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Although pain is a widely known phenomenon and an important clinical symptom that occurs in numerous diseases, its mechanisms are still barely understood. Owing to the scarce information concerning its pathophysiology, particularly what is involved in the transition from an acute state to a chronic condition, pain treatment is frequently unsatisfactory, therefore contributing to the amplification of the chronic pain burden. In fact, pain is an extremely complex experience that demands the recruitment of an intricate set of central nervous system components. This includes cortical and subcortical areas involved in interpretation of the general characteristics of noxious stimuli. It also comprises neural circuits that process the motivational-affective dimension of pain. Hence, the reward circuitry represents a vital element for pain experience and modulation. This review article focuses on the interpretation of the extensive data available connecting the major components of the reward circuitry to pain suffering, including the nucleus accumbens, ventral tegmental area, and the medial prefrontal cortex; with especial attention dedicated to the evaluation of neuroplastic changes affecting these structures found in chronic pain syndromes, such as migraine, trigeminal neuropathic pain, chronic back pain, and fibromyalgia.

The control of hypertensive patients' blood pressure and heart rate using vasoconstrictors during surgical procedures under anesthesia is still a major concern in everyday surgical practice. This clinical trial aimed to evaluate the variation of blood pressure and heart rate in nonhypertensive and controlled hypertensive voluntary subjects undergoing oral surgery under local anesthesia with lidocaine hydrochloride and epinephrine at 1:100,000 (Alphacaine; DFL, Brazil), performed in the Oral Surgery Department, Dentistry School, Fluminense Federal University. In total, 25 voluntary subjects were divided into 2 groups: nonhypertensive (n = 15) and controlled hypertensives (n = 10). Blood pressure and heart rate were measured at 4 different times: T0, in the waiting room; T1, after placement of the surgical drapes; T2, 10 minutes after anesthesia injection; and T3, at the end of the surgical procedure. A statistically significant difference (P < 0.05) between the groups was found at times T0 and T2 for the systolic pressure but only at time T0 for the diastolic pressure. The assessment of the heart rate of both groups showed a statistically significant difference (P < 0.05) at time T1. An analysis of the employed anesthetic volume indicated no statistically significant difference (P > 0.05) between the amount administered to nonhypertensive and hypertensive subjects. It was concluded that the local anesthetics studied could safely be used in controlled hypertensive and nonhypertensive patients in compliance with the maximum recommended doses.

Background To quantify pain severity in patients and the efficacy treatments, researchers and clinicians apply tools such as the traditional visual analog scale (VAS) that leads to inaccurate interpretation of the main sensory pain. Objective This study aimed to validate the pain measurements of a neuroscience-based 3D body pain mobile app called GeoPain. Methods Patients with temporomandibular disorder (TMD) were assessed using GeoPain measures in comparison to VAS and positive and negative affect schedule (PANAS), pain and mood scales, respectively. Principal component analysis (PCA), scatter score analysis, Pearson methods, and effect size were used to determine the correlation between GeoPain and VAS measures. Results The PCA resulted in two main orthogonal components: first principal component (PC1) and second principal component (PC2). PC1 comprises a combination score of all GeoPain measures, which had a high internal consistency and clustered together in TMD pain. PC2 included VAS and PANAS. All loading coefficients for GeoPain measures in PC1 were above 0.70, with low loadings for VAS and PANAS. Meanwhile, PC2 was dominated by a VAS and PANAS coefficient >0.4. Repeated measure analysis revealed a strong correlation between the VAS and mood scores from PANAS over time, which might be related to the subjectivity of the VAS measure, whereas sensory-discriminative GeoPain measures, not VAS, demonstrated an association between chronicity and TMD pain in locations spread away from the most commonly reported area or pain epicenter (P=.01). Analysis using VAS did not detect an association at baseline between TMD and chronic pain. The long-term reliability (lag >1 day) was consistently high for the pain area and intensity number summation (PAINS) with lag autocorrelations averaging between 0.7 and 0.8, and greater than the autocorrelations for VAS averaging between 0.3 and 0.6. The combination of higher reliability for PAINS and its objectivity, displayed by the lack of association with PANAS as compared with VAS, indicated that PAINS has better sensitivity and reliability for measuring treatment effect over time for sensory-discriminative pain. The effect sizes for PAINS were larger than those for VAS, consequently requiring smaller sample sizes to assess the analgesic efficacy of treatment if PAINS was used versus VAS. The PAINS effect size was 0.51 SD for both facial sides and 0.60 SD for the right side versus 0.35 SD for VAS. Therefore, the sample size required to detect such effect sizes with 80% power would be n=125 per group for VAS, but as low as n=44 per group for PAINS, which is almost a third of the sample size needed by VAS. Conclusions GeoPain demonstrates precision and reliability as a 3D mobile interface for measuring and analyzing sensory-discriminative aspects of subregional pain in terms of its severity and response to treatment, without being influenced by mood variations from patients.

