The Clinical journal of pain
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The study examined symptom-specific muscle hyperreactivity in patients with chronic pain with upper limb cumulative trauma disorder (CTD). ⋯ The results indicate that symptom-specific psychophysiological responses may be limited to certain subgroups rather than being characteristic of chronic musculoskeletal pain patients in general.
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The authors aimed to provide an educational update on the current evidence of the effectiveness of drug therapy in the treatment of musculoskeletal pain and to offer a perspective of possible future developments. ⋯ The effectiveness of the currently available drugs in the treatment of musculoskeletal pain conditions is disappointing. Recent developments may open new perspectives in this area of pain medicine.
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The peripheral apparatus of muscle pain consists of nociceptors that can be excited by endogenous substances and mechanical stimuli. Histologically, the nociceptors are free nerve endings supplied by group III (thin myelinated) and group IV (nonmyelinated) afferents with conduction velocities less than 30 m/s. At the molecular level, nociceptors have receptors for algesic substances, such as bradykinin, serotonin, and prostagladin E2. ⋯ For example, animal studies showed that serotonin sensitizes muscle nociceptors to chemical and mechanical stimuli. Later, human studies showed that serotonin combined with bradykinin induces muscle hyperalgesia to pressure. The sensitization process by endogenous substances that are likely to be released during trauma or inflammatory injury is probably the best established peripheral mechanism for muscle tenderness and hyperalgesia.