The journal of pain : official journal of the American Pain Society
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Comparative Study
Fear-induced hypoalgesia in humans: effects on low intensity thermal stimulation and finger temperature.
Prior research indicates that exposure to fear-inducing stimuli inhibits finger withdrawal to sudden onset and high intensity radiant heat in humans. Although withdrawal latencies to intense heat are thought to reflect changes in spinal nociceptive processing, supraspinal measures are needed to determine whether pain perception is altered. The present study used gradual onset and low intensity radiant heat to induce a finger withdrawal response that depends on supraspinal processes. After baseline pain threshold tests, 57 healthy human participants were randomly assigned to 1 of 2 groups. In the fear group, participants received 3 brief shocks. In the neutral group, participants did not receive shock. Results suggest that finger withdrawal latencies to low intensity heat were increased after shock presentation, providing additional evidence that fear reduces pain on a measure that is influenced by supraspinal processes. Both self-report and physiological (skin conductance level, heart rate, and blood pressure) measures of emotion confirmed that the intended affective states were induced. Finger temperature was unaffected by emotion manipulations; thus, skin cooling does not appear to mediate increased withdrawal latencies. These findings provide additional evidence that fear not only inhibits spinal nociceptive reflexes, it also inhibits supraspinal measures of pain. ⋯ From a clinical perspective, these data suggest that patients who experience intense fear in response to unpredictable threatening events will show a reduction in pain perception.
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Comparative Study
Neonatal hind paw injury alters processing of visceral and somatic nociceptive stimuli in the adult rat.
Tissue damage during the first few weeks after birth can have profound effects on sensory processing in the adult. We have recently reported that a short-lasting inflammation of the neonatal rat hind paw produces baseline hypoalgesia and exacerbated hyperalgesia after reinflammation of that hind paw in the adult. Because the contralateral hind paw and forepaws also displayed hypoalgesia, we speculated that effects of the initial injury were not somatotopically restricted and would alter visceral sensory processing as well. In the present study we tested this hypothesis by examining the effects of neonatal hind paw injury at P3 or P14 on visceral and somatic sensitivity in the adult rat. In P3 rats, the visceromotor response evoked by colorectal distention in the absence of colonic inflammation was attenuated in carrageenan-treated neonatal rats compared to naive rats. Colonic inflammation in the adult reversed this hypoalgesia and evoked a level of visceral hyperalgesia similar to naive rats. There were no consequences of the P14 injury observed in the adult. In a second experiment, colonic inflammation in naive rats induced viscerosomatic inhibition to thermal stimulation of the forepaw and hind paw. This inhibition was reversed, and the paw withdrawal latency was slightly decreased in neonatal (P3) carrageenan-treated rats. Rats treated on P14 appeared similar to naive rats. These data support the hypothesis that neonatal hind paw injury during a critical period permanently alters sensory processing of multiple sensory modalities in the adult. Animals develop with greater inhibitory processing of somatic and visceral stimuli throughout the neuraxis. However, inflammation in the adult in previously uninjured tissue reverses the hypoalgesia and evokes development of normal hyperexcitability associated with tissue injury. ⋯ Trauma experienced by premature infants can lead to alterations in sensory processing throughout life. This study shows that short-term somatic tissue injury to neonatal rats during a well-defined critical period alters several aspects of viscerosensory processing in the adult, demonstrating that injury to one tissue affects sensory processing throughout the body.
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Comparative Study
Results of the Leeds assessment of neuropathic symptoms and signs pain scale in Turkey: a validation study.
Classification of pain and identification of the specific pain mechanisms through utilization of clinical data are helpful to the physician in choosing the appropriate treatment model. For discrimination between different pain types, various tests could be used. The Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) Pain Scale is a scale based on the analysis of data obtained during bedside examination. The LANSS Pain Scale, as first used by Bennett, is a very useful tool that provides immediate information in the clinical setting and helps distinguish nociceptive pain from neuropathic pain. In this study we targeted validation of the LANSS Pain Scale in the Turkish population. A total of 104 patients who consulted the Algology Department of Istanbul Faculty of Medicine Outpatient Clinic were enrolled in our validation study. The sensitivity and specificity of the scale were found to be 89.9% and 94.2%, respectively. These results suggest a high validity level for the Turkish version of the LANSS Pain Scale. We believe that this scale is a useful tool for the differential diagnosis of neuropathic pain and can be used in future pharmacologic studies. ⋯ Any measures that aid in differentiating neuropathic pain from nociceptive pain would facilitate effective management of pain. In daily practice the simplicity of the classification method is important. The present study suggests that Turkish version of LANSS can be used for the discrimination between neuropathic and nociceptive types of pain.
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Sex differences in clinical and experimental pain responses have been widely reported; however, few studies have examined sex differences in outcomes from interventional pain treatment and the predictors thereof. The aims of this study were to examine sex differences in (1) the acute pain produced by epidural steroid injections (ESIs), (2) clinical improvements in pain and pain-related psychological distress and disability after ESIs, and (3) predictors of the clinical response to ESIs. A total of 57 patients (37 menopausal women and 20 men), seen in the pain clinic of a regional medical center for ESI therapy, participated. Patients rated the painfulness of the ESI procedure itself. Also, clinical pain, depression, and disability were assessed before treatment and at 2 weeks and 2 months after the ESIs. Participants also were queried about their expectations of successful pain relief, coping strategies, and pain-related anxiety, which were examined as predictors of treatment outcome. Men reported significantly greater pain intensity and unpleasantness than women for the first injection only. All groups showed significant reductions in clinical pain, depression, and disability at 2 weeks compared to baseline, but minimal change occurred between 2 weeks and 2 months past baseline. No sex differences in the magnitude of treatment response emerged; however, specific dimensions of pain coping were associated with treatment responses in a sex-dependent manner. These findings suggest that the determinants of ESI pain and treatment outcome might differ across sex. ⋯ Sex-related influences on pain responses have been widely reported, but few studies have explored sex-dependent predictors of treatment response. These findings indicate that pain coping was differentially associated with outcomes after ESI in women versus men.
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The purpose of this article is to explore the multidimensionality of the pain experience for patients with chronic pain by using a within-person, longitudinal approach. An Ecological Momentary Assessment design with a patient electronic diary was used to collect random momentary pain assessments several times a day for 2 weeks. We examined the within-person relationships between pain intensity, sensory characteristics, affective qualities, and activities limited by pain. All 3 dimensions (sensory, affective, and activities) were significantly related to pain intensity in a monotonic, but nonlinear, manner. These results expand our understanding of the pain experience by showing that changes of pain over time are associated with changes in sensory symptoms, affective distress, and activity limitations. ⋯ Although the relationships between pain dimensions have been examined between people, the results have been interpreted as within-persons. This article confirms that pain intensity is significantly related to sensory characteristics of pain, affective qualities of pain, and activity limitations due to pain within a person.