Pain
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Randomized Controlled Trial
Referred sensation location can be altered by a strong heterotopic nociceptive stimulus: Implications for clinical pain conditions.
Referred sensations (RS) are a common clinical phenomenon in patients with musculoskeletal pain; however, the underlying mechanisms of RS and implications for diagnosis and management are poorly understood. The location of referral seems to have a preferred site, but studies have suggested it can be redirected to a site of previous injury and pain. However, it is not known if the same phenomenon can occur for a much shorter-lasting painful stimulus in the trigeminal system. ⋯ However, the RS location was displaced on average 1.2 cm between the baseline and postinfusion assessments for the hypertonic saline infusion, which was significantly increased when compared with the isotonic saline infusion which was on average 0.4 cm. These novel findings indicate the potential to modify the location of RS in the trigeminal system following a relatively brief noxious input. Clinicians need to be aware of the possible rerouting of RS in patients with complex orofacial pain.
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In neonates, a noxious stimulus elicits pain-related facial expression changes and distinct brain activity as measured by electroencephalography, but past research has revealed an inconsistent relationship between these responses. Facial activity is the most commonly used index of neonatal pain in clinical settings, with clinical thresholds determining if analgesia should be provided; however, we do not know if these thresholds are associated with differences in how the neonatal brain processes a noxious stimulus. The objective of this study was to examine whether subclinical vs clinically significant levels of pain-related facial activity are related to differences in the pattern of nociceptive brain activity in preterm and term neonates. ⋯ Results revealed a sequence of nociceptive cortical network activation that was independent of pain-related behavior; however, a separate but interleaved sequence of early activity was related to the magnitude of the immediate behavioural response. Importantly, the degree of pain-related behavior is related to how the brain processes a stimulus and not simply the degree of cortical activation. This suggests that neonates who exhibit clinically significant pain behaviours process the stimulus differently and that neonatal pain-related behaviours reflect just a portion of the overall cortical pain response.
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Pain management for patients with dementia is challenging because many experience pain while being unable to communicate their pain. The aim of this study was to describe pain, pain management, and to perform a thorough clinical examination of chronic pain conditions among patients with dementia. Residents (n = 498) from 12 nursing homes were assessed for dementia (Clinical Dementia Rating scale [CDR]) and for pain with the Mobilization-Observation-Behavior-Intensity-Dementia-2 (MOBID-2) assessment form. ⋯ Chronic widespread pain was the most prevalent (14.5%) followed by nonspecific pain from the back (13.4%), whereas the most prevalent chronic secondary pain conditions were chronic pain caused by osteoarthritis (15.4%) and stroke (8.0%). One-fourth received opioids, which was significantly associated with severe pain ( P < 0.001) compared with moderate pain, although no significant association was found between opioid use and the type of pain condition. Although knowledge of the severity and specific types of pain conditions is recommended to direct the choice of treatment, these areas are not sufficiently explored in the nursing home populations with dementia and may hinder a better treatment of pain in this population.
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Descending control of nociception (DCN; also known as conditioned pain modulation [CPM], the behavioral correlate of diffuse noxious inhibitory controls) is the phenomenon whereby pain inhibits pain in another part of the body and is the subject of increasing study because it may represent a biomarker of chronic pain. We recently discovered that pain modulation on the application of a DCN paradigm involving low-intensity test stimuli occurs in the direction of hyperalgesia in healthy mice and rats, whereas the use of high-intensity stimuli produces analgesia. To elucidate the physiological mechanisms underlying hyperalgesic DCN, we administered agonists and antagonists of norepinephrine (NE) and serotonin (5-HT) receptors, key neurochemical players in the production of analgesic DCN. ⋯ By contrast, analgesic DCN was found to be reversed by atipamezole and SB269970 themselves, with no effect of reboxetine or fluoxetine. Thus, hyperalgesic DCN seems to be the neurochemical opposite to analgesic DCN. These data further validate and help elucidate a preclinical paradigm that mimics dysfunctional CPM and thus may form the basis of translational experiments that aim to reveal preventative pharmacological strategies for individuals predisposed to persistent pain.