European journal of pain : EJP
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Chronic pain patients often suffer from widespread and long lasting pain. The integrative effect of combined spatial and temporal summation on pain intensity has not been quantitatively tested. The present study was designed to investigate: (1) if the size of the stimulation area would facilitate the temporal summation of pain to repetitive pressure stimulation, and (2) if temporal summation is effective when stimulating separated sites, repetitively. ⋯ There was no temporal summation of pain to stimuli with ISI 5 and 30s when stimulating the separated sites. The current study indicated that spatial summation facilitated the temporal summation of pain for stimuli given at 5s and 30s ISI. The combination of temporal and spatial integration of nociceptive input facilitates the pain intensity, suggesting that temporal summation is clinically relevant in conditions with widespread pain.
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The present study is the first demonstration of prolonged nociceptive behavior in the trigeminal region following compression of the trigeminal ganglion in rats. Experiments were carried out on male Sprague-Dawley rats mounted onto a stereotaxic frame under pentobarbital sodium anesthesia. For compression of the trigeminal ganglion, a 4% agar solution (8microl) was injected into the trigeminal ganglion through a stainless steel injector (24 gauge), which extended 2mm beyond the end of a guide cannula (21 gauge). ⋯ Although mechanical allodynia and hyperalgesia appeared bilaterally, the ipsilateral side was significantly more sensitive. Intraperitoneal treatment with carbamazepine significantly blocked mechanical allodynia produced by compression of the trigeminal ganglion. These findings suggest that prolonged nociceptive behavior following compression of the trigeminal ganglion may mimic trigeminal neuralgia in this animal model.
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Randomized Controlled Trial
Perioperative ketamine does not prevent chronic pain after thoracotomy.
Thoracotomy is often responsible for chronic pain, possibly of neuropathic origin. To confirm preclinical studies, the preventive effects of perioperative ketamine were tested in a randomized, double-blind, placebo-controlled clinical trial on persistent neuropathic pain after thoracotomy. Eighty-six patients scheduled for thoracotomy under standardised general anaesthesia were randomised to receive either ketamine (1 mg kg(-1) at the induction, 1 mg kg(-1) h(-1) during surgery, then 1 mg kg(-1) during 24 h; n=42) or normal saline (n=44). ⋯ Ketamine improved immediate postoperative pain, but the groups were similar in terms of neuropathic pain and intake of analgesics, 6 weeks (NPSI score: ketamine: 1.25 [0-4.125]; placebo: 1 [0-4]) and 4 months after surgery. Thus, ketamine given in 24-h infusion failed to prevent chronic neuropathic pain after thoracotomy. Other perioperative preventive long-lasting treatments or techniques could be tested in this context.
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Randomized Controlled Trial
Lack of efficacy of alpha-lipoic acid in burning mouth syndrome: a double-blind, randomized, placebo-controlled study.
A systematic review from the Cochrane Collaboration stated that alpha-lipoic acid (ALA) may help in the management of burning mouth syndrome (BMS). Because all of the data on ALA came from a single group, it has been stressed that its effectiveness should be reproduced in other populations. ⋯ The fairly high placebo effect observed is very similar to data obtained from patients affected by atypical facial pain. This study failed to support a role for ALA in the treatment of BMS, and further investigations are needed to identify the cause of BMS in order to develop efficacious therapies.
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Although psychological aspects of SCI-related pain have been investigated in those with chronic pain, little data is available regarding these factors in those early in the course of the injury. Using a sample admitted for SCI rehabilitation, this paper describes the relationships between usual pain intensity, mood, disability and both pain and SCI-related psychological factors. The sample were largely similar to other samples of individuals with SCI-related chronic pain in terms of mood, but were noted to be less catastrophic in their thinking about pain than a comparative pain clinic sample. ⋯ SCI self-efficacy was also significantly positively associated with physical function scores. These findings suggest that pain-related psychological factors may have importance even early in the clinical course following SCI, but that it is important, however, to consider more general SCI-related psychological factors alongside them. In addition, these findings suggest the possibility that early interventions based upon the cognitive behavioural treatment of pain may be integrated into SCI rehabilitation programmes.