RESUMEN

Definitions of human pain acknowledge at least two dimensions of pain, affective and sensory, described as separable and thus potentially differentially modifiable. Using electroencephalography, we investigated perceptual and neural changes of emotional pain modulation in healthy individuals. Painful electrical stimuli were applied after presentation of priming emotional pictures (negative, neutral, positive) and followed by pain intensity and unpleasantness ratings. We found that perceptual and neural event-related potential responses to painful stimulation were significantly modulated by emotional valence. Specifically, pain unpleasantness but not pain intensity ratings were increased when pain was preceded by negative compared to neutral or positive pictures. Amplitudes of N2 were higher when pain was preceded by neutral compared to negative and positive pictures, and P2 amplitudes were higher for negative compared to neutral and positive pictures. In addition, a hierarchical regression analysis revealed that P2 alone and not N2, predicted pain perception. Finally, source analysis showed the anterior cingulate cortex and the thalamus as main spatial clusters accounting for the neural changes in pain processing. These findings provide evidence for a separation of the sensory and affective dimensions of pain and open new perspectives for mechanisms of pain modulation.

Asunto(s)

RESUMEN

In a randomized, controlled study, whole-body electromyostimulation (WB-EMS) was investigated as a promising alternative treatment technique compared to conventional strength training for the management of knee osteoarthritis (OA). Seventy-two overweight participants with symptomatic knee OA were randomly assigned to WB-EMS (n = 36) or a usual care group (UCG, n = 36). For seven months, the WB-EMS group received three times per fortnight a WB-EMS training, while the UCG was prescribed six-times physiotherapeutic treatments. We observed significant effects for the primary outcome "pain", as determined by the Knee injury and Osteoarthritis Outcome Score (KOOS), with more favourable changes in the WB-EMS group vs UCG (between-group difference 9.0 points, 95%CI 2.9-15.1, p = 0.004). Secondary outcomes, including the other KOOS subscales (symptoms, function in daily living, function in sports/recreational activities and quality of life), 7 day pain diary, hip/leg extensor strength and lower limb function (30s sit-to-stand test), were also statistically significant in favour of the WB-EMS group. Overall, WB-EMS was found to be effective in relieving knee pain symptoms and improving physical function in individuals with symptomatic knee OA compared to usual care treatment. WB-EMS could be used as an alternative therapy in the management of knee OA; particularly for patients that cannot be motivated for conventional training.

Asunto(s)

RESUMEN

Background: Posttraumatic stress disorder and medically unexplained pain frequently co-occur. While pain is common during traumatic events, the processing of pain during trauma and its relation to audiovisual and pain intrusions is poorly understood.Objective: Here we investigate neural activations during painful analogue trauma, focusing on areas that have been related to threat and pain processing, and how they predict intrusion formation. We also examine the moderating role of cumulative lifetime adversity.Methods: Sixty-five healthy women were assessed using functional magnetic resonance imaging. An analogue trauma was induced by an adaptation of the trauma-film paradigm extended by painful electrical stimulation in a 2 (film: aversive, neutral) x 2 (pain: pain, no-pain) design, followed by 7-day audiovisual and pain intrusion assessment using event-based ecological momentary assessment. Intrusions were fitted with Bayesian multilevel regression and a hurdle lognormal distribution.Results: Conjunction analysis confirmed a wide network including anterior insula (AI) and dorsal anterior cingulate cortex (dACC) being active both, during aversive films and pain. Pain resulted in activation in areas amongst posterior insula and deactivation in a network around ventromedial prefrontal cortex (VMPFC). Higher AI and dACC activity during aversive>neutral film predicted greater audiovisual intrusion probability over time and predicted greater audiovisual intrusion frequency particularly for participants with high lifetime adversity. Lower AI, dACC, hippocampus, and VMPFC activity during pain>no-pain predicted greater pain intrusion probability particularly for participants with high lifetime adversity. Weak regulatory VMPFC activation was associated with both increased audiovisual and pain intrusion frequency.Conclusions: Enhanced AI and dACC processing during aversive films, poor pain vs. no-pain discrimination in AI and dACC, as well as weak regulatory VMPFC processing may be driving factors for intrusion formation, particularly in combination with high lifetime adversity. Results shed light on a potential path for the etiology of PTSD and medically unexplained pain.

