Pain
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Clinical Trial
Electrophysiological testing of the trigeminofacial system: aid in the diagnosis of atypical facial pain.
The aim of this study was to evaluate the yield of objective electrophysiological testing of the trigeminofacial system in atypical facial pain (AFP). In addition to the clinical neurological examination, two brainstem reflexes covering both the peripheral parts and the central connections of the trigeminal and the facial nerves, the blink and jaw reflexes (BR and JR), were recorded in 17 AFP patients. The control group consisted of 18 healthy volunteers with no history of facial pain or chronic headache. ⋯ Additionally, one patient had abnormal BAEP and EEG recordings. On the group level, the AFP patients had significantly higher thresholds of the tactile R1 component of the BR than the control subjects. Electrophysiological testing may offer a valuable tool for both the clinical evaluation, and the scientific study of AFP.
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Opioids used topically may exercise several useful clinical effects. Opioids may cause immediate local analgesia and also may work indirectly through decreasing the inflammation process. ⋯ The side effects of topical opioids were none or minimal. Possible mechanisms of topical analgesia are discussed.
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Safe and efficient use of spinal drugs requires neurotoxicologic animal studies before ethical application. We have evaluated the neurotoxicologic interruptions of intrathecal administration of midazolam in rabbits. Eighteen white New Zealand rabbits were randomly assigned into three groups consisting of six rabbits each. ⋯ Light and fluorescence microscopy evaluations were performed on transverse spinal cord sections by a neurohistopathologist in a blind fashion. Midazolam and preservative free midazolam treated rabbits showed significant histologic changes in light and fluorescence microscopy. The histologic and vascular lesions with the use of midazolam and preservative free midazolam suggested neurotoxic effects; thus chronic intrathecal administration of midazolam should be avoided in humans.
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The behaviour of rats with spinal nerve ligation-induced neuropathic pain was studied using tests developed to measure depression and anxiety. Adult male Sprague-Dawley rats were tested with the open field test, elevated plus maze, two compartment test and forced swimming test. Spontaneous motility was measured in a photocell observation box. ⋯ The results were also comparable when rats that developed a high degree of neuropathy were compared with the rats with low degree of neuropathy and the sham operated group. In conclusion, spinal nerve ligation injury of the spinal nerves L5-6 induces mechanical and cold allodynia, but it does not seem to produce general suffering or measurable anxiety to the animals. Furthermore, tests for anxiety and depression were not able to predict which animals were vulnerable to express symptoms of neuropathic pain after nerve injury.
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Previous findings indicate that the brain stem descending system becomes more active in modulating spinal nociceptive processes during the development of persistent pain. The present study further identified the supraspinal sites that mediate enhanced descending modulation of behavior hyperalgesia and dorsal horn hyperexcitability (as measured by Fos-like immunoreactivity) produced by subcutaneous complete Freund's adjuvant (CFA). Selective chemical lesions were produced in the nucleus raphe magnus (NRM), the nuclei reticularis gigantocellularis (NGC), or the locus coeruleus/subcoeruleus (LC/SC). ⋯ The persistent hyperalgesia and neuronal hyperexcitability may be mediated in part by a descending pain facilitatory system involving NGC. Thus, the intensity of perceived pain and hyperalgesia is fine-tuned by descending pathways. The imbalance of these modulating systems may be one mechanism underlying variability in acute and chronic pain conditions.