Pain
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Randomized Controlled Trial Comparative Study Clinical Trial
The effects of racemic ketamine on painful stimulation of skin and viscera in human subjects.
Evidence suggests that NMDA receptors may have a differential role in the modulation of visceral and somatic pain. Specifically, animal data indicate an analgesic role of NMDA-R antagonists in acute visceral but not acute somatic pain. In humans analgesic effects are documented in acute somatic pain, while the role of NMDA-R antagonists in acute visceral pain is still questionable. ⋯ In addition, ketamine did not alter the perception of innocuous stimuli in either modality. Our results confirm the analgesic effects of low-dose ketamine, with minimal side effects, on acute visceral pain and indicate a similar but smaller effect on acute cutaneous pain. A decrease in the unpleasantness but not in the intensity of cutaneous pain may reflect the differential effect of NMDA-R antagonists for the two pain states observed in animal models.
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Randomized Controlled Trial Comparative Study Clinical Trial
The effect on mechanical pain threshold over human muscles by oral administration of granisetron and diclofenac-sodium.
Previous studies indicate that plasma levels of serotonin (5-HT) and intramuscular prostaglandin E2 (PGE2) participate in determining the mechanical pain threshold and tolerance level to pressure applied on the skin over healthy muscles. Other studies reported gender differences regarding responses to noxious stimuli. The present study aimed to determine whether the mechanical pain threshold of healthy muscles is influenced by oral administration of 5-HT3 or PGE2-inhibitors and if there are any gender differences in this respect. ⋯ Diclofenac-sodium did not influence the PPT and there was no difference compared to placebo. Although the basal PPT values were lower in females, the PPT response to granisetron differed significantly between genders only in the tibialis anterior muscle. In conclusion, the results of this study showed that oral administration of the 5-HT3-antagonist granisetron increased the PPT over healthy trunk and limb muscles but not over orofacial muscles, and that the response in the limb muscles was greater in males.
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Randomized Controlled Trial Comparative Study Clinical Trial
Do high TSH values protect against chronic musculoskeletal complaints? The Nord-Trøndelag Health Study (HUNT).
The aim of this large cross-sectional population-based study was to examine a possible positive or negative association between thyroid dysfunction and chronic musculoskeletal complaints (MSC). Between 1995 and 97, all 94,197 adults in Nord-Trøndelag County in Norway were invited to participate in a health survey. A total of 64,787 (69%) responded to questions related to MSC, whereof thyroid-stimulating hormone (TSH) was measured in 34,960 individuals. ⋯ Among these, chronic MSC was less likely (OR=0.6, 95% CI 0.4-0.8) if TSH >or=10 mU/L than in women with normal TSH (0.2-4 mU/L). Chronic MSC was less likely among women with high TSH values. The mechanism is unclear and, theoretically, may reflect a fundamental gender-specific relationship between TSH and pain perception in the central nervous system.
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Comparative Study
Chronic spinal pain and physical-mental comorbidity in the United States: results from the national comorbidity survey replication.
This paper investigates comorbidity between chronic back and neck pain and other physical and mental disorders in the US population, and assesses the contributions of chronic spinal pain and comorbid conditions to role disability. A probability sample of US adults (n=5692) was interviewed. Chronic spinal pain, other chronic pain conditions and selected chronic physical conditions were ascertained by self-report. ⋯ However, comorbid conditions explained about one-third of the gross association of chronic spinal pain with role disability. We conclude that chronic spinal pain is highly comorbid with other pain conditions, chronic diseases, and mental disorders, and that comorbidity plays a significant role in role disability associated with chronic spinal pain. The societal burdens of chronic spinal pain need to be understood and managed within the context of comorbid conditions.
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Some electrophysiologic studies demonstrate new, excitatory alpha2-adrenoceptors on peripheral nociceptors and their dorsal root ganglion (DRG) cell bodies after nerve injury, yet administration of alpha2-adrenoceptor agonists at these sites reduces hypersensitivity rather than worsens it. Since TRPV-1 expressing nociceptor afferents are important in many pain states, we examined the expression of this channel and its co-expression with alpha2C-adrenoceptors in injured DRG cell bodies and the ability of alpha2-adrenoceptors to inhibit responses to stimulation. Rats underwent tight ligation of the left L5 and L6 spinal nerves, followed by behavioral testing, removal of L5 and L6 DRGs, and either immunostaining for TRPV-1 channels and alpha2C-adrenoceptors or intracellular calcium videomicroscopy in response to electrical field stimulation before and after perfusion with clonidine and capsaicin. ⋯ The proportion of clonidine inhibited cells which responded to capsaicin increased 5 fold after injury. We conclude that TRPV-1 and alpha2C-adrenoceptors are up-regulated in some injured medium and large size neurons after nerve ligation. Increased co-expression by immunocytochemistry, and increased proportion of cells inhibited by clonidine and expressing functional TRPV-1 channels suggest that these cells may play an important role in the analgesic effects of alpha2-adrenoceptor agonists in neuropathic pain.