Pain
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The myofascial trigger point (MTrP) is the hallmark physical finding of the myofascial pain syndrome (MPS). The MTrP itself is characterized by distinctive physical features that include a tender point in a taut band of muscle, a local twitch response (LTR) to mechanical stimulation, a pain referral pattern characteristic of trigger points of specific areas in each muscle, and the reproduction of the patient's usual pain. ⋯ This paper reports an initial attempt to establish the interrater reliability of the trigger point examination that failed, and a second study by the same examiners that included a training period and that successfully established interrater reliability in the diagnosis of the MTrP. The study also showed that the interrater reliability of different features varies, the LTR being the most difficult, and that the interrater reliability of the identification of MTrP features among different muscles also varies.
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Clinical Trial Controlled Clinical Trial
Peripheral alpha-adrenoreceptors are involved in the development of capsaicin induced ongoing and stimulus evoked pain in humans.
While the sympathetic nervous system seems to be involved in some pain states, the mechanisms linking the sensory and sympathetic nervous system are unclear. In this study the possible involvement of peripheral alpha-adrenoreceptors in the development of capsaicin induced ongoing pain and mechanical hypersensitivity was examined in humans. Intradermal capsaicin injections in the volar aspect of the arm gave rise to ongoing burning pain and dysesthesia as well as mechanical hypersensitivity. ⋯ The area in which pain could be evoked on the phentolamine injected side was restricted to the area of flare and was significantly smaller than on the saline injected side. Mechanical stimulation gave rise to aftersensation and radiation of pain on the saline injected side in all subjects but only in one case on the phentolamine injected side. Peripheral alpha-adrenoreceptors thus seem to be involved in functional changes of primary afferents which contribute to ongoing pain and mechanical stimulus evoked pain.
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Clinical Trial
Quantification of local and referred muscle pain in humans after sequential i.m. injections of hypertonic saline.
The aim of the present study was to test (1) whether muscle pain is influenced by temporal and spatial summation, and (2) whether sequential noxious muscle stimuli applied at hourly interstimulus-intervals could produce an increased sensation of pain due to central hyperexcitability. In the study eleven healthy men were exposed to computer-controlled intramuscular infusion of saline (5%) given over 20 s in m. tibialis anterior (m. TA). ⋯ The infusion given 4 h after the sequential infusions tended to produce an increase in the referred pain area and in the pain intensity. In all three experiments significant correlations were found between the VAS peak and the size of the local (R = 0.64, P < 0.0001, n = 231) and referred (R = 0.47, P < 0.0001, n = 231) pain areas. Based on the above results it can be concluded that experimental muscle pain is influenced by temporal and spatial summation.
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Adequate pain relief in patients with far advanced cancer sometimes requires intrathecal (IT) administration of a combination of opioids and local anesthetics. Tumor progression as well as the IT administration of local anesthetics can lead to neurologic dysfunction during treatment. ⋯ Unexpectedly, neurologic evaluation suggested compression of the cauda equina and spinal cord, which was confirmed radiographically. Manifestation of new neurologic symptoms during low dose bupivacaine infusion intrathecally might therefore be an early indicator of space-occupying processes within the spinal canal in cancer patients.
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Temporomandibular disorders (TMD) are common pain conditions that have their highest prevalence among women of reproductive age. The higher prevalence of TMD pain among women, pattern of onset after puberty and lowered prevalence rates in the post-menopausal years suggest that female reproductive hormones may play an etiologic role in TMD. Two epidemiologic studies were designed to assess whether use of exogenous hormones is associated with increased risk of TMD pain. ⋯ Use of OCs was also associated with referral for TMD care, with an increased risk of TMD of approximately 20% for OC users, after controlling for health services use (P < 0.05). These results suggest that female reproductive hormones may play an etiologic role in orofacial pain. This relationship warrants further investigation through epidemiologic, clinical and basic research.