The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial
Virtual reality helmet display quality influences the magnitude of virtual reality analgesia.
Immersive Virtual Reality (VR) distraction can be used in addition to traditional opioids to reduce procedural pain. The current study explored whether a High-Tech-VR helmet (ie, a 60-degree field-of-view head-mounted display) reduces pain more effectively than a Low-Tech-VR helmet (a 35-degree field-of-view head-mounted display). Using a double-blind between-groups design, 77 healthy volunteers (no patients) aged 18-23 were randomly assigned to 1 of 3 groups. Each subject received a brief baseline thermal pain stimulus, and the same stimulus again minutes later while in SnowWorld using a Low-Tech-VR helmet (Group 1), using a High-Tech-VR helmet (Group 2), or receiving no distraction (Group 3, control group). Each participant provided subjective 0-10 ratings of cognitive, sensory, and affective components of pain, and amount of fun during the pain stimulus. Compared to the Low-Tech-VR helmet group, subjects in the High-Tech-VR helmet group reported 34% more reduction in worst pain (P < .05), 46% more reduction in pain unpleasantness (P = .001), 29% more reduction in "time spent thinking about pain" (P < .05), and 32% more fun during the pain stimulus in VR (P < .05). Only 29% of participants in the Low-Tech helmet group, as opposed to 65% of participants in the High-Tech-VR helmet group, showed a clinically significant reduction in pain intensity during virtual reality. These results highlight the importance of using an appropriately designed VR helmet to achieve effective VR analgesia (see ). ⋯ Pain during medical procedures (eg, burn wound care) is often excessive. Adjunctive virtual reality distraction can substantially reduce procedural pain. The results of the present study show that a higher quality VR helmet was more effective at reducing pain than a lower quality VR helmet.
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Randomized Controlled Trial Comparative Study
The pain quality assessment scale: assessment of pain quality in carpal tunnel syndrome.
The Neuropathic Pain Scale (NPS) is a valid measure of the pain qualities and perceived depth of neuropathic pain. However, it does not include a number of pain qualities commonly seen in some neuropathic and non-neuropathic pain conditions. To address this limitation, additional items were added to the NPS to create a 20-item measure (Pain Quality Assessment Scale, PQAS) that would be even more useful for assessing neuropathic pain and also would be used to assess pain qualities associated with non-neuropathic pain. To evaluate the responsivity of the PQAS items to pain treatment, secondary analyses were conducted on data from a trial that compared the efficacy of lidocaine patch 5% versus a single steroid injection in 40 patients with carpal tunnel syndrome. Statistically significant (P < .0025) decreases in 10 of the 20 PQAS pain descriptor ratings occurred with both treatments, and 8 ratings showed nonsignificant trends (.0025 < P < .05) for decreasing before treatment to after treatment. No significant differences were found between the 2 treatment conditions on any of the items. The results support the validity of the PQAS items for assessing the effects of pain treatment on pain qualities of carpal tunnel syndrome. ⋯ Clinical trials that include measures of pain qualities can be used to identify the effects of treatments on distinct pain qualities. Measures such as the PQAS can potentially be used to help clinicians target analgesics more efficiently.
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Fibromyalgia syndrome (FMS) is more prevalent in women than in men. The skewed sex distribution in the prevalence has prompted questions of if and how sex hormones may be involved in the pathophysiology of FMS. In this study, we evaluated the levels of sex hormones and pain sensitivity at different phases of a menstrual cycle in regularly menstruating women with FMS relative to age-matched healthy women. Participants (n = 74 in each group) underwent a 9-day urine test to identify the date of ovulation. Three laboratory visits were scheduled to ascertain the varying levels of estrogen (E) and progesterone (P): Late-follicular phase (high E, low P); mid-luteal phase (high E, high P); and perimenstrual phase (low E, low P). At each visit, blood was drawn and ischemic pain testing was performed. The groups did not differ in the fluctuation of luteal hormone, follicular-stimulating hormone, E, and testosterone across a menstrual cycle. FMS patients showed slightly elevated P levels during the mid-luteal phase relative to healthy women but levels were within the normal range. Women with FMS showed consistently lower pain thresholds and tolerance relative to healthy women throughout the menstrual cycle. Pain threshold at the late follicular phase was modestly related to the P level. The results suggest that the disproportionate prevalence of females with FMS is not likely to be attributable to hormonal factors. Furthermore, the role of sex hormones in pain sensitivity for both FMS and healthy women seems to be limited. ⋯ Normally menstruating women with FMS and healthy women do not seem to show fluctuating threshold and tolerance to the ischemic pain test. The role of sex hormones in the hyperalgesia of FMS appears limited.
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The activation of spinal cord microglia and astrocytes after peripheral nerve injury or inflammation contributes to behavioral hypersensitivity. The contribution of spinal cord glia to mechanical hypersensitivity after hind paw incision has not been investigated previously. Male Sprague-Dawley rats underwent a unilateral plantar hind paw incision, and the development of mechanical hypersensitivity was assessed by using von Frey filaments. The activation of spinal cord microglia and astrocytes was measured 1, 2, 3, and 5 days after hind paw incision by using immunohistochemistry. The glial activation inhibitor, fluorocitrate, was administered intrathecally 24 hours after hind paw incision to determine glial involvement in mechanical hypersensitivity. Hind paw incision induced an activation of spinal astrocytes ipsilateral to incision within 24 hours. Both microglia and astrocytes reached a maximum activation 3 days after hind paw incision. Fluorocitrate produced a dose-dependent reduction in mechanical hypersensitivity when administered 24 hours after hind paw incision. Spinal cord glial activation contributes to the mechanical hypersensitivity that develops after hind paw incision. ⋯ Hind paw incision produces mechanical hypersensitivity that can be alleviated with the inhibition of spinal cord glia. Our results suggest that the activation of spinal cord astrocytes within 24 hours of incision contributes to mechanical hypersensitivity. Therefore, spinal cord astrocytes might represent a novel target for the treatment of postoperative pain.