Changes In Pain Perception Research Articles

An electroencephalography (EEG) study of short-term electromyography (EMG) biofeedback training in patients with myofascial pain syndrome in the upper trapezius.

[Purpose] In the present study, electroencephalography was used to explore neural activity related to electromyography biofeedback training, focusing on pain perception before and after electromyography biofeedback. [Participants and Methods] Twenty-seven participants (female=23; mean age: 28.85 ± 4.99 years) with mild-to-moderate myofascial pain syndrome in the upper trapezius were recruited for this study. All participants underwent electroencephalography recording before, during, and after (0 and 15 min) electromyography biofeedback training. Quantitative electroencephalography analysis was performed to obtain the absolute power of the four main frequency bands. Pain scores before and after electromyography biofeedback were also evaluated by subjective rating. [Results] Electromyography biofeedback increased alpha power and decreased delta power 15 minutes after training, suggestive of relaxation. However, although a tendency for scores to decrease was observed, no significant improvements in pain scores were observed following the intervention. Such results may be due to the short duration of the biofeedback session and the subjective nature of pain assessments. [Conclusion] Despite no obvious changes in pain perception, brief electromyography biofeedback training may induce relaxation in patients with myofascial pain syndrome of the upper trapezius muscle.

The effect of spinal manipulative therapy on heart rate variability and pain in patients with chronic neck pain: a randomized controlled trial

BackgroundRecent experimental research has suggested that spinal manipulative therapy (SMT) may reduce pain through modulation of the ascending pain signals and/or the central pain-regulating mechanisms. People with persistent neck pain (NP) have also been found to have disturbances in autonomic nervous system (ANS) regulation. A common way to study the ANS is to measure heart rate variability (HRV). It is not known whether deviations in HRV are related to changes in pain perception or to the treatment response to SMT.Commonly, an individual in pain will experience pain reduction when exposed to a second pain stimulus, a mechanism known as conditioned pain modulation (CPM). Patients with persistent pain have been found to have a reduced CPM reaction. It is not known whether this is predictive of treatment response to SMT.The aim of the study is to examine the effects of SMT on HRV and pain. Further, a secondary aim is to test whether a CPM test can be used to predict treatment response in a population of patients with recurrent and persistent NP.Method/designA multicentre randomized controlled clinical trial will be carried out in multidisciplinary primary care clinics. This setting is chosen to minimize bias resulting from patient preference for the treatment modality and provider.The subjects are either self-referred or referred from other health care practitioners locally. The treatment modalities are two well-known interventions for NP; SMT and stretching exercises compared to stretching exercises alone.HRV will be measured using a portable heart monitor. The subjective pain experience will be investigated by assessing pain intensity and the affective quality of pain. CPM will be measured with a standardized cold pressor test. Measurements will be performed three times during a 2-week treatment series.DiscussionThe study will utilize normal clinical procedures, which should aid the transferability and external validity of the results. The study will provide knowledge regarding the underlying mechanisms of the effects of SMT. Furthermore, the study will examine whether a CPM test is predictive of treatment outcome in a population of patients with recurrent and persistent NP.Trial registrationClinicalTrials.gov, NCT03576846. Registered on 3 July 2018.