AI and dACC play a common role for both trauma- and pain-processing.In combination with high lifetime adversity, higher AI and dACC aversive film processing was associated with higher audiovisual intrusion frequency, whereas weaker AI and dACC pain discrimination enhanced the chance for pain intrusions.Weak regulatory VMPFC activity in aversive situations increased both audiovisual and pain intrusion formation.

Asunto(s)

Asunto(s)

RESUMEN

The brain integrates information from pain-predictive cues and noxious inputs to construct the pain experience. Although previous studies have identified neural encodings of individual pain components, how they are integrated remains elusive. Here, using a cue-induced pain task, we examined temporal functional magnetic resonance imaging activities within the state space, where axes represent individual voxel activities. By analyzing the features of these activities at the large-scale network level, we demonstrated that overall brain networks preserve both cue and stimulus information in their respective subspaces within the state space. However, only higher-order brain networks, including limbic and default mode networks, could reconstruct the pattern of participants' reported pain by linear summation of subspace activities, providing evidence for the integration of cue and stimulus information. These results suggest a hierarchical organization of the brain for processing pain components and elucidate the mechanism for their integration underlying our pain perception.

Asunto(s)

RESUMEN

Osgood Schlatter's disease (OSD) is characterized by pain at the tibial tuberosity provoked during knee-loading activities, and is common in adolescent athletes. The aim of this study was to characterize clinical, pain and ultrasound imaging characteristics in participants with OSD compared to controls. This cross-sectional study included adolescents diagnosed with OSD and matched controls. Following baseline evaluation including ultrasound, participants completed the following aggravating activities in a randomized order: single-leg isometric knee hold, single-leg squat, single-leg vertical jump, hopping, running, cutting, lunges, and walking. Participants rated pain intensity on a numeric rating scale (0-10; no pain to worst pain imaginable) and localization during activities. We included 35 participants with OSD (48.5% females, age 13.0 [SD 1.5]) and 21 controls (47.6% females, age 13.4 [SD1.4]). Doppler signal was more prevalent in OSD participants at the tendon (77% vs. 30%) and tuberosity (29% vs. 10%). Tendon thickness was greater in OSD at distal (mean difference = 4.5 mm 95% CI 1.5-7.5) and proximal sites (mean difference = 4.2 95% CI 0.1-8.3). Aggravating activities induced higher pain in OSD. The greatest differences between OSD and control were the dynamic single-leg squat (mean difference = 4.2 (95% CI 3.22-5.1)). Pain was localized at the tibial tuberosity and patellar tendon during activities. Sex, sports participation, bilateral pain, and Doppler were associated with greater pain during aggravating activities. Single-leg activities loading the tibial tuberosity through the tendon appear to provoke OSD-related pain more than other sports specific movements. This may be useful to guide adolescents on which activities are likely to aggravate pain.

Asunto(s)

RESUMEN

BACKGROUND: Electroencephalography (EEG) is a promising tool for identifying the physiological biomarkers of fibromyalgia (FM). Evidence suggests differences in power band and density between individuals with FM and healthy controls. EEG changes appear to be associated with pain intensity; however, their relationship with the quality of pain has not been examined. We aimed to investigate whether abnormal EEG in the frontal and central points of the 10-20 EEG system in individuals with FM is associated with pain's sensory-discriminative and affective-motivational dimensions. The association between EEG and the two dimensions of emotional disorders (depression and anxiety) was also investigated. METHODS: In this cross-sectional pilot study, pain experience (pain rating index [PRI]) and two dimensions of emotional disorders (depression and anxiety) were assessed using the McGill Pain Questionnaire (PRI-sensory and PRI-affective) and Hospital Anxiety and Depression Scale (HADS), respectively. In quantitative EEG analysis, the relative spectral power of each frequency band (delta, theta, alpha, and beta) was identified in the frontal and central points during rest. RESULTS: A negative correlation was found between the relative spectral power for the delta bands in the frontal (r= -0.656; p = 0.028) and central points (r= -0.624; p = 0.040) and the PRI-affective scores. A positive correlation was found between the alpha bands in the frontal (r = 0.642; p = 0.033) and central points (r = 0.642; p = 0.033) and the PRI-affective scores. A negative correlation between the delta bands in the central points and the anxiety subscale of the HADS (r = -0.648; p = 0.031) was detected. CONCLUSION: The affective-motivational dimension of pain and mood disorders may be related to abnormal patterns of electrical activity in patients with FM. TRIAL REGISTRATION: Retrospectively registered on ClinicalTrials.gov (NCT05962658).

