Pain
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Elevated resting blood pressure (BP) is hypoalgesic in healthy individuals, but this effect is absent in adults with chronic somatic pain. This study tested whether BP-related hypoalgesia is similarly altered in individuals with a history of chronic visceral pain in childhood. Resting BP was assessed in 94 adolescents and young adults with a known history of childhood functional abdominal pain (FAP) and 55 comparable healthy controls. ⋯ Subgroup analyses indicated that BP-related hypoalgesia (in healthy controls) and FAP-linked absence of this hypoalgesia was observed only among females. Result suggest that childhood visceral chronic pain may be associated with relatively long-lasting dysfunction in overlapping systems modulating pain and BP that persists even after FAP resolves. Potential implications for later hypertension risk are discussed.
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Randomized Controlled Trial
Low-dose amitriptyline for treatment of persistent arm pain due to repetitive use.
Amitriptyline is sometimes used to treat arm pain related to repetitive use, but rigorous evidence of its benefit is lacking. This randomized controlled trial investigated whether amitriptyline provided greater pain relief or improved arm function than a placebo pill in adults with arm pain associated with repetitive use that had persisted for at least 3 months. Participants (N=118) were randomly assigned to receive 25mg of amitriptyline or a placebo pill for 6 weeks. ⋯ The most frequent side effect was drowsiness. In conclusion, this study found that low-dose amitriptyline did not significantly decrease arm pain among these participants but did significantly improve arm function and well being. Future research is needed to explore the effects of higher doses and longer duration of treatment.
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Randomized Controlled Trial
A randomized placebo-controlled trial of intradiscal methylene blue injection for the treatment of chronic discogenic low back pain.
A preliminary report of clinical study revealed that chronic discogenic low back pain could be treated by intradiscal methylene blue (MB) injection. We investigated the effect of intradiscal MB injection for the treatment of chronic discogenic low back pain in a randomized placebo-controlled trial. We recruited 136 patients who were found potentially eligible after clinical examination and 72 became eligible after discography. ⋯ The patients in MB injection group showed a mean reduction in pain measured by NRS of 52.50, a mean reduction in Oswestry disability scores of 35.58, and satisfaction rates of 91.6%, compared with 0.70%, 1.68%, and 14.3%, respectively, in placebo treatment group (p<0.001, p<0.001, and p<0.001, respectively). No adverse effects or complications were found in the group of patients treated with intradiscal MB injection. The current clinical trial indicates that the injection of methylene blue into the painful disc is a safe, effective and minimally invasive method for the treatment of intractable and incapacitating discogenic low back pain.
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Comparative Study
Sympathetic skin response following painful electrical stimulation is increased in major depression.
Patients with major depressive disorder have repeatedly been described to exhibit increased thresholds upon experimentally applied pain stimuli to the skin as compared to respective controls. Since the sensory-discriminative component of stimulus perception, e.g. for warmth, cold and vibration, appears to be unaltered in depression, higher central nervous centres have been assumed to cause this phenomenon. To date, hardly any attention has been paid to the efferent components of the noxious reflex loop. ⋯ Intriguingly, the noxious stimuli were still perceived less painful in the patient group. Pain perception weakly correlated with disease severity. From these data, we conclude that despite the diminished pain perception, the autonomic reflex loop following noxious stimulation is not affected in patients with major depressive disorder, and that the increase in sympathetic outflow is not directly related to the perceived pain as in controls, but might rather be attributed to the autonomic dysfunction known for the disease.
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It is widely assumed that distraction reduces pain. Similarly, it is assumed that pain distracts from concurrent, unrelated cognitive processing, reducing performance on difficult tasks. Taken together, these assumptions suggest pain processing and cognitive function engage an overlapping set of domain-general, capacity-limited mental resources. ⋯ Path analyses showed that variations in pain completely mediated this effect, and that even within a given heat level, trial-by-trial fluctuations in pain predicted decrements in performance. In sum, these findings argue that overlapping cognitive resources play a role in both pain processing and executive working memory. Future studies could use this paradigm to understand more precisely which components of executive function or other cognitive resources contribute to the experience of pain.