European journal of pain : EJP
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Pain possesses both sensory and affective dimensions, which are highly correlated yet distinct. Comparison of these dimensions within experimental pain settings has resulted in the construct of relative unpleasantness. Relative unpleasantness is defined as the amount of affective unpleasantness elicited for a given sensory magnitude. ⋯ Relative unpleasantness was not correlated with distress, anxiety, or depression, which were pronounced in the FM group. Clinical pain in patients with FM was perceived to be more unpleasant than the evoked pain stimuli. These results are consistent with the concept that chronic pain may reduce the relative unpleasantness of evoked pain sensations.
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It is well known that the response to painful stimuli varies between individuals and this could be consequence of individual differences to pain sensitivity that may be related to genetic factors. Catechol-O-methyltransferase (COMT) is one of the enzymes that metabolize catecholamine neurotransmitters. Differences in the activity of COMT influence the functions of these neurotransmitters. ⋯ To elucidate the possible role of COMT polymorphism in the susceptibility to neuropathic pain, we have performed a case-control study in a Spanish population. Analysis of the (Val158Met) COMT polymorphism was performed by PCR amplification and DNA digestion with restriction enzymes. Our study concludes that functional Val158Met polymorphism of COMT gene is not associated to increased susceptibility to neuropathic pain.
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Randomized Controlled Trial Clinical Trial
The causal status of pain catastrophizing: an experimental test with healthy participants.
In the current study we report findings on the effects of experimentally induced catastrophizing about pain on expected pain, experienced pain and escape/avoidance behavior during a cold pressor task in a sample of healthy participants. It was hypothesized that increasing the level of catastrophizing would result in a higher level of expected pain, a higher level of experienced pain, and a shorter duration of ice-water immersion. ⋯ The results demonstrated that despite the successful attempt to induce catastrophizing, this neither significantly affected expected pain, experienced pain, and duration of ice-water immersion, nor were these relations moderated by the pre-experimental level of catastrophizing. Although the level of catastrophizing was successfully manipulated, more similar experiments are necessary in order to give a more definite answer on the possible causal status of pain catastrophizing.
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Comparative Study
Psychiatric comorbidity in medication overuse headache patients with pre-existing headache type of episodic tension-type headache.
Medication overuse headache (MOH) mostly evolves from migraine and episodic tension-type headache (ETTH). Chronic tension-type headache (CTTH) is another headache type that evolves over time from ETTH. It is well known that psychiatric comorbidity is high in MOH patients. ⋯ Psychiatric comorbidity in MOH patients with pre-existing ETTH is common as in those with pre-existing migraine headache and MOH with regard to developing psychiatric disorders should be interpreted as a risk factor in chronic daily headache patients.
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Ligand-PET studies are attracting increasing interest in experimental and clinical research. As the most elaborated of PET techniques, ligand-PET allows the demonstration of receptor distributions, and thus, the delineation of neurochemical pathologies in the disease state. Recent developments are promising that ligand-PET will even allow to characterize dynamic and short-term changes in neurotransmission and will tremendously add to the understanding of neurophysiology on the receptor level. ⋯ One possible interpretation of these changes is that the PET-ligand might be displaced by endogenous opioidergic ligands. One major region, where this "ligand displacement" was observed, was the thalamus. These findings highlight the importance of the opioidergic system in pain processing and the power of ligand-PET to advance the understanding of pain.