The value of inquiring patients about local discomfort during blood pressure measurement for fibromyalgia detection. A cross-sectional study.

BACKGROUND: Fibromyalgia overlaps and/or mimics other rheumatic diseases and may be a confounding factor in the clinimetric assessment of these illnesses. Allodynia is a distinctive fibromyalgia feature that can be elicited during routine blood pressure measurement. For epidemiological purposes fibromyalgia can be diagnosed using the 2016 Wolfe et al. criteria questionnaire. No physical examination is required. OBJECTIVE: To evaluate the role of a straightforward question formulated during routine blood pressure measurement for fibromyalgia detection in a rheumatology outpatient clinic. PATIENTS AND METHODS: All adult patients attending our Rheumatology outpatient clinic were invited to participate. While awaiting their medical consultation, they filled-out the 2016 Wolfe et al. FM diagnostic criteria questionnaire. During the ensuing routine physical examination, the physician advanced the following guideline: "I am going to take your blood pressure; tell me if the cuff's pressure causes pain". Then, blood pressure cuff was inflated to 170 mm/Hg. Sphygmomanometry induced allodynia was defined as any local discomfort caused by blood pressure measurement. If a patient voiced any uneasiness, a follow-up dichotomic question was formulated "did it hurt much or little". Sphygmomanometry-induced allodynia was correlated with the presence of fibromyalgia according to the 2016 Wolfe diagnostic criteria. RESULTS: Four hundred and ninety-one patients were included in the study; most of them (84%) were female. The female cohort displayed the following features: Twenty five percent had fibromyalgia. Twenty seven percent had sphygmomanometry-induced allodynia. In women, sphygmomanometry-evoked allodynia had 63% sensitivity and 84% specificity for fibromyalgia diagnosis. The area under curve was 0.751. Moreover, having "much" local pain elicitation during blood pressure testing had 23% sensitivity and 96% specificity for fibromyalgia diagnosis. Men behaved differently; 15% fulfilled the fibromyalgia diagnostic criteria, but only 2% had sphygmomanometry induced allodynia. CONCLUSIONS: Inquiring female patients about local discomfort during routine blood pressure measurement is a simple and efficient procedure for fibromyalgia detection. This undemanding approach could be implemented in all clinical settings. There is marked sexual dimorphism in the link between sphygmomanometry-induced allodynia and fibromyalgia diagnosis. The presence of fibromyalgia is almost certain in those individuals having substantial pain elicitation during blood pressure measurement.

Allodynia in Menstrually Related Migraine: Score Assessment by Allodynia Symptom Checklist (ASC-12).

OBJECTIVE: The aim of this study was to compare the allodynia score in headache attacks related and not related to menstruation in women diagnosed with menstrually related migraine without aura. BACKGROUND: Allodynia is an important symptom in migraine and has been associated with migraine chronification. No study has yet compared prospectively allodynia in menstrual vs non-menstrual attacks within the same cohort of patients. METHODS: This is a prospective cohort study, where participants had the 12-item Allodynia Symptom Checklist (ASC-12) assessed after 1, 2, 4, and 24 hours from the onset of migraine attacks in 2 different conditions, with menstrual migraine attack (MM+) and with non-menstrual migraine attack (MM-). RESULTS: A total of 600 women with headache complaints were screened from March 2013 to July 2014 in a headache outpatient or headache tertiary clinic. From these, 55 participants were recruited, and 32 completed the study. Participants' mean age was 27 years, BMI was 22.1, menarche age 12 years, migraine history was 11.5 years, and most women were young (ranged from 17 to 44 years of age), were in higher school (13/32 = 41%), single (20/32 = 63%), and used contraceptives (22/32 = 69%). Multiple pairwise comparisons of ANCOVA's test showed significant higher ASC-12 scores in MM+ group compared to MM- group at 2 hours [mean, 95% CI of difference: 2.3 (0.31, 4.7), P = .049)]. For the ASC-12 categorical scores (absent, mild, moderate, and severe) MM+ yielded higher scores than MM- at 1 hour (z = -3.08, P = .021) and 4 hours (z = -2.97, P = .03). CONCLUSION: This study demonstrated that in the patents from tertiary headache center assessed, menstrual-related migraine attacks augment allodynia scores in the beginning of attacks compared to non-menstrual migraine attacks.

Spinal TASK-1 and TASK-3 modulate inflammatory and neuropathic pain.

