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1.
J Clin Neurosci ; 95: 180-187, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34929643

RESUMO

OBJECTIVE: This study aims to observe the effects of direct suppression of the parabrachial nucleus (PBN) on chronic neuropathic pain (CNP) and CNP-related behaviors in mice. METHODS: A CNP model was established using partial sciatic nerve ligation (PSNL) in mice. Two groups were established: the experimental (PSNL) group and the control (sham) group. An assessment of PBN-region c-Fos expression was conducted following von Frey hair stimulation in the PSNL group and the sham group, and the effects of pain induction were detected using behavioral experiments. The PBN activity of the mice with CNP was manipulated using the designer receptors exclusively activated by designer drugs method. Effective and empty virus groups were used to study the effects of PBN activity inhibition on the pain threshold and pain-related behavior in mice with CNP. RESULTS: The mechanical pain threshold (MPT) of the mice in the PSNL group was significantly lower than in the sham group. After von Frey stimulation, the c-Fos-positive, PBN-region neurons in the PSNL group were increased compared with the sham group. The central distance in the open field test and the time spent in the central area were lower in the PSNL group than in the sham group. The mice in the PSNL group had a lower duration and fewer entries in the open arm of the elevated plus-maze than the mice in the sham group. There was no difference in immobility time between the PSNL group and the sham group. PBN activity inhibition in mice with CNP did not affect their MPT or anxiety-like behavior. CONCLUSION: CNP can induce anxiety-like behavior and increase PBN-induced pain in mice. However, direct inhibition of the PBN neuron activity alone cannot improve CNP or CNP-related behavior.


Assuntos
Neuralgia , Núcleos Parabraquiais , Animais , Camundongos , Neurônios , Limiar da Dor , Nervo Isquiático
2.
Rev Assoc Med Bras (1992) ; 67(12): 1798-1803, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34909952

RESUMO

OBJECTIVE: The objective of the study was to correlate the thermal pain threshold (heat and cold) on myofascial trigger points with measurements of pain and skin temperature in patients with chronic neck pain. METHODS: This is a cross-sectional study. We included participants of both genders, aged between 18-45 years, with chronic neck pain (>90 days), and with active bilateral myofascial trigger point centrally located in the upper trapezius muscle. Neck Disability Index, Numerical Rating Scale, Pain-Related Catastrophizing Thoughts Scale, algometry, infrared thermography, and quantitative sensory testing were used for the evaluation. RESULTS: A significant, weak, and negative association was observed between pain intensity and heat pain threshold on the myofascial trigger point to the right (rho -0.381, p=0.022) and to the left (rho -0.334, p=0.049), and a significant, weak, and positive association was observed between pain intensity and cold pain threshold on the myofascial trigger point to the right (rho 0.471, p=0.004) and to the left (rho 0.339, p=0.043). CONCLUSION: Thermal pain threshold (heat and cold) on myofascial trigger points is associated with pain intensity in individuals with chronic neck pain.


Assuntos
Síndromes da Dor Miofascial , Pontos-Gatilho , Adolescente , Adulto , Catastrofização , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cervicalgia , Medição da Dor , Limiar da Dor , Temperatura Cutânea , Adulto Jovem
3.
Ger Med Sci ; 19: Doc14, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34955699

RESUMO

Background and aims: This randomized cross-over study in healthy volunteers was designed primarily to evaluate the potential impact of investigator gender on electrical pain threshold (EPT) and corresponding pain intensity levels, and secondly to evaluate potential differences in those interventions between female and male study participants. Methods: Forty adult volunteers (22 females) were included. An electrical stimulation device was used to determine EPT levels (in pain magnitude scores) in series of three in each study participant - once by a female, and once by a male investigator - according to a predefined cross-over design schedule. Corresponding levels of pain intensity were scored on a visual analog scale (VAS) slide ruler. Results: Study data was obtained and analysed in all participants. Significantly higher EPT levels were determined by the female investigator compared with the male investigator (median 22 (IQR 12-31) vs. 8 (6-10) pain magnitude scores; p<0.0001), despite similar levels of reported pain intensity (1.9 (1.2-3.0) vs. 2.0 (1.1-3.4) VAS units; p>0.300). There were no differences in EPT levels between female and male subjects evaluated by female (p>0.300) and male (p=0.125) investigators, or between the first and second series of stimulation (p>0.300). Conclusions: Our finding of significantly higher EPT levels when study participants of both genders - despite no difference in reported pain intensity - were evaluated by a female than by a male investigator, indicates a potential impact of investigator gender on the individual perception of pain. Implications: By contributing to a better understanding of how individual pain threshold levels are potentially influenced by investigator gender, this study might facilitate future evaluation of pain conditions in both preclinical and clinical settings.


