Pain
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Randomized Controlled Trial Clinical Trial
A new analogue scale for assessing children's pain: an initial validation study.
A new instrument was designed to provide a practical clinical measure for assessing children's pain intensity and pain affect. The pocket size measure includes a Coloured Analogue Scale (CAS) to assess intensity and a facial affective scale to assess the aversive component of pain. Both scales have numerical ratings on the back, so that the person administering it can quickly note the numbers that represent a child's pain. ⋯ The new instrument has equivalent psychometric properties to a 165 mm VAS. However, the CAS was rated as easier to administer and score than the VAS, so it may be more practical for routine clinical use. Since the CAS has fulfilled the first two criteria for a pain measure (psychophysical properties and discriminant validity), it is ethical to proceed with the formal definitive test for construct validity, in which children from various clinical populations use the CAS scale to assess their own pain.
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Central pain syndromes (CPS) could be caused by disinhibition of spinothalamic excitability or by other central nervous system (CNS) changes caused by reduced spinothalamic function. To examine these possibilities, we studied 11 patients (ages 51-82 years) with unilateral central pain and with reproducible cerebral evoked vertex potentials in response to cutaneous stimulation of the normal side with pulses from an infra-red CO2 laser. All patients had normal tactile and kinesthetic sensation; one had slightly decreased vibratory sense bilaterally. ⋯ In contrast, laser stimulation of the affected side failed to evoke either N or P potentials in 6 patients, all of whom had lateralized increased thresholds for warm, heat pain, or deep pain, or reduced ratings of laser pulse sensation. Although 1 patient had increased ratings of laser pulse sensation, the amplitude of the LEP was always reduced on the side of increased pain or heat threshold in these CPS patients (Fisher exact test: P = 0.015). These results reflect primarily a deficit in spinothalamic tract function and do not suggest excessive CNS responses to synchronous activation of cutaneous heat nociceptors in patients with CPS.
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Many aspects of bilateral presentation or recurrence of reflex sympathetic dystrophy (RSD) are unknown. For this reason 1183 consecutive patients with RSD were analyzed. In 10 patients RSD started in symmetrical limbs. ⋯ Reflex sympathetic dystrophy may recur in the same or in another limb, although only in a minority of patients. Recurrences occur especially in younger patients and in the symmetrical limb. Diagnosis of a recurrence is difficult, for often the recurrence is spontaneous and presents with few signs and symptoms.
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In this study, we developed a rat model of incisional pain. A 1-cm longitudinal incision was made through skin, fascia and muscle of the plantar aspect of the hindpaw in halothane-anesthetized rats. Withdrawal responses were measured using von Frey filaments at different areas around the wound before surgery and for the next 6 days. ⋯ Even remote sites as much as 10 mm from the wound showed persistent mechanical hyperalgesia. Selective denervations of the rat hindpaw prior to foot incision revealed both the sural and tibial nerves were responsible for transmitting input from the incision that produces hyperalgesia. This model should allow us to understand mechanisms of sensitization caused by surgery and investigate new therapies for postoperative pain in humans.
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Randomized Controlled Trial Clinical Trial
Peripheral analgesic effect of intra-articular clonidine.
Sympathetic nervous system stimulation, which releases noradrenaline, influences the nociceptor activity which develops after tissue injury. The alpha 2-adrenergic agonist, clonidine, produces analgesia through a central mechanism but also inhibits noradrenaline release at terminal nerve fibre endings. Clonidine may induce analgesia when administered at peripheral sites. ⋯ The difference was not significant between group 4 (300 +/- 419 min) and the other groups. We conclude that a low dose of intra-articular clonidine produces analgesia unrelated to vascular uptake of the drug. This study further supports a peripheral analgesic effect of clonidine.