Prodromal Parkinson's and RBD: Clinical signs and polysomnographical changes

The current diagnosis of Parkinson’s disease (PD) includes only motor symptoms: two of the three cardinal motor features, hypokinesia, tremor and rigidity, have to be present according to UK Parkinson’s Disease Society Brain Bank Criteria (Gibb and Lees, JNNP 1988). “Prodromal Parkinson” includes signs in the gastrointestinal system, in sleep-wake regulation, and in the autonomic nervous system, changes in pain perception and psychopathological alterations. When motor symptoms start, more than 50% of dopaminergic neurons are already degenerated, and long before the affection of these midbrain areas α-synuclein positive pathology occurs in the lower brainstem and olfactory bulb. REM sleep behavior disorder (RBD) is currently the most specific prodromal feature of α-synuclein pathology, which may manifest even a decade before motor symptoms. In an 18-year follow-up study more than 80% of the subjects of a cohort with idiopathic RBD have developed a neurodegenerative disease (Schenck et al Sleep Med 2013). Idiopathic RBD is defined by the International Classification of Sleep Disorders in its current 2014 version (ICSD-3, (Sleep 2014)). Clinical RBD is characterized by vocalizations, jerky movements of the extremities or the whole body, bed falls or complex movements and are shown in videos taken from patients with idiopathic RBD or RBD in PD. RBD includes a pathologically increased muscle tone of the chin (REM without atonia, RWA) recorded during REM sleep in polysomnography. For measurement of RWA surface electromyography (EMG) activity of the mentalis muscle is commonly quantified according to the method published by the SINBAR group (Frauscher et al Sleep 2012), with an amplitude exceeding twice the background EMG activity and a cut-off value of >18.2%. The prevalence of RBD in newly diagnosed PD patients is about 25%, with an increasing percentage during the course of the disease, such as a marker of progression of PD (Sixel-Doering et al, MDJ abstr 2019). RBD occurs in synucleinopathies such as PD and even more frequently in dementia with Lewy Bodies (DLB) and in multiple system atrophy (MSA). Unfortunately none of these non-motor parameters and RBD can be shown in each single PD patient, some PD patients even miss many of these non-motor features or develop them later in the disease. Therefore the term “Prodromal Parkinson” has still to be elucidated by larger studies to delineate the most specific pattern of premotor signs.

Nitrous Oxide - a Viable and Modern Alternative for Inhalation Analgesia in Labor

Pain in labor is an important factor in establishing the prognosis of birth and the quality of the conception product, painful uterine contractions being the main physical and psychological stress factor for the pregnant woman that can be decisive for the birth plan. In the management of labor, individualized analgesic therapy is needed to ensure anesthetic comfort as well as cooperation of the pregnant woman in the last part of labor. Analgesia is not supposed to interfere with the mechanisms that are essential during the expulsion, namely with the intensity and duration of the uterine contraction. The last two decades have consecrated natural birth with controlled pain, which allowed the keeping of a limited incidence of caesarean surgery, attitude recommended by the World Health Organization. However, in Romania the trend towards caesarean births has spiked, including due to little promotion of analgesic techniques for natural birth. One of the most used techniques of analgesia, administration of nitrous oxide - N2O and oxygen - O2 50-50% gaseous mixture represents a viable possibility of pain modulation. Our paper is a descriptive study, examining objective changes of pain perception in a sample of pregnant women with low obstetrical risk, aiming to analyze the quality of analgesia offered by the N2O and O2 50-50% gaseous mixture.

Impact of menopause and ageing on joints

Musculoskeletal pain, arthralgia and arthritis are all more common in women and their frequency increases with age. Musculoskeletal pain is one of the commonest symptoms reported at the time of the menopause, present in up to 50% of women. The effects of ageing and of estrogen deficiency on joint tissues are discussed, and how this might manifest in the clinic. Changes in muscle (sarcopenia), soft tissues (tendon, ligament), cartilage volume and bone health, as well as changes in pain perception are seen in both conditions. Separating the effects of ageing and other changes due to menopause can therefore be challenging. The evidence for the role of sex hormone deficiency in the aetiology of musculoskeletal pain and arthritis will be reviewed, both in preclinical models and in human studies. There have been few interventional studies specifically within this group of symptomatic patients. Although there may be strong circumstantial evidence, a proven causal link between hormonal changes at the time of menopause and the pathogenesis of conditions such as fibromyalgia, osteoarthritis or rheumatoid arthritis has not been demonstrated. There remains much still to understand about how we might approach preventing or treating musculoskeletal pain and arthritis at the time of the menopause.