Assuntos
Limiar da Dor , Dor , Adulto , Estudos Cross-Over , Feminino , Voluntários Saudáveis , Humanos , Masculino , Dor/diagnóstico , Dor/epidemiologia , Dor/etiologia , Medição da Dor
4.
Sheng Li Xue Bao ; 73(6): 953-962, 2021 Dec 25.
Artigo em Chinês | MEDLINE | ID: mdl-34961870

RESUMO

Nicotine is the main addictive component in cigarettes that motivates dependence on tobacco use for smokers and makes it difficult to quit through regulating a variety of neurotransmitter release and receptor activations in the brain. Even though nicotine has an analgesic effect, clinical studies demonstrated that nicotine abstinence reduces pain threshold and increases pain sensitivity in smoking individuals. The demand for opioid analgesics in nicotine abstinent patients undergoing surgery has greatly increased, which results in many side effects, such as nausea, vomiting, and respiratory depression, etc. In addition, these side effects would hinder patients' physical and psychological recovery. Therefore, identifying the neural mechanism of the increase of pain sensitivity induced by nicotine abstinence and deriving a way to cope with the increased demand for postoperative analgesics would have enormous basic and clinical implications. In this review, we first discussed different experimental pain stimuli (e.g., cold, heat, and mechanical pain)-induced pain sensitivity changes after a period of nicotine dependence/abstinence from both animal and human studies. Then, we summarized the effects of the brain neurotransmitter release (e.g., serotonin, norepinephrine, endogenous opioids, dopamine, and γ-aminobutyric acid) and their corresponding receptor activation changes after nicotine abstinence on pain sensitivity. Finally, we discussed the limits in recent studies. We proposed that more attention should be paid to human studies, especially studies among chronic pain patients, and functional magnetic resonance imaging might be a useful tool to reveal the mechanisms of abstinence-induced pain sensitivity changes. Besides, considering the influence of duration of nicotine dependence/abstinence and gender on pain sensitivity, we proposed that the effects of nicotine abstinence and individual differences (e.g., duration of abstinence from smoking, chronic/acute abstinence, and gender) on abstinence-induced pain sensitivity should be fully considered in formulating pain treatment protocols. In summary, this paper could deepen our understanding of nicotine abstinence-induced pain sensitivity changes and its underlying neural mechanism, and could also provide effective scientific theories to guide clinical pain diagnosis and treatment, which has important clinical significance.


Assuntos
Abandono do Hábito de Fumar , Tabagismo , Animais , Humanos , Nicotina/efeitos adversos , Dor , Limiar da Dor
5.
J Headache Pain ; 22(1): 134, 2021 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-34749638

RESUMO

BACKGROUND: Headache affects 90-99% of the population. Based on the question "Do you think that you never ever in your whole life have had a headache?" 4% of the population say that they have never experienced a headache. The rarity of never having had a headache suggests that distinct biological and environmental factors may be at play. We hypothesized that people who have never experienced a headache had a lower general pain sensitivity than controls. METHODS: We included 99 male participants, 47 headache free participants and 52 controls, in an observer blinded nested case-control study. We investigated cold pain threshold and heat pain threshold using a standardized quantitative sensory testing protocol, pericranial tenderness with total tenderness score and pain tolerance with the cold pressor test. Differences between the two groups were assessed with the unpaired Student's t-test or Mann-Whitney U test as appropriate. RESULTS: There was no difference in age, weight or mean arterial pressure between headache free participants and controls. We found no difference in pain detection threshold, pericranial tenderness or pain tolerance between headache free participants and controls. CONCLUSION: Our study clearly shows that freedom from headache is not caused by a lower general pain sensitivity. The results support the hypothesis that headache is caused by specific mechanisms, which are present in the primary headache disorders, rather than by a decreased general sensitivity to painful stimuli. TRIAL REGISTRATION: Registered at ClinicalTrials.gov ( NCT04217616 ), 3rd January 2020, retrospectively registered.


