Pain
-
Comparative Study
Sensory and autonomic function in the hands of patients with non-specific arm pain (NSAP) and asymptomatic office workers.
Chronic pain in the upper limb associated with repetitive movements of the arm and hand is often seen in patients in the absence of specific pathology such as epicondylitis, carpal tunnel syndrome and tenosynovitis. This condition has been given many names and will be referred to here as non-specific arm pain (NSAP). Previous work has shown elevated vibration thresholds and reduced flare suggesting a neuropathic cause for this condition. ⋯ Over the median innervated area on the hand, vibration threshold was elevated by 47% in the patients and by 21% in the office workers. These results confirm previous findings showing reduced function associated with both small and large sensory fibres in the NSAP patients and additionally, for the first time, demonstrate a functional change related to sympathetic fibres. Office workers demonstrate a similar but smaller trend for reduced nerve function associated with both small and large sensory fibre function, but had no change in the sympathetic reflex.
-
Untreated complex regional pain syndrome (CRPS) may progress from acute stages with increased hair and nail growth in the affected limb to chronic stages with atrophy of the skin, muscles and bones. The aim of this study was to investigate whether tissue hypoxia could be one mechanism responsible for this late CRPS symptoms. Nineteen patients with CRPS and two control groups (healthy control subjects, surgery patients with edema) participated in this study. ⋯ Our results indicate skin hypoxia in CRPS. Impairment of nutritive blood flow in the affected limb may be one factor contributing to atrophy and ulceration in chronic CRPS. The investigation of patients after surgery revealed that edema could not be the only reason for hypoxia.
-
Comparative Study
Prolonged duration local anesthesia from tetrodotoxin-enhanced local anesthetic microspheres.
There is interest in developing prolonged duration local anesthesics. Here we examine whether tetrodotoxin (TTX) can be used to prolong the block from bupivacaine microspheres with and without dexamethasone. Rats received sciatic nerve blocks with 75 mg of microspheres containing 0.05% (w/w) TTX, 50% (w/w) bupivacaine and/or 0.05% (w/w) dexamethasone. 0.1% (w/w) TTX microspheres were also tested. ⋯ In summary, coencapsulation of TTX in controlled release devices containing bupivacaine and dexamethasone resulted in very prolonged nerve blocks. As formulated here, this preparation had a narrow margin of safety. While the myotoxicity appears consistent with the well-known reversible myotoxicity associated with local anesthetics, its long-term significance remains to be established.
-
The aim of this study was to examine how men and women observe experimentally induced pain in male and female participants and to specifically determine the accuracy of observed pain ratings, the possible interactions between the sex of the viewer and the sex of the individual being observed, and the influence of gender role expectations on observed pain ratings. The sample comprised 29 participants (15 females). They each completed a battery of psychological questionnaires and viewed a presentation of 10 randomly ordered video clips. ⋯ When endurance expectations were controlled, sex of the viewer no longer significantly predicted observed pain ratings. The 'willingness to report pain' variable was not a significant predictor of observed pain ratings. Our results show that women are perceived to have more pain than men, that there was a tendency by both sexes to underestimate pain in others, but men showed even greater underestimation, and that gender role expectations of pain endurance given by the video observers accounted for substantial variance in their ratings of pain in the videos.
-
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.