The effects of chiropractic spinal manipulation on central processing of tonic pain - a pilot study using standardized low-resolution brain electromagnetic tomography (sLORETA)

The objectives of the study were to investigate changes in pain perception and neural activity during tonic pain due to altered sensory input from the spine following chiropractic spinal adjustments. Fifteen participants with subclinical pain (recurrent spinal dysfunction such as mild pain, ache or stiffness but with no pain on the day of the experiment) participated in this randomized cross-over study involving a chiropractic spinal adjustment and a sham session, separated by 4.0 ± 4.2 days. Before and after each intervention, 61-channel electroencephalography (EEG) was recorded at rest and during 80 seconds of tonic pain evoked by the cold-pressor test (left hand immersed in 2 °C water). Participants rated the pain and unpleasantness to the cold-pressor test on two separate numerical rating scales. To study brain sources, sLORETA was performed on four EEG frequency bands: delta (1–4 Hz), theta (4–8 Hz), alpha (8–12 Hz) and beta (12–32 Hz). The pain scores decreased by 9% after the sham intervention (p < 0.05), whereas the unpleasantness scores decreased by 7% after both interventions (p < 0.05). sLORETA showed decreased brain activity following tonic pain in all frequency bands after the sham intervention, whereas no change in activity was seen after the chiropractic spinal adjustment session. This study showed habituation to pain following the sham intervention, with no habituation occurring following the chiropractic intervention. This suggests that the chiropractic spinal adjustments may alter central processing of pain and unpleasantness.

New life for an old idea: Assessing tonic heat pain by means of participant controlled temperature

BackgroundTemporal changes of pain perception to prolonged tonic heat pain are conventionally assessed using a computerized visual analog scale. Such a rating-based approach is, however, prone to floor and ceiling effects, which limit the assessment of temporal changes in perception. Thus, alternative methods that overcome these shortcomings are warranted. New methodThe aim of this study was to assess the feasibility and reliability of a psychophysical approach, i.e., participant-controlled temperature (PCT), to evaluate ongoing human perception of tonic heat pain. Fifty participants were presented with a 45 °C stimulus on the non-dominant hand, and were instructed to maintain their initial sensation for two minutes via a feedback controller in the dominant hand. A subset of participants (n = 17) performed PCT tonic heat protocols on two different days to determine the test-retest reliability. As participants controlled temperature to maintain a stable pain perception, any adjustments made reflected shifts in their perception of heat. ResultsIn 33 (71.7%) participants, we observed an initial adaptation (participant increased temperature) followed by temporal summation of pain (participant decreased temperature). Twelve participants (26.1%) showed only adaptation and one (2.2%) only temporal summation. No sex differences were observed, nor did the initial rating of pain have an effect on PCT outcomes. Temporal summation of pain showed moderate to substantial reliability upon retest. ConclusionsPCT represents can be reliably performed using a contact heat stimulator to measure the temporal summation of pain. The standardized setup and overall good reliability of the outcome measures facilitate a sound implementation into the clinical work-up of patients with pain conditions.

Congenital Laser-Induced Burns: A Potential Complication after Laser Photocoagulation in Monochorionic Twin Pregnancy

Background: Fetoscopic laser photocoagulation can directly injure fetal skin and may at birth resemble aplasia cutis congenita (ACC). Case report: A twin monochorionic pregnancy was complicated by twin-to-twin transfusion syndrome requiring in utero laser photocoagulation, resulting in the death of one twin. After birth, the viable baby presented skin lesions in both legs that were congruent with laser-induced burns. Conclusions: Laser-induced burns present as asymmetric superficial non-necrotic or ulcerated lesions, with a geographic outline, which turn into scars with no retraction or contractures and no changes in pain perception or motor limitations over time. ACC lesions are bilateral and symmetric, with a regular outline, an ulcerated or necrotic appearance, a higher degree of skin involvement affecting all skin layers and, over time, they turn into scars with retraction and contractures. These differential features may help clinicians in a challenging approach to the diagnosis of congenital skin defects.

Attenuation of capsaicin-induced ongoing pain and secondary hyperalgesia during exposure to an immersive virtual reality environment

