Pain
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Randomized Controlled Trial Clinical Trial
Assessing the stages of pain processing: a multivariate analytical approach.
A four-stage model of pain processing was proposed, consisting of pain sensation intensity, pain unpleasantness (stage 1 affect), suffering (stage 2 affect), and pain behavior. We studied 506 chronic pain patients (230 male and 276 female) using a multivariate statistical technique (LISREL) in order to demonstrate the structural relationship among multiple indicators of pain processing; and to characterize these stages in terms of their interactions. A strong relationship was revealed between the majority of the underlying indicators of each pain processing stage. ⋯ A confirmatory LISREL analysis was conducted with an additional sample of 502 chronic pain patients. In this replication analysis the structural equation model consisted of pain intensity, unpleasantness (stage 1 affect), emotional suffering (stage 2 affect), and pain behavior. This study extends the validation of these pain dimensions, as well as the validity of the measure(s) of each separate stage.
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The effects of combined single oral treatments with non-steroidal anti-inflammatory drugs (NSAIDs) and the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist dextromethorphan (DM) on arthritic pain were examined in a rat model of adjuvant-induced arthritis. Although 12.5-100 mg/kg doses of DM alone produced no reliable effects, treatments with ibuprofen (IB, 50 and 100 mg/kg but not 12.5 or 25 mg/kg) produced mild analgesia in arthritic rats as determined using the Randall-Sellito test. IB showed a dose-response relationship which appeared to plateau at doses of 50 and 100 mg/kg. ⋯ For all six NSAIDS, the addition of 50 mg/kg DM reliably increased their analgesic potency, as indicated by reliable increases in previously effective NSAID doses (all six NSAIDs) as well as previously ineffective NSAID doses (IB, NP, DC, and PIR). These data demonstrate that DM greatly potentiates the analgesic activity of IB, DC, NP, PIR, ET, and KT and increases the peak effect over the NSAIDs alone. Similiar to DM's previously demonstrated enhancement of opioid analgesia in acute pain, the combination of DM and an NSAID may represent a novel analgesic approach to improved management of arthritic pain.
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Randomized Controlled Trial Clinical Trial
The initial effects of a cervical spine manipulative physiotherapy treatment on the pain and dysfunction of lateral epicondylalgia.
Manipulative therapy is frequently used in the management of musculoskeletal pain. A frequently reported clinical feature of this treatment is the immediacy with which it appears to initiate improvement in pain and function. A randomised, double blind, placebo controlled, repeated measures design was employed to study the initial effects of a cervical spine treatment technique in a group of 15 patients with lateral epicondylalgia. ⋯ Differences between the pre-post measures were used as indicators of change in subject's symptom profiles. The treatment condition produced significant improvement in pressure pain threshold, pain-free grip strength, neurodynamics and pain scores relative to placebo and control conditions (P < 0.05). In summary, this study demonstrates that manipulative therapy is capable of eliciting a rapid hypoalgesic effect.
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Spinal cord injury (SCI) results in variable motor recoveries and chronic central pain syndromes develop in the majority of SCI patients. To provide a basis for further studies, we report a new rodent model of chronic central pain following spinal cord trauma. Male Sprague-Dawley rats (N = 10) were hemisectioned at T13 and were tested both preoperatively and postoperatively and compared to sham-operated controls (N = 10) for locomotor function, and mechanical and thermal thresholds of both paw withdrawal and supraspinal responses. ⋯ Hemisected animals vocalized to von Frey hair bending forces of 49.8 with a mean of 6.0 +/- 1.2 times out of 10 stimuli compared to intra-animal presurgical and sham control values of zero. Supraspinal responses of hemisected animals to thermal stimuli occurred at lower temperatures that were statistically significant compared to sham control or preoperative values (P < 0.05). These chronic changes in thresholds to both mechanical and thermal stimuli represent the development and persistence of mechanical and thermal allodynia after SCI.
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Neuropathic pain following nerve injury is believed to involve excitatory amino acids (EAAs) and Ca2+-mediated neuronal plastic changes in the central nervous system (CNS). This study was designed to investigate the changes in glutamate and aspartate contents in the dorsal half of the spinal cord following chronic constrictive injury (CCI) of the rat common sciatic nerve. We also examined the changes in intracellular calcium ion concentration ([Ca2+]i) of the spinal dorsal horn in transverse spinal slices in the same animal model. ⋯ MK-801 suppressed the increases in the contents of glutamate and aspartate and in [Ca2+]i on days 4 and 7. However, the ipsilateral contents of glutamate and aspartate significantly increased on day 14 (P < 0.001 and 0.003, respectively); the increased [Ca2+]i was also observed on day 14 (P < 0.001), and the spatial pattern of the increased regions was similar to untreated CCI rats. We interpret these results to indicate that neuropathic hyperalgesia induced by CCI in the rat is associated with an increase in glutamate and aspartate contents and the subsequent activation of NMDA receptors, followed by an increase in [Ca2+]i within dorsal horn of the spinal cord.