European journal of pain : EJP
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We used functional magnetic resonance imaging (fMRI) to analyze changes in brain activity associated with stimulation of the cutaneous trigger zone in patients with classic trigeminal neuralgia (CTN). Fifteen consecutive patients with CTN in the second or third division of the nerve, were included in this study. The fMRI paradigm consisted of light tactile stimuli of the trigger zone and the homologous contralateral area. ⋯ Such sensitization may depend on pain modulatory systems involving both the brainstem (i.e. periaqueductal gray and adjacent structures) and interconnected cortical structures (i.e. ACC). The fact that large portions of the classical 'pain neuromatrix' were also activated during nonpainful stimulation of the trigger zone, could reflect a state of maintained sensitization of the trigeminal nociceptive systems in CTN.
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The objective was to investigate the 3-year course of secondary chronic headaches (⩾15days per month for at least 3months) in the general population. An age and gender stratified random sample of 30,000 persons aged 30-44years from the general population received a mailed questionnaire. All with self-reported chronic headache, 517 in total, were interviewed by neurological residents. ⋯ The headache index (frequency×intensity×duration) was significantly reduced from baseline to follow-up in chronic posttraumatic headache and HACRS, but not in CEH. We conclude that secondary chronic headaches seem to have various course dependent of subtype. Recognizing the different types of secondary chronic headaches is of importance because it might have management implications.
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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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Injury to the insular cortex in humans produces a lack of appropriate response to pain. Also, there is controversial evidence on the lateralization of pain modulation. The aim of this study was to test the effect of insular cortex lesions in three models of pain in the rat. ⋯ All the RAIC lesion groups showed diminished pain-related behaviours in inflammatory (increased PWL) and neuropathic models (diminished mechanical nociceptive response and autotomy score). The lesion of the RAIC produces a significant decrease in pain-related behaviours, regardless of the side of the lesion. This is a clear evidence that the RAIC plays an important role in the modulation of both inflammatory and neuropathic - but not acute - pain.
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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.