Pain
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Comparative Study
Retigabine, the specific KCNQ channel opener, blocks ectopic discharges in axotomized sensory fibres.
The M-current has been proposed as a potential target for analgesia under neuropathic pain conditions. M-currents and/or their molecular correlates, KCNQ proteins, have been demonstrated in key elements of the nociceptive system including spinal and dorsal root ganglion neurons. Here we demonstrate that retigabine, a selective KCNQ channel opener, applied at neuromatose endings modulates the excitability of axotomized fibres inhibiting ectopic discharges. ⋯ Application of XE-991 (10 microM), a KCNQ channel blocker, had no effect on responses to stimulation of the neuroma but blocked the effects of retigabine indicating a specific involvement of KCNQ channels. In contrast to the strong effects on ectopic discharges, retigabine did not change responses to stimulation recorded from intact receptors. Results indicate that KCNQ channel opening at axotomized endings may constitute a novel and selective mechanism for modulation of some neuropathic pain symptoms.
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Comparative Study
Brain dynamics for perception of tactile allodynia (touch-induced pain) in postherpetic neuralgia.
Postherpetic neuralgia (PHN) is a debilitating chronic pain condition often accompanied by a sensation of pain when the affected region is touched (tactile allodynia). Here we identify brain regions involved in stimulus-induced touch-evoked pain (dynamical mechanical allodynia, DMA), compare brain activity between DMA and spontaneous pain (described earlier for the same patients in [Geha PY, Baliki MN, Chialvo DR, Harden RN, Paice JA, Apkarian AV. Brain activity for spontaneous pain of postherpetic neuralgia and its modulation by lidocaine patch therapy. ⋯ However, mainly responses in the bilateral putamen and left medial temporal gyrus were related to the magnitude of allodynia. Both DMA and spontaneous pain perceptions were best represented within the same sub-cortical structures but with minimal overlap, implying that PHN pain modulates behavioral learning and hedonics. These results have important clinical implications regarding adequate therapy.
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Comparative Study
Estimation of pain intensity in emergency medicine: a validation study.
This study was designed to estimate the validity of an 11-point verbal numerical rating scale (VNRS) and a 100 Unit (U) plasticized visual analogue scale (VASp) using a 100mm paper visual analogue scale (VAS) as a gold standard, to recommend the best method of reporting the intensity of acute pain in an emergency department (ED). A convenience sample of 1176 patients with acute pain were recruited in the ED of a teaching hospital. Patients >18 years and able to use the different scales were included. ⋯ In conclusion, the VASp has a small bias, acceptable limits of agreement and an excellent intra-class correlation. It is probably a valid tool to estimate acute pain in the ED. However, the VNRS is less valid in that context because of its wide limits of agreement and variable bias (mainly in lower scores).