Patients with symptomatic permanent atrial fibrillation show quantitative signs of pain sensitisation

Background/Introduction Most patients with atrial fibrillation (AF) report symptoms, while around one-third are asymptomatic. We hypothesized that sensory processing, in particular pain, differs in patients with symptomatic and asymptomatic AF. Purpose To assess differences in pain sensitisation in patients with symptomatic and asymptomatic AF. Methods Thirty individuals with permanent AF (15 symptomatic, 15 asymptomatic) completed the AF6 and SF-36 questionnaires and underwent quantitative pain sensitisation testing using pressure algometry at the sternum (referred pain area) and the tibialis anterior muscle (generalized pain area). The primary objective was to assess differences in pressure pain thresholds (PPT), temporal summation of pain (TSP), and conditioned pain modulation (CPM) in the two groups. The secondary objective was to determine association of demographic and clinical parameters to quantitative measures of pain sensitisation. Results The symptomatic group had lower PPTs at both tibialis (p=0.004) and sternum (p=0.01), as well as impaired CPM (p=0.025) and facilitated TSP (p=0.008) at the tibialis but not sternum, compared to the asymptomatic group. The AF6 sum score was negatively correlated to PPT on both tibialis (r=−0.50, p=0.005) and sternum (r=−0.42, p=0.02) and positively correlated to TSP of both tibialis (r=0.57, p=0.001) and sternum (r=0.45, p=0.01), but not to CPM. The physical component summary score was positively correlated to the PPT on both tibialis (r=0.52, p=0.003) and sternum (r=0.40, p=0.03) and negatively to TSP on the tibialis (r=−0.53, p=0.003) but not sternum. Conclusions Patients with symptomatic AF exhibit lower pain tolerance than patients with asymptomatic AF, as well as impaired pain inhibitory control and facilitated summation of pain, indicating that pain sensitisation may be of importance in symptomatic AF. FUNDunding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Department of Cardiology, Örebro University, Sweden PPTs tibialis anterior muscle PPTs sternum

Spatiotemporal patterns of pain distribution and recall accuracy: a dose-response study

Objectives Clinical decisions rely on a patient’s ability to recall and report their pain experience. Monitoring pain in real-time (momentary pain) may reduce recall errors and optimize the clinical decision-making process. Tracking momentary pain can provide insights into detailed changes in pain intensity and distribution (area and location) over time. The primary aims of this study were (i) to measure the temporal changes of pain intensity, area, and location in a dose-response fashion and (ii) to assess recall accuracy of the peak pain intensity and distribution seven days later, using a digital pain mapping application. The secondary aims were to (i) evaluate the influence of repeated momentary pain drawings on pain recall accuracy and (ii) explore the associations among momentary and recall pain with psychological variables (pain catastrophizing and perceived stress). Methods Healthy participants (N=57) received a low (0.5 ml) or a high (1.0 ml) dose of hypertonic saline (5.8%) injection into the right gluteus medius muscle and, subsequently, were randomized into a non-drawing or a drawing group. The non-drawing groups reported momentary pain intensity every 30-s. Whereas the drawing groups reported momentary pain intensity and distribution on a digital body chart every 30-s. The pain intensity, area (pixels), and distribution metrics (compound area, location, radiating extent) were compared at peak pain and over time to explore dose-response differences and spatiotemporal patterns. All participants recalled the peak pain intensity and the peak (most extensive) distribution seven days later. The peak pain intensity and area recall error was calculated. Pain distribution similarity was determined using a Jaccard index which compares pain drawings representing peak distribution at baseline and recall. The relationships were explored among peak intensity and area at baseline and recall, catastrophizing, and perceived stress. Results The pain intensity, area, distribution metrics, and the duration of pain were lower for the 0.5 mL than the 1.0 mL dose over time (p<0.05). However, the pain intensity and area were similar between doses at peak pain (p>0.05). The pain area and distribution between momentary and recall pain drawings were similar (p>0.05), as reflected in the Jaccard index. Additionally, peak pain intensity did not correlate with the peak pain area. Further, peak pain intensity, but not area, was correlated with catastrophizing (p<0.01). Conclusions This study showed differences in spatiotemporal patterns of pain intensity and distribution in a dose-response fashion to experimental acute low back pain. Unlike pain intensity, pain distribution and area may be less susceptible in an experimental setting. Higher intensities of momentary pain do not appear to influence the ability to recall the pain intensity or distribution in healthy participants. Implications The recall of pain distribution in experimental settings does not appear to be influenced by the intensity despite differences in the pain experience. Pain distribution may add additional value to mechanism-based studies as the distribution reports do not vary with pain catastrophizing. REC# N-20150052