Introduction:There is growing evidence that virtual reality (VR) can be used in the treatment of chronic pain conditions. However, further research is required to better understand the analgesic mechanisms during sensitised pain states.Objectives:We examined the effects of an immersive polar VR environment on capsaicin-induced ongoing pain and secondary hyperalgesia. We also investigated whether the degree of analgesia was related to baseline conditioned pain modulation (CPM) responses.Methods:Nineteen subjects had baseline CPM and electrical pain perception (EPP) thresholds measured before the topical application of capsaicin cream. Visual analogue scale ratings were measured to track the development of an ongoing pain state, and EPP thresholds were used to measure secondary hyperalgesia. The effects of a passive polar VR environment on ongoing pain and secondary hyperalgesia were compared with sham VR (ie, 2D monitor screen) in responders to capsaicin (n = 15).Results:Virtual reality was associated with a transient reduction in ongoing pain and an increase in EPP thresholds in an area of secondary hyperalgesia. Baseline CPM measurements showed a significant correlation with VR-induced changes in secondary hyperalgesia, but not with VR-induced changes in ongoing pain perception. There was no correlation between VR-induced changes in pain perception and VR-induced changes in secondary hyperalgesia.Conclusion:Virtual reality can reduce the perception of capsaicin-induced ongoing pain and secondary hyperalgesia. We also show that CPM may provide a means by which to identify individuals likely to respond to VR therapy.

Assessment of spinal arthrodesis in dorsolumbar spine trauma using hydroxyapatite, tricalcium phosphate, and 60% hydroxyapatite + 40% tricalcium phosphate: A comparative study

Study Design: Open level experimental design. Purpose: Ceramics are effective, safe, and good alternatives of iliac crest autograft for spinal fusion. There were not enough study available to compare among ceramics for fusion in spinal surgery. Our aim was comparative assessment of posterolateral spinal arthrodesis radiologically and clinically in dorsolumbar spine trauma using hydroxyapatite (HA), tricalcium phosphate (TCP), and 60% HA + 40% TCP. Overview of Literature: Surgical management of thoracolumbar spine injury has encouraged early rehabilitation and avoided adverse effects of prolonged recumbency. Instrumentation enhanced spinal fusion which was the main technique of spinal stabilization. Although iliac crest autograft is the gold standard for spinal fusion,the procedure is not devoid of major and minor complications. A variety of ceramics are available as good alternatives for spinal arthrodesis. There are not any studies in the literature comparing spinal fusion rate among commonly used ceramics. Materials and Methods: Patients having Thoraco Lumbar Injury Classification and Severity score ≥4 underwent pedicle screw fixation and decompression (if required). We applied chips of HA, TCP, or 60% HA + 40% TCP for fusion. At 12-month follow-up, computed tomography scan of involved spine was done to assess posterolateral fusion by Lenke classification. Clinical follow-up was done evaluating pain status (visual analog scale). Mean follow-up duration was 27.8 months. Radiological and clinical parameters were compared among three groups. Results: A total of 45 patients (16 received HA, 15 received TCP, and 14 received [60%HA + 40%TCP]) were analyzed. About 28.88% of total patients had Lenke Grade A fusion and 51.11% had Grade B, but no statistically significant difference (P = 0.09) among three groups. Although reduction of pain score occurred individually in all three groups,no significant difference (P = 0.3)was noted among three groups. Conclusions: There was no statistically significant difference in fusion rate and change in pain perception with applied ceramics (HA/TCP/[60%HA + 40%TCP]).

Noninvasive brain stimulation over dorsolateral prefrontal cortex for pain perception and executive function in aging

ObjectivesBased on the evidence that the dorsolateral prefrontal cortex (DLPFC) is the main region affected by the aging process, and that tDCS modulates cortical excitability, the aim of the study is to prove the feasibility of tDCS for pain perception and executive function of community-dwelling elderly individuals. MethodsWe performed a double-blind, single-arm trial, including a sham period. 5 consecutive anodal tDCS was applied over DLPFC of twenty-four elderly for 20 min during each intervention periods (in order of Sham-1 mA–2 mA). First, we classified chronic non-inflammatory pain sites into three domain (Neck and upper extremity, low back, lower extremity). Then, we used visual analogue scale, pain self-efficacy scale, Tampa scale for kinesiophobia, and Global perceived Effect scale to observe the change in pain perception, as well as Trailing Making Test and Timed Up and Go (dual) to observe the change in executive function. The changes in maximal grip strength and 12-item Short Form survey were measured secondarily. ResultsIn the results, we observed significant improvement in pain perception and quality of life, while executive function and grip strength did not change significantly. ConclusionOur findings demonstrated the feasibility of tDCS for aging-related pain perception and suggest that further randomized controlled trials with longer duration are necessary to examine the effects on executive function.

