European journal of pain : EJP
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Glutamate may be released from muscle nociceptors and thereby contribute to mechanisms underlying acute and chronic muscle pain. In vivo concentration of glutamate during muscle pain has not previously been studied in either animals or humans. In the present study, we aimed to study the in vivo concentration of glutamate before, during and after acute pain of trapezius muscle in humans using the microdialysis technique. ⋯ Muscle blood flow increased significantly over time in response to infusion of chemical mixture and placebo (p = 0.001). However, we found no difference in changes in muscle blood flow between chemical mixture and placebo (p > 0.05). In conclusion, the present study demonstrates no signs of increased release of glutamate from myofascial nociceptors during and after acute experimentally induced muscle pain and tenderness.
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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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Comparative Study
Health related quality of life and quantitative pain measurement in females with chronic non-malignant pain.
The aim of the present study was to assess, compare, and correlate the pain response to an experimental pain stimulus (hyperalgesia to pressure pain threshold (PPT) measured from different body sites), the pain intensity (VAS) of the habitual pain, and quality of life parameters (SF-36) in groups of females with chronic non-malignant pain syndromes. Forty female pain patients with fibromyalgia/whiplash (n = 10), endometriosis (n = 10), low back pain (n = 10), or rheumatoid arthritis (n = 10), as well as 41 age-matched healthy female controls participated in the study. The fibromyalgia/whiplash patients scored significantly higher (p < 0.04) VAS ratings (median rating = 7.0) than the endometriosis (6.0), low back pain (6.0), and rheumatoid arthritis (3.5) patients. ⋯ A significant negative correlation was found between VAS rating and quality of life (p < 0.04). Significant correlation (p < 0.05) was found between pressure hyperalgesia measured at lowest PPT sites and the impairment of SF-36 physical function as well as mental health parameters. This study demonstrates significant generalised pressure hyperalgesia in four groups of chronic pain patients, correlations between degree of pressure hyperalgesia and impairment of some quality of life parameters, and increased pain intensity of the ongoing pain is associated with decreased quality of life.
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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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This study was designed to assess the impact of a refractory angina programme on the health related quality of life for patients with chronic refractory angina (CRA) one year following enrolment. ⋯ Implementation of the national refractory angina guidelines in a prospective study of 69 consecutive CRA patients significantly improved health related quality of life status at one year.