Pain
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In adult patients with migraine, transcranial magnetic stimulation (TMS) has been used to examine cortical excitability between attacks, but there have been discrepant results. No TMS study has examined cortical excitability in children or adolescents with migraine. Here, we employed TMS to study regional excitability of the occipital (phosphene threshold [PT] and suppression of visual perception) and motor (resting motor threshold and cortical silent period) cortex in ten children suffering from migraine without aura and ten healthy age-matched controls. ⋯ Motor cortex excitability was not altered in patients and did not change during the migraine cycle. These findings show that pediatric migraine without aura is associated with a systematic shift in occipital excitability preceding the migraine attack. Similar systematic fluctuations in cortical excitability might be present in adult migraineurs and may reflect either a protective mechanism or an abnormal decrease in cortical excitability that predisposes an individual to a migraine attack.
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Although evidence shows that several dopamine neurotransmission pathway genes are associated with specific clinical pain syndromes, such as fibromyalgia, chronic headache, and postoperative pain, the exact role of dopamine in pain processing is not fully understood. The aim of this study was to explore the relationship between functional polymorphisms in dopaminergic candidate genes and sensitivity to pain in healthy subjects. Healthy subjects (n=192; 105 F, 87 M) were exposed to experimental tonic cold pain (1 degrees C) and phasic heat pain (47 degrees C) stimuli. ⋯ Significant associations between cold pain tolerance and DAT-1 (p=0.008) and MAO-A (p=0.024) polymorphisms were found. Specifically, tolerance was shorter for carriers of allele 10 and the rarer allele 11, as compared to homozygous for allele 9, and for carriers of allele 4 as compared to homozygous for allele 3, respectively. These results, together with the known function of the investigated candidate gene polymorphisms, suggest that low dopaminergic activity can be associated with high pain sensitivity and vice versa.
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Randomized Controlled Trial Clinical Trial
Analgesic efficacy of tramadol, pregabalin and ibuprofen in menthol-evoked cold hyperalgesia.
We investigated the analgesic efficacy of single doses of ibuprofen, tramadol and pregabalin in menthol-evoked cold pain in a randomized, placebo-controlled four-way cross-over study in 20 healthy volunteers. Tramadol 100mg significantly reduced menthol-evoked cold hyperalgesia. Effects of ibuprofen 600mg and pregabalin 100mg were not significant. ⋯ Minor side effects also accompanied analgesic effects of pregabalin and ibuprofen in subjects responding to these drugs, mostly fatigue, dizziness and difficulties to concentrate for pregabalin and gastric upset for ibuprofen. Five out of 18 subjects had a 50% reduction of cold hyperalgesia with tramadol, three of these additionally responded to pregabalin, and two with all three drugs. The numbers needed to treat (NNT >or= 50% for tramadol 4.5, for pregabalin 9) largely agree with the reported efficacy of tramadol and of moderate dosages of pregabalin in patients with peripheral or central neuropathic pain suggesting that menthol-evoked cold pain hypersensitivity may represent a valid model for neuropathic pain, particularly cold allodynia.
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Randomized Controlled Trial
Outpatient intravenous ketamine for the treatment of complex regional pain syndrome: a double-blind placebo controlled study.
Complex regional pain syndrome (CRPS) is a severe chronic pain condition that most often develops following trauma. The pathophysiology of CRPS is not known but both clinical and experimental evidence demonstrate the important of the NMDA receptor and glial activation in its induction and maintenance. Ketamine is the most potent clinically available safe NMDA antagonist that has a well established role in the treatment of acute and chronic pain. ⋯ This study showed that intravenous ketamine administered in an outpatient setting resulted in statistically significant (p<0.05) reductions in many pain parameters. It also showed that subjects in our placebo group demonstrated no treatment effect in any parameter. The results of this study warrant a larger randomized placebo controlled trial using higher doses of ketamine and a longer follow-up period.
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Randomized Controlled Trial Clinical Trial
Motor cortex electrical stimulation applied to patients with complex regional pain syndrome.
Motor cortex stimulation (MCS) is useful to treat patients with neuropathic pain syndromes, unresponsive to medical treatment. Complex regional pain syndrome (CRPS) is a segmentary disease treated successfully by spinal cord stimulation (SCS). However, CRPS often affects large body segments difficult to cover by SCS. ⋯ VAS and McGill pain scales diminished significantly (p<0.01) throughout the follow-up, accompanied by disappearance of the sensory (allodynea and hyperalgesia) and sympathetic signs. MCS is effective not only to treat pain, but also improve the sympathetic changes in CPRS. Mechanism of action is actually unclear, but seems to involve sensory input at the level of the spinal cord.