Pain Perception Research Articles

Towards non-invasive imaging through spinal-cord generated magnetic fields.

Non-invasive imaging of the human spinal cord is a vital tool for understanding the mechanisms underlying its functions in both healthy and pathological conditions. However, non-invasive imaging presents a significant methodological challenge because the spinal cord is difficult to access with conventional neurophysiological approaches, due to its proximity to other organs and muscles, as well as the physiological movements caused by respiration, heartbeats, and cerebrospinal fluid (CSF) flow. Here, we discuss the present state and future directions of spinal cord imaging, with a focus on the estimation of current flow through magnetic field measurements. We discuss existing cryogenic (superconducting) and non-cryogenic (optically-pumped magnetometer-based, OPM) systems, and highlight their strengths and limitations for studying human spinal cord function. While significant challenges remain, particularly in source imaging and interference rejection, magnetic field-based neuroimaging offers a novel avenue for advancing research in various areas. These include sensorimotor processing, cortico-spinal interplay, brain and spinal cord plasticity during learning and recovery from injury, and pain perception. Additionally, this technology holds promise for diagnosing and optimizing the treatment of spinal cord disorders.

Establishing the convergent and divergent validity of the Return-to-Work Assessment Scale among poststroke survivors

ABSTRACT Background: Stroke is a leading cause of disability worldwide, for which the concept of return to work (RTW) plays a crucial role in rehabilitation. The RTW Assessment Scale (RAS) was first developed to assess RTW among poststroke survivors; however, its validity requires further investigation. This cross-sectional study therefore aimed to determine the convergent and divergent validity of the RAS among poststroke survivors in Southeastern Nigeria. Methods: This cross-sectional study in Southeast Nigeria evaluated the convergent and divergent validity of the RAS in 101 poststroke survivors. The purposive sampling technique was used to select eligible individuals from several randomly selected locations. Consecutive participants who met the inclusion criteria were enrolled in this study. Descriptive statistics, correlation analysis, and Spearman’s rank correlation coefficients were used for data analysis. Results: The RAS exhibited strong convergent validity with the World Health Organization Disability Assessment Schedule scores (r = −0.874 to −0.529), indicating a significant relationship between RTW and overall disability. We further observed a weak negative correlation between the RAS scores and the Visual Analog Scale (VAS) scores, with correlation coefficients (r) ranging from r = −0.371 to −0.235, indicating a lesser association between RTW and pain perception of VAS, suggesting divergent validity of RAS. Conclusion: The study concluded that the RAS demonstrated strong convergent and divergent validity, affirming its reliability in assessing RTW among poststroke survivors.

Assessment of Cochlear Implant Rehabilitation Success by Speech-Language Therapists Using International Classification of Functioning, Disability and Health Criteria.

This study aims to introduce an assessment questionnaire based on the International Classification of Functioning, Disability and Health (ICF) to enable quantifiable clinical documentation. The questionnaire assists speech-language therapists (SLTs) in evaluating both non-audiological and audiological rehabilitation outcomes of patients with cochlear implants (CIs). Six SLTs were recruited to evaluate the effectiveness of CI care using ICF criteria. We carefully selected 20 pertinent ICF criteria, and SLTs received thorough training in how to apply them uniformly. A cohort of 48 patients was evaluated at three distinct time points: presurgery, postsurgery, and 6 months post-initial CI fitting. Patients underwent dedicated speech-language therapy sessions throughout the treatment course. A total of 144 complete datasets were scrutinized using a two-factor analysis of variance for ranks. Following CI care, patients exhibited substantial improvements in auditory perception, characterized by enhanced sound recognition and speech discrimination. Additionally, patients demonstrated improved attentional focus, proficiency in daily tasks and increased conversational engagement over time. Environmental factors, particularly sound perception, improved markedly, correlating with reported reductions in stress levels. Minimal changes were noted in stress management and communication techniques. Articulatory function, speech functions, and pain perception exhibited the least alteration. The data extracted from the ICF-based assessments underscore the vital significance of incorporating speech therapy-based metrics to evaluate both non-audiological and audiological factors in assessing the success of CI care within the SLTs domain. This approach proves to be highly relevant both in terms of demonstration and clinical applicability.

Neonatal analgesic prescription practices in central India: A cross-sectional survey.

