Articles: hyperalgesia.
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We report a novel symptom in many patients with low back pain (LBP) that sheds new light on the underlying pain mechanism. By means of quantitative sensory testing, we compared patients with radicular LBP (sciatica), axial LBP (LBP without radiation into the leg), and healthy controls, searching for cutaneous allodynia in response to weak tactile and cooling stimuli on the leg and low back. Most patients with radicular pain (~60%) reported static and dynamic tactile allodynia, as well as cooling allodynia, on the leg, often extending into the foot. ⋯ The presence of central sensitization also provides the first cogent account of shooting pain in sciatica as a wave of activity sweeping vectorially across the width of the sensitized dorsal horn. Finally, the results endorse leg allodynia as a pain biomarker in animal research on LBP, which is commonly used but has not been previously validated. In addition to informing the underlying mechanism of LBP, bedside mapping of allodynia might have practical implications for prognosis and treatment.
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To investigate the role of preoperative pain sensitivity and preoperative symptom severity for prediction of postoperative pain intensity after lumbar spine surgery. ⋯ The study highlights that each preoperative back pain and individual pain sensitivity could predict the different aspects of postoperative pain after lumbar surgery.
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Pharmacol. Biochem. Behav. · Dec 2014
Antihyperalgesic effect of 5-HT7 receptor activation on the midbrain periaqueductal gray in a rat model of neuropathic pain.
The 5-HT7 receptor is the most recently discovered receptor for 5-hydroxytryptamine (5-HT), and only little is known about the analgesic potential of this receptor. Adenosine triphosphate (ATP) modulates pain transmission by activating P2X/P2Y receptors, in which the P2X3 subtype is an important target for this effect. This study examined the antihyperalgesic effect of the 5-HT7 receptors in the ventrolateral midbrain periaqueductal gray (vlPAG), a crucial site for endogenous pain inhibition. ⋯ Furthermore, the antihyperalgesic effect of the 5-HT7 receptor was partially but significantly blocked by A-317491 pretreatment. These data indicate that the 5-HT7 receptor in the vlPAG exerts an antihyperalgesic effect on rats with neuropathic pain. The 5-HT7 and P2X3 receptors interact in the vlPAG and exhibit an analgesic action through the enhanced function of the endogenous analgesic system.
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There is a strong association between migraine and depression. The aim of this study is to identify migraine-specific factors involved in this association. ⋯ This study identified allodynia, in addition to high migraine attack frequency, as a new migraine-specific factor associated with depression.
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Neuroscience bulletin · Dec 2014
Post-stroke pain hypersensitivity induced by experimental thalamic hemorrhage in rats is region-specific and demonstrates limited efficacy of gabapentin.
Intractable central post-stroke pain (CPSP) is one of the most common sequelae of stroke, but has been inadequately studied to date. In this study, we first determined the relationship between the lesion site and changes in mechanical or thermal pain sensitivity in a rat CPSP model with experimental thalamic hemorrhage produced by unilateral intra-thalamic collagenase IV (ITC) injection. Then, we evaluated the efficacy of gabapentin (GBP), an anticonvulsant that binds the voltage-gated Ca(2+) channel α2δ and a commonly used anti-neuropathic pain medication. ⋯ GBP had a dose-related anti-allodynic effect after a single administration (1, 10, or 100 mg/kg) on day 7 post-ITC, with significant effects lasting at least 5 h for the higher doses. However, repeated treatment, once a day for two weeks, resulted in complete loss of effectiveness (drug tolerance) at 10 mg/kg, while effectiveness remained at 100 mg/kg, although the time period of efficacious analgesia was reduced. In addition, GBP did not change the basal pain sensitivity and the motor impairment caused by the ITC lesion, suggesting selective action of GBP on the somatosensory system.