This study assessed the participation of spinal TWIK-related acid-sensitive K+ channels 1 and 3 (TASK-1 and TASK-3) in inflammatory (formalin test) and neuropathic (spinal nerve ligation, SNL) pain in rats. Intrathecal pre-treatment (-10 min) with the TASK-1 blocker ML365 or TASK-3 blocker PK-THPP, but not vehicle, enhanced in a dose-dependent manner 1% formalin-induced acute and long-lasting secondary mechanical allodynia and mechanical hyperalgesia in rats. In contrast, intrathecal pre-treatment with terbinafine, an activator of TASK-3, reduced formalin-induced flinching and allodynia/hyperalgesia. Both blockers and terbinafine had similar effects on female and male rats. In addition, intrathecal injection of ML365 or PK-THPP blocked the terbinafine-induced antiallodynic effect in neuropathic rats, but they did not modify baseline withdrawal threshold in naïve or sham-operated rats. TASK-1 and TASK-3 mRNA and protein were expressed in L4 and L5 dorsal root ganglia (DRG) and dorsal and ventral spinal cord of naïve animals. Interestingly, formalin injection increased TASK-1 expression in ipsilateral L5 DRG, but not in the spinal cord. Moreover, formalin injection transiently enhanced TASK-3 expression in ipsilateral L5 DRG and dorsal spinal cord. In contrast, SNL down-regulated TASK-3 expression in the ipsilateral L4 and L5 DRG but not in dorsal or ventral spinal cord, while SNL did not modify TASK-1 expression at any tissue. The pharmacological and molecular results suggest that TASK-1 and TASK-3 have a relevant antinociceptive role in inflammatory and neuropathic pain.

A non-reflexive method based on the variability of temperature and bioimpedance in measuring inflammatory hyperalgesia and analgesia in mice.

BACKGROUND: Preclinical studies measure withdrawal responses to evoking thermal and mechanical stimuli instead of the more clinically important spontaneous pain. NEW METHOD: Therefore, we studied the effect of peripheral inflammation induced by intraplantar administration of complete Freund's adjuvant (CFA) in mice on the variability of temperature and bioimpedance as an index of pain produced by inflammation. To this end, we initially determined mathematical scores based on changes in temperature and bioimpedance (STB) for animals with an inflamed paw and compared these scores with commonly used measures of inflammatory pain. We then pharmacologically validated the tool using dexamethasone. RESULTS: The STB analysis resembled the response found in the von Frey Hair (vFH) test. The CFA-induced increase in STB and vFH tests were reversed by intraperitoneal administration of dexamethasone. The correlation between the STB and vFH measurements showed a high correlation coefficient (R2 = 0.911, p < 0.001). COMPARISON WITH EXISTING METHOD: Our results also demonstrated that CFA paw injection induced mechanical hyperalgesia in mice and remained virtually unaltered during all time-points tested for 5 days, as measured with vFHs. The administration of CFA into the paw induced a large increase in paw volume that was apparent 1 and 5 days after the injection. The CFA injection resulted in a significant (p < 0.05) decrease in the response latency to the heat stimulus, as evaluated on day 4 post-CFA injection. CONCLUSIONS: The data presented here suggest that STB may provide a novel non-invasive approach for inflammatory pain detection.

How to use Rome IV criteria in the evaluation of esophageal disorders.

PURPOSE OF REVIEW: In 2016, the Rome IV process and criteria were published. They provide a system to standardize patient diagnostic requirements for clinical studies and pharmaceutical trials on functional gastrointestinal disorders (FGIDs), which are now called disorders of gut-brain interaction (DGBI). Although the Rome criteria have limitations in clinical practice, an understanding of the criteria can help clinicians to manage symptoms in patients with DGBI, and with organic diseases as well. RECENT FINDINGS: In this report, the Rome IV criteria for esophageal DGBI, the updated algorithms for esophageal symptoms, and the multidimensional clinical profile (MDCP) are reviewed. SUMMARY: The esophageal DGBI comprise functional esophageal chest pain, functional heartburn, globus, functional dysphagia, and the newly introduced reflux hypersensitivity. They are characterized by the presence of chronic symptoms attributed to the esophagus without evidence of esophageal structural, inflammatory, or motility abnormalities. Also, Rome IV suggests for the first time the possibility that functional heartburn or reflux hypersensitivity might overlap with gastroesophageal reflux disease. Accordingly, testing with endoscopy and biopsies, esophageal pH ±â€Šimpedance monitoring and high-resolution esophageal manometry are necessary to establish esophageal DGBI diagnoses. Algorithms aid in this diagnostic process, and the MDCP that captures the full dimension of each patient's presentation is helpful in planning personalized treatment regimens.