This descriptive survey assessed knowledge, attitude and practice regarding analgesic prescription practices in neonates. A web-based questionnaire was developed and circulated to 150 physicians working in public and private neonatal intensive care units, of whom 87% were aware of neonatal pain perception; however, only 57.3% had any definite pain management policy. Some 66% were aware of a pain assessment tool in neonates, yet none had used it, though 80% used analgesics in their neonatal intensive care unit but only 44.3% were satisfied with the subsequent pain management. The most commonly used agents were midazolam and fentanyl. A total of 55% thought that opioid analgesia should not be used in neonates and morphine was used by only 5%; however, there seemed a general acceptance of opioid use since 86% used fentanyl as an analgesic. Non-pharmacological methods were used by 81%. Pain treatment in neonatal intensive care units is thus suboptimal and requires more attention.

Temporal Dynamics of Pain: Examining the Relationship Between Intramuscular Injection Duration and Pain Perception: A Crossover Randomized Controlled Trial.

Background Effective pain management is crucial for optimizing the patient experience and satisfaction with care. Many factors affect the intensity of injection pain, and one of these factors is the duration of the injection. This study aimed to evaluate the impact of intramuscular injection duration on perceived pain intensity in adults. Methods Fifty participants received injections according to a predetermined research protocol. Each participant served as their own control group. The intervention group was administered the drug over 40 seconds. The control group was given the same drug on the other side dorsogluteal region the following day, according to the unit's routine, in 10 seconds. Pain intensity was measured using the Wong-Baker Faces Pain Rating Scale and the Numerical Rating Scale. Statistical analysis was performed using SPSS (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp), including Wilcoxon and correlation analyses, with a significance level set at p < 0.05. Results The Wilcoxon test revealed a significant decrease in pain scores for the intervention group (p < 0.05), indicating that longer injection durations were associated with lower pain intensity. Significant correlations were found between hospital phobia and the use of pain relief measures, with pain perception (p < 0.05). Conclusion This research establishes a correlation between extended durations of intramuscular injections and pain intensity. These findings have implications for pain management during medical procedures and can contribute to optimizing patient comfort.

Comparison of three management approaches for dental caries in primary molars: A two-year randomized clinical trial

Aimto compare two-year clinical success rates of caries management in children (Hall Technique HT, Nonrestorative caries treatment NRCT, Conventional restorations CR), and to evaluate pain perception, behaviour, technique acceptability by patients, parents and dentists. Methods122, 3–8–year-olds were enrolled in 2-year parallel group randomised controlled trial (CR, n = 52, HT, n = 35, NRCT, n = 35). Caries was recorded using Nyvad criteria to measure clinical success/ failure rates. Child's pain perception (Visual Analogue Scale of Faces), child behaviour (Frankl scale), parents’ and dentists’ treatment opinions (5-point Likert scale) were assessed. Statistical analysis included Chi-square, non-parametric Kruskal–Wallis, Bonferroni-corrected Mann-Whitney U tests (p < 0.05), absolute risk reduction (ARR) and number needed to treat (NNT). ResultsAfter two years, with 116 participants, clinical success rates were: CR=60.8 % (n = 31), HT=93.8 % (n = 30), NRCT=42.5 % (n = 14) (p < 0.001). Major/minor failure rates differed: CR=17.6 % (n = 9) / 21.6 % (n = 11); HT=6.2 % (n = 2)/ 0 %, NRCT=33.3 % (n = 11)/ 24.2 % (n = 8), (p < 0.05). When comparing HT to CR, ARR = 0.33; NNT= 3 (95 % CI 0.02 -0.58); NRCT to CR, - no observed benefit from NRCT. More than 70 % of children demonstrated “positive/definitely positive” behaviour during treatment. Pain intensity was “very low/low” in 92.3 % of cases for CR, 88.6 % for HT, and 77.1 % for NRCT . NRCT was “very easy” to perform for 82.9 % of participants, compared to 42.3 % for CR and 17.1 % for HT (p < 0.05). CR were reported to take longer than NRCT and HT (p < 0.05). ConclusionClinical success rates of HT were superior to CR and NRCT. All treatment techniques were well tolerated by children, CR was more time-consuming and HT – technically more difficult to perform. Clinical significancecaries management in primary molars can be successfully performed using minimal intervention, particularly, sealing in caries lesions with Hall technique. NRCT can prevent caries progression when adequate access to mechanical plaque disruption and fluoride is provided. However, occasional fluoride application, and uncontrolled toothbrushing with fluoride toothpaste cannot replace restorative procedures.