Stimulation of Myofascial Trigger Points in the Sternocleidomastoid Evokes Facial Thermal Response Correlated with the Referred Pain

The purpose of this research is to identify and correlate the referred pain evocated by myofascial trigger points (TrPs) pressure pain threshold (PPT) in the sternocleidomastoid muscle using thermal infrared imaging (IR). Facial IR images of 46 volunteers (21 male and 25 female, average age 32 ± 6.3) undergoing PPT of five TrPs locations on the sternocleidomastoid belly were recorded. Each PPT lasted 10 s, with an interstimulus interval of 2 min. Sixteen thermal IR images were recorded for each subject: at baseline (t0), 2 s before PPT (t1), 2 s (t2) and 60 s (t3) after PPT of each TrPs location. During the interstimulus interval, subjects were asked to draw over a head–neck template displayed on a computer screen the areas of referred pain eventually evoked by the stimulation and the referred pain intensity by means of a Visual Analogue Scale (VAS). The VAS template was then superimposed with the IR records. Two temperature (T) variations were calculated: ΔT1 = T(t2) − T(t1) and ΔT2 = T(t3) − T(t1). Differences in ∆T range ≥ 0.2 °C have been considered significant. In 77% of the superimpositions, the referred pain area corresponded to a ΔT2 ≥ 0.2 °C while only the 59% corresponded to a ΔT1 ≥ 0.2 °C. In 19% of superimpositions, a ΔT2 ≥ 0.2 °C did not correspond to a referred pain area indicated by the patient, and this percentage lowers to 4% for ΔT1 ≥ 0.2 °C. None of the areas that reported a VAS of 0 or 1 showed a ΔT1 ≥ 0.2 °C or a ΔT2 ≥ 0.2 °C. Considering the limitations of this pilot study, IR could be used to identify referred pain evocated by TrPs on sternocleidomastoid muscle.

Patients with symptomatic permanent atrial fibrillation show quantitative signs of pain sensitisation

ObjectiveMost patients with atrial fibrillation (AF) report symptoms, while one-third are asymptomatic. We hypothesised that sensory processing, in particular pain, differs in patients with symptomatic and asymptomatic AF.MethodsThirty individuals with permanent AF (15 symptomatic and 15 asymptomatic) completed the Atrial Fibrillation 6 (AF6) and short form 36 Health Survey questionnaires and underwent quantitative pain sensitisation testing using pressure algometry at the sternum (referred pain area) and the tibialis anterior muscle (generalised pain area). The primary objective was to assess differences in pressure pain thresholds (PPT), temporal summation of pain (TSP) and conditioned pain modulation (CPM) in the two groups. The secondary objective was to determine association of demographic and clinical parameters to measures of pain sensitisation.ResultsThe symptomatic group had lower PPTs at both tibialis (p=0.004) and sternum (p=0.01), and impaired CPM (p=0.025) and facilitated TSP (p=0.008) at the tibialis but not sternum, compared with the asymptomatic group. The AF6 sum score was negatively correlated to PPT on both tibialis (r=−0.50, p=0.005) and sternum (r=−0.42, p=0.02) and positively correlated to TSP on both tibialis (r=0.57, p=0.001) and sternum (r=0.45, p=0.01), but not to CPM. The physical component summary score was positively correlated to the PPT on both tibialis (r=0.52, p=0.003) and sternum (r=0.40, p=0.03) and negatively to TSP on the tibialis (r=−0.53, p=0.003) but not sternum.ConclusionsPatients with symptomatic AF exhibit lower pain tolerance than patients with asymptomatic AF, as well as impaired pain inhibitory control and facilitated summation of pain, indicating that pain sensitisation may be of importance in symptomatic AF.Trial registration numberNCT04649437.

