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Purpose: Temporal summation (TS) of pain occurs when pain increases over repeated presentations of identical noxious stimuli. TS paradigms can model central sensitization, a state of hyperexcitability in nociceptive pathways that promotes chronic pain onset and maintenance. Many experimenters use painful heat stimuli to measure TS (TS-heat); yet, TS-heat research faces unresolved challenges, including difficulty evoking summation in up to 30-50% of participants. Moreover, substantial variability exists between laboratories regarding the methods for evoking and calculating TS-heat., Patients and Methods: To address these limitations, this study sought to identify optimal parameters for evoking TS-heat in healthy participants with a commercially available constant contact heat stimulator, the Medoc TSA-II. Working within constraints of the TSA-II, stimulus trains with varying parameters (eg, stimulus frequency, baseline temp, peak temp, peak duration, testing site) were tested in a sample of 32 healthy, chronic pain-free participants to determine which combination best evoked TS-heat. To determine whether TS scoring method altered results, TS-heat was scored using three common methods., Results: Across all methods, only two trains successfully evoked group-level TS-heat. These trains shared the following parameters: site (palmar hand), baseline and peak temperatures (44°C and 50°C, respectively), and peak duration (0.5 s). Both produced summation that peaked at moderate pain (~50 out of 100 rating)., Conclusion: Future TS-heat investigations using constant contact thermodes and fixed protocols may benefit from adopting stimulus parameters that include testing on the palmar hand, using 44°C baseline and 50°C peak temperatures, at ≥0.33 Hz stimulus frequency, and peak pulse durations of at least 0.5 seconds., Competing Interests: The authors have no conflicts of interest to report in this work., (© 2024 Kell et al.)

Research has documented neurophysiological indicators of anticipation (Stimulus Preceding Negativity [SPN]) and perception (Late Positive Potential [LPP]) of threat, yet little is known as to how self-focused attention manipulations influence emotion processing within the context of cued picture viewing. With self-referent attention moderating attention to external stimuli, it is necessary to document how self-focused attention impacts attention and the ability to emotionally process external threat. The goal of the present study was to evaluate the impact of self-focused attention on the anticipation and perceptual processing of unpleasant pictures within a cued-picture viewing paradigm among 33 participants. Overall, the results suggest that the self-focused attention manipulations disrupted anticipation but not processing of pictures, as indexed by the SPN and LPP respectively. Self-focused attention appears to disrupt the preparatory attention for upcoming unpleasant stimuli, potentially through loading cognitive resources or activation of associative defensive responding. Collectively, these findings demonstrate the impact of self-focused attention within the context of emotional picture processing and suggest further areas of investigation., (© 2022. The Psychonomic Society, Inc.)

The most widely accepted definition of pain considers it a sensory and emotional experience associated with potential or actual physical harm. However, research tends to generalize findings from predominantly European American samples thereby assuming universality across cultures. Because of the high prevalence of pain within the AI group, it is important to consider whether their conceptualization of pain is similar to the universal definition. To accomplish this aim, a semi-structured interview was conducted with 152 AIs (primarily Southern Plains and eastern Oklahoma tribes) and 150 NHWs. Both groups were asked questions including what words describe hurtful experiences, the purpose of painful experiences, individual and culture-specific meanings of pain, and what constituted the opposite of pain. Many similarities were found between groups as well as differences. For example, NHWs used the word pain more often to describe physically hurtful experiences and were more likely to consider pain to be a signal or warning of an abnormality or pathology. By contrast, only AIs reported culture-specific meanings of pain, such as references to AI rituals or ceremonies. These observed differences are attenuated by small effect sizes. These findings are important to consider when hypothesizing the differences in pain among cultural groups.

Native Americans (NAs) experience higher rates of chronic pain. To examine the mechanisms for this pain inequity, we have previously shown that NAs report higher levels of pain-related anxiety and pain catastrophizing, which are in turn related to pronociceptive (pain-promoting) processes. But, it is currently unclear why NAs would report greater pain-related anxiety and catastrophizing. Given that NAs are also more likely to experience adverse life events (ALEs) and associated psychological distress, it was hypothesized that higher anxiety/catastrophizing in NAs would be partially explained by higher rates of ALEs and psychological distress. Structural equation modeling was used to analyze these pathways (NA ethnicity ➔ ALEs ➔ psychological distress ➔ pain anxiety/catastrophizing) in 305 healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). Pain-related anxiety and situational pain catastrophizing were assessed in response to a variety of painful tasks. The Life Events Checklist was used to assess cumulative exposure to ALEs that directly happened to each participant. A latent psychological distress variable was modeled from self-reported perceived stress and psychological symptoms. Results found that NAs experienced more ALEs and greater psychological distress which was associated with higher rates of pain-related anxiety and pain catastrophizing. Notably, NAs did not report greater psychological distress when controlling for ALE exposure. This suggests that a higher risk of chronic pain in NAs may be due, in part, to psychological distress, pain-related anxiety, and pain catastrophizing that are promoted by exposure to ALEs. These results highlight several targets for intervention to decrease NA pain risk., (© 2021. W. Montague Cobb-NMA Health Institute.)