A Synbiotic Combining Chitin-Glucan and Lactobacillus acidophilus NCFM Induces a Colonic Molecular Signature Soothing Intestinal Pain and Inflammation in an Animal Model of IBS.

Chitin-glucan (CG) is a new generation of prebiotic. Lactobacillus acidophilus NCFM® (NCFM) is a probiotic with the ability to decrease abdominal pain. We evaluate the functional and molecular gastrointestinal responses to a synbiotic administration combining CG and NCFM in a rat model of long-lasting colon hypersensitivity. The intracolonic pressure was assessed during the 9-week experiment in animals receiving CG in association or not with NCFM and compared to that in Lacticaseibacillus paracasei Lpc-37®-treated animals and control rats receiving tap water. The effects of the synbiotic were evaluated using the Wallace score, the quantification of colon myeloperoxidase (MPO) and the master genes driving analgesia and inflammation. CG 1.5 alone and NCFM 109 colony forming units (CFU) alone similarly decreased the visceral pain sensitivity. Lpc-37 had no significant effect. The best profile of pain perception inhibition was obtained with the combination of CG 1.5 g and NCFM 109 CFU, confirming a synbiotic property. This synbiotic treatment significantly reduced macroscopic colonic lesions and MPO concentrations, and induced master genes involved in analgesia (CB1, CB2, MOR, PPARα), with a downregulation of inflammatory cytokines (IL-1β, TNFα) and an induction of IL-10 and PPARγ. In conclusion, CG 1.5 g + NCFM 109 CFU significantly decreased visceral pain perception and intestinal inflammation through the regulation of master genes.

Nocebo Effect on Pain Perception and Attention with Children With and Without Attention Deficit And/Or Hyperactivity Disorder.

Attention deficit disorder with or without hyperactivity (ADHD) has negative consequences for children. The effectiveness of medical interventions and educational outcomes are strongly influenced by expectations, which can be modulated by nocebo effects. The aims of this study were to compare the nocebo effect on pain perception and attention in children with and without ADHD as well as to characterize the associations of the nocebo effect with personal variables, such as anxiety, sleep, and pain catastrophizing. Data were collected from 30 children with and without ADHD. The nocebo effect was induced using an inactive pill, "increasing" pain perception and attention deficits. Experimental thermal pain was evoked using a thermode and recorded using a computerized visual analog scale. Attention abilities were measured with the Stop-Signal Task. We also used questionnaires to measure personal variables. When combining groups, the nocebo treatment led to comparable nocebo effects for pain (increased pain perception) and attention (increased time needed for inhibition). When comparing groups, the nocebo effect on pain perception was similar for children with and without ADHD. Inattention, learning problems, anxiety, and sleep problems were associated with the nocebo response for pain and attention. This exploratory study conducted in an experimental setting emphasizes the importance of managing children's expectations for pain perception and attention as well as the potentially deleterious impact of negative suggestions on elementary school children.

NaV1.8/NaV1.9 double deletion mildly affects acute pain responses in mice.

The 2 tetrodotoxin-resistant (TTXr) voltage-gated sodium channel subtypes NaV1.8 and NaV1.9 are important for peripheral pain signaling. As determinants of sensory neuron excitability, they are essential for the initial transduction of sensory stimuli, the electrogenesis of the action potential, and the release of neurotransmitters from sensory neuron terminals. NaV1.8 and NaV1.9, which are encoded by SCN10A and SCN11A, respectively, are predominantly expressed in pain-sensitive (nociceptive) neurons localized in the dorsal root ganglia (DRG) along the spinal cord and in the trigeminal ganglia. Mutations in these genes cause various pain disorders in humans. Gain-of-function missense variants in SCN10A result in small fiber neuropathy, while distinct SCN11A mutations cause, i. a., congenital insensitivity to pain, episodic pain, painful neuropathy, and cold-induced pain. To determine the impact of loss-of-function of both channels, we generated NaV1.8/NaV1.9 double knockout (DKO) mice using clustered regularly interspaced short palindromic repeats/Cas-mediated gene editing to achieve simultaneous gene disruption. Successful knockout of both channels was verified by whole-cell recordings demonstrating the absence of NaV1.8- and NaV1.9-mediated Na+ currents in NaV1.8/NaV1.9 DKO DRG neurons. Global RNA sequencing identified significant deregulation of C-LTMR marker genes as well as of pain-modulating neuropeptides in NaV1.8/NaV1.9 DKO DRG neurons, which fits to the overall only moderately impaired acute pain behavior observed in DKO mice. Besides addressing the function of both sodium channels in pain perception, we further demonstrate that the null-background is a very valuable tool for investigations on the functional properties of individual human disease-causing variants in NaV1.8 or NaV1.9 in their native physiological environment.