Assuntos
Limiar da Dor , Cefaleia do Tipo Tensional , Estudos de Casos e Controles , Cefaleia/epidemiologia , Humanos , Masculino , Dor
6.
J Psychosom Res ; 150: 110624, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34600309

RESUMO

INTRODUCTION: Chronic fatigue syndrome (CFS) and fibromyalgia (FM) are both complex conditions that are challenging to treat. This may be related to an incomplete understanding of their pathophysiology, itself obfuscated by their heterogeneity. The symptomatic overlap between them and their common comorbidity suggests a shared vulnerability, which might be explained by central sensitisation. METHODS: 19 CFS cases, 19 FM cases and 20 age and sex matched healthy controls (HC) were recruited primarily from secondary care clinics in London. Those with other pain disorders, psychiatric diagnoses and those taking centrally acting or opiate medications were excluded. Participants were asked to abstain from alcohol and over the counter analgaesia 48 h prior to assessment by static and dynamic quantitative sensory tests, including measures of temporal summation (TS) and conditioned pain modulation (CPM). RESULTS: CS, as defined by the presence of both enhanced TS and inefficient CPM, was present in 16 (84%) CFS cases, 18 (95%) FM cases, and none of the HC (p < 0.001). Pressure pain thresholds were lower in CFS (Median222kPaIQR 146-311; p = 0.04) and FM cases (Median 189 kPa; IQR 129-272; p = 0.003) compared to HC (Median 311 kPa; IQR 245-377). FM cases differed from HC in cold-induced (FM = 22.6 °C (15.3-27.7) vs HC = 14.2 °C (9.0-20.5); p = 0.01) and heat-induced (FM = 38.0 °C (35.2-44.0) vs HC = 45.3 °C (40.1-46.8); p = 0.03) pain thresholds, where CFS cases did not. CONCLUSION: Central sensitisation may be a common endophenotype in chronic fatigue syndrome and fibromyalgia. Further research should address whether central sensitisation is a cause or effect of these disorders.


Assuntos
Síndrome de Fadiga Crônica , Fibromialgia , Estudos de Casos e Controles , Sensibilização do Sistema Nervoso Central , Síndrome de Fadiga Crônica/epidemiologia , Fibromialgia/epidemiologia , Humanos , Limiar da Dor
7.
J Oral Facial Pain Headache ; 35(3): 199-207, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34609378

RESUMO

AIMS: To evaluate the efficacy of a gluten-free diet (GFD) as a treatment modality for pain management in women with chronic myofascial pain in masticatory muscles. METHODS: In this randomized controlled trial, 39 female subjects were evaluated according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and divided into three groups: a healthy group (n = 14; mean ± SD age = 34.57 ± 9.14 years); a control group (n = 12; age = 31.50 ± 7.38 years); and an experimental group (n = 13; age 30.00 ± 7.64 years). The outcome variables were: pain intensity, mechanical pain threshold (MPT), and pressure pain threshold (PPT). MPT was performed on the masseter muscle, and PPT was performed on both the masseter and anterior temporalis muscles. A nutritionist prescribed a 4-week individualized GFD for the experimental group. The healthy group was analyzed only initially, whereas the control and experimental groups were analyzed again after 4 weeks. Data were subjected to statistical analysis with a significance level of 5% (one-way analysis of variance followed by Bonferroni post hoc, paired t, Wilcoxon signed rank, Kruskal-Wallis/Dunn, and Pearson chi-square tests). RESULTS: Participants who underwent a GFD showed reduction in pain intensity (P = .006) and an increase in PPT of the masseter (P = .017) and anterior temporalis (P = .033) muscles. The intervention did not influence the MPT of the masseter muscle (P = .26). In contrast, the control group showed no improvement in any parameter evaluated. CONCLUSION: GFD seemed to reduce pain sensitivity in women with TMD and may be beneficial as an adjunctive therapy for chronic myofascial pain in masticatory muscles; however, further studies in the fields of orofacial pain and nutrition are required.


Assuntos
Dieta Livre de Glúten , Músculos da Mastigação , Adulto , Dor Facial , Feminino , Humanos , Medição da Dor , Limiar da Dor , Adulto Jovem
8.
Artigo em Inglês | MEDLINE | ID: mdl-34639438

RESUMO

The purpose of this study was to determine if the severity of headache is reduced by decreasing hamstring tension in patients with tension headache. Thirty patients participated in this study. The participants were randomly allocated to two groups: hamstring relaxation program (HR) group (n = 15) and control group (n = 15). The participants in the HR group participated in a HR program for 25 min per day, three times per week, for a period of 4 weeks, and the control group participated in an electrotherapy for 25 min per day, three times per week, for a period of 4 weeks. Both groups participated in a self-myofacial release for 5 min per day, three times per week, for a period of 4 weeks. Headache was evaluated using the headache impact test (HIT-6) and visual analog scale (VAS). The pain pressure threshold (PPT) was evaluated using a digital pressure algometer. The range of motion (ROM) was evaluated using a goniometer and two special tests: straight leg raise test (SLRT) and popliteal angle test (PAT). The two groups showed no significant differences in terms of age, sex, height, and weight. The VAS and HIT-6 scores (p < 0.05) and neck and hamstring PPT showed significant improvements (p < 0.05). Neck flexion ROM and SLRT and PAT scores showed significant improvements (p < 0.05) in both groups, and the HR group showed significantly more improvements than the control group. This study confirmed that the HR program has positive effects on tension headache and is a good intervention for alleviating headaches in patients with tension headache.


