Articles: hyperalgesia.
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Anesthesia and analgesia · Sep 2007
The evolution of primary hyperalgesia in orthopedic surgery: quantitative sensory testing and clinical evaluation before and after total knee arthroplasty.
Quantitative sensory testing (QST) allows precise characterization of sensory deficits and painful symptoms and may offer additional information on the pathophysiology of postoperative pain. ⋯ Heat hyperalgesia was the predominant QST symptom associated with perioperative pain after total knee arthroplasty, and was predictive of postoperative morphine consumption.
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Randomized Controlled Trial
The result of treatment on vestibular and general pain thresholds in women with provoked vestibulodynia.
To correlate changes in vestibular pain thresholds to general pain thresholds in a subgroup of women with provoked vestibulodynia taking part in a treatment study. ⋯ Treating provoked vestibulodynia by either topical lidocaine or electromyographic biofeedback increased vestibular pain thresholds, reduced dyspareunia, and improved bodily pain. The patients showed a general hypersensitivity to pressure pain compared with controls and in this study the hypersensitivity did not seem to be affected by treating the superficial dyspareunia.
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Chronic muscle pain is a major clinical problem that is often associated with fatigue. Conversely, chronic fatigue conditions are commonly associated with muscle pain. We tested the hypothesis that muscle fatigue enhances hyperalgesia associated with injection of acidic saline into muscle. We evaluated mechanical sensitivity of the paw (von Frey) in mice after 2 intramuscular injections of saline (20 microL; pH 4, pH 5, pH 6, pH 7.2) in a fatigue and a control group. To induce fatigue, mice were run for 2 h/day for 2 days prior to the first injection and 2 h/day for 2 days prior to the second injection. Muscle lactate, pCO(2), pO(2), creatinine kinase, phosphate, and histology were examined after the fatigue task and compared to a control group. Grip force was significantly decreased after 2 h of running indicating fatigue. The fatigue task did not induce muscle damage as there was no difference in muscle lactate, pCO(2), pO(2), creatinine kinase, phosphate, or histology. The fatigue task altered the dose-response relationship to intramuscular acidic saline injections. Mechanical hyperalgesia was observed in both fatigue and control groups after intramuscular injection of pH 4.0, but only the fatigue group after injection of pH 5. Neither the fatigue nor the control group developed hyperalgesia in response to intramuscular injection of pH 6 or pH 7.2. In conclusion, fatigue modified the susceptibility of mice to acid injection of pH 5.0 to result in mechanical hyperalgesia after 2 injections of pH 5.0. The fatigue task did not produce measurable changes in the muscle tissue suggesting a central mechanism mediating the enhancement of hyperalgesia. ⋯ These data therefore show that muscle fatigue can enhance the likelihood that one develops pain to a mild insult. Clinically, this could relate to the development of pain from such conditions as repetitive strain injury, and may relate to the interrelationship between chronic pain and fatigue.
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Experimental neurology · Sep 2007
Segmental hypersensitivity and spinothalamic function in spinal cord injury pain.
The mechanisms underlying central pain following spinal cord injury (SCI) are unsettled. The purpose of the present study was to examine differences in spinothalamic tract function below injury level and evoked pain in incomplete SCI patients with neuropathic pain below injury level (central pain) versus those without such pain. A clinical examination, quantitative sensory testing and magnetic resonance imaging (MRI) were performed in 10 SCI patients with below-level pain and in 11 SCI patients without neuropathic pain. ⋯ SCI patients with central pain had sensory hypersensitivity in dermatomes corresponding to the lesion level more frequently than SCI patients without pain, but this may in part be explained by the exclusion of at-level spontaneous pain in the pain-free group. The rostral-caudal extent of the lesion measured by MRI did not differ between the two patient groups, and there were no statistically significant differences in any of the predefined areas of interest on the axial plane images. This study suggests that neuronal hyperexcitability plays a key role in central SCI pain and furthermore - in contrast to previous findings - that loss of spinothalamic functions does not appear to be a predictor for central neuropathic pain in spinal cord injury.