Asunto(s)

Asunto(s)

Asunto(s)

RESUMEN

The absence of a comprehensive understanding of the neural basis of spontaneous pain limits the development of therapeutic strategies targeting this primary complaint of patients with chronic pain. Here we report a distinct neuronal ensemble within the prelimbic cortex which processes signals related to spontaneous pain in rats with chronic inflammatory pain. This neuronal ensemble specifically encodes spontaneous pain-related behaviors, independently of other locomotive and evoked behaviors. Activation of this neuronal ensemble elicits marked spontaneous pain-like behaviors and enhances nociceptive responses, whereas prolonged silencing of its activities alleviates spontaneous pain and promotes overall recovery from inflammatory pain. Notably, afferents from the primary somatosensory cortex and infralimbic cortex bidirectionally modulate the activities of the spontaneous pain-responsive prelimbic cortex neuronal ensemble and pain behaviors. These findings reveal the cortical basis of spontaneous pain at the neuronal level, highlighting a distinct neuronal ensemble within the prelimbic cortex and its associated pain-regulatory brain networks.

Asunto(s)

RESUMEN

The insular cortex is an important hub for sensory and emotional integration. It is one of the areas consistently found activated during pain. While the insular's connections to the limbic system might play a role in the aversive and emotional component of pain, its connections to the descending pain system might be involved in pain intensity coding. Here, we used anterograde tracing with viral expression of mCherry fluorescent protein, to examine the connectivity of insular axons to different brainstem nuclei involved in the descending modulation of pain in detail. We found extensive connections to the main areas of descending pain control, namely, the periaqueductal gray (PAG) and the raphe magnus (RMg). In addition, we also identified an extensive insular connection to the parabrachial nucleus (PBN). Although not as extensive, we found a consistent axonal input from the insula to different noradrenergic nuclei, the locus coeruleus (LC), the subcoereuleus (SubCD) and the A5 nucleus. These connections emphasize a prominent relation of the insula with the descending pain modulatory system, which reveals an important role of the insula in pain processing through descending pathways.

Asunto(s)

RESUMEN

BACKGROUND: Foot problems are common in the general adult population. Whereas older people experience foot problems because of multiple chronic diseases, younger people often have musculoskeletal foot problems related to overuse. Symptoms and severity may differ depending on the anatomical location of the problem, such as forefoot and rearfoot problems. We aimed to compare the differences in spatiotemporal gait characteristics, balance, and pain in musculoskeletal forefoot and rearfoot problems. METHODS: Twenty-six patients with forefoot (14 participants) and rearfoot (12 participants) problems participated in this prospective study. Spatiotemporal gait characteristics (velocity, cadence, step time, step length, step-extremity ratio, stride length, base support, percentage of swing phase, percentage of stance phase, swing time, and stance time) were evaluated using an electronic walkway, and balance assessment was made using a balance check screener and trainer. The visual analog scale foot and ankle was used to determine patient pain levels. The Mann-Whitney U test was used to determine differences between groups. RESULTS: There were no significant differences between groups regarding spatiotemporal gait characteristics (P > .05). The eyes closed normal stability and eyes open perturbed stability scores were lower in patients with rearfoot problems (P < .05). Pain intensity evaluated with the visual analog scale foot and ankle was higher in patients with rearfoot problems (P < .05). CONCLUSIONS: Pain levels and balance deficits in this study were higher in patients with rearfoot problems. The balance evaluation and possible effects of pain management on balance should be considered, especially in patients with rearfoot problems, in aspects of treatment.

