NFR.

RESULTS

Low-to-moderate levels experimentally induced localized muscle and mental fatigue did not affect the NFR in healthy adults. These results suggest that descending pain inhibitory processes to dampen spinal nociception are resistant to the effects of localized muscle and mental fatigue.

CONCLUSIONS

The relative robustness of the NFR to fatigue may be beneficial in both clinical and research settings where the influence of confounders complicates interpretation. Furthermore, the findings possibly help enhance our understanding on why even demanding cognitive/physical exercise-based treatment programs form effective treatment strategies for patients with chronic pain.

SIGNIFICANCE

The present study unraveled that low-to-moderate levels experimentally induced localized muscle and mental fatigue did not affect the NFR. These results suggest that descending pain inhibitory processes to dampen spinal nociception are resistant to the effects of localized muscle and mental fatigue. This relative robustness of the NFR may be beneficial in a clinical setting in which the evaluation of spinal nociception that is unaffected by clinical symptoms of fatigue may be useful (e.g. chronic fatigue syndrome, cancer-related fatigue, etc.).

Efficacy and Feasibility of Behavioral Treatments for Migraine, Headache, and Pain in the Acute Care Setting

PURPOSE OF REVIEW

This narrative review examines the use of behavioral interventions for acute treatment of headache and pain in the emergency department (ED)/urgent care (UC) and inpatient settings.

RECENT FINDINGS

Behavioral interventions demonstrate reductions of pain and associated disability in headache, migraine, and other conditions in the outpatient setting. Behavioral treatments may be a useful addition for patients presenting with acute pain to hospitals and emergency departments. We review challenges and limitations and offer suggestions for implementation of behavioral interventions in the acute setting. Some evidence exists for relaxation-based treatments, mindfulness-based treatments, hypnosis/self-hypnosis, and immersive virtual reality for acute pain, migraine, and headache. There are few high-quality studies on behavioral treatments in the inpatient and emergency department settings. Further research is warranted to determine the efficacy and cost-effectiveness of these interventions. Given the general safety and cost-effectiveness of behavioral interventions, healthcare professionals may want to include these therapies in treatment plans.

Pain-related anxiety promotes pronociceptive processes in Native Americans: bootstrapped mediation analyses from the Oklahoma Study of Native American Pain Risk

INTRODUCTION

Evidence suggests Native Americans (NAs) experience higher rates of chronic pain than the general US population, but the mechanisms contributing to this disparity are poorly understood. Recently, we conducted a study of healthy, pain-free NAs (n = 155), and non-Hispanic whites (NHWs, n = 150) to address this issue and found little evidence that NAs and NHWs differ in pain processing (assessed from multiple quantitative sensory tests). However, NAs reported higher levels of pain-related anxiety during many of the tasks.

OBJECTIVE

The current study is a secondary analysis of those data to examine whether pain-related anxiety could promote pronociceptive processes in NAs to put them at chronic pain risk.

METHODS

Bootstrapped indirect effect tests were conducted to examine whether pain-related anxiety mediated the relationships between race (NHW vs NA) and measures of pain tolerance (electric, heat, ischemia, and cold pressor), temporal summation of pain and the nociceptive flexion reflex (NFR), and conditioned pain modulation of pain/NFR.

RESULTS

Pain-related anxiety mediated the relationships between NA race and pain tolerance and conditioned pain modulation of NFR. Exploratory analyses failed to show that race moderated relationships between pain-related anxiety and pain outcomes.

CONCLUSION

These findings imply that pain-related anxiety is not a unique mechanism of pain risk for NAs, but that the greater tendency to experience pain-related anxiety by NAs impairs their ability to engage descending inhibition of spinal nociception and decreases their pain tolerance (more so than NHWs). Thus, pain-related anxiety may promote pronociceptive processes in NAs to place them at risk for future chronic pain.