Role of the Excitability Brake Potassium Current IKD in Cold Allodynia Induced by Chronic Peripheral Nerve Injury.

Cold allodynia is a common symptom of neuropathic and inflammatory pain following peripheral nerve injury. The mechanisms underlying this disabling sensory alteration are not entirely understood. In primary somatosensory neurons, cold sensitivity is mainly determined by a functional counterbalance between cold-activated TRPM8 channels and Shaker-like Kv1.1-1.2 channels underlying the excitability brake current IKD Here we studied the role of IKD in damage-triggered painful hypersensitivity to innocuous cold. We found that cold allodynia induced by chronic constriction injury (CCI) of the sciatic nerve in mice, was related to both an increase in the proportion of cold-sensitive neurons (CSNs) in DRGs contributing to the sciatic nerve, and a decrease in their cold temperature threshold. IKD density was reduced in high-threshold CSNs from CCI mice compared with sham animals, with no differences in cold-induced TRPM8-dependent current density. The electrophysiological properties and neurochemical profile of CSNs revealed an increase of nociceptive-like phenotype among neurons from CCI animals compared with sham mice. These results were validated using a mathematical model of CSNs, including IKD and TRPM8, showing that a reduction in IKD current density shifts the thermal threshold to higher temperatures and that the reduction of this current induces cold sensitivity in former cold-insensitive neurons expressing low levels of TRPM8-like current. Together, our results suggest that cold allodynia is largely due to a functional downregulation of IKD in both high-threshold CSNs and in a subpopulation of polymodal nociceptors expressing TRPM8, providing a general molecular and neural mechanism for this sensory alteration.SIGNIFICANCE STATEMENT This paper unveils the critical role of the brake potassium current IKD in damage-triggered cold allodynia. Using a well-known form of nerve injury and combining behavioral analysis, calcium imaging, patch clamping, and pharmacological tools, validated by mathematical modeling, we determined that the functional expression of IKD is reduced in sensory neurons in response to peripheral nerve damage. This downregulation not only enhances cold sensitivity of high-threshold cold thermoreceptors signaling cold discomfort, but it also transforms a subpopulation of polymodal nociceptors signaling pain into neurons activated by mild temperature drops. Our results suggest that cold allodynia is linked to a reduction of IKD in both high-threshold cold thermoreceptors and nociceptors expressing TRPM8, providing a general model for this form of cold-induced pain.

Structural determinants of the hyperalgesic activity of myotoxic Lys49-phospholipase A2

Background Bothropstoxin-I (BthTx-I) is a Lys49-phospholipase A2 (Lys49-PLA2) from the venom of Bothrops jararacussu, which despite of the lack of catalytic activity induces myotoxicity, inflammation and pain. The C-terminal region of the Lys49-PLA2s is important for these effects; however, the amino acid residues that determine hyperalgesia and edema are unknown. The aim of this study was to characterize the structural determinants for the Lys49-PLA2-induced nociception and inflammation. Methods Scanning alanine mutagenesis in the active-site and C-terminal regions of BthTx-I has been used to study the structural determinants of toxin activities. The R118A mutant was employed as this substitution decreases PLA2 myotoxicity. In addition, K115A and K116A mutants - which contribute to decrease cytotoxicity - and the K122A mutant - which decreases both myotoxicity and cytotoxicity - were also used. The H48Q mutant - which does not interfere with membrane damage or myotoxic activity - was used to evaluate if the PLA2 catalytic site is relevant for the non-catalytic PLA2-induced pain and inflammation. Wistar male rats received intraplantar injections with mutant PLA2. Subsequently, hyperalgesia and edema were evaluated by the paw pressure test and by a plethysmometer. Native and recombinant BthTx-I were used as controls. Results Native and recombinant BthTx-I induced hyperalgesia and edema, which peaked at 2 h. The R118A mutant did not induce nociception or edema. The mutations K115A and K116A abolished hyperalgesia without interfering with edema. Finally, the K122A mutant did not induce hyperalgesia and presented a decreased inflammatory response. Conclusions The results obtained with the BthTx-I mutants suggest, for the first time, that there are distinct residues responsible for the hyperalgesia and edema induced by BthTx-I. In addition, we also showed that cytolytic activity is essential for the hyperalgesic effect but not for edematogenic activity, corroborating previous data showing that edema and hyperalgesia can occur in a non-dependent manner. Understanding the structure-activity relationship in BthTx-I has opened new possibilities to discover the target for PLA2-induced pain.(AU)

Nociceptive and Neuronal Evaluation of the Sciatic Nerve of Wistar Rats Subjected to Compression Injury and Treated with Resistive Exercise.