Effects of continuous theta-burst stimulation of the primary motor and secondary somatosensory areas on the central processing and the perception of trigeminal nociceptive input in healthy volunteers.

Noninvasive modulation of the activity of pain-related brain regions by means of transcranial magnetic stimulation promises an innovative approach at analgesic treatments. However, heterogeneous successes in pain modulation by setting reversible "virtual lesions" at different brain areas point at unresolved problems including the optimum stimulation site. The secondary somatosensory cortex (S2) has been previously identified to be involved in the perception of pain-intensity differences. Therefore, impeding its activity should impede the coding of the sensory component of pain intensity, resulting in a flattening of the relationship between pain intensity and physical stimulus strength. This was assessed using inactivating spaced continuous theta-burst stimulation (cTBS) in 18 healthy volunteers. In addition, cTBS was applied on the primary motor cortex (M1) shown previously to yield moderate and variable analgesic effects, whereas sham stimulation at both sites served as placebo condition. Continuous theta-burst stimulation flattened the relationship between brain activation and stimulus strength, mainly at S2, the insular cortex, and the postcentral gyrus (16 subjects analyzed). However, these effects were observed after inactivation of M1 while this effect was not observed after inactivation of S2. Nevertheless, both the M1 and the S2-spaced cTBS treatment were not reflected in the ratings of the nociceptive stimuli of different strengths (17 subjects analyzed), contrasting with the clear coding of stimulus strength by these data. Hence, while modulating the central processing of nociceptive input, cTBS failed to produce subjectively relevant changes in pain perception, indicating that the method in the present implementation is still unsuitable for clinical application.

Opioid analgesics prescription in people with and without cancer in France.

According to World Health Organization recommendations, opioids prescription is a key aspect of improvement in cancer pain relief. However, studies on opioids prescription in France are scarce. This study aimed principally to investigate the impact of cancer on opioids prescription and then to identify factors associated with this prescription, focusing on patients& characteristics impact. We matched the following two cohorts: cancer survivors (N = 6,760) and individuals without cancer (N = 6,760). Using French health insurance databases, we compared the prevalence of prescribed opioids in 2009-2015 in people with and without cancer and we applied afterwards conditional Poisson regressions to estimate relative risks for monthly opioids prescription. For cancer survivors only (N = 3,055), multivariate negative binomial regressions were performed to identify factors associated with opioids prescription. Cancer was associated with a higher analgesics prescription in the cancer population. While Step II and III opioids prescription decreased over time, the latter remained marginal and tended to stabilize. Older people were most adversely affected by underprescription of opioids, especially Step III opioids. Furthermore, although the matched case/control study suggested that men were prescribed opioids more often than women, multivariate analysis did not support this finding. The inconsistency between our findings and existing literature regarding both opioids prescription trends and postdiagnosis pain chronicity in cancer survivors over the medium term suggests possible changes in pain perception and the evolution of cancer pain management strategies. Further research should explore these hypotheses and investigate patient characteristics& effect in cancer pain management.

Has aerobic exercise effect on pain perception in persons with migraine and coexisting tension-type headache and neck pain? A randomized, controlled, clinical trial.

A large subset of persons with migraine suffers from coexisting tension-type headache and neck pain which may adversely affect the prognosis of migraine. Aerobic exercise has been shown to decrease migraine burden in these persons. Therefore, the aim of this study was to investigate whether the effect of aerobic exercise in persons with migraine and coexisting tension-type headache and neck pain can be explained by changes in pain perception. Seventy consecutively recruited persons with migraine and coexisting tension-type headache and neck pain were randomized into exercise group or control group. Aerobic exercise consisted of bike/cross-trainer/brisk walking for 45min, three times/week for 3months. Controls continued their usual daily activities. Pericranial tenderness, pain thresholds, supra-thresholds and temporal summation were assessed at baseline, after treatment and at follow-up (6months from baseline). Fifty-two persons with migraine and coexisting tension-type headache and neck pain completed the study. Aerobic exercise did not induce consistent changes in nociceptive pathways measured by pericranial tenderness, pressure pain thresholds and sensitivity to electrical stimulation. The effect of aerobic exercise cannot be explained by measurable effects on the pain modulation system. Thus, the positive effect on migraine burden may rather be explained by positive alteration of avoidance behaviour. Aerobic exercise can be recommended as a safe and inexpensive migraine treatment strategy. This study adds further knowledge about the positive effect of aerobic exercise for persons with migraine and coexisting tension-type headache and neck pain. This effect cannot be measured by changes in pain modulation, but may rather be explained by positive alteration of avoidance behaviour.