Modified Biofeedback (Conditioned Biofeedback) Promotes Antinociception by Increasing the Nociceptive Flexion Reflex Threshold and Reducing Temporal Summation of Pain: A Controlled Trial

This study examined whether a modified version of biofeedback (ie, Conditioned Biofeedback) that incorporated placebo analgesia-like manipulations could promote antinociception in healthy, pain-free participants. During Conditioned Biofeedback (n = 28), sympathetic arousal level was displayed visually and participants were asked to reduce it while they received painful electric stimulations that were surreptitiously controlled by their arousal level. Thus, electric pain decreased as arousal decreased to associate successful arousal-reduction/relaxation with pain relief, and to promote expectations for future pain relief. A Biofeedback Only group (n = 24) controlled for the general effects of biofeedback/relaxation. A Biofeedback+Shock group (n = 21) controlled for the effects of practicing biofeedback during painful shocks. Nociceptive flexion reflex (NFR) threshold and temporal summation of pain (TS-pain) were used to assess changes in spinal nociception and pain facilitation, respectively. Results indicated all groups showed pre- to postbiofeedback increases in NFR threshold, but only the Conditioned Biofeedback group showed pre- to postbiofeedback reductions in TS-pain. Moreover, Conditioned Biofeedback resulted in a persistent (prebiofeedback) increase in NFR threshold across sessions, whereas Biofeedback Only resulted in a persistent (prebiofeedback) decrease in TS-pain. In sum, Conditioned Biofeedback may promote antinociception in healthy participants thus reducing risk for chronic pain. The study was registered prospectively on ClinicalTrials.gov (TU1560). PERSPECTIVE: A modified version of biofeedback that employs placebo analgesia manipulations was successful in increasing descending inhibition and reducing pain facilitation in healthy volunteers. As a result, it may be an effective means of reducing risk of future chronic pain onset by promoting an antinociceptive pain profile.

The effect of neuromuscular reversal agent on postoperative pain after laparoscopic gastric cancer surgery: Comparison between the neostigmine and sugammadex

Use of sugammadex for neuromuscular block reversal is associated with fewer postoperative complications than neostigmine; however, the effects on postoperative pain outcomes are largely unknown. In this retrospective study, we investigated the relationship between neuromuscular reversal agents and postoperative pain-related outcomes following laparoscopic gastric cancer surgery.We reviewed the electronic health records of patients who underwent laparoscopic gastric cancer surgery between January 2010 and June 2017. Patients were divided into a sugammadex group and a neostigmine group, according to the neuromuscular block reversal agent used. We compared the pain outcomes in the first 3 days postoperatively (POD 0-3), length of hospital stay, and postoperative complications (Clavien-Dindo grade ≥II).During the study period, 3056 patients received sugammadex (n = 901) or neostigmine (n = 2155) for neuromuscular reversal. After propensity score matching, 1478 patients (739 in each group) were included in regression analysis. In linear regression analysis, intravenous morphine equivalent consumption (mg) during POD 0 to 3 was higher in the sugammadex group than in the neostigmine group [coefficient 103.41, 95% confidence interval (CI): 77.45-129.37; P <.001]. However, hospital stay was shorter (coefficient: -0.60, 95% CI -1.12 to -0.08; P = .025) and postoperative complication rate was lower (odds ratio: 0.20, 95% CI 0.07-0.58; P = .003) in the sugammadex group.In this retrospective study, patients undergoing laparoscopic gastric cancer surgery who received sugammadex for neuromuscular block reversal exhibited greater postoperative analgesic requirements than those who received neostigmine but had a shorter hospital stay and a lower postoperative complication rate. A randomized and blinded study should be conducted in the future to confirm the findings of the present study.

Promoting self-management of breast and nipple pain in breastfeeding women: Protocol of a pilot randomized controlled trial