Asunto(s)

Asunto(s)

RESUMEN

The somatosensory system is widely studied to understand its functioning mechanisms. Multiple tests, based on different devices and methods, have been performed not only on humans but also on animals andex-vivomodels. Depending on the nature of the sample under analysis and on the scientific aims of interest, several solutions for experimental stimulation and for investigations on sensation or pain have been adopted. In this review paper, an overview of the available devices and methods has been reported, also analyzing the representative values adopted during literature experiments. Among the various physical stimulations used to study the somatosensory system, we focused only on mechanical and thermal ones. Based on the analysis of their main features and on literature studies, we pointed out the most suitable solution for humans, rodents, andex-vivomodels and investigation aims (sensation and pain).

Asunto(s)

RESUMEN

ABSTRACT: Rodents and human studies indicate that the hippocampus, a brain region necessary for memory processing, responds to noxious stimuli. However, the hippocampus has yet to be considered a key brain region directly involved in the human pain experience. One approach to answer this question is to perform quantitative sensory testing on patients with hippocampal damage-ie, medial temporal lobe epilepsy. Some case studies and case series have performed such tests in a handful of patients with various types of epilepsy and have reported mixed results. Here, we aimed to determine whether mechanical pain sensitivity was altered in patients diagnosed with temporal lobe epilepsy. We first investigated whether mechanical pain sensitivity in patients with temporal lobe epilepsy differs from that of healthy individuals. Next, in patients with temporal lobe epilepsy, we evaluated whether the degree of pain sensitivity is associated with the degree of hippocampal integrity. Structural integrity was based on hippocampal volume, and functional integrity was based on verbal and visuospatial memory scores. Our findings show that patients with temporal lobe epilepsy have lower mechanical pain sensitivity than healthy individuals. Only left hippocampal volume was positively associated with mechanical pain sensitivity-the greater the hippocampal damage, the lower the sensitivity to mechanical pain. Hippocampal measures of functional integrity were not significantly associated with mechanical pain sensitivity, suggesting that the mechanisms of hippocampal pain processing may be different than its memory functions. Future studies are necessary to determine the mechanisms of pain processing in the hippocampus.

Asunto(s)

RESUMEN

Astrocytes play an active role in the function of the brain integrating neuronal activity and regulating back neuronal dynamic. They have recently emerged as active contributors of brain's emergent properties such as perceptions. Here, we analyzed the role of astrocytes in pain perception from the lens of systems neuroscience, and we do this by analyzing how astrocytes encode nociceptive information within brain processing areas and how they are key regulators of the internal state that determines pain perception. Specifically, we discuss the dynamic interactions between astrocytes and neuromodulators, such as noradrenaline, highlighting their role in shaping the level of activation of the neuronal ensemble, thereby influencing the experience of pain. Also, we will discuss the possible implications of an "Astro-NeuroMatrix" in the integration of pain across sensory, affective, and cognitive dimensions of pain perception.

Asunto(s)

RESUMEN

While rodents are used extensively for studying pain, there is a lack of reported direct comparisons of thermal and mechanical pain testing methods in rats of different genetic backgrounds. Understanding the range of interindividual variability of withdrawal thresholds and thermal latencies based on these testing methods and/or genetic background is important for appropriate experimental design. Testing was performed in two common rat genetic backgrounds: outbred Sprague-Dawley (SD) and inbred Fischer 344 (F344). Male and female, 10- to 14-wk-old F344 and SD rats were used to assess withdrawal thresholds in 3 different modalities: the Randall-Selitto test (RST), Hargreaves test (HT), and tail flick test (TFT). The RST was performed by using an operator-controlled handheld instrument to generate a noxious pressure stimulus to the left hind paw. The HT and the TFT used an electronically controlled light source to deliver a noxious thermal stimulus to the left hind paw or tail tip, respectively. Rats of each sex and genetic background underwent one type of test on day 0 and day 7. Withdrawal thresholds and thermal latencies were compared among tests. No significant differences were observed. Our findings can serve as a guide for researchers considering these nociceptive tests for their experiments.