Background. To investigate the climb stairs resistance exercise on nociception and axonal regeneration in the sciatic nerve of rats. Methods. 24 Wistar rats were divided: control group (CG-no injury), exercise group (EG-no injury with physical exercise), lesion group (LG-injury, but without exercise), and treated group (LEG-injury and physical exercise). LG and LEG were subjected to sciatic nerve compression with hemostat. From the 3rd day after injury began treatment with exercise, and after 22 days occurs the removal of a nerve fragment for morphological analysis. Results. Regarding allodynia, CG obtained values less than EG (p = 0.012) and larger than LG and LEG (p < 0.001). Histological results showed that CG and EG had normal appearance, as LG and LEG showed up with large amounts of inflammatory infiltration, degeneration and disruption of nerve fibers, and reduction of the myelin sheath; however LEG presented some regenerated fibers. From the morphometric data there were significant differences, for nerve fiber diameter, comparing CG with LG and LEG and comparing axon diameter and the thickness of the myelin of the CG to others. Conclusion. Climb stairs resistance exercise was not effective to speed up the regenerative process of axons.

Female Adults with Patellofemoral Pain Are Characterized by Widespread Hyperalgesia, Which Is Not Affected Immediately by Patellofemoral Joint Loading.

OBJECTIVE: Compare pressure pain thresholds (PPTs) at the knee and a site remote to the knee in female adults with patellofemoral pain (PFP) to pain-free controls before and after a patellofemoral joint (PFJ) loading protocol designed to aggravate symptoms. DESIGN: Cross-sectional study SETTING: Participants were recruited via advertisements in fitness centers, public places for physical activity and universities. SUBJECTS: Thirty-eight females with patellofemoral pain, and 33 female pain-free controls. METHODS: All participant performed a novel PFJ loading protocol involving stair negotiation with an extra load equivalent 35% of body mass. PPTs and current knee pain (measured on a visual analogue scale) was assessed before and after the loading protocol. PPTs were measured at four sites around the knee and one remote site on the upper contralateral limb. RESULTS: Females with PFP demonstrated significantly lower PPTs locally and remote to the knee, both before and after the PFJ loading protocol when compared to control group. Following the loading protocol, PPTs at knee were significantly reduced by 0.54 kgf (95%CI = 0.33; 0.74) for quadriceps tendon, 0.38 kgf (95%CI = 0.14; 0.63) for medial patella, and 0.44 kgf (95%CI = 0.18; 0.69) for lateral patella. No significant change in PPT remote to the knee was observed - 0.10 kgf (95%CI = -0.04; 0.24). CONCLUSIONS: Female adults with PFP have local and widespread hyperalgesia compared to pain free controls. A novel loading protocol designed to aggravate symptoms, lowers the PPTs locally at the knee but has no effect on PPT on the upper contralateral limb. This suggests widespread hyperalgesia is not affected by acute symptom aggravation.

12 item allodynia symptom checklist/Brasil: cross-cultural adaptation, internal consistency and reproducibility.

Since there was no Portuguese questionnaire to evaluate cutaneous allodynia, which has been pointed out as a risk factor of migraine, we aimed to perform the cross-cultural adaptation of the 12 item Allodynia Symptom Checklist for the Brazilian population and to test its measurement properties. It consisted in six stages: translation, synthesis, back translation, revision by a specialist committee, pretest and submission the documents to the committee. In the pretest stage, the questionnaire was applied to 30 migraineurs of both sexes, who had some difficulty in understanding it. Thus, a second version was applied to 30 additional subjects, with no difficulties being reported. The mean filling out time was 3'36", and the internal consistency was 0.76. To test reproducibility, 15 other subjects filled out the questionnaire at two different times, it was classified as moderate (weighted kappa=0.58). We made available to Brazilian population an easy, quick and reliable questionnaire.