The majority of women experience pain during breastfeeding initiation with few strategies to manage breast and nipple pain. In fact, women cite breast and nipple pain as among the most common reasons for breastfeeding cessation. To address this important issue, we developed a breastfeeding self-management (BSM) intervention, based on the Individual and Family Self-Management Theory Framework. In this framework, self-management is conceptualized as a process in which women use knowledge, beliefs, and social facilitation to achieve breastfeeding goals. The purpose of this longitudinal pilot randomized controlled trial was to test the feasibility, acceptability, and preliminary efficacy of the BSM intervention with women initiating breastfeeding. Recruitment of 60 women intending to breastfeed occurred within 48 hr of delivery and women were randomized to either the intervention or usual care group. The BSM intervention group received BSM education modules that included information of how to manage breast and nipple pain and self-management support through biweekly texting from the study nurse, and were asked to complete a daily breastfeeding journal. Primary outcomes measured at baseline, 1, 2, and 6 weeks will be used to (a) evaluate feasibility, acceptability, and preliminary efficacy of the BSM intervention, and (b) assess the influence of protective and risk factors of breastfeeding pain (including individual genetic polymorphisms related to pain sensitivity) on process variables for self-management of breastfeeding and breastfeeding pain, and on proximal (breastfeeding pain severity and interference, breastfeeding frequency) and distal outcomes (breastfeeding exclusivity and duration and general well-being).

Conditioned Pain Modulation in Sexual Assault Survivors

Sexual assault (SA) is associated with an increased risk of chronic pain, but the mechanisms for this relationship are poorly understood. To explore whether disrupted descending inhibition is involved, this study used a conditioned pain modulation task to study the inhibition of pain and the nociceptive flexion reflex (NFR; a correlate of spinal nociception) in 32 pain-free SA survivors. This group was compared with 32 pain-free, trauma-exposed persons without SA and a group of 40 pain-free persons who reported no trauma exposure. Conditioned pain modulation was assessed from painful electric stimulations (test stimulus) delivered to the ankle before, during, and after participants submerged their hand in painful 10°C water (conditioning stimulus). Pain ratings and NFR were assessed in response to test stimuli. All groups demonstrated significant inhibition of pain during conditioned pain modulation. However, only the no trauma exposure group demonstrated significant inhibition of NFR. The persons without SA group showed no inhibition of NFR, whereas the SA group showed significant facilitation of the NFR. These findings suggest that trauma exposure may impair inhibitory cerebrospinal circuits, but that SA may specifically promote facilitation of spinal nociception. Perspective: This study suggests that trauma exposure disrupts the cerebrospinal inhibition of spinal nociception, but that exposure to SA further promotes chronic pain risk by facilitating spinal nociception. This finding help may help to elucidate the pain risk mechanisms in trauma survivors.

The Influence of Placebo Analgesia Manipulations on Pain Report, the Nociceptive Flexion Reflex, and Autonomic Responses to Pain

Expectations for pain relief and experience/conditioning are psychological factors that contribute to placebo analgesia, yet few studies have studied the physiological mechanisms underlying their effects. This study randomized 133 participants to 4 groups: an expectation only (E-only) group, a conditioning only (C-only) group, an expectation plus conditioning (E+C) group, and a natural history (NH) control group. Painful electric stimulations were delivered before and after an inert cream was applied to the site of stimulation. Pain-related outcomes (pain ratings, nociceptive flexion reflex [NFR], skin conductance response, and heart rate acceleration) were recorded after each stimulation. NFR (a measure of spinal nociception) assessed if placebo analgesia inhibited spinal processing of pain. E+C was the only manipulation that significantly inhibited pain and skin conductance response. Surprisingly, NFR was facilitated in the E+C and E-only groups. No effects were noted for C-only. Mediation analysis suggested 2 descending processes were engaged during E+C that influenced spinal nociception: 1) descending facilitation and 2) descending inhibition that was also responsible for pain reduction. These results suggest that E+C manipulations produce the strongest analgesia and have a complex influence on spinal nociception involving both inhibitory and facilitatory processes. PERSPECTIVE: This study assessed whether placebo analgesia manipulations that include expectations, conditioning, or both modulate the NFR (measure of spinal nociception). Only the manipulation that involved expectations and conditioning inhibited pain, but both expectation manipulations facilitated NFR. This suggests a complex modulation of spinal neurons by placebo manipulations.

