Pain
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Chronic neuropathic pain is associated with long-term changes at multiple levels of the neuroaxis, including in the brain, where electrical stimulation has been used to manage severe pain conditions. However, the clinical outcome of deep brain stimulation is often mixed, and the mechanisms are poorly understood. By means of electrophysiologic methods, we sought to characterize the changes in neuronal activity in the ventral posterolateral nucleus of the thalamus (VPL) in a rat model of peripheral neuropathic pain, and to reverse these changes with low-voltage, high-frequency stimulation (HFS) in the VPL. ⋯ Compared to naive rats, burst firing properties (burst events, percentage of spikes in burst, and mean interburst time) were altered in rats with CCI, whereas these changes were reversed to near normal after HFS. Thermal hyperalgesia in rats with CCI was significantly attenuated by HFS. Therefore, this study demonstrates that electrical stimulation within the VPL can effectively modulate some nociceptive phenomena associated with peripheral neuropathic pain.
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Fear of pain (FOP) and its effect on placebo analgesia was investigated. It was hypothesized that FOP should interfere with placebo-mediated pain inhibition and result in weaker placebo responding in pain intensity, pain unpleasantness, stress, and event-related potentials to contact heat pain. Thirty-three subjects participated in a balanced 2 condition (natural history, placebo)×3 test (pretest, posttest 1, posttest 2) within-subject design, tested on 2 separate days. ⋯ FOP was related to reduced placebo responding on P2 amplitude, whereas placebo responding on N2 amplitude was unaffected by FOP. Higher placebo responses on N2 and P2 amplitudes were both related to higher placebo analgesic magnitude in pain unpleasantness. In conclusion, increased FOP was found to reduce subjective and electrophysiological placebo analgesic responses.
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Parent perceptions of and responses to pain have been identified as important factors in understanding pain-related disability among children and adolescents with chronic pain. The ability to accept chronic pain rather than focus on ways to avoid or control it has been linked to positive outcomes in chronic pain research. To examine parent beliefs about child acceptance of pain, the Chronic Pain Acceptance Questionnaire, parent report (CPAQ-P), was developed and administered to 195 parents of children with persistent pain evaluated in a multidisciplinary pain clinic. ⋯ For construct validity, parent beliefs about child acceptance were negatively correlated with parent pain catastrophizing and parent fear of pain. Greater acceptance was also negatively associated with protective parent responses to pain. These results support the CPAQ-P as a promising measure for assessing parent beliefs about child acceptance of pain and reinforce the importance of the social context and parental influence on child functioning.