Pain
-
A unilateral chronic constriction injury (CCI) of the sciatic nerve produced bilateral effects in both pain related behaviors and in the pattern of forebrain activation. All CCI animals exhibited spontaneous pain-related behaviors as well as bilateral hyperalgesia and allodynia after CCI. Further, we identified changes in baseline (unstimulated) forebrain activation patterns 2 weeks following CCI by measuring regional cerebral blood flow (rCBF). ⋯ For example, the hindlimb region of somatosensory cortex was significantly activated (22%) as well as multiple thalamc nuclei, including the ventral medial (8%), ventral posterior lateral (10%) and the posterior (9%) nuclear groups. In addition, several forebrain regions considered to be part of the limbic system showed pain-induced changes in rCBF, including the anterior dorsal nucleus of the thalamus (23%), cingulate cortex (18%), retrosplenial cortex (30%), habenular complex (53%), interpeduncular nucleus (45%) and the paraventricular nucleus of the hypothalamus (30%). Our results suggest that bilateral somatosensory and limbic forebrain structures participate in the neural mechanisms of prolonged persistent pain produced by a unilateral injury.
-
Randomized Controlled Trial Clinical Trial
Effect of propranolol and granisetron on experimentally induced pain and allodynia/hyperalgesia by intramuscular injection of serotonin into the human masseter muscle.
We have previously reported that intramuscular injection of serotonin (5-HT) into the masseter muscle elicits pain and allodynia/hyperalgesia in healthy subjects. The aim of this study was to investigate whether the 5-HT(3) receptor antagonist granisetron or 5-HT(1A) receptor antagonist propranolol can reduce 5-HT induced pain and allodynia/hyperalgesia in the masseter muscle. Twenty-four healthy individuals (12 males and 12 females) without pain from the masseter muscle region participated. ⋯ The difference between 5-HT and granisetron+5-HT was significant. In conclusion, the results of this study indicate that injection of granisetron and propranolol into the human masseter muscle reduces pain induced by local administration of 5-HT, but that the effect of granisetron is stronger than that of propranolol. In addition, granisetron totally abolishes allodynia/hyperalgesia.
-
Clinical Trial
Motor cortex stimulation for chronic neuropathic pain: a preliminary study of 10 cases.
There is growing evidence to support the use of motor cortex stimulation (MCS) in the management of patients with chronic neuropathic pain. A prospective audit of ten patients using a modified staged technique for motor cortex implantation provides further evidence for the analgesic effectiveness of this technique. ⋯ We conclude that motor cortex stimulation is an effective analgesic intervention in some patients with chronic neuropathic pain, but it is difficult if not impossible to predict those patients who may respond to treatment prior to implantation. Randomised controlled trials are now urgently needed to test the effectiveness of motor cortex stimulation under double-blind conditions.
-
Clinical Trial
The reliability and validity of the COMFORT scale as a postoperative pain instrument in 0 to 3-year-old infants.
The aim of this study was to test the reliability and validity of the COMFORT scale as a postoperative pain instrument for children aged 0-3 years. Subjects were 158 neonates and toddlers after major abdominal or thoracic surgery. Trained nurses rated the children's pain at 3, 6 and 9 h postoperative on the Pediatric Surgical Intensive Care Unit using the COMFORT and a VAS for pain. ⋯ Stability of COMFORT 'behaviour' and VAS pain was moderate which might be due to varying painful episodes in this sample. HR and MAP, although stable across time, were weakly related to VAS pain and COMFORT 'behaviour'. These findings support the use of the COMFORT 'behaviour' scale to assess postoperative pain in neonates and infants.
-
Several lines of evidence suggest that secondary hyperalgesia to punctate mechanical stimuli arises from central sensitization to the input from primary afferent nociceptors. Conventional C-fiber nociceptors respond to heat stimuli and yet heat hyperalgesia is absent in the region of secondary hyperalgesia. This evidence suggests that the central sensitization to nociceptor input does not involve heat sensitive nociceptors. ⋯ However, touch threshold and pain to pinching stimuli were not significantly altered. The intradermal capsaicin injection led to the development of a similar degree of secondary hyperalgesia at both the vehicle and capsaicin treatment areas. These results indicate that capsaicin insensitive nociceptive afferents play a dominant role not only in normal mechanical pain but also in secondary hyperalgesia to noxious mechanical stimuli.