Brief relaxation training is not sufficient to alter tolerance to experimental pain in novices

Relaxation techniques, such as deep breathing and muscle relaxation, are aspects common to most forms of mindfulness training. There is now an abundance of research demonstrating that mindfulness training has beneficial effects across a wide range of clinical conditions, making it an important tool for clinical intervention. One area of extensive research is on the beneficial effects of mindfulness on experiences of pain. However, the mechanisms of these effects are still not well understood. One hypothesis is that the relaxation components of mindfulness training, through alterations in breathing and muscle tension, leads to changes in parasympathetic and sympathetic nervous system functioning which influences pain circuits. The current study seeks to examine how two of the relaxation subcomponents of mindfulness training, deep breathing and muscle relaxation, influence experiences of pain in healthy individuals. Participants were randomized to either a 10 minute deep breathing, progressive muscle relaxation, or control condition after which they were exposed to a cold pain task. Throughout the experiment, measures of parasympathetic and sympathetic nervous system activity were collected to assess how deep breathing and progressive muscle relaxation alter physiological responses, and if these changes moderate any effects of these interventions on responses to pain. There were no differences in participants’ pain tolerances or self-reported pain ratings during the cold pain task or in participants’ physiological responses to the task. Additionally, individual differences in physiological functioning were not related to differences in pain tolerance or pain ratings. Overall this study suggests that the mechanisms through which mindfulness exerts its effects on pain are more complex than merely through physiological changes brought about by altering breathing or muscle tension. This indicates a need for more research examining the specific subcomponents of mindfulness, and how these subcomponents might be acting, to better understand their utility as a clinical treatment.

Patient Participation Approach to Reduction of Anterior Shoulder Dislocation: P-R-I-M/O-Y-E-S

A variety of successful techniques are available for reduction of shoulder dislocation; none have been shown to be clearly superior to another. Analgesic methods vary as well from none to deep sedation-analgesia. The literature hints at the importance of optimal muscle relaxation as a factor of success. Yet, the literature describes only cursorily the means by which muscle relaxation is optimized. Patient-centered participation and relaxation methods have been used in other contexts to reduce pain, anxiety, and muscle tension. This article proposes to integrate a patient-centered participation approach to the reduction of anterior shoulder dislocation as a way to optimize muscular relaxation nonpharmacologically. It can be used in the field in combination with the practitioner's reduction technique of choice. It minimizes risks because it entails no deep pharmacological sedation. The mnemonic P-R-I-M/O-Y-E-S is used to respectively represent the four phases: Preparation, Rehearsal, Intervention, and Mobilization as well as the 4 repeated steps in each phase of the procedure: Observe, Yield control, Explain, and Support. The focus is on (1) securing optimal patient participation within a patient-centered approach and (2) achieving nonpharmacological muscular relaxation through a simple relaxation routine. More studies are needed to identify the factors that determine success and guide the practitioner's choice among available options in shoulder dislocation reductions.

The effect of progressive muscle relaxation on daily cortisol secretion

Abbreviated progressive muscle relaxation (APMR) is a much used stress-management technique. Its efficacy relevant to placebo control is already established in the literature and the primary aim of the present study was to ascertain whether its proven impact on psychological stress measures is matched by a decrease in prevailing levels of the stress-associated hormone cortisol, using accurate and robust measurement based on multiple sampling of full diurnal cortisol secretion profiles. First-year university students can face significant stress in adjustment to academic demands and immersion in a novel social network and provided a convenient study population. One hundred and one first-year students completed APMR with prevailing stress levels assessed a week before and after intervention. Both cortisol and self-report measures were significantly reduced post-intervention by 8% and 10%, respectively. The efficacy of the intervention was independent of, and not modulated by neuroticism, gender, age and smoking status. We also demonstrated that cortisol reduction was unlikely to have been a consequence of adaptation to any initial cortisol elevation prompted by the challenge of the demanding saliva collection protocol. We conclude that the efficacy of APMR in this population extends to reduction in biologically expressed stress levels as well as levels based solely on self-report.