A retrospective study of duloxetine for phantom limb pain post lower‐limb amputation

AbstractBackgroundPhantom limb pain (PLP) refers to the painful sensory perception of a missing limb after amputation, which can have physical and psychological impacts.AimTo determine the effectiveness of duloxetine for pain management in PLP by the reduction of opioid doses and other neuropathic analgesics when introduced into multimodal pain management strategies in the subacute rehabilitation setting.MethodThis was a retrospective observational case‐matched cohort study of patients who were admitted to a geriatric and rehabilitation unit at a tertiary Australian hospital from January 2005–December 2017 with PLP after lower‐limb amputation. Patients were included if they had a new amputation and experienced PLP. The primary outcome was a difference in oxycodone dose equivalents at discharge between the two cohorts. Univariable analysis was used to compare groups. Ethical approval was granted by the Metro South Low Negligible Risk Ethics Committee (Reference no: LNR/2018/QMS/47370) and the study conforms with the National statement on ethical conduct in human research.ResultsThirty patients from the duloxetine treatment cohort and 57 patients from the non‐duloxetine cohort were identified. Participants were predominantly male (81%) and had a median age of 63 years (interquartile range = 10.7). Both populations showed a similar rate of opioid dose reduction comparing doses at admission with those at discharge. There were no significant differences in absolute oxycodone equivalent doses at the two observed check points: admission and discharge.ConclusionThis study demonstrated that opioid consumption in post‐surgical lower‐limb amputees reporting PLP was not significantly different between populations that used and did not use duloxetine. Future research should evaluate the efficacy of duloxetine in PLP pain management using a multisite prospective study design.

Effects of Iron, Copper, Zinc, and Magnesium on Chronic Widespread Pain: A Two-Sample Mendelian Randomization.

Background: Chronic widespread pain (CWP) affects approximately 10% of the adult population globally, causing significant physical and psychological distress. Micronutrients, such as iron, copper, zinc, and magnesium, are essential in various physiological functions, and their imbalances may impact pain perception and chronic pain conditions. Methods: This study used Mendelian randomization (MR) to investigate the causal relationships between micronutrient levels and CWP. Data were obtained from genome-wide association studies (GWASs) for iron, copper, zinc, and magnesium, and CWP data were sourced from large-scale GWASs with 461,857 European participants. Genetic variants were used as instrumental variables to infer causal relationships, minimizing confounding factors. Results: MR analysis revealed a significant association between higher iron levels and an increased risk of CWP (IVW, OR 1.01, 95% CI: 1.00-1.01, p = 0.029). This finding was supported by the weighted median and MR-Egger methods. No significant associations were found for copper, zinc, and magnesium levels. Conclusions: These results suggest that iron levels may influence pain perception and chronic pain conditions. Balanced iron levels are crucial for managing chronic pain. Regular monitoring and personalized treatment plans could benefit individuals with CWP. Further research is needed to understand the mechanisms linking micronutrient levels to chronic pain and to develop targeted therapeutic interventions.

Postoperative pain after parotid surgery-comparison between superficial/total parotidectomy and extracapsular dissection: a prospective observational study.

