Pain
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Randomized Controlled Trial Comparative Study Clinical Trial
Morphine injected around the stellate ganglion does not modulate the sympathetic nervous system nor does it provide pain relief.
Six patients with a presumptive diagnosis of upper limb reflex sympathetic dystrophy and 1 patient with anaesthesia dolorosa had pain and sympathetic activity assessed before and after injection of bupivacaine and morphine around the stellate ganglion. Sympathetic modulation was assessed by measuring the effect of each injection on the inspiratory gasping response (IGR), a measure of central arousal, the sympathetic skin response (SSR), a measure of peripheral sudomotor activity and the plethsymographic wave (PW), a measure of peripheral vasomotor activity. There were 5 women and 2 men with a mean age of 49 years (range: 41-66 years). ⋯ Bupivacaine did provide short-term pain relief in 4 out of 7 patients. Morphine did not produce any demonstrable effect on the sympathetic nervous system nor did it provide pain relief for any patient. Thus these data do not support injection of morphine around the stellate ganglion as it neither modulated sympathetic activity nor provided pain relief.
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The aim of the study was to evaluate the effects of pre- and postinjury infiltration with lidocaine on alterations in mechanical and thermal sensitivity after heat injury to the skin. In the first part of the study, burn injuries (15 x 25 mm rectangular thermode, 50 degrees C, 7 min) were produced twice in each subject on the medial side of the left and right calves at least 24 h apart in 8 healthy, unmedicated male volunteers, in order to investigate the effects of the injury on sensitivity in untreated skin. In the second part of the study, burn injuries (15 x 25 mm rectangular thermode, 50 degrees C, 6 min) were produced twice in each subject on the medial side of the left and right calves at least 24 h apart (n = 10). ⋯ In the second part of the study, it was observed that pre-injury infiltration with lidocaine reduced hyperalgesia to pinprick and brush outside the injury more effectively than postinjury block, but only for the first 70 min after injury, while no significant difference was observed 100-190 min after injury. Likewise, there was no difference in thermal thresholds inside the injury between pre- and postinjury treatment at the end of the study period. It is concluded, that a shortlasting 'preemptive' infiltration with lidocaine may postpone but not prevent the occurrence of hyperalgesia outside a thermal injury.