Sustainable Reduction of Sleepiness through Salutogenic Self-Care Procedure in Lunch Breaks: A Pilot Study

The aim of the study was to elucidate the immediate, intermediate, and anticipatory sleepiness reducing effects of a salutogenic self-care procedure called progressive muscle relaxation (PMR), during lunch breaks. The second exploratory aim deals with determining the onset and long-term time course of sleepiness changes. In order to evaluate the intraday range and interday change of the proposed relaxation effects, 14 call center agents were assigned to either a daily 20-minute self-administered PMR or a small talk (ST) group during a period of seven months. Participants' levels of sleepiness were analyzed in a controlled trial using anticipatory, postlunchtime, and afternoon changes of sleepiness as indicated by continuously determined objective reaction time measures (16,464 measurements) and self-reports administered five times per day, once per month (490 measurements). Results indicate that, in comparison to ST, the PMR break (a) induces immediate, intermediate, and anticipatory reductions in sleepiness; (b) these significant effects remarkably show up after one month, and sleepiness continues to decrease for at least another five months. Although further research is required referring to the specific responsible mediating variables, our results suggest that relaxation based lunch breaks are both accepted by employees and provide a sustainable impact on sleepiness.

Psychological processing in chronic pain: a neural systems approach

Our understanding of chronic pain involves complex brain circuits that include sensory, emotional, cognitive and interoceptive processing. The feed-forward interactions between physical (e.g., trauma) and emotional pain and the consequences of altered psychological status on the expression of pain have made the evaluation and treatment of chronic pain a challenge in the clinic. By understanding the neural circuits involved in psychological processes, a mechanistic approach to the implementation of psychology-based treatments may be better understood. In this review we evaluate some of the principle processes that may be altered as a consequence of chronic pain in the context of localized and integrated neural networks. These changes are ongoing, vary in their magnitude, and their hierarchical manifestations, and may be temporally and sequentially altered by treatments, and all contribute to an overall pain phenotype. Furthermore, we link altered psychological processes to specific evidence-based treatments to put forth a model of pain neuroscience psychology.

Impact of applied progressive deep muscle relaxation training on the level of depression, anxiety and stress among prostate cancer patients: a quasi-experimental study

BACKGROUND

The aim of this study was to determine the impact of applied progressive muscle relaxation training on the levels of depression, anxiety and stress among prostate cancer patients.

MATERIALS AND METHODS

A quasi-experimental study was conducted at the University Malaya Medical Centre (UMMC) and Universiti Kebangsaan Malaysia Medical Centre (UKMMC) over six months. Prostate cancer patients from UMMC received the intervention and patients from UKMMC were taken as controls. The level of depression, anxiety and stress were measured using Depression, Anxiety Stress Scales - 21 (DASS-21).

RESULTS

A total of 77 patients from the UMMC and 78 patients from the UKMMC participated. At the end of the study, 90.9% and 87.2% of patients from the UMMC and UKMMC groups completed the study respectively. There were significant improvements in anxiety (p<0.001, partial ?2=0.198) and stress (p<0.001, partial ?2=0.103) at the end of the study in those receiving muscle training. However, there was no improvement in depression (p=0.956).

CONCLUSIONS

The improvement in anxiety and stress showed the potential of APMRT in the management of prostate cancer patients. Future studies should be carried out over a longer duration to provide stronger evidence for the introduction of relaxation therapy among prostate cancer patients as a coping strategy to improve their anxiety and stress.

Effects of patterns of pressure application on resting electromyography during massage

BACKGROUND

To increase the understanding of the physiological mechanisms by which massage therapy produces health benefits such as pain relief and anxiety reduction, the relationship between specific elements of massage and physiological outcomes must be addressed.

PURPOSE

The effects on resting muscular activity of applying varying levels of pressure during massage were investigated.

METHODS

In this clinical crossover study, conducted in a simulated clinical setting, human subjects (n = 25; mean age: 34.1 years) received 3 different levels of massage pressure to the legs. A licensed therapist applied pressure to the rectus femoris in a distal-to-proximal direction. Each volunteer received the 3 levels of pressure in 2 different orders-increasing (IP) and decreasing pressures (DP)-separated by at least 4 weeks. Surface electromyography (EMG) was used to measure muscle activity levels at baseline and after each pressure level.

RESULTS

During the trials of IP, EMG did not vary significantly [Greenhouse-Geisser corrected analysis of variance F(1.71 df) = 0.30, p = 0.71]. During the trials of DP, EMG varied significantly [Greenhouse-Geisser corrected analysis of variance F(1.58 df) = 4.49, p = 0.03], with the largest variation, an increase of 235%, noted between baseline activity and activity after deep pressure. After application of light pressure, activity returned to baseline levels. Interestingly, the overall levels of force required to achieve subjective pressure levels as reported by the client were higher in the DP protocol than in the IP protocol (p < 0.02).