Changes in Pain Perception following Psychotherapy: The Mediating Role of Psychological Components.

Chronic pain is frequently associated with significant psychological issues, such as depression or anxiety. Psychological treatments, such as psychotherapy, can often alleviate both psychological and pain symptoms. However, there is limited research about the association between psychological symptoms and perceived pain in the context of psychotherapeutic interventions. We conducted a retrospective study that analyzed, in a hospital context, how changes in psychological functioning and well-being were associated with pain reduction. Thirty-seven records of patients with chronic pain attending psychotherapy in a public hospital were included. All patients were assessed before psychotherapy, as well as after 6 and 10 months, with self-reported questionnaires about pain, anxiety, depression, and psychological functioning. Results indicate that reductions in anxiety, depression, psychological problems, risk factors, and well-being are strongly related with a reduction in pain, further confirming the hypothesis that psychological morbidity is associated with pain severity.

408 Assessment of variables in perception of noxious and non-noxious stimuli in dermatological surgery patients

Various dermatologic treatments necessitate that patients experience pain, the most common being in office injection of local anesthetic prior to invasive procedures. Indeed, across all medical fields, there are over 300 million annual administrations of buffered lidocaine with epinephrine. The pain of the injection causes a significant number of patients to experience anxiety and, as such, many patients actively avoid treatment of potentially devastating cutaneous malignancies. The aim of our study is to discern the clinical and ultimately physiological variability by which pain and tactile perception is experienced across cohorts of surgical patients. Studies have delineated a milieu of factors by which pain perception varies including age, gender, psychological parameters, and history of chronic pain. However, few studies have analyzed these results in the setting of dermatological surgery. By then broadly categorizing patients into pain-tolerant and pain-intolerant subgroups, we test how these two groups differentially interpret non-noxious stimuli, such as hot, cold, and vibration. We hypothesize that those with a predilection for pain perception will show less tolerability of non-noxious stimuli. Our final aim is to preempt patients with a non-noxious stimulus and then analyze how immediately subsequent pain perception changes. While prior studies from our group have found that the use of vibration immediately preceding injection significantly reduces the pain of injections, there is no understanding how pain masking varies across different pain-tolerant cohorts. Future studies will aim to determine the specific neuronal pathways involved in pain-masking and augmentation. Our working hypothesis is that pain-masking is based in gate-control theory: the activation of non-noxious Aβ fibers inhibiting the noxious fast spiking Aδ and slow unmyelinated C fibers. Ultimately, this information will allow us to derive patient specific, algorithmic augmentation of tactile stimulation to minimize the perception of pain during procedures.

A comparison of isometric, isotonic concentric and isotonic eccentric exercises in the physiotherapy management of subacromial pain syndrome/rotator cuff tendinopathy: study protocol for a pilot randomised controlled trial