12 item Allodynia Symptom Checklist/Brasil: cross-cultural adaptation, internal consistency and reproducibility / 12 item Allodynia Symptom Checklist/Brasil: adaptação transcultural, consistência interna e reprodutibilidade

Since there was no Portuguese questionnaire to evaluate cutaneous allodynia, which has been pointed out as a risk factor of migraine, we aimed to perform the cross-cultural adaptation of the 12 item Allodynia Symptom Checklist for the Brazilian population and to test its measurement properties. It consisted in six stages: translation, synthesis, back translation, revision by a specialist committee, pretest and submission the documents to the committee. In the pretest stage, the questionnaire was applied to 30 migraineurs of both sexes, who had some difficulty in understanding it. Thus, a second version was applied to 30 additional subjects, with no difficulties being reported. The mean filling out time was 3'36", and the internal consistency was 0.76. To test reproducibility, 15 other subjects filled out the questionnaire at two different times, it was classified as moderate (weighted kappa=0.58). We made available to Brazilian population an easy, quick and reliable questionnaire.

Levando em consideração que não há nenhum questionário em português disponível para avaliação da alodinia cutânea, sintoma que tem sido apontado como fator de cronificação da migrânea, o objetivo do trabalho foi realizar a adaptação transcultural do 12 item Allodynia Symptom Checklist para a população brasileira e testar suas características psicométricas. A adaptação foi realizada em seis estágios: tradução, síntese, retrotradução, revisão pelo comitê de especialistas, pré-teste e submissão dos documentos ao comitê. No estágio do pré-teste, foram aplicados 30 questionários em migranosos de ambos os sexos, que relataram dificuldades de compreensão. Por isso, foi criada uma segunda versão e aplicada a mais 30 sujeitos, não tendo sido relatadas dificuldades nesta versão. O tempo médio de preenchimento foi de 3'36", e a consistência interna encontrada foi 0,76. Para testar a reprodutibilidade, outros 15 sujeitos preencheram o questionário, em dois momentos, tendo sido a reprodutibilidade classificada como moderada (kappa ponderado=0,58). Portanto, disponibilizamos, para uso na população brasileira, um questionário fácil, rápido e confiável.

After-effects of consecutive sessions of transcranial direct current stimulation (tDCS) in a rat model of chronic inflammation.

Transcranial direct current stimulation (tDCS) induces cortical excitability changes in animals and humans that can last beyond the duration of stimulation. Preliminary evidence suggests that tDCS may have an analgesic effect; however, the timing of these effects, especially when associated with consecutive sessions of stimulation in a controlled animal experiment setting, has yet to be fully explored. To evaluate the effects of tDCS in inflammatory chronic pain origin immediately and 24 h after the last treatment session, complete Freund's adjuvant (CFA) was injected (100 µl) in the right footpad to induce inflammation. On the 15th day after CFA injection, rats were divided into two groups: tDCS (n = 9) and sham (n = 9). The tDCS was applied for 8 days. The hot plate and Von Frey tests were applied immediately and 24 h after the last tDCS session. Eight 20-min sessions of 500 µA anodal tDCS resulted in antinociceptive effects as assessed by the hot plate test immediately (P = 0.04) and 24 h after the last tDCS session (P = 0.006), for the active tDCS group only. There was increased withdrawal latency in the Von Frey test at 24 h after the last session (P = 0.01). Our findings confirm the hypothesis that tDCS induces significant, long-lasting, neuroplastic effects and expands these findings to a chronic pain model of peripheral inflammation, thus supporting the exploration of this technique in conditions associated with chronic pain and peripheral inflammation, such as osteoarthritis.

Antihyperalgesic effects of myrsinoic acid B in pain-like behavior induced by inflammatory and neuropathic pain models in mice.

BACKGROUND: Myrsinoic acid B (MAB) is a diprenylated benzoic acid widely found in the vegetal kingdom. Recent studies demonstrate that MAB has important antinociceptive effects in models of chemically or thermally induced nociception in mice. METHODS: In the present study we evaluated the effect of MAB in different models of inflammatory and neuropathic hypersensitivity in mice. RESULTS: This study demonstrates that the pretreatment with MAB, given orally (8.4 to 83.8 µmol/kg), inhibited carrageenan- and complete Freund adjuvant-induced mechanical hypersensitivity. When administered after the induction of hypersensitivity, MAB also reduced the mechanical hypersensitivity in the ipsilateral and in the contralateral hindpaws of mice injected with complete Freund adjuvant, interfering with a signaling cascade already established. MAB reversed the hypersensitivity (mechanical and thermal) of operated animals, with similar results to those observed with gabapentin. MAB activity was evident when administered either systemically (PO or IV) or intrathecally, suggesting interference in the central pathways of pain control. Furthermore, MAB seems to present an antiinflammatory effect evidenced by the interference in both the neutrophil migration and in the increase of interleukin-1ß levels after carrageenan injection. Of note, MAB treatment did not interfere with mechanical or thermal sensitivity in healthy mice, a frequent characteristic of commonly used analgesics, such as morphine or gabapentin. Side effects including interference in locomotor activity, motor performance, and body temperature in animals treated with MAB were absent. CONCLUSIONS: MAB reduced mechanical and thermal hypersensitivity in mice submitted to models of inflammatory and neuropathic pain, showing excellent potential for treating persistent pain in humans.