To evaluate postoperative pain and discomfort after parotid surgery with regard to different surgical approaches. This clinical study was carried out at a single tertiary referral center (2021-2022) and included 2 groups of adult patients (mean age 56.6 ± 12.7 vs. 53.4 ± 14.1years) following elective parotid surgery due to a parotid tumor of any entity.The first group (SP/TP group) consisted of 31 patients after superficial parotidectomy (SP) or total parotidectomy (TP) (n = 31). The second group (ECD group) included all patients who had undergone extracapsular dissection (ECD) (n = 51). Primary endpoints comprised pain on ambulation as well as maximum and minimum pain (NRS 0-10) on the first three postoperative days (PODs). A neuropathic pain component (evaluated on POD 1 and 3), the analgesic score (collected from the patient file on POD 1-3), treatment-related side-effects/pain-associated impairments, and patient satisfaction (all measured on the 1st POD) were defined as secondary endpoints. Patients were surveyed using the standardized and validated "Quality Improvement in Postoperative Pain Treatment" (QUIPS) questionnaire and the painDETECT® questionnaire. Comparisons were performed using independent t tests, Wilcoxon tests, and χ2 tests, and the respective effect sizes were calculated. Looking at the first postoperative day, patients of both groups (SP/TP vs. ECD) reported comparable pain on ambulation (2.8 ± 2.0 vs. 2.6 ± 1.8; p = 0.628, r = 0.063), maximum (3.5 ± 2.2 vs. 3.5 ± 2.3; p = 0.992, r = 0.002) and minimum pain (1.1 ± 1.04 vs. 1.0 ± 1.2; p = 0.206, r = 0.157). Furthermore, there were no significant differences in pain-related restrictions or pain medication requirement. The patients in both groups were equally satisfied with their pain therapy (p = 0.282, R = 0.135). The sum score of the painDETECT® questionnaire delivered clearly negative (< 12) results on average (POD1: 6.81; POD3: 6.59); no significant difference between the groups was found (p = 0.991, R2 < .001). Neither surgical technique on the parotid gland was significantly superior to the other in terms of postoperative pain perception. Overall, postoperative pain can be classified as mild to moderate following parotid surgery. A neuropathic pain component could be excluded for the acute postoperative phase. The study was registered in the German Registry for Clinical Studies (DRKS) (application No.: DRKS00016520).

Protocol to evaluate human thermoregulation before and after thermal stress

Problem and motivationThe human body dissipates 60 % of its heat by emitting infrared radiation, it can be studied using Infrared Thermography (IRT). IRT images serve as thermal maps of the body, useful in medical applications to investigate the physiopathological of diseases that present symptoms such as swelling, pain, infection, rash, and increased local skin temperature. AimTo design a protocol to capture IRT images before and after physical activity. The protocol collects skin temperature data of the entire body, in the frontal (anterior and posterior) and sagittal (right and left) planes. MethodologyThe protocol was designed considering clinical, environmental, and technical factors and ensuring its reproducibility in both healthy and pathological populations. Thermographic images were acquired both at rest and after thermal stress (modified Bruce test). In addition, questionnaires were prepared to collect and store information on demographic data, core temperature, environmental conditions, pain perception, and level of physical activity. ResultsThe protocol combines the acquisition of IRT images with the application of the modified Bruce protocol on a treadmill as a thermal stress generator. Further impactThis protocol offers a valuable tool for studying the thermoregulatory capacity of the human body in the presence of different medical conditions.

Effects of single- and bilateral limb immersion on systemic and cerebral hemodynamic responses to the cold pressor test.