BackgroundSubacromial pain syndrome (SPS) involving rotator cuff tendinopathy is a common cause of shoulder pain and disability. Evidence suggests that structured physiotherapy may be as effective as surgery in this condition with significant improvements demonstrated in trials involving scapular retraining, rotator cuff strengthening and flexibility exercises. Most published programs typically utilise isotonic concentric and/or eccentric strengthening modes. Recently, immediate analgesic effects and muscle strength gains following heavy-load isometric exercises in lower limb tendinopathy conditions have been observed. It is pertinent to ascertain whether such outcomes can be replicated in SPS/rotator cuff tendinopathy. The primary aim of this study is to establish the feasibility of undertaking a full-scale randomised controlled trial (RCT) that compares the effects of isometric, isotonic concentric and isotonic eccentric rotator cuff contractions when used as part of a semi-standardised exercise-based physiotherapy program in patients diagnosed with SPS. The secondary aim is to explore potential trends or treatment effects of the exercise intervention.MethodsThirty-six participants diagnosed with SPS will be randomised to one of three intervention groups and undergo a one-on-one exercise-based physiotherapy intervention, involving scapular and rotator cuff muscle retraining and strengthening. Each group will utilise a different mode of rotator cuff strengthening—isometric, isotonic concentric or isotonic eccentric. Rotator cuff tendon responses to isometric loading are not yet established in the literature; hence, individualised, progressive loading will be used in this pilot study in accordance with symptoms. The intervention will involve two phases: during Phase 1 (weeks 1–6) participants undertake the active group-specific physiotherapy treatment; in Phase 2 (weeks 6–12), they undertake a progressive, but no longer group-specific exercise program. To determine feasibility, an evaluation of key study parameters including (a) ease of recruitment (rate and number as well as suitability of the assessment algorithm), (b) adherence to all phases of the exercise intervention including home program compliance and logbook completion, (c) participant non-completion (drop out number and rate) and (d) adverse events (nature and number) will be undertaken. Secondary outcomes will measure immediate effects: (i) within-treatment changes in pain perception (verbal rating scale (VRS) and shoulder muscle strength (hand-held dynamometer) as well as longer-term changes: (ii) shoulder-related symptoms and disability (Western Ontario Rotator Cuff Index (WORC) and Shoulder Pain and Disability Index (SPADI)), (iii) perception of pain (11-point numerical rating scale (NRS), (iv) shoulder muscle strength (hand-held dynamometer) and (v) perceived global rating of change score. The immediate within-treatment assessment of pain and muscle strength will be undertaken in treatments 2 and 3, and the longer term measures will be collected at the primary (conclusion of Phase 1 at 6 weeks) and secondary (conclusion of Phase 2 at 12 weeks) end-points of the study.DiscussionThe findings of this pilot study will permit evaluation of this study design for a full-scale RCT.Trial registrationAustralian New Zealand Clinical Trials Registry, ACTRN12616001676404

Endometriosis alters anxiety, depression and pain perception as well as brain electrophysiology and gene expression in mice

Although various psychological and behavioral symptoms are observed in endometriosis patients, the underlying changes in the brain remain unknown. Identifying specific molecular mechanisms associated with pain, depression and anxiety in endometriosis patients is necessary to develop targeted treatment strategies for women who are undergoing these symptoms. This study aim to determine if endometriosis could cause central pain sensitization, anxiety and depression in a mouse model and the molecular changes in the brain that are mechanistically responsible. Endometriosis was induced in experimental mice to identify changes in pain perception, brain electrophysiology and differential gene expression that were induced by endometriosis by performing behavioral tests, qRT-PCR and patch-clamp testing. Experimental endometriosis was created in 9 weeks old female C57BL/6 mice by suturing uterine tissue into the peritoneal cavity while controls underwent sham surgery (N= 5). Behavioral tests including hot plate, open field and tail suspension were performed at serial time point. Mice were sacrificed after 12 weeks of surgery and brain was collected (insula, amygdala, hippocampus and cerebral cortex) by microdissection. Differential gene expression was detected by affymetrix array followed by qRT-PCR validation. Protein expression was detected by immunohistochemical staining. Electrophysiology studies were carried out by whole-cell patch clamp (at -60 mV) in coronal slices of amygdala or insular cortex (300 μm thick) to observe miniature excitatory postsynaptic currents (mEPSCs) and miniature inhibitory postsynaptic currents (mIPSCs) in layer 11/ III pyramidal cells. In the presence of tetrodotoxin (TTX, 0.5μM), mEPSCs were recorded under voltage clamp at -60 mV and mIPSCs were recorded at 0 mV from the same cells, respectively. Behavioral tests revealed that endometriosis mice were more sensitive to pain, depressed and anxious compared to sham controls. We identified differential gene expression in the insula, amygdala, hippocampus and cerebral cortex of endometriosis mice by microarray studies. Genes such as Nptx2 and Lcn2 from amygdala and Lct, Serpina3n, Gpr88 and Glra3 from insula which are involved in anxiety, locomotion and pain were further reconfirmed by qRT-PCR as well as IHC. Patch clamp recordings in the amygdala were altered in endometriosis mice. Endometriosis induced central pain sensitization, anxiety and depression through modulating brain gene expression and electrophysiology. Brain modulation may underlie pain sensitization reported in women with endometriosis and other chronic pain syndromes.

