Pain
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Comparative Study
Relationship between pain symptoms and referred sensory and trophic changes in patients with gallbladder pathology.
The relationship was investigated between algogenic potential of gallbladder pathology and occurrence/extent of sensory and trophic changes in the referred area. Five groups of subjects were studied, with: symptomatic gallbladder calculosis (3-20 colics); asymptomatic calculosis; symptomatic gallbladder shape abnormality (8-18 colics); asymptomatic shape abnormality; normal gallbladder/no symptoms. At the cystic point (CP) and contralaterally, all underwent measurement of: pain thresholds to electrical stimulation of skin, subcutis and muscle; thickness of subcutis and muscle via ultrasounds. ⋯ Patients with symptomatic calculosis were re-evaluated after 6 months; those not presenting further colics showed a significant increase in subcutis and muscle thresholds at CP, while those who continued presenting colics showed a further significant threshold decrease (0.01
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Comparative Study
Sensory and motor effects of experimental muscle pain in patients with lateral epicondylalgia and controls with delayed onset muscle soreness.
This study compares the effect of experimental muscle pain on deep tissue sensitivity and force attenuation in the wrist extensors of patients with lateral epicondylalgia (n=20), and healthy controls (n=20) with experimentally induced sensori-motor characteristics simulating lateral epicondylalgia. Delayed onset muscle soreness (DOMS) in wrist extensors of healthy controls was induced by eccentric exercise in one arm 24h prior to injection (Day 0). Saline-induced pain intensity (visual analogue scale, VAS), distribution, and quality were assessed quantitatively in both arms for both groups. ⋯ Patients demonstrated significant bilateral hyperalgesia at extensor carpi radialis brevis during and post saline-induced pain compared to pre-injection and healthy controls (P<0.04). The sore arm in patients and the DOMS arms in healthy subjects showed significantly reduced maximal force (P<0.0001), at all Day 1 times compared with the control arms. In patients, the bilateral increase in deep tissue sensitivity and enlarged referred pain areas during saline-induced pain might suggest involvement of central sensitisation.
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The pain enhancing (hyperalgesic) effect of morphine was characterized in relation to pain stimulus (thermal, mechanical), dose, mode of administration (acute, chronic), sex and mechanism. We found that a low (subanalgesic) dose of morphine enhanced the sensitivity to thermal and mechanical noxious stimuli in a dose- and sex-related manner. Morphine hyperalgesia was inversely related to dose (0.002-0.2mg/kg) and was more pronounced in female than male rats. ⋯ Sex-related differences in morphine's analgesic action (male>female) were attenuated. Development of tolerance to the analgesic effect of morphine was delayed. The present findings may have an implication for the use of mu opioids in the clinical setting.
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Randomized Controlled Trial Comparative Study Clinical Trial
Is successful rehabilitation of complex regional pain syndrome due to sustained attention to the affected limb? A randomised clinical trial.
In complex regional pain syndrome (CRPS1) initiated by wrist fracture, a motor imagery program (MIP), consisting of hand laterality recognition followed by imagined movements and then mirror movements, reduces pain and disability, but the mechanism of effect is unclear. Possibilities include sustained attention to the affected limb, in which case the order of MIP components would not alter the effect, and sequential activation of cortical motor networks, in which case it would. Twenty subjects with chronic CRPS1 initiated by wrist fracture and who satisfied stringent inclusion criteria, were randomly allocated to one of three groups: hand laterality recognition, imagined movements, mirror movements (RecImMir, MIP); imagined movements, recognition, imagined movements (ImRecIm); recognition, mirror movements, recognition (RecMirRec). ⋯ Imagined movements imparted a further reduction in pain and disability, but only if they followed hand laterality recognition. Mirror movements also imparted a reduction in pain and disability, but only when they followed imagined movements. The effect of the MIP seems to be dependent on the order of components, which suggests that it is not due to sustained attention to the affected limb, but is consistent with sequential activation of cortical motor networks.
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Electrical tooth stimulation was used to investigate whether humans develop tolerance to nitrous oxide (N(2)O) analgesia within a single administration as well as over repeated administrations. In a double-blind cross-over experiment, 77 subjects received a 40-min administration of 38% N(2)O at one session and placebo gas at the other. The sessions were separated by 1 week and the order of gas administration was counterbalanced. ⋯ For both detection and pain threshold measures, acute tolerance developed during the initial N(2)O exposure and chronic tolerance developed over repeated administrations. Although chronic tolerance developed, a test for Pavlovian drug conditioning found no evidence of conditioned effects on sensory thresholds. In conclusion, acute and chronic tolerance develop to N(2)O's analgesic effects in humans.