European journal of pain : EJP
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The cost of low back pain (LBP) to employers is high, with an estimated pound 9090 million lost in the United Kingdom in 1998. Economic analysis of LBP has focused on work absence among the employed. There is little research characterising individuals who report reduced duties or who are not in employment because of LBP. ⋯ These findings indicate that the economic impact of LBP may be higher than previously estimated when data on reduced duties is combined with work absence. The additional impact of unemployment due to LBP should also be included in future assessments of the impact of LBP on the workforce.
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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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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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A position of scapula depression will maintain the upper trapezius muscle region in a lengthened position, causing excessive strain. This strain could lead to peripheral nociceptive nerves sensitization in the affected area, changing the pressure pain threshold (PPT). Thus, people with a faulty alignment of scapular depression may have lower PPT levels in the upper trapezius region when compared to subjects with normal vertical scapular position. ⋯ An electronic pressure algometer was used to measure the PPT on the upper trapezius muscle region. The results showed a significant difference between groups, with the DS group (19.0+/-9.0 N/cm(2)) demonstrated lower mean PPT values when compared to NS group (26.1+/-9.6 N/cm(2)) (p<0.01). Our results showed that healthy young subjects with depressed scapula position had significant lower upper trapezius PPT values when compared to subjects with normal scapula position.