Assuntos
Cefaleia do Tipo Tensional , Cefaleia , Humanos , Dor , Limiar da Dor , Amplitude de Movimento Articular , Cefaleia do Tipo Tensional/terapia
10.
Chiropr Man Therap ; 29(1): 34, 2021 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-34479585

RESUMO

INTRODUCTION: Little is known about the underlying biomechanical cause of low back pain (LBP). Recently, technological advances have made it possible to quantify biomechanical and neurophysiological measurements, potentially relevant factors in understanding LBP etiology. However, few studies have explored the relation between these factors. This study aims to quantify the correlation between biomechanical and neurophysiological outcomes in non-specific LBP and examine whether these correlations differ when considered regionally vs. segmentally. METHODS: This is a secondary cross-sectional analysis of 132 participants with persistent non-specific LBP. Biomechanical data included spinal stiffness (global stiffness) measured by a rolling indenter. Neurophysiological data included pain sensitivity (pressure pain threshold and heat pain threshold) measured by a pressure algometer and a thermode. Correlations were tested using Pearson's product-moment correlation or Spearman's rank correlation as appropriate. The association between these outcomes and the segmental level was tested using ANOVA with post-hoc Tukey corrected comparisons. RESULTS: A moderate positive correlation was found between spinal stiffness and pressure pain threshold, i.e., high degrees of stiffness were associated with high pressure pain thresholds. The correlation between spinal stiffness and heat pain threshold was poor and not statistically significant. Aside from a statistically significant minor association between the lower and the upper lumbar segments and stiffness, no other segmental relation was shown. CONCLUSIONS: The moderate correlation between spinal stiffness and mechanical pain sensitivity was the opposite of expected, meaning higher degrees of stiffness was associated with higher pressure pain thresholds. No clinically relevant segmental association existed.


Assuntos
Dor Lombar , Limiar da Dor , Estudos Transversais , Temperatura Alta , Humanos , Região Lombossacral
11.
Anesth Analg ; 133(5): 1321-1330, 2021 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-34524124

RESUMO

BACKGROUND: The maternal pain threshold gradually increases during pregnancy, especially in late pregnancy. A series of mechanisms underlying pregnancy-induced analgesia have been reported. However, these mechanisms are still not completely clear, and the underlying molecular mechanisms need further investigation. We examined the relationship between the antinociceptive effect and the expression level of programmed cell death ligand-1 (PD-L1) during pregnancy and further observed the changes in pain thresholds and expression levels of cytokines in late-pregnant mice before and after blockade of PD-L1 or programmed cell death-1 (PD-1). METHODS: Part 1: Female mice were assigned to 3 groups (nonpregnant, late-pregnant, and postpartum). Part 2: Late-pregnant mice were assigned to 3 treatment groups (control [phosphate buffer solution], RMP1-14 [mouse anti-PD-1 antibody], and soluble PD-1 [sPD-1]). Behavioral testing (mechanical and thermal) and tissue (serum and spinal cord) analysis were performed on all groups. PD-L1, interleukin (IL)-10, tumor necrosis factor-α (TNF-α), and IL-6 expression levels in tissue were examined via reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and Western blot analysis. RESULTS: The mechanical and thermal pain thresholds were significantly increased in late pregnancy and decreased after delivery. PD-L1 expression was also elevated in late pregnancy and decreased after delivery. In addition, in the late stage of gestation, the maternal inflammatory microenvironment was dominated by anti-inflammatory factors. After administration of RMP1-14 or sPD-1, the pain thresholds of late-pregnant mice were significantly reduced. In late-pregnant mice, the high level of IL-10 was obviously reduced, and the low levels of TNF-α and IL-6 were elevated. CONCLUSIONS: The PD-L1/PD-1 pathway mediates pregnancy-induced analgesia, partially via the regulation of cytokines.


