Pain
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Botulinum toxin type A (BoNT-A) produced by the bacterium Clostridium botulinum is a potent inhibitor of acetylcholine release in the neuromuscular junction and has been used to treat many disorders related to excessive muscle contraction. However, BoNT-A has recently been used in pain therapy to treat myofascial pain, low back pain and various types of headaches, including migraine. The purpose of this study is to investigate the antinociceptive effect of BoNT-A and its underlying mechanism in the rat formalin inflammatory pain model. ⋯ Pre-treatment of rats with BoNT-A (3.5, 7 or 15 U/kg) all significantly reduced formalin-evoked glutamate (Glu) release. These results demonstrate that local peripheral injection of BoNT-A significantly reduces formalin-induced nociceptive behaviors with the absence of obvious muscle weakness. Such an antinociceptive effect of BoNT-A is associated with the inhibition of formalin-induced release of Glu (and/or neuropeptides) from primary afferent terminals.
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Comparative Study
Oral health attitudes and communication with laypersons about orofacial pain among middle-aged and older adults.
Communication patterns with persons outside the health care system during a pain episode are poorly understood, yet can have a significant influence on patient behavior. This study examined associations between attitudes and beliefs about oral disease and dental care and talking about orofacial pain with laypersons and health care professionals. The subjects were 724 participants in the Florida Dental Care Study, a longitudinal study of oral health among community-dwelling adults. ⋯ Our data are consistent with the hypothesis that lay consultation during a pain episode may substitute for formal care for persons with less positive views of the health care system. Intensity ratings and temporal characteristics of pain were also important determinants of these pain-related communication patterns. These findings emphasize the importance of understanding the communication between persons with pain and non-health care professionals, and how these attitudes and communication preferences relate to the management of pain.
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Comparative Study
Phantom phenomena in mastectomized patients and their relation to chronic and acute pre-mastectomy pain.
Chronic and acute pre-mastectomy pain as well as prevalence and characteristics of phantom phenomena following mastectomy were investigated by interview in a sample of 39 women who had undergone unilateral breast amputation. Twenty of 39 participants reported phantom sensations in the breast. Nine of the participants with phantom sensations experienced phantom pain and 11 non-painful phantom sensations. ⋯ This difference may be explained by the absence of kinesthesis and the small representation of the human breast. Seven of the 39 participants experienced chronic and six acute breast pain prior to the amputation. The amount of chronic pre-mastectomy breast pain weighted by the amount of involved tissue was significantly higher among participants with non-painful phantom sensations, compared to women with painful phantoms and those without phantom phenomena.
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To better understand the association between pain recalled over a previous week and the average of multiple momentary reports of pain taken during the same period, 68 patients with chronic pain completed both weekly recall and momentary reports over a 2-week period and assessed their change in pain over the 2 weeks. Pearson correlations and intraclass correlation coefficients were computed to index three different ways of comparing the measures on both a between-person and within-person basis. ⋯ Judged change was only weakly related to changes over a week computed from weekly recall or from average momentary reports. Given the importance of within-person change for treatment studies, these results indicate a serious nonequivalence in weekly recall and averaged momentary reports of pain.
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Comparative Study
Evidence for spinal cord hypersensitivity in chronic pain after whiplash injury and in fibromyalgia.
Patients with chronic pain after whiplash injury and fibromyalgia patients display exaggerated pain after sensory stimulation. Because evident tissue damage is usually lacking, this exaggerated pain perception could be explained by hyperexcitability of the central nervous system. The nociceptive withdrawal reflex (a spinal reflex) may be used to study the excitability state of spinal cord neurons. ⋯ We provide evidence for spinal cord hyperexcitability in patients with chronic pain after whiplash injury and in fibromyalgia patients. This can cause exaggerated pain following low intensity nociceptive or innocuous peripheral stimulation. Spinal hypersensitivity may explain, at least in part, pain in the absence of detectable tissue damage.