Temporomandibular disorders and cutaneous allodynia are associated in individuals with migraine.

The objective of this study was to estimate and contrast the occurrence of ictal and interictal cutaneous allodynia (CA) in individuals with migraine with and without temporomandibular disorders (TMD). Both TMD and CA are common in migraine and may be associated with migraine transformation from episodic into a chronic form. Herein we hypothesize that TMD contributes to the development of CA and to more severe headaches. In a clinic-based sample of individuals with episodic migraine, the presence of TMD was assessed using the research diagnostic criteria for myofascial or mixed (myofascial and arthralgic) TMD. Ictal CA was quantified using the validated Allodynia Symptom Checklist (ASC-12). The ASC-12 measures CA over the preceding month by asking 12 questions about the frequency of allodynia symptoms during headaches. Interictal CA was assessed in the domains of heat, cold and mechanical static allodynia using quantitative sensory testing. Our sample consists of 55 individuals; 40 (73%) had TMD (23 with myofascial TMD and 17 with the mixed type). CA of any severity (as assessed by ASC-12) occurred in 40% of those without TMD (reference group), 86.9% of those with myofascial TMD (P = 0.041, RR = 3.2, 95% CI = 1.5-7.0) and in 82.3% of those with mixed TMD (P = 0.02, RR = 2.5, 95% CI = 1.2-5.3). Individuals with TMD were more likely to have moderate or severe CA associated with their headaches. Interictally (quantitative sensory testing), thresholds for heat and mechanical nociception were significantly lower in individuals with TMD. Cold nociceptive thresholds were not significantly different in migraine patients with and without TMD. TMDs were also associated with change in extra-cephalic pain thresholds. In logistical regression, TMD remained associated with CA after adjusting for aura, gender and age. TMD and CA are associated in individuals with migraine.

Analgesic effect in rodents of native and recombinant Ph alpha 1beta toxin, a high-voltage-activated calcium channel blocker isolated from armed spider venom.

Calcium influx through neuronal voltage-sensitive calcium channels (VSCC S) mediates nociceptive information in the spinal dorsal horn. In fact, spinally administered VSCC S blockers, such as omega-conotoxin MVIIA, have analgesic effect apart of their low therapeutic index and many side effects. Here we study the analgesic potential of Ph alpha 1beta, a calcium channel blocker, in rodent models of acute and persistent pain. Spinally administered Ph alpha 1beta showed higher efficacy and long-lasting analgesia in a thermal model of pain, when compared with omega-conotoxin MVIIA. Moreover, Ph alpha 1beta was more effective and potent than omega-conotoxin MVIIA not only to prevent, but especially to reverse, previously installed persistent chemical and neuropathic pain. Furthermore, the analgesic action of both toxins are related with the inhibition of Ca2+-evoked release of pro-nociceptive neurotransmitter, glutamate, from rat spinal cord synaptosomes and decrease of glutamate overflow in cerebrospinal fluid. When side effects were assessed, we found that Ph alpha 1beta had a therapeutic index wider than omega- conotoxin MVIIA. Finally, recombinant Ph alpha 1beta expressed in Escherichia coli showed marked analgesic activity similar to the native toxin. Taken together, the present study demonstrates that native and recombinant Ph alpha 1beta have analgesic effects in rodent models of pain, suggesting that this toxin may have potential to be used as a drug in the control of persistent pathological pain.

Pain and tactile stimuli during arterial puncture in preterm neonates.