Assuntos
Antígeno B7-H1/metabolismo , Citocinas/metabolismo , Mediadores da Inflamação/metabolismo , Limiar da Dor , Dor/prevenção & controle , Receptor de Morte Celular Programada 1/metabolismo , Medula Espinal/metabolismo , Animais , Comportamento Animal , Feminino , Camundongos , Dor/metabolismo , Dor/fisiopatologia , Gravidez , Transdução de Sinais , Medula Espinal/fisiopatologia
12.
Exp Brain Res ; 239(11): 3405-3415, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34505162

RESUMO

The nociceptive withdrawal reflex (NWR) threshold is commonly employed in the lower limb to assess clinical and experimentally induced pain. However, no studies to date have investigated changes in spinal nociception in the upper limb, via the NWR threshold, following experimentally induced central sensitization (CS). We tested the hypothesis that experimentally induced CS of the C5-C6 spinal segment significantly reduces NWR thresholds in muscles of the upper limb. Upper limb NWR thresholds from 20 young, healthy adults were assessed by applying noxious electrical stimuli to the right index finger and recording muscle activity from the biceps brachii (BI), triceps brachii (TRI), flexor carpi ulnaris (WF), and extensor carpi radialis longus (WE) muscles via surface electromyography. Topical cream (either 0.075% capsaicin, or control) was applied to the C5-C6 dermatome of the lateral forearm (50 cm2). NWR thresholds were compared at baseline, and four 10-min intervals after topical application. WF muscle NWR thresholds were significantly reduced in the capsaicin session compared to control, while TRI muscle NWR thresholds were significantly reduced 40 min after capsaicin application only (p < 0.05). There were no significant differences for BI or WE muscle NWR thresholds. We observed poor to moderate test-retest reliability for all upper limb NWR thresholds, a key contributor to the selective reduction in NWR thresholds among muscles. Accordingly, while our findings demonstrate some comparability to previously reported lower limb NWR studies, we concurrently report limitations of the upper limb NWR technique. Further exploration of optimal parameters for upper limb NWR acquisition is needed.


Assuntos
Capsaicina , Nociceptividade , Adulto , Sensibilização do Sistema Nervoso Central , Estimulação Elétrica , Eletromiografia , Humanos , Músculo Esquelético , Limiar da Dor , Reflexo , Reprodutibilidade dos Testes , Extremidade Superior
13.
Rev Assoc Med Bras (1992) ; 67(5): 708-712, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34550260

RESUMO

OBJECTIVE: The aim of this study was to evaluate the intra- and inter-rater reliability of pressure pain threshold measurement on myofascial trigger points in the trapezius muscle in women with chronic neck pain. METHODS: This reliability study involved 30 volunteers with neck pain for more than 90 days. The assessment procedures were performed by blinded researchers. Two examiners, who were previously trained in the use of algometry, independently performed two assessments of the pressure pain threshold at two time intervals, one week apart. RESULTS: The study sample consisted of 30 young adult women. Excellent intra- and inter-rater reliability were found for the pressure pain threshold on myofascial trigger points, with intraclass correlation coefficient values ranging between 0.752 and 0.874, standard error of measurement ranging between 0.18 and 0.22 kg/cm2, and minimum detectable change ranging between 0.45 and 0.62 kg/cm2. CONCLUSION: The present study showed that the assessment of pressure pain threshold through algometry presents satisfactory intraclass correlation coefficient values, considering different time and examiners, contributing to the spread of the use of this tool as a quantitative method of pain evaluation in myofascial trigger points.


Assuntos
Síndromes da Dor Miofascial , Músculos Superficiais do Dorso , Feminino , Humanos , Síndromes da Dor Miofascial/diagnóstico , Cervicalgia/diagnóstico , Limiar da Dor , Reprodutibilidade dos Testes , Pontos-Gatilho , Adulto Jovem
14.
Pain Physician ; 24(6): E783-E794, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34554698

