European journal of pain : EJP
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Tonic pain in one body segment can inhibit the perception of pain in another body segment. This phenomenon is mediated by diffuse noxious inhibitory controls (DNIC), and its efficacy in craniofacial regions is investigated in this study. A compressive device that evoked a tonic, moderate/severe, headache-like, conditioning pain (∼8/10 on a visual analogue scale) was applied for 15min. ⋯ PPTol was unchanged. In the period after the painful conditioning stimulation PPT was depressed compared to control. This study shows that pain evoked from the craniofacial region evokes DNIC-like mechanisms on segmental as well as heterosegmental sites.
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The aim of this study was to determine whether peripheral N-methyl-d-aspartate (NMDA) receptors are involved in inflammation-induced mechanical hypersensitivity of the temporomandibular joint (TMJ) region. We developed a rat model of mechanical sensitivity to Complete Freund's Adjuvant (CFA; 2μl containing 1μg Mycobacterium tuberculosis)-induced inflammation of the TMJ and examined changes in sensitivity following injection of NMDA receptor antagonists (dl-2-amino-5-phosphonovaleric acid (AP5) or Ifenprodil) with CFA. CFA injected into the TMJ resulted in an increase in mechanical sensitivity relative to pre-injection that peaked at day 1 and lasted for up to 3days (n=8, P<0.05). ⋯ Immunohistochemical studies showed that 99% and 28% of trigeminal ganglion neurons that innervated the TMJ contained the NR1 and NR2B subunits respectively. Our findings suggest a role for peripheral NMDA receptors in inflammation-induced pain of the TMJ region. Targeting peripheral NMDA receptors with peripheral application of NMDA receptor antagonists could provide therapeutic benefit and avoid side effects associated with blockade of NMDA receptors in the central nervous system.
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Pain self-efficacy and fear of movement have been proposed to explain how pain can lead to disability for patients with chronic low back pain. However the extent to which pain self-efficacy and fear of movement mediate the relationship between pain and disability over time has not been investigated. This study aimed to investigate whether pain self-efficacy and/or fear of movement mediate the relationship between pain intensity and disability in patients with recent onset chronic low back pain. ⋯ However, in the longitudinal analyses, only improvements in self-efficacy beliefs partially mediated the relationship between changes in pain and changes in disability over a 12months period. We found no support for the theory that fear of movement beliefs mediate this relationship. Therefore, we concluded that pain self-efficacy may be a more important variable than fear of movement beliefs in terms of understanding the relationship between pain and disability.
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Multicenter Study
Validation of an acute pain-behavior scale for older persons with inability to communicate verbally: Algoplus.
To compensate for poor acute pain detection in elderly inpatients with inability to communicate verbally (ICV), the Doloplus Collective team devised the 5-item Algoplus behavior-assessment scale specifically aimed at quickly detecting acute pain in these individuals. Algoplus was developed in three successive phases, including expert opinions, caregivers interviews, patient video recordings and statistical procedures. Among the 1500 recorded primary pain behaviors, 48 were selected and clustered into a 5-item scale. ⋯ Excellent correlations were observed between Algoplus and experts' clinical judgment, acute pain clinical situations or each comparator self-rating-pain score. For patients with acute pain conditions, a score ⩾2 out of 5 on the Algoplus scale was retained as the threshold for the presence of acute pain in elderly ICV inpatients, with 87% sensitivity and 80% specificity. In addition, the very brief rating time of ∼1min is particularly relevant in acute-care settings, where repetitive pain-monitoring is required.
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Neuropathic pain following peripheral nerve lesion is highly resistant to conventional pain treatments but may respond well to direct electrical peripheral nerve stimulation (PNS). In the 1980s, we treated a series of 11 peripheral neuropathic pain patients with PNS. A first outcome assessment, conducted after a 52-month follow-up, revealed that the majority of the patients were significantly improved. ⋯ PNS led to increased blood flow not only in primary somatosensory cortex, but also in anterior cingulate and insular cortices, suggesting that besides activation of the dorsal column lemniscal system, other mechanisms may play a role in its analgesic effects. These data show that PNS can provide truly long-term pain relief in carefully selected patients and they provide some objective quantitative data in support of this. They encourage the planning of future prospective studies in a larger cohort of patients.