Articles: neuralgia.
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Randomized Controlled Trial Clinical Trial
Efficacy of oxycodone in neuropathic pain: a randomized trial in postherpetic neuralgia.
Although opioid analgesics are used in the management of neuropathic pain syndromes, evidence of their efficacy remains to be established. We evaluated the clinical efficacy and safety of oxycodone in neuropathic pain using postherpetic neuralgia as a model. ⋯ Controlled-release oxycodone is an effective analgesic for the management of steady pain, paroxysmal spontaneous pain, and allodynia, which frequently characterize postherpetic neuralgia.
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Spinal cord stimulation is an accepted treatment for neuropathic pain. Technical advances in electrode design and better patient selection have led to better and sustained pain control by these devices. Multilead electrical stimulation is the latest innovation in implantable electrostimulation (Mattrix, Medtronic Minneapolis, USA). ⋯ Dual channel stimulation is cost saving in patients implanted with two electrodes. This is presented in a third patient with an electrode in the thalamus--as pain treatment for cervicobrachialgia and a second in the epidural space--as treatment for the failed back surgery syndrome. These electrodes were connected to the Mattrix stimulator.
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Neuroscience letters · May 1998
Motor denervation induces altered muscle fibre type densities and atrophy in a rat model of neuropathic pain.
Loose ligation of a sciatic nerve in rats (chronic constriction injury; CCI) provokes sensory, autonomic, and motor disturbances like those observed in humans with partial peripheral nerve injury. So far, it is unknown whether these motor disturbances result from (mechanical) allodynia or from damage to the motor neuron. These considerations prompted us to assess, in CCI rats, the density of motor axons in both the ligated sciatic nerve and the ipsilateral femoral nerve. ⋯ In line with these findings, we observed altered fibre type densities in muscle tissue innervated by the ligated sciatic nerve as well as the non-ligated femoral nerve indicative of motor denervation rather than hypokinesia. The findings of this study suggest that the motor disorder induced by partial nerve injury involves degeneration of motor nerve fibres not only within the primarily affected nerve but also within adjacent large peripheral nerves. This spread outside the territory of the primarily affected nerve suggests degeneration of motor neurons at the level of the central nervous system.
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Clinical Trial
Neural activation during acute capsaicin-evoked pain and allodynia assessed with PET.
The PET H2 15O-bolus method was used to image regional brain activity in normal human subjects during intense pain induced by intradermal injection of capsaicin and during post-capsaicin mechanical allodynia (the perception of pain from a normally non-painful stimulus). Images of regional cerebral blood flow were acquired during six conditions: (i) rest; (ii) light brushing of the forearm; (iii) forearm intradermal injection of capsaicin, (iv) and (v) the waning phases of capsaicin pain; and (vi) allodynia. Allodynia was produced by light brushing adjacent to the capsaicin injection site after ongoing pain from the capsaicin injection had completely subsided. ⋯ The cerebellar vermis was strongly activated by capsaicin, whereas light brush and experimental allodynia produced little or no activation, suggesting a selective association with C-fibre stimulation and nociceptive second-order spinal neurons. The experimental allodynia activated a network that partially overlapped those activated by both pain and light brush alone. Unlike capsaicin-induced pain, allodynia was characterized by bilateral activation of inferior prefrontal cortex, suggesting that prefrontal responses to pain are context dependent.
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A local inflammatory reaction may play an important role in the development of neuropathic pain following peripheral nerve injury. One important participant in the inflammatory response of injured peripheral nerve may be nitric oxide (NO). In this work, we examined physiological and morphological evidence for nitric oxide synthase (NOS) activation in the chronic constriction injury model of neuropathic pain in rats. ⋯ NOS-like immunoreactivity of the neuronal and endothelial isoforms was identified just proximal to the constriction at 48 h. iNOS-like immunoreactivity was observed at 7 and 14 days at the constriction and distal sites, respectively. This work provides evidence for local NOS expression and NO action in the chronic constriction injury model of neuropathic pain. NO has local physiological actions that include vasodilatation of microvessels and that may be important in the development of pain sensitivity.