RESUMO

BACKGROUND: Simple tools are needed to predict postoperative pain. Questionnaire-based tools such as the Pain Sensitivity Questionnaire (PSQ) are validated for this purpose, but prediction could be improved by incorporating other parameters. OBJECTIVES: To explore the potency of sensitivity to nonpainful stimuli and biometric data to improve prediction of pain. STUDY DESIGN: Transversal exploratory study. SETTING: Single clinical investigation center. METHODS: Eighty-five healthy volunteers of both genders underwent a multimodal exploration including biometry, questionnaire-based assessment of anxiety, depression, pain catastrophizing, sensitivity to smell, and the PSQ, followed by a psychophysical assessment of unpleasantness thresholds for light and sound, and sensitivity to mechanical, heat, and cold pain. These last 3 parameters were used to calculate a composite pain score. After a multi-step selection, multivariable analyses identified the explanative factors of experimental pain sensitivity, by including biometric, questionnaire-based, and psychophysical nonnociceptive sensitivity parameters, with the aim of having each domain represented. RESULTS: Female gender predicted mechanical pain, a younger age and dark eyes predicted cold pain, and the PSQ predicted heat pain. Sensitivity to unpleasantness of sound predicted mechanical and heat pain, and sensitivity to unpleasantness of light predicted cold pain. Sensitivity to smell was unrelated. The predictors of the composite pain score were the PSQ, the light unpleasantness threshold, and an interaction between gender and eye color, the score being lower in light-eyed men and higher in all women. The final multivariable multi-domain model was more predictive of pain than the PSQ alone (R2 = 0.301 vs 0.122, respectively). LIMITATIONS: Sensitivity to smell was only assessed by a short questionnaire and could lack relevance. Healthy volunteers were unlikely to elicit psychological risk factors such as anxiety, depression, or catastrophizing. These results have not been validated in a clinical setting (e.g., perioperative). CONCLUSION: The predictive potential of the PSQ can be improved by including information about gender, eye color, and light sensitivity. However, there is still a need for a technique suitable for routine clinical use to assess light sensitivity.


Assuntos
Catastrofização , Limiar da Dor , Feminino , Humanos , Masculino , Medição da Dor , Dor Pós-Operatória , Inquéritos e Questionários
15.
Clin Oral Investig ; 25(12): 6547-6559, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34487241

RESUMO

OBJECTIVES: This meta-analysis aimed to evaluate quantitative sensory testing (QST) evidence for pain processing in patients with the muscle pain subtype of temporomandibular disorders (mTMD). MATERIALS AND METHODS: A comprehensive systematic electronic search strategy was performed in online literature databases. All full-text observational studies published up to July 2021 with the aim of investigating pain sensitization in humans with mTMD using QST measures were eligible for inclusion. Meta-analysis of QST data was performed using a random effects model, which included results comparing patients with mTMD to healthy controls, and standard mean difference (SMD) results were analyzed. RESULTS: Twelve studies with 732 participants (371 patients with mTMD and 361 healthy controls) were analyzed following screening and quality appraisal. Compared with healthy controls, patients with mTMD had significantly lower pressure pain threshold (SMD - 1.10, 95% confidence interval [CI] - 1.52 to - 0.68) with high heterogeneity (Tau2 = 0.61, I2 = 86%), and significantly lower mechanical pain threshold (SMD - 0.64, 95% CI - 0.95 to - 0.32) with no heterogeneity (Tau2 = 0.00, I2 = 0%). No difference was observed in the cold pain threshold (SMD 0.16, 95% CI - 0.13 to 0.45), heat pain threshold (SMD - 0.13, 95% CI - 0.40 to 0.15), and wind-up ratio (SMD 0.63, 95% CI - 0.11 to 1.38) between patients with mTMD and healthy controls. Other QST parameters were also discussed. CONCLUSIONS: The study results suggest that the pain processing of deep tissues is likely sensitized in mTMD and calls for more QST studies with standard procedures to reduce inter-study heterogeneity. CLINICAL RELEVANCE: The major findings of this meta-analysis support using PPT to examine the pain processing in patients with mTMD in clinical scenario.


Assuntos
Mialgia , Transtornos da Articulação Temporomandibular , Humanos , Medição da Dor , Limiar da Dor
16.
Scand J Pain ; 21(2): 355-363, 2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-34387949

RESUMO

OBJECTIVES: The effect of stretching on joint range of motion is well documented, and although sensory perception has significance for changes in the tolerance to stretch following stretching the underlining mechanisms responsible for these changes is insufficiently understood. The aim of this study was to examine the influence of endogenous pain inhibitory mechanisms on stretch tolerance and to investigate the relationship between range of motion and changes in pain sensitivity. METHODS: Nineteen healthy males participated in this randomized, repeated-measures crossover study, conducted on 2 separate days. Knee extension range of motion, passive resistive torque, and pressure pain thresholds were recorded before, after, and 10 min after each of four experimental conditions; (i) Exercise-induced hypoalgesia, (ii) two bouts of static stretching, (iii) resting, and (iv) a remote, painful stimulus induced by the cold pressor test. RESULTS: Exercise-induced hypoalgesia and cold pressor test caused an increase in range of motion (p<0.034) and pressure pain thresholds (p<0.027). Moderate correlations in pressure pain thresholds were found between exercise-induced hypoalgesia and static stretch (Rho>0.507, p=0.01) and exercise-induced hypoalgesia and the cold pressor test (Rho=0.562, p=0.01). A weak correlation in pressure pain thresholds and changes in range of motion were found following the cold pressor test (Rho=0.460, p=0.047). However, a potential carryover hypoalgesic effect may have affected the results of the static stretch. CONCLUSIONS: These results suggest that stretch tolerance may be linked with endogenous modulation of pain. Present results suggest, that stretch tolerance may merely be a marker for pain sensitivity which may have clinical significance given that stretching is often prescribed in the rehabilitation of different musculoskeletal pain conditions where reduced endogenous pain inhibition is frequently seen.