The objective of this study was to investigate the bone repair of carbonate apatite (cHA) in comparison to hydroxyapatite (HA, control group), on osseous repair of non-critical size defect in rat calvaria. Spheres (400<ø>500μm) of both materials were synthesized under 37°C (cHA) and 90°C (HA) and were not sintered. Fifteen rats Wistar were submitted to general anesthesia and two perforations (4mm each) were made, one in each parietal bone, for implantation of cHA (left side) and HA spheres (right side). After 1, 3 and 6 weeks, five animals of each group were killed and the two fragments with the biomaterial were collected from the calvaria. The bone blocks with biomaterial were demineralized and 5μm thick semi-serial sections were done for histological analysis. The experimental group of 6 weeks did not show the presence of spheres of both biomaterials and few spheres were observed after 1 and 3 weeks. Histological analysis showed the connective tissue repairing the surgical defect after 1 week and newly formed bone after 3 weeks of surgery. Thus, we concluded both materials are biocompatible, promote osteoconduction and in all studied periods the biomaterials showed to be resorbable.

ObjectiveTo investigate the presence of changes in vibration detection and pressure pain threshold in patients with burning-mouth syndrome (BMS).Design of the studyCase-control study. The sample was composed of 30 volunteers, 15 with BMS and 15 in the control group. The pressure-pain threshold (PPT) and vibration-detection threshold (VDT) were examined. The clinical evaluation was complemented with the McGill Pain Questionnaire (MPQ), Douleur Neuropathique 4 (DN4) and Beck Depression and Anxiety Inventories (BDI and BAI, respectively).ResultsBMS subjects showed a statistically significant higher PPT in the tongue (p = 0.002), right (p = 0.001) and left (p = 0.004) face, and a significant reduction of the VDT in the tongue (p = 0.013) and right face (p = 0.030). Significant differences were also found when comparing the PPT and the VDT of distinct anatomical areas. However, a significant interaction (group × location) was only for the PPT. BMS subjects also showed significantly higher levels of depression (p = 0.01), as measured by the BDI, compared to controls; and a significant inverse correlation between the VDT in the left face and anxiety levels was detected.ConclusionsThe study of somatosensory changes in BMS and its correlations with the clinical features as well as the levels of anxiety and depression expands current understanding of the neuropathic origin and the possible contribution of psychogenic factors related to this disease.