Iliac Crest Autograft Harvesting by Mosaicplasty Technique

INTRODUCTION: The aim of this study to present the results of patients with iliac wing autograft using the mosaicplasty method in order to reduce donor site morbidity and pain, which are two of the most common complications. METHOD: Between 2011-2018, 35 patients (19 men,16 women) who were harvested autograft from the iliac wing were included in the study.The average age of patients was determined to be 42 (10-64) years, the mean follow-up was 39.9 months (12-101). All patients were operated on for pseudoarthrosis surgery.The same orthopedic surgeon harvested all autografts. The patients were evaluated at post-op 15th day, the first month, and the sixth month. Patients were evaluated in their last follow-up (at sixth month) and monofilament test, two-point discrimination test, visual analog scale (VAS), pain duration, numbness, gait problems, major pain area, cosmetic satisfaction were questioned. RESULTS: The mean of the monofilament test was 4.16 (2.83-6.65). The mean two-point discrimination test was 36.5 mm (9-100 mm). The mean VAS was found to be 2.94 (1-4). In the post-op period, the duration of pain was determined as one month in 21 patients, two months in 5 patients, and four months in 2 patients, while seven patients did not complain of pain at all. It was observed that ten patients complained of numbness in the thigh region (28.5%), and 11 patients complained of gait problem and limping (31.4%). Fifteen patients used an assistive walking device after surgery (42.8%). Only two patients complained of pain in the graft area when the major pain region was questioned after surgery (5.7%). Twenty-one patients were found to be cosmetically satisfied (60%) following the surgery scar in the graft region. CONCLUSİON: We believe that iliac autografts taken with the mosaicplasty technique can be used safely in suitable patients with low complication rates and high patient satisfaction

The Area of Pressure-Induced Referred Pain Is Dependent on the Intensity of the Suprathreshold Stimulus: An Explorative Study

Objective To investigate the pain referral area (number of pixels) and extent (vector length) as elicited from increasing intensities of pressure-induced pain at the shoulder. Design Cross-sectional design. Setting Clinical laboratory setting. Participants Twenty-two healthy men and women participated in two experimental sessions. Methods Delayed onset of muscle soreness (DOMS) was induced in the dominant shoulder and assessed 24 hours later. Participants rated the level of DOMS on a 6-point Likert scale. Four different intensities (pressure pain threshold [PPT]+20%, PPT+30%, PPT+40%, and PPT+50%) were applied to the infraspinatus in a randomized, balanced fashion for 60 seconds from low to high intensity or vice versa. The resulting location, area, and extent of referred pain as drawn by the participants on a digital body chart were extracted and expressed in pixels. The extent of pain was defined as the vector length extending from the ipsilateral earlobe to the most distal location of the pain. Results The referred pain area from PPT+20% was smaller than PPT+30%, PPT+40%, and PPT+50%. The extent of referred pain did not differ between the pressure pain intensities. Conclusions Pressure intensity at PPT+30%, but no more, produces the greatest referred pain area as compared with the traditional pressure intensity of PPT+20%. Thus, the intensity of PPT+30% may be ideal for exploring the mechanisms of referred pain. The extent of the pain represents an independent expression of the intensity of the provoking stimulus and may be more closely related to the location of the stimulus.