Assuntos
Limiar da Dor , Dor , Estudos Cross-Over , Humanos , Masculino , Percepção da Dor , Amplitude de Movimento Articular
17.
Scand J Pain ; 21(2): 364-371, 2021 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-34387950

RESUMO

OBJECTIVES: Ultra-endurance research interest has increased in parallel with an increased worldwide participation in these extreme activities. Pain-related data for the growing population of ultra-endurance athletes, however, is insufficient. More data is especially needed regarding the variation in the aging populations of these athletes. We have previously shown that peripheral and central pain sensitivity increases during an ultra-marathon. To further clarify these changes in pain sensitivity during ultra-endurance competition we investigated these variations in two age populations: Younger runners ≤ 39-year-old (younger) and an older group of runners being ≥ 40 years of age (older). METHODS: Subjects were recruited from ultra-marathon competitions held over a three-year period in Florida, USA. All courses were flat with either hard macadam surface or soft sandy trails; run in hot, humid weather conditions. Pressure pain threshold (PPT) was measured with a pressure algometer on the distal, dominant arm before and immediately after an ultra-marathon. Conditioned pain modulation (CPM) was also measured pre and post, immediately after the PPT by placing the non-dominant hand in a cold-water bath maintained at 13.5 ± 1.5 °C. The difference between the pre and post measurements for both PPT and CPM were calculated and referred to as ΔPPT and ΔCPM, respectively for analysis. Data were analyzed with a Mixed 2 × 2 (Within X Between) MANOVA. RESULTS: Both PPT and CPM decreased during the ultra-marathons (p<0.05) in the younger group of runners. In the older runners there was not a statistically significant decrease in PPT during the ultramarathons whereas CPM did significantly decrease statistically (p=0.031). The ΔPPT was less in the older group compared to the younger group (p=0.018). The difference between the younger and older groups ΔCPM approached statistical significance at p=0.093. CONCLUSIONS: This statistical evidence suggests that the overall increase in peripheral and possibly central pain sensitivity was different between our age groups. Pain sensitivity during the ultra-marathon increased more in our younger group of runners than in our older group. This study suggests that there is an unidentified factor in an older population of ultra-marathon runners that results in an attenuated increase in pain sensitivity during an ultra-endurance activity. These factors may include a decreased innate immune response, lower fitness level, lower exertion during the ultra-marathon, variation in endorphin, enkephalin, endocannabinoid and psychological factors in the older age runners.


Assuntos
Limiar da Dor , Corrida , Adulto , Idoso , Humanos , Corrida de Maratona , Dor , Resistência Física
18.
Spinal Cord Ser Cases ; 7(1): 72, 2021 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-34365469

RESUMO

INTRODUCTION: Chronic neuropathic pain (NeP) often develops following traumatic spinal cord injury (SCI). This case report explores variability in clinical and neurophysiological aspects of pain evaluation in early post-trauma stages. CASE PRESENTATION: A 34-year old female presenting with acute incomplete sensorimotor tetraplegia C4 AIS D was examined by neurological examination and pain assessment at three time points after acute trauma T1 (8 weeks), T2 (11 weeks), and T3 (24 weeks). Quantitative sensory testing (QST) and laser-evoked potentials (LEPs) were measured above (control area), at (area of NeP), and below (foot) the neurological level of injury (NLI). Musculo-skeletal and neuropathic pain were clinically present already during T1 but showed variations in localization and occurrence over time. Neuropathic pain classification varied between time points due to shifting of NLI. Above-level QST revealed minor, less pronounced abnormalities similar to at-level site. At-level QST (site of NeP) showed loss for thermal and mechanical detection thresholds but also gain of function for mechanical pain thresholds with a tendency of amelioration over time. QST below-level did not reveal remarkable changes over time. LEPs above- and below-level were within normal limits. At-level LEPs abolished after T1. DISCUSSION: In early stages post injury (up to 6 month) variations in pain presentation for both, musculo-skeletal and neuropathic pain as well as QST and LEP could be demonstrated. These findings suggest ongoing adaption mechanisms in sensory pathways, which require further exploration and may be relevant for prognostic and preventive strategies against the development of chronic neuropathic and nociceptive pain.