The purpose of this study was to assess the behavioral and physiological reactivity of preterm neonates during different phases of a blood collection procedure involving arterial puncture. The sample consisted of 43 preterm and very low birth weight neonates with a postnatal age of 1 to 21 days who were hospitalized in the Neonatal Intensive Care Unit. The neonates were evaluated during the whole blood collection procedure. The assessment was divided into five consecutive phases: Baseline (BL); Antisepsis (A), covering the period of handling of the neonate for antisepsis prior to puncture; Puncture (P); Recovery-Dressing (RD), covering the period of handling of the neonate for dressing until positioning for rest in the isolette; and Recovery-Resting (RR). Facial activity was videotaped and analyzed using the Neonatal Facial Coding System (NFCS). The sleep-wake state and heart rate were registered at the bedside. There was a significant increase in NFCS score and heart rate, and more active behavior during phases A, P, and RD relative to BL. Regarding the tactile stimulation of the infant in pre-puncture (A) and post-puncture (RD), it was observed increased NFCS score, heart rate, and active behavior in comparison to the BL and RR phases. There was evidence of distress responses immediately before and after a painful event, quite apart from the pain reaction to the puncture procedure.

Neuroplasticidad y dolor / Neuroplasticity and pain

Todas las formas de dolor incluyen el desarrollo de un estado de hiperalgesia que ilustra la naturaleza dinámica y plástica de la sensación de dolor. La hiperalgesia es la característica más importante del proceso doloroso y es la expresión de la hipersensibilidad de las vías del dolor inducida por la sensibilización de los receptores periféricos que registran eventos dolorosos y de las neuronas que transmiten y procesan esta información sensorial al SNC. Los nociceptores periféricos se sensibilizan adquiriendo una mayor y a veces nueva capacidad de respuesta a los estímulos periféricos. Por otra parte, un proceso de plasticidad sináptica, del cual se ha identificado una variedad de componentes moleculares, interviene en la amplificación central de las señales de las aferencias nociceptivas, lo cual evoca la hipersensibilidad de las neuronas centrales. El resultado final es un proceso sensorial que, a pesar de haber sido puesto en marcha inicialmente por una lesión, puede no mantener una relación estrecha con la lesión original y convertirse en un estado de dolor crónico sin tener una causa definida.

All froms of pain include the development of a hyperalgesic state that illustrates the dynamic and plastic nature of pain sesation. Hyperalgesia is the most prominent feature of the pain process and is the expression of hypersensitivity of the pain pathway induced by the sensitization of the peripheral receptors that signal painful events and of the neurons that transmit and process this sensory information to the CNS. Peripheral nociceptors can be sensitized, acquiring enhanced, and sometimes novel, responsiveness to peripheral stimuli. On the other hand a process of synaptic plasticity, of which several molecular components have already been identified, mediates the central amplification of the afferent signals that leads to the hypersensitivity of central neurons. The final result is a sensory process that, although initially triggered by injury, may not keep a close relationship with the originating injury and develop into a chronic pain state in the absence of a defined cause.

Oxytocin and electrical stimulation of the paraventricular hypothalamic nucleus produce antinociceptive effects that are reversed by an oxytocin antagonist.

In recent years, oxytocin has been implicated in a wide diversity of functions. The role of oxytocin in analgesia and pain modulation represents an important new function of an endogenous system controlling sensorial information. The paraventricular (PV) nucleus of the hypothalamus is one of the most important sources of oxytocin, and it has a very well-defined projection to the spinal cord. The location of this PV spinal cord projection correlates well with oxytocin binding sites at the dorsal horn of the spinal cord. In this work, we used rats with a chronic (46 days) sciatic loose ligature, an electrical stimulating electrode, and an intrathecal cannula, which reached the L4-L5 levels of the spinal cord. We compared the oxytocin effects with electrical stimulation of the PV and observed a significant reduction of the withdrawal responses to mechanical and cold stimulation applied to the ipsilateral and contralateral hind paws. An oxytocin antagonist administered intrathecally blocked the PV effects. Naloxone was also intrathecally injected 2 min before the PV stimulation, and we also observed a significant reduction of the withdrawal responses; however, this reduction was less pronounced. Our results support the hypothesis that oxytocin is part of the descending inhibitory control mechanisms having an important antinociceptive action. We cannot exclude a minor opiate participation in the OT action.