Experimental Pain and Fatigue Induced by Excessive Chewing

Background: The study was aiming to optimize excessive gum chewing as an experimental model to induce jaw muscle pain and fatigue similar to those in painful TMDs with durations that would allow immediate investigations of jaw-motor function. Further, if any sex differences would be detected in the expression of pain. Methods: This randomized, double blinded study included 31 healthy participants of both sexes. A standardized chewing protocol of either 40- or 60-minutes of chewing was used with a wash-out period of one week. Subjective fatigue, pain characteristics and functional measures were assessed. For statistical analyses, Wilcoxon Signed Rank test, Mann–Whitney Rank Sum test and Friedman’s ANOVA with Tukey post-hoc test were used. Results: High subjective fatigue scores that lasted up to 20 minutes after the end of the trial were significantly induced both in the 40- and 60-minute chewing trials (P<0.001*). Significant but mild pain was induced only in the 60-minute trial (P=0.004*) and only in men (P=0.04*). Also, the induced pain area was significantly bigger in the 60-minute trial (P=0.009*). However, this increase in pain and pain area did not last to the first 10-minute follow-up. There were no significant differences neither between the 40- and 60-minute chewing trials, except regarding the pain area (P=0.008*), nor between the sexes. Conclusion: Taken together, excessive chewing in its current form does not seem to be a proper pain experimental model. The model needs further adjustments in order to mimic TMD-pain especially in women and to prolong the pain duration.

Pain Drain

This chapter examines chronic pain. Pain starts as a symptom—associated, for example, with arthritis or neuropathy—and, for one in five Americans, this symptom becomes “chronic,” that is, it lasts for weeks, or months, or even years. Chronic pain has its own reliable neurobiology and its own brain activation signature—although it cannot be localized in any specific “pain area” like other sensory perceptions, such as smell or sight. Still, pain changes the brain’s structure, its neuronal configurations. Moreover, pain’s significance in a person’s life is highly individualized. The experience of chronic pain can be altered by mood, sleep quality, distraction, suggestion, or even anticipation of new pain. This implies that pain may be exacerbated by social conditions—by violence, by anxiety. Living in poverty, for example, increases the odds of living with chronic pain. Although pain is real, it is still doubted and disputed. In the legal system, it is the subject of arguments over payment for disability claims and personal injury suits. The lack of an objective measure of pain means that some who might deserve compensation miss out because they cannot “prove” their discomfort. Assessing and treating pain, recognizing the pain of others, coping with its presence, and limiting its ruinous effects without misusing opioids or taking one’s own life remain central tests of people’s empathy and their efforts to promote health.

Experimental Pain and Fatigue Induced by Excessive Chewing

Background The study was aiming to optimize excessive gum chewing and investigate if it could be an experimental model to induce jaw muscle pain and subjective fatigue similar to those in painful TMDs. Secondarily, to investigate if the induced pain and fatigue had a duration that would allow immediate investigations of jaw-motor function. Finally, if any sex differences would be detected in the expression of pain. Methods This randomized, double blinded study included 31 healthy participants of both sexes. A standardized chewing protocol of either 40- or 60-minutes of chewing was used with a wash-out period of one week. Subjective fatigue, pain characteristics and functional measures were assessed. For statistical analyses, Wilcoxon Signed Rank test, Mann–Whitney Rank Sum test and Friedman’s ANOVA with Tukey post-hoc test were used. Results High subjective fatigue scores that lasted up to 20 minutes after the end of the trial were significantly induced both in the 40- and 60-minute chewing trials. Significant but mild pain was induced only in the 60-minute trial and only in men. Also the induced pain area was significantly bigger in the 60-minute trial. However, this increase in pain and pain area did not last to the first 10-minute follow-up. Although there were significant differences detected regarding fatigue within both of the trials and pain within the 60-minute trial, there were no significant differences neither between the trials, other than regarding the pain area, nor between sexes. Conclusion Taken together, excessive chewing in its current form does not seem to be a proper pain experimental model. The model needs further adjustments in order to mimic TMD-pain especially in women and to prolong the pain duration.

Orofacial pain resembling hypnic headache: A case report

The International Classification of Orofacial Pain (ICOP) classifies orofacial pain resembling primary headache as orofacial migraine and tension-type, trigeminal autonomic, and neurovascular orofacial pain. We used the ICOP classification style to make a diagnosis on a 76-year-old woman with orofacial pain, which developed only during sleep three times per week, caused awakening, and lasted 3–4 h without cranial autonomic symptoms or restlessness. Except for the pain area, her symptoms fulfilled the diagnostic criteria for hypnic headache. We diagnosed her with orofacial pain resembling hypnic headache. We should review the cases of such patients and classify them according to the ICOP.