European journal of pain : EJP
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Voltage-gated K+ (Kv) channels are one of the important physiological regulators of the membrane potentials in excitable cells, including sensory ganglion neurons. The aim of the present study was to investigate whether temporomandibular joint (TMJ) inflammation alters expression of Kv channel subtype 1.4 (Kv1.4) of trigeminal ganglion (TRG) neurons innervating TMJ relating allodynia (pain caused by normally innoxious stimulation), by using both behavioral and immunohistochemical techniques. TMJ inflammation was induced by injection of Complete Freund's Adjuvant (CFA) into the rat TMJ. ⋯ The mean numbers of Kv1.4-/neurofilament (NF) 200(myelinated fiber marker) positive- and negative-immunoreactivities FG-labeled small-/medium-diameter TRG neurons in inflamed rats were significantly decreased when compared with those in the naïve rats. These findings suggest that TMJ inflammation reduces the expression of Kv1.4 subunits in the small-/medium sized (Adelta-/C-) TRG neurons and this may contribute to trigeminal inflammatory allodynia in TMJ disorder. These results lead us to suggest that Kv channel openers may be a potential therapeutic agents for prevention of mechanical allodynia.
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Randomized Controlled Trial
Home visits by specially trained nurses after discharge from multi-disciplinary pain care: a cost consequence analysis based on a randomised controlled trial.
To analyse the cost consequences of a nurse follow-up intervention for chronic non-malignant pain patients discharged from multidisciplinary pain treatment. ⋯ The nurse intervention did not significantly influence patients' health status. Patients in the intervention group tended to use fewer health care resources than those in the control group and the cost of the intervention was more than balanced out by savings in other health care resources.
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Spinal cord stimulation (SCS) consisting of electrical stimulation of the dorsal spinal cord using epidural electrodes has been shown to relieve chronic neuropathic pain. To analyze the cerebral activation patterns related to SCS, and to evaluate the effects of SCS on the processing of acute experimental pain, we performed functional magnetic resonance imaging (fMRI) on eight patients suffering from failed back surgery syndrome who were also being treated with SCS for severe pain in their legs and lower back. Three types of stimulation were used, each lasting 36s: (i) SCS, (ii) heat pain (HP) applied to the leg affected by neuropathic pain, and (iii) simultaneous HP and SCS. ⋯ The activation of the primary motor cortex, insula and S2 during SCS may directly interfere with the processing of neuropathic pain. When SCS is associated with heat pain, the paralimbic association cortex and cerebellum show activation exceeding the sum of activations resulting from separate SCS and heat pain stimulation. The explanation of this could possibly rest with the continuous comparisons of simultaneous pain and somatosensory sensations occurring in a single dermatome.
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In the Swedish Hernia Register 2834 inguinal hernia repairs in 2583 patients were registered in the county of Uppsala 1998-2004. In May 2005 the 2421 patients still alive were requested by mail to fill in a validated questionnaire concerning postherniorrhaphy pain. The final response rate became 72%. ⋯ Factors not associated with occurrence of residual pain were gender, method of anaesthesia during surgery, hernia sac diameter, postoperative complications, hernia type, need for emergency operation, reducibility of the hernia sac and complete dissection of the hernia sac. Factors found to be associated with impairment of function due to pain in a multivariate logistic regression analysis were: age below median, female gender, medial hernia, open repair technique, postoperative complications, need for operation for recurrence, presence of preoperative pain and less than three years from surgery. The possibility of long-term pain as an outcome after hernia operations should be taken into consideration in the decision making prior to operation.
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Case Reports
Spinal cord stimulation in adolescents with complex regional pain syndrome type I (CRPS-I).
Complex regional pain syndrome type I (CRPS-I) is not uncommon in children, particularly in adolescent girls. Most often, the condition involves a foot and is characterized by spontaneous pain, tactile allodynia and dysautonomic signs. There is usually a history of a minor, local trauma but sometimes no reasonable cause can be identified, and there are no signs of persistent tissue injury giving rise to ongoing nociception. ⋯ In one case, a local infection necessitated the removal of the electrode; nevertheless a few days of trial stimulation produced substantial pain relief that still persists. In four patients, the SCS use was gradually diminished and eventually the device could be removed. The favourable outcome in all seven cases with no or minor remaining symptoms and without severe recurrences illustrates that SCS may also be an efficient treatment in paediatric cases with exceptionally therapy resistant forms of CRPS I.