Asunto(s)

RESUMEN

The multidimensional etiology of pain may explain the beneficial effects of regular physical activity, as evidenced by increased pain tolerance. Physically active people find it easier to exert themselves, which enables them to increase their physical activity, which in turn leads to a reduction in pain. However, no study investigated the physical activity and exercise tests as modulators of pain sensitivity in pregnant women. Therefore, this study aimed to investigate the changes in pain perception in pregnant women during pregnancy, with a particular interest in the effects of maximal progressive exercise test (CPET) and self-performed physical activity (PA). Thirty-one women with an uncomplicated singleton pregnancy (aged 23-41 years; M = 31.29, SD = 4.18) were invited to participate in pain sensitivity measurements before and after CPET twice during pregnancy (with an 8-week break). We found that pregnant women had a significantly lower pain threshold after a maximal exercise test than before, regardless of whether the test was performed in the second or third trimester of pregnancy. This effect was most pronounced in women with low levels of physical activity. Second, women with high physical activity had higher pain tolerance than women with moderate and low physical activity. In addition, physical activity levels predicted changes in pain tolerance over the course of pregnancy, with negative changes in women with low physical activity and positive changes in women with moderate physical activity. Finally, these associations were not reflected in differences in the subjective pain experience.

Asunto(s)

RESUMEN

Different empathic responses are often reported in autism but remain controversial. To investigate which component of empathy is most affected by autism, we examined the affective, cognitive, and motivational components of empathy in 25 5- to 8-year-old autistic and 27 neurotypical children. Participants were presented with visual stimuli depicting people's limbs in painful or nonpainful situations while their eye movements, pupillary responses, and verbal ratings of pain intensity and empathic concern were recorded. The results indicate an emotional overarousal and reduced empathic concern to others' pain in autism. Compared with neurotypical children, autistic children displayed larger pupil dilation accompanied by attentional avoidance to others' pain. Moreover, even though autistic children rated others in painful situations as painful, they felt less sorry than neurotypical children. Interestingly, autistic children felt more sorry in nonpainful situations compared with neurotypical children. These findings demonstrated an emotional overarousal in response to others' pain in autistic children, and provide important implications for clinical practice aiming to promote socio-emotional understanding in autistic children.

Asunto(s)

RESUMEN

Physical pain and negative emotions represent two distinct drinking motives that contribute to harmful alcohol use. Proactive avoidance, in contrast, can reduce consumption in response to these motives but appears to be impaired in those with problem drinking. Despite such evidence, proactive avoidance and its underlying neural deficits have not been assessed experimentally. How these deficits inter-relate with drinking motives to influence alcohol use also remains unclear. The current study leveraged neuroimaging data in forty-one problem and forty-one social drinkers who performed a probabilistic learning go/nogo task featuring proactive avoidance of painful outcomes. We identified the brain responses to proactive avoidance and contrasted the neural correlates of drinking to avoid negative emotions vs. physical pain. Behavioral results confirmed proactive avoidance deficits in problem drinking individuals' learning rate and performance accuracy, both which were associated with greater alcohol use. Imaging findings in the problem drinking group showed that negative emotions as a drinking motive predicted attenuated right anterior insula activation during proactive avoidance. In contrast, physical pain motive predicted reduced right putamen response. These regions' activations as well as functional connectivity with the somatomotor cortex also demonstrated a negative relationship with drinking severity and positive relationship with proactive avoidance performance. Path modeling further delineated the pathways through which physical pain and negative emotions influenced the neural and behavioral measures of proactive avoidance. Taken together, the current findings provide experimental evidence for proactive avoidance deficits in alcohol misuse and establish the link between their neural underpinnings and drinking behavior.

Asunto(s)