The cold pressor test (CPT) involves cold water immersion of either the upper or lower limb(s) and elicits increases in sympathetic nervous activity (SNA), heart rate (HR), and mean arterial pressure (MAP) via stimulation of pain and cutaneous thermoreceptors. Greater pain perception during the CPT is associated with greater increases in SNA and more robust physiological responses. Due to potential differential sensitivity to both painful and thermal stimuli between upper and lower limbs, as well as potential effects of total exposure area, it is unclear whether the choice of limb(s) in CPT protocol design differentially affects systemic and cerebral hemodynamic responses. Our objective was to assess systemic and cerebral hemodynamic and ventilatory responses to different CPT protocols of the hand (CPTH), foot (CPTF), or bilateral feet (CPTBF). We hypothesized CPTBF would elicit greatest physiological responses due to increased exposure area to the cold stimulus. Twenty-eight (14 M, 14 F) healthy young adults [23.4 (SD: 2.4) yr] participated in three 3-min CPT protocols during a single visit. Blood pressure, HR, middle cerebral artery blood velocity (MCAv) and cerebrovascular conductance index, and end-tidal carbon dioxide ([Formula: see text]) were averaged over the final 30 s of each minute of the CPT for each protocol, and perceived pain was recorded at the end of each minute of the CPT. We found significant effects of the time-CPT protocol interaction on systolic blood pressure (P = 0.02), diastolic blood pressure (P < 0.01), MAP (P < 0.01), and HR (P < 0.001). There were no differences between CPT protocols on either MCAv (P = 0.4) or cerebrovascular conductance index (P = 0.1). HR responses peaked in the first minute of the CPT, and changes from baseline were greater in CPTBF [Δ14(16) beats/min] compared with CPTH [Δ5(13) beats/min; P = 0.01] and CPTF [Δ4.04(13.3) beats/min; P = 0.02]. MAP responses peaked in minute 2 of the CPT, and changes from baseline were greater in CPTH [Δ12(8) mmHg) and CPTBF (Δ13(9) mmHg] compared with CPTF [Δ8(7) mmHg; P < 0.01]. Perceived pain was significantly greater in the CPTBF [CPT1 7(2.3), CPT2 6.5(2.3), CPT3 6(3)] condition compared with CPTH [CPT1 6(1.3), CPT2 6(2.3), CPT3 6(2.3)] and CPTF [CPT1 6(3.0), CPT2 6(2.0), CPT3 5.5(3.0)] protocols at all three stages of the CPT (P ≤ 0.01). Our findings suggest choice of limb(s) in CPT protocols may lead to differences in systemic hemodynamic responses, with pain perception potentially influencing these responses. Based on our results, we suggest that choice of limb should be considered in future design of CPT studies, with hand CPT providing the best balance between participant tolerability and robust physiological responses.NEW & NOTEWORTHY Choice of limb(s) in cold pressor test (CPT) studies appears to influence systemic hemodynamics. Hand and bilateral feet induce more robust responses than single-foot CPT, potentially due to increased exposure area and pain perception. Despite no significant cerebrovascular effects, a sustained hyperventilatory response was noted in bilateral feet CPT. Hand CPTs may provide a balance between robust physiological responses and tolerability. These findings underscore the need for careful limb selection in future CPT studies.

Generalization and enhancement of the effects of an active placebo nasal spray on sadness

IntroductionThe placebo effect, i.e., the psychobiological response arising from administering an inert treatment, influences various domains, such as pain perception and emotional regulation. Positive framing might enhance this effect. This study tested whether the effect of an active placebo (mimicking drug side effects to enhance treatment credibility) on is generalized between two different contexts of sadness induction and if positive framing of side effects enhances this effect. MethodsNinety-six healthy participants were randomly assigned to one of three groups: Placebo+positive framing (PPF), Placebo+standard information (PSI), or no treatment control (NTC). Participants underwent a sadness induction protocol during an in-person lab session and a 20-min online follow-up at home six hours later. Primary outcome was self-reported sadness, secondary outcome was self-reported side effects. ResultsBoth the PPF and PSI groups showed a significant decrease in sadness compared to the NTC group after placebo administration during the lab session (p < 0.001) and at follow-up (p < 0.05). At follow-up, only the PPF group did not experience a significant increase in sadness. Positive framing did not improve side effect tolerability. LimitationsSelf-reported measures introduce subjective bias. The sample restriction to healthy volunteers limits generalizability. The six-hour period may not capture clinically relevant long-term effects. ConclusionsThe active placebo nasal spray effectively reduced sadness, with effects persisting for six hours and across different contexts. Positive framing did not enhance side effect tolerability but may have helped maintain effectiveness at follow-up. Further research is needed in clinical populations and to explore long-term effects.

Neural correlates of systemic lidocaine administration in healthy adults measured by functional MRI: a single arm open label study.