CONCLUSIONS

These results suggest that the physiological response of the muscle depends on the pattern of applied pressure during massage. That finding is consistent with a mechanism by which light- or moderate-pressure massage (or a combination) may reduce the gain of spinal nociceptive reflexes. As those reflexes are elevated in chronic pain syndromes, pressure variation provides a possible mechanism for the relief of chronic pain by massage therapy.

Stress and tension-type headache mechanisms

Stress is widely demonstrated as a contributing factor in tension-type headache (TTH). The mechanisms underlying this remain unclear at present. Recent research indicates the importance of central pain processes in tension-type headache (TTH) pathophysiology. Concurrently, research with animals and healthy humans has begun to elucidate the relationship between stress and pain processing in the central nervous system, including central pain processes putatively dysfunctional in TTH. Combined, these two fields of research present new insights and hypotheses into possible mechanisms by which stress may contribute to TTH. To date, however, there has been no comprehensive review of this literature. The present paper provides such a review, which may be valuable in facilitating a broader understanding of the central mechanisms by which stress may contribute to TTH.

Differential development of sensory hypersensitivity and a measure of spinal cord hyperexcitability following whiplash injury

Widespread sensory hypersensitivity is present in acute whiplash and is associated with poor recovery. Decreased nociceptive flexion reflex (NFR) thresholds (spinal cord hyperexcitability) are a feature of chronic whiplash but have not been investigated in the acute to chronic injury stage. This study compared the temporal development of sensory hypersensitivity and NFR responses from soon after injury to either recovery or to transition to chronicity. It also aimed to identify predictors of persistent spinal cord hyperexcitability. Pressure and cold pain thresholds, NFR responses (threshold and pain VAS) were prospectively measured in 62 participants at <3 weeks, 3 and 6 months post whiplash injury and in 22 healthy controls on two occasions a month apart. Pain levels and psychological distress (GHQ-28; IES) were measured at baseline. Whiplash participants were classified at 6 months post-injury using the Neck Disability Index: recovered (8%), mild pain and disability (10-28%) or moderate/severe pain and disability (30%). All whiplash groups demonstrated spinal cord hyperexcitability (lowered NFR thresholds) at 3 weeks post-injury. This hyperexcitability persisted in those with moderate/severe symptoms at 6 months but resolved in those who recovered or reported lesser symptoms at 6 months. In contrast generalized sensory hypersensitivity (pressure and cold) was only ever present in those with persistent moderate/severe symptoms and remained unchanged throughout the study period. This suggests different mechanisms underlie sensory hypersensitivity and NFR responses. In multivariate analyses only initial NDI scores (p=0.003) were a unique predictor of persistent spinal cord hyperexcitability indicating possible ongoing peripheral nociception following whiplash injury.

Cervical lateral glide increases nociceptive flexion reflex threshold but not pressure or thermal pain thresholds in chronic whiplash associated disorders: A pilot randomised controlled trial

Sensory hypersensitivity indicative of augmented central pain processing is a feature of chronic whiplash associated disorders (WAD). This study investigated the immediate effects of a cervical spine manual therapy (SMT) technique on measures of central hyperexcitability. In a randomised, single blind, clinical trial, 39 participants with chronic WAD were randomly assigned to a cervical SMT (lateral glide) or manual contact intervention. The Neck Disability Index (NDI) and GHQ-28 were administered at baseline. Pressure pain thresholds (PPTs), thermal pain thresholds (TPTs) and Nociceptive Flexion Reflex (NFR) responses (threshold and VAS of pain) were measured pre and post intervention. There was a significantly greater increase in NFR threshold following SMT compared to the manual contact intervention (p = 0.04). PPTs at the cervical spine increased following both SMT (mean +/- SE: 24.1 +/- 7.3%) and manual contact (21 +/- 8.4%) with no difference between interventions. There was no difference between interventions for pain ratings with the NFR test, PPTs at the Median Nerve or Tibialis Anterior, heat or cold TPT. SMT may be effective in reducing spinal hyperexcitability in chronic WAD.