Hiperalgesia visceral e dor abdominal crônica: abordagem diagnóstica e terapêutica / Visceral hyperalgesia and chronic abdominal pain: diagnostic and therapeutic approach

JUSTIFICATIVA E OBJETIVOS: A dor abdominal crônica é uma das razões mais freqüentes para consulta médica. Não existe, entretanto, um protocolo bem estabelecido para a abordagem diagnóstica e, na maioria das vezes, essa investigação se torna uma prática médica onerosa e invasiva. A finalidade desta revisão é tentar esclarecer a fisiopatologia da dor visceral e estabelecer metas diagnósticas e terapêuticas, para portadores desta morbidade, baseada em critérios específicos. CONTEUDO: A dor abdominal crônica inespecífica ou funcional representa uma interação complexa entre distúrbio de motilidade, hipersensibilidade visceral e respostas neuroendócrina e psicossocial inadequadas. Mecanismos periféricos e centrais de nocicepção parecem estar envolvidos na hiperalgesia visceral. A abordagem diagnóstica requer uma avaliação minuciosa da história e exame clínico, levando em consideração os critérios de Roma II. Baseado nos mecanismos fisiopatológicos conhecidos, ou supostos, novas drogas vêm sendo pesquisadas, e algumas utilizadas mais recentemente, como os agonistas dos receptores 5-HT4 e bloqueadores dos canais de sódio, para o controle da dor abdominal. CONCLUSÕES: Os mecanismos fisiopatológicos da dor abdominal crônica, ainda não estão esclarecidos. A abordagem terapêutica e diagnóstica requer o conhecimento de tais mecanismos, bem como dos critérios de Roma II. Por outro lado, uma boa relação médico-paciente e a atuação de equipe intermultidisciplinar parecem fundamentais para melhorar a resposta ao tratamento instituído e a qualidade de vida do paciente.

BACKGROUND AND OBJECTIVES: Chronic abdominal pain is one of the most frequent reasons for medical consultation. There is, however, no well-established protocol for its diagnostic approach and, most of the times, investigation becomes an expensive and invasive medical practice. This review aimed at explaining visceral pain pathophysiology and establishing diagnostic and therapeutic goals for these patients, based on specific criteria. CONTENTS: Chronic nonspecific or functional abdominal pain is a complex interaction among impaired motility, visceral hypersensitivity and inadequate neuroendocrine and psychosocial responses. Peripheral and central nociception mechanisms seem to be involved in visceral hyperalgesia. Diagnosis requires detailed history and clinical evaluation, taking into consideration Rome II criteria. Based on known or assumed pathophysiological mechanisms, new drugs have been researched, and some have been more recently used to control abdominal pain, such as 5-HT4 receptor agonists and sodium channel blockers. CONCLUSIONS: Chronic pathophysiological abdominal pain mechanisms are still not well understood. Therapy and diagnosis require the understanding of such mechanisms, as well as of Rome II criteria. On the other hand, good patient-physician relationship and multidisciplinary team’s performance seem to be critical in improving treatment response and patients’ quality of life.

JUSTIFICATIVA Y OBJETIVOS: El dolor abdominal crónico es una de las razones más frecuentes para una consulta médica. No existe, entretanto, un protocolo bien establecido para el abordaje diagnóstico y, en la mayoría de las veces, esa investigación se hace una práctica médica onerosa e invasiva. La finalidad de esta revisión es tentar esclarecer la fisiopatología del dolor visceral y establecer metas diagnósticas y terapéuticas, para portadores de esta morbididad, fundamentada en criterios específicos. CONTENIDO: El dolor abdominal crónico inespecífico o funcional representa una interacción compleja entre disturbio de motilidad, hipersensibilidad visceral y respuestas neuroendócrina y psicosocial inadecuadas. Mecanismos periféricos y centrales de nocicepción parecen estar envueltos en la hiperalgesia visceral. El abordaje diagnóstico requiere una evaluación minuciosa de la historia y examen clínico, llevando en consideración los criterios de Roma II. Fundamentado en los mecanismos fisiopatológicos conocidos, o supuestos, nuevas drogas vienen siendo pesquisadas, y algunas utilizadas más recientemente, como los agonistas de los receptores 5-HT4 y bloqueadores de los canales de sodio, para el control del dolor abdominal. CONCLUSIONES: Los mecanismos fisiopatológicos del dolor abdominal crónico, aún no están esclarecidos. El abordaje terapéutico y diagnóstico requiere el conocimiento de tales mecanismos, así como de los criterios de Roma II. Por otro lado, una buena relación médico-paciente y la actuación de grupo intermultidiciplinar parecem fundamentais para mejorar la respuesta al tratamiento instituido y la calidad de vida del paciente.