European journal of pain : EJP
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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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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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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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This investigation aimed to quantify and compare sensory responses to hypertonic saline-induced pain in the tendoachilles and the common extensor tendon of the elbow. Healthy subjects (n=14; seven males) received in randomised order, injections of sterile saline (0.5ml, 5.8% hypertonic or 0.9% isotonic saline) at each tendon bilaterally at two sessions separated by one week. Mechanical sensitivity (pressure pain threshold), muscle pain intensity (visual analogue scale; VAS area-under-curve, pain duration, peak pain) and pain distribution were assessed pre, immediately after and post saline injection. ⋯ Significant maximal force attenuation occurred immediately after hypertonic saline injections in both tendons (P<0.001) compared with control injections. The greater induced deep tissue pain and hyperalgesia demonstrated at tendoachilles compared with the common extensor tendon may relate to anatomical differences such as higher nociceptor density or increased vascular perfusion at the injection site. This translational tendon pain model may contribute to the further understanding of pain mechanisms in tendinopathic conditions.
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Previous research demonstrates that men and women differ in the way that they perceive and process pain. Much of this work has been done in healthy adults with a lack of consensus in clinical pain populations. The purpose of this study was to investigate how men and women with shoulder pain differ in their experience of experimental and clinical pain and whether psychological processes differentially affect these responses. ⋯ There were no sex differences in psychological association with experimental and clinical pain in this cohort. The relationship between clinical and experimental pressure pain was stronger in women as compared to men. These findings offer insight into the interactions between biological and psychosocial influences of pain and how these interactions vary by sex.