Intravenous lidocaine is increasingly used as a nonopioid analgesic, but how it acts in the brain is incompletely understood. We conducted a functional MRI study of pain response, resting connectivity, and cognitive task performance in volunteers to elucidate the effects of lidocaine at the brain-systems level. We enrolled 27 adults (age 22-55 yr) in this single-arm, open-label study. Pain response task and resting-state functional MRI scans at 3 T were obtained at baseline and then with a constant effect-site concentration of lidocaine. Electric nerve stimulation, titrated in advance to 7/10 intensity, was used for the pain task (five times every 10 s). Group-level differences in pain task-evoked responses (primary outcome, focused on the insula) and in resting connectivity were compared between baseline and lidocaine conditions, using adjusted P<0.05 to account for multiple comparisons. Pain ratings and performance on a brief battery of computer-based tasks were also recorded. Lidocaine infusion was associated with decreased pain-evoked responses in the insula (left: Z=3.6, P<0.001, right: Z=3.6, P=0.004) and other brain areas including the cingulate gyrus, thalamus, and primary sensory cortex. Resting-state connectivity showed significant diffuse reductions in both region-to-region and global connectivity measures with lidocaine. Small decreases in pain intensity and unpleasantness and worse memory performance were also seen with lidocaine. Lidocaine was associated with broad reductions in functional MRI response to acute pain and modulated whole-brain functional connectivity, predominantly decreasing long-range connectivity. This was accompanied by small but significant decreases in pain perception and memory performance. NCT05501600.

Abnormalities in pain perception among individuals with depressive disorders: Evidence from meta-analysis

Abnormalities in pain perception among individuals with depressive disorders: Evidence from meta-analysis

The effect of Ozone therapy on pain perception after free gingival graft surgery in patients with mucogingival defects. A Randomized Controlled Clinical Trial.

The effect of Ozone therapy on pain perception after free gingival graft surgery in patients with mucogingival defects. A Randomized Controlled Clinical Trial.

Prefrontal oxygenation during experimental pain in adolescents engaging in non-suicidal self-injury

BackgroundThe intricate role of pain in non-suicidal self-injury (NSSI) makes the investigation of alterations in brain function during pain processing a critical yet underexplored topic. The aim of this study was to investigate fNIRS correlates of experimental pain and how these differed between adolescent patients engaging in NSSI and healthy controls. Methods154 adolescent patients with NSSI and 48 healthy controls underwent a heat pain stimulation with linearly increasing temperature from 32 °C to max. 50 °C, during which fNIRS activity was recorded. Associations between fNIRS activity and pain perception (i.e. pain threshold, pain tolerance and pain intensity) were examined using linear mixed models and linear regression analyses. ResultsAcross groups, we found a decrease in prefrontal oxygenation during increasing pain stimulation: Oxygenated hemoglobin was higher during baseline than during pain threshold (b = −0.36, p < .001) and higher during pain threshold than during pain tolerance (b = −0.10, p < .001). We did not find differential patterns of prefrontal oxygenation across the pain assessment between patients and healthy controls. Also, no association between pain intensity and fNIRS activity was found. LimitationsfNIRS was only recorded in prefrontal regions and our design did not include a non-painful stimulation as a control condition. ConclusionWhile our study adds to the understanding of prefrontal hemodynamic changes associated with pain processing, it did not contribute further evidence to the few existing findings regarding altered neural processing of pain in adolescents engaging in NSSI.

Principles of Pain Management.

This article introduces the general principles of assessing, diagnosing, and managing pain relevant to neurologic practice. Scientific understanding of and clinical practices related to pain and pain management are advancing. The field is remarkable for the diversity of health professions engaged in this effort, including physicians, scientists, psychologists, pharmacists, and many others. Pain classification is transforming with pending changes to the International Classification of Diseases diagnostic coding system, and pain assessment has moved toward consistent application of the biopsychosocial model. The diagnosis of pain has continued to become more sophisticated with the development of additional testing modalities, clearer classification systems, and diagnostic criteria. Pain management requires both pharmacologic and nonpharmacologic elements; systematic review evidence for both of these and interventional and surgical management are increasingly available. The context of treatment remains important given the impact of social determinants of health and limitations of access to diagnostic and treatment resources. Due to global and interprofessional collaborations as well as new research funding, the outlook is positive. Pain is a protean experience for humans; functional MRI (fMRI) and other research modalities show that pain perception is highly multifocal, and modulation occurs at many nervous system levels. Neurologists bring special skills to pain evaluation and management, are well equipped to appreciate both the focal and diffuse nature of pain, and can envision how pain attenuates sleep, cognitive function, mobility, motivation, and social connection. By operationalizing expert knowledge of the nervous system, implementing relevant therapies, and collaborating with diverse health professions to manage pain, neurologists can succeed at and find meaning in optimizing patient outcomes.