BACKGROUND Chronic pain is a significant health care problem. To quantify the pain severity in patients and the efficacy of new or current treatments, researchers and clinicians apply tools such as the traditional visual analogue scale (VAS), that lead to inaccurate and subjective interpretation related to the main sensory pain. OBJECTIVE To validate pain measurements of a neuroscience-based 3D body mobile application called GeoPain. METHODS Temporomandibular disorder (TMD) patients were assessed using GeoPain measures in comparison to traditional pain and mood scales, respectively VAS and Positive and Negative Affects (PANAS). Principal Component Analysis (PCA), scatter score analysis, Pearson’s methods and effect size were used to determine the correlation among GeoPain and VAS measures. RESULTS The PCA analysis resulted in two main orthogonal components: PC1 and PC2. PC1 comprises a combination score of all GeoPain measures, which had a high internally consistent, and clustered together in TMD pain. PC2 included VAS and both positive and negative effects (PANAS). All loading coefficient for GeoPain measures in PC1 were above .70, with low loadings for VAS and PANAS. Meanwhile, PC2 were dominated by VAS and PANAS > 0.4. Repeated measure analysis revealed a strong correlation between the VAS and mood scores from PANAS over time that might be related with the subjectivity of VAS measure, whereas sensory-discriminative GeoPain measures, not VAS, demonstrated an association between chronicity and TMD pain in locations spread away from the most commonly reported area, or pain epicenter (P = .01). Analysis using VAS did not detect an association at baseline between TMD pain and chronicity. The long-term reliability (lag > 1 day) was consistently high for P.A.I.N.S. with lag autocorrelations averaging between 0.7 and 0.8, and greater than the autocorrelations for VAS averaging between 0.3 to 0.6. The combination of higher reliability for P.A.I.N.S. and its objectivity displayed by the lack of association with PANAS as compared to VAS indicated that P.A.I.N.S. has a better sensitivity and reliability for measuring treatment effect over time for sensory-discriminative pain. The effect sizes for P.A.I.N.S. were larger compared to VAS, consequently requiring smaller sample sizes to assess the analgesic efficacy of treatment if P.A.I.N.S. is used versus VAS. P.A.I.N.S. effect size was 0.51SD for both facial sides and 0.60SD for the right side versus 0.35SD for VAS. Therefore, the sample size required to detect such effect sizes with 80% power would be n = 125/group for VAS, but for P.A.I.N.S. as low as o n = 44/group, almost 1/3 of the sample size needed by VAS. CONCLUSIONS GeoPain demonstrated precision and reliability as a 3D mobile interface for measuring and analyzing sensory-discriminative aspects of (sub)regional pain regarding its severity and response to treatment, without been influenced by mood variations from patients as noticed in the more traditional VAS. CLINICALTRIAL Registration: Clinicaltrials.gov, NCT02247063, https://clinicaltrials.gov/ct2/show/NCT02247063.

BackgroundMultiple therapeutic strategies have been adopted to reduce pain, odynophagia, and oral mucositis in head and neck cancer patients. Among them, transcranial direct current stimulation (tDCS) represents a unique analgesic modality. However, the details of tDCS mechanisms in pain treatment are still unclear.Aims(1) to study the analgesic effects of a protocol that encompassed supervised-remote and in-clinic tDCS sessions applied in head and neck patients undergoing chemoradiation therapy; (2) to explore the underlining brain mechanisms of such modulation process, using a novel protocol that combined functional near-infrared spectroscopy (fNIRS), and electroencephalograph (EEG), two distinct neuroimaging methods that bring information regarding changes in the hemodynamic as well as in the electrical activity of the brain, respectively.MethodsThis proof-of-concept study was performed on two subjects. The study protocol included a 7-week-long tDCS stimulation procedure, a pre-tDCS baseline session, and two post-tDCS follow-up sessions. Two types of tDCS devices were used. One was used in the clinical setting and the other remotely. Brain imaging was obtained in weeks 1, 2, 5, 7, 8, and after 1 month.ResultsThe protocol implemented was safe and reliable. Preliminary results of the fNIRS analysis in weeks 2 and 7 showed a decrease in functional connections between the bilateral prefrontal cortex (PFC) and the primary sensory cortex (S1) (p &lt; 0.05, FDR corrected). Changes in EEG power spectra were found in the PFC when comparing the seventh with the first week of tDCS.ConclusionThe protocol combining remote and in-clinic administered tDCS and integrated fNIRS and EEG to evaluate the brain activity is feasible. The preliminary results suggest that the mechanisms of tDCS in reducing the pain of head and neck cancer patients may be related to its effects on the connections between the S1 and the PFC.