Pain
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Comparative Study
Long term effects of oral sustained release morphine on neuropsychological performance in patients with chronic non-cancer pain.
Morphine is increasingly used in patients with chronic non-cancer pain, but a major concern associated with chronic use relates to possible cognitive side-effects. The aim of this long-term prospective study was to evaluate the cognitive impact of oral sustained release morphine in patients with non-cancer pain. A battery of neuropsychological tests to explore attention, psychomotor speed and memory was administered. ⋯ Morphine induced persisting effects on pain, and to a lesser extent on quality of life and mood. The visual analog scale score for side-effects increased at 12 months and essentially consisted of gastrointestinal disorders. This study demonstrates that 12 months treatment with oral morphine does not disrupt cognitive functioning in patients with chronic non-cancer pain and instead results in moderate improvement of some aspects of cognitive functioning, as a consequence of the pain relief and concomitant improvement of well-being and mood.
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Comparative Study
Functional self-efficacy and pain-related disability among older veterans with chronic pain in a primary care setting.
We examined the relationship between functional self-efficacy and pain-related disability in a sample of older veterans with chronic pain. A total of 1045 veterans aged 65 years or older who received primary care at the VA Connecticut Healthcare System in West Haven, CT, were assessed for the presence of chronic pain (i.e. pain due to a non-cancer cause for >/=3 consecutive months in the past 12 months); 303 (26%) screened positive; and 245 (81%) participated. Using a ten-item functional self-efficacy questionnaire (scale: 0-40), participants were categorized into three functional self-efficacy groups: low, score
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Comparative Study
Heat pain thresholds and cerebral event-related potentials following painful CO2 laser stimulation in chronic tension-type headache.
Current opinion concerning the pathophysiology of tension-type headache (TTH) and its related pericranial muscle tenderness proposes a primary role of central sensitization at the level of dorsalhorn/trigeminal nucleus as well as the supraspinal level. Investigation of these phenomena can be conducted using laser-evoked potentials (LEPs), which are objective and quantitative neurophysiological tools for the assessment of pain perception. In the present study we examined features of LEPs, as well as cutaneous heat-pain thresholds to laser stimulation, in relation to the tenderness of pericranial muscles in chronic TTH resulting from pericranial muscle disorder, during a pain-free phase. ⋯ The TTS scores at almost all pericranial sites were higher in TTH patients than in normal controls. The amplitude of the N2a-P2 complex elicited by stimulation of the pericranial zone was greater in TTH patients than in controls; the amplitude increase was significantly associated with the TTS score. Our findings suggest that pericranial tenderness may be a primary phenomenon that precedes headache, and is mediated by a greater pain-specific hypervigilance at the cortical level.
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Comparative Study
Selective attentional bias, conscious awareness and the fear of pain.
It has been suggested that healthy individuals with a high fear of pain possess a selective attentional bias in favour of pain-related material. However, evidence is limited since only a few studies have been conducted to date. In addition, these studies have not yet examined whether such attentional biases are relatively automatic, and so are outside conscious control. ⋯ Furthermore, we also found that when stimuli were masked, this bias was reversed. Neither effect was found amongst participants high in the fear of pain. Together, these findings suggest that the ability to orient away from pain-related stimuli may be under conscious control in low fearful people, whereas such a mechanism does not seem to exist in those high in the fear of pain.
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Comparative Study
DPDPE-UK14,304 synergy is retained in mu opioid receptor knockout mice.
When agonists to alpha(2)adrenergic receptor (AR) and delta opioid receptor (DOR) are co-administered, they act synergistically to inhibit nociceptive elicited behavior. Some previous studies of synergism have used the DOR-selective agonist [D-Pen(2),D-Pen(5)]-enkehphalin (DPDPE), however, DPDPE has been shown to be less potent in mu opioid receptor-knockout (MOR-KO) mice. It is possible, therefore, that MOR contributes to the synergism of DPDPE with the alpha(2)AR agonists. ⋯ Interestingly, isobolographic analysis showed that, despite substantial loss of DPDPE potency in MOR-KO, DPDPE-UK14,304 synergism is fully retained. Collectively, these experiments demonstrate that although MOR participates in DELT II- and DPDPE-mediated spinal antinociception, DOR independently participates in synergistic antinociception with alpha(2)AR. Resolution of the roles of the opioid receptor subtypes in opioid agonist-induced effects may require comparison of the effects of multiple selective agonists in knockout animals.