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., (Copyright © 2021 United States Association for the Study of Pain, Inc. Published by Elsevier Inc. All rights reserved.)

Native Americans (NAs) have a higher prevalence of chronic pain than other U.S. racial/ethnic groups, but there have been few attempts to understand the mechanisms of this pain disparity. This study used a comprehensive battery of laboratory tasks to assess peripheral fiber function (cool/warm detection thresholds), pain sensitivity (eg, thresholds/tolerances), central sensitization (eg, temporal summation), and pain inhibition (conditioned pain modulation) in healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). Multiple pain stimulus modalities were used (eg, cold, heat, pressure, ischemic, and electric), and subjective (eg, pain ratings and pain tolerance) and physiological (eg, nociceptive flexion reflex) outcomes were measured. There were no group differences on any measure, except that NAs had lower cold-pressor pain thresholds and tolerances, indicating greater pain sensitivity than NHWs. These findings suggest that there are no group differences between healthy NAs and NHWs on peripheral fiber function, central sensitization, or central pain inhibition, but NAs may have greater sensitivity to cold pain. Future studies are needed to examine potential within-group factors that might contribute to NA 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., Competing Interests: The authors have no conflicts of interest to declare.Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article., (Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The International Association for the Study of Pain.)

Background: Oral antipyretics are commonly used to treat pediatric patients who develop fevers. However, patients presenting to the emergency department or undergoing surgery are frequently unable to tolerate oral antipyretics. Rectal formulations are available; however, this route of administration is unpredictable. The main objectives of this randomized controlled study was to evaluate the efficacy and safety of single or multiple doses of intravenous ibuprofen to acetaminophen (oral or suppository) in pediatric patients with fever and to assess plasma ibuprofen concentrations., Methods: This multi-center study was conducted in hospitalized patients, ≤ 16 years, with a new onset of fever ≥ 38.3°C. Patients were randomly assigned to receive either 10 mg/kg intravenous ibuprofen or acetaminophen. Study drug was administered at hour 0, and thereafter every 4 h as needed, up to 5 days. The primary outcome was to evaluate the effect of a single dose of intravenous ibuprofen compared to acetaminophen in reducing temperature in the first 2 h after administration. Data were compared using an analysis of variance model for continuous measurements and Cochran-Mantel-Haenszel test of general association for categorical data. A two-sided testing was used and a p-value ≤ 0.05 was considered significant., Results: A total of 103 patients received study medication. Intravenous ibuprofen resulted in a greater reduction in temperature as measured by the area under the change from baseline at 2 h (p = 0.005) and 4 h (<0.001); in a greater reduction in change from baseline temperature compared to treatment with acetaminophen, and it reduced fever throughout a 24 h dosing period. There were no differences in safety parameters or serious adverse events., Conclusions: A single 10 mg/kg dose of intravenous ibuprofen provided a significant reduction of temperature for febrile pediatric patients compared to those that received 10 mg/kg acetaminophen at 2 h and 4 h post-treatment. A reduction in temperature was also demonstrated over 24 h; however the reduction was not considered statically significant. Intravenous ibuprofen provides an effective option for reducing fever in hospitalized pediatric patients., Trial Registration: The study was registered on ClinicalTrials.gov on 26 October 2009, Study Identifier: NCT01002573.

Inpatient falls are the most common adverse hospital events. Despite the recognized importance of reducing inpatient falls, tracking and reporting methods are inconsistent. Moreover, recommended methods and statistical tests for comparing rates are complicated. This article demonstrates how to calculate fall rates using 3 common methods, summarizes the advantages and disadvantages of each method, and recommends best practices.

We report the case of a 58-year-old man born in the United States with a history of complete childhood immunizations who presented to the Emergency Department with trismus. Past medical history was significant only for Elephantiasis. After an exhaustive workup the patient was found to have Tetanus, with no identifiable portal of entry. The patient was successfully treated for Tetanus with complete recovery. Tetanus is caused by the organism Clostridium Tetani, which usually requires an open lesion to cause infection. Our patient was unique in that he was previously immunized with no obvious lesion. Tetanus should be suspected and treated empirically in any patient presenting with typical signs and symptoms even without an apparent entry site.