Assuntos
Neuralgia , Traumatismos da Medula Espinal , Adulto , Feminino , Humanos , Neuralgia/diagnóstico , Neuralgia/etiologia , Exame Neurológico , Medição da Dor , Limiar da Dor , Traumatismos da Medula Espinal/diagnóstico
19.
Eur J Obstet Gynecol Reprod Biol ; 264: 247-253, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34340095

RESUMO

OBJECTIVE: Pelvic floor pain, abdominal wall pain, and central nervous system pain amplification can be contributing factors in chronic pelvic pain (CPP), however; limited research has investigated the association of pelvic floor, abdominal, and uterine tenderness with central nervous system pain amplification. We assessed whether pressure pain thresholds on the non-dominant thumbnail, a marker of central nervous system pain amplification, were associated with pelvic floor, abdominal, and uterine tenderness among women with endometriosis or CPP. STUDY DESIGN: We conducted a cross-sectional study among 88 females with endometriosis and/or CPP. Abdominal (6 locations), pelvic floor (6 locations) and uterine (1 location) tenderness were assessed via a standardized physical exam. Participants reported their pain levels (0-10 scale) with application of 2 kg of pressure at each area, with a pain rating of ≥4 on the 0-10 scale considered moderate to severe pain. Pain sensitivity was measured on the non-dominant thumbnail by applying discrete pressure stimuli using a previously validated protocol. RESULTS: Overall, 50% (44/88), 42% (37/88), and 58% (51/88) of participants reported high pelvic floor, abdominal, and uterine tenderness, respectively. Pressure intensities needed to elicit 'faint' and 'mild' pain were lower for participants with high vs. low pelvic floor tenderness (median intensity for 'faint' pain = 0.50 kgf/cm2(min-max:0.25-3.25) vs. 1.06(0.25-3.00), p-value = 0.006; median intensity for 'mild' pain = 2.00(0.63-4.88) vs. 2.63(0.75-6.00), p-value = 0.03). No association was observed between pressure pain sensitivity and abdominal or uterine tenderness (p > 0.11). Participants with endometriosis without pain were less likely to have high pelvic floor (22.2%), abdominal (11.1%), and uterine (25.9%) tenderness compared to participants with endometriosis with pain (63.0%, 50%, 65.2%, respectively) and participants with chronic pelvic pain (60%, 73.3%, 93.3%, respectively). CONCLUSIONS: These results suggest that high pelvic floor tenderness among women with endometriosis/CPP may be a marker of heightened pain sensitivity suggestive of central nervous system pain amplification and may impact treatment response. Future research should examine whether this clinical phenotype predicts response to medical and behavioral treatments (e.g, anti-convulsants, behavioral therapy, Physical Therapy).


Assuntos
Dor Crônica , Endometriose , Dor Abdominal , Dor Crônica/etiologia , Estudos Transversais , Endometriose/complicações , Feminino , Humanos , Limiar da Dor , Diafragma da Pelve , Dor Pélvica/etiologia
20.
Sci Rep ; 11(1): 15673, 2021 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-34341446

RESUMO

Nocifensive behavior induced by injection of glutamate or nerve growth factor (NGF) into rats masseter muscle is mediated, in part, through the activation of peripheral NMDA receptors. However, information is lacking about the mechanism that contributes to pain and sensitization induced by these substances in humans. Immunohistochemical analysis of microbiopsies obtained from human masseter muscle was used to investigate if injection of glutamate into the NGF-sensitized masseter muscle alters the density or expression of the NMDA receptor subtype 2B (NR2B) or NGF by putative sensory afferent (that express SP) fibers. The relationship between expression and pain characteristics was also examined. NGF and glutamate administration increased the density and expression of NR2B and NGF by muscle putative sensory afferent fibers (P < 0.050). This increase in expression was greater in women than in men (P < 0.050). Expression of NR2B receptors by putative sensory afferent fibers was positively correlated with pain characteristics. Results suggest that increased expression of peripheral NMDA receptors partly contributes to the increased pain and sensitivity induced by intramuscular injection of NGF and glutamate in healthy humans; a model of myofascial temporomandibular disorder (TMD) pain. Whether a similar increase in peripheral NMDA expression occurs in patients with painful TMDs warrants further investigation.


Assuntos
Músculo Masseter , Substância P , Animais , Estimulação Elétrica , Ácido Glutâmico/metabolismo , Masculino , Fator de Crescimento Neural , Nociceptores/metabolismo , Limiar da Dor , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/metabolismo , Substância P/metabolismo
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