Swearing as a response to pain: A cross-cultural comparison of British and Japanese participants

Background and aimsResearch suggests swearing can moderate pain perception. The present study assessed whether changes in pain perception due to swearing reflect a “scripting” effect by comparing swearing as a response to pain in native English and Japanese speakers. Cognitive psychology denotes a ‘script’ to be a sequence of learnt behaviours expected for given situations. Japanese participants were included as they rarely, if ever, swear as a response to pain and therefore do not possess an available script for swearing in the context of pain. It was hypothesised that Japanese participants would demonstrate less tolerance and more sensitivity to pain than English participants, and – due to a lack of an available script of swearing in response to pain – that Japanese participants would not experience swearword mediated hypoalgesia. MethodsFifty-six native English (mean age=23 years) and 39 Japanese (mean age=21) speakers completed a cold-pressor task whilst repeating either a swear on control word. A 2 (culture; Japanese, British)×2 (word; swear; non-swear) design explored whether Japanese participants showed the same increase in pain tolerance and experienced similar levels of perceived pain when a swearing intervention was used as British participants. Pain tolerance was assessed by the number of seconds participants could endure of cold-pressor exposure and self-report pain measurements. Levels of perceived pain were assessed using a 120-mm horizontal visual analogue scale anchored by descriptors in the participant's native language of “no pain” (left) and “terrible pain” (right). The participant was asked to mark a 10mm vertical line to indicate overall pain intensity. The score was measured from the zero anchor to the participant's mark. ResultsJapanese participants reported higher levels of pain (p<0.005) and displayed lower pain tolerance than British participants (p<0.05). Pain tolerance increased in swearers regardless of cultural background (p<0.001) and no interaction was found between word group and culture (p=0.96), thereby suggesting that swearing had no differential effect related to the cultural group of the participant. ConclusionsThe results replicate previous findings that swearing increases pain tolerance and that individuals from an Asian ethnic background experience greater levels of perceived pain than those from a Caucasian ethnic background. However, these results do not support the idea of pain perception modification due to a “scripting” effect. This is evidenced as swearword mediated hypoalgesia occurs irrespective of participant cultural background. Rather, it is suggested that modulation of pain perception may occur through activation of descending inhibitory neural pain mechanisms. ImplicationsAs swearing can increase pain tolerance in both Japanese and British people, it may be suggested that swearword mediated hypoalgesia is a universal phenomenon that transcends socio-cultural learnt behaviours. Furthermore, swearing could be encouraged as an intervention to help people cope with acute painful stimuli.

The effect of rigid taping with tension on mechanical displacement of the skin and change in pain perception

ObjectivesTo investigate the effect of rigid taping that induces mechanical displacement of the skin on pain perception. DesignSingle group experiment design with repeated measures. MethodsTwenty-three active healthy volunteers (12 men and 11 women) participated in the study. All participants received three different taping procedures: no tape, taping with tension, and taping without tension. The order of three taping conditions was randomised. Skin displacement was measured during taping with tension. A pressure algometer was used to measure the level of pain perception once before taping, and again after each taping condition, in one testing session. The participants were blind to the values of their pressure pain threshold (PPT) during the experimental period. ResultsThe mean±SD skin displacement in the condition of taping with tension was 2.58±0.49cm. There were significant differences in PPT between taping with tension and taping without tension (mean difference (mean diff)±standard error (SE) 36.43±4.22kPa, p=0.000) and no tape (mean diff±SE 44.31±3.13kPa, p=0.000). No significant difference in PPT between no tape and taping without tension was found (mean diff±SE 7.88±2.83kPa, p=0.067). ConclusionsTaping with tension increases the threshold of pressure pain perception. Therefore, stretch and compression caused by rigid taping with tension could disturb the nociceptive signal transmission and alter pain perception.