Pain
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Capsaicin applied topically to human skin produces itching, pricking and burning sensations due to excitation of nociceptors. With repeated application, these positive sensory responses are followed by a prolonged period of hypalgesia that is usually referred to as desensitization, or nociceptor inactivation. Consequently, capsaicin has been recommended as a treatment for a variety of painful syndromes. ⋯ Discontinuation of capsaicin was followed by reinnervation of the epidermis over a 6-week period with a return of all sensations, except cold, to normal levels. We conclude that degeneration of epidermal nerve fibers contributes to the analgesia accredited to capsaicin. Furthermore, our data demonstrate that ENFs contribute to the painful sensations evoked by noxious thermal and mechanical stimuli.
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Comparative Study
A comparison of diffuse noxious inhibitory controls in men and women.
Results from clinical and experimental pain studies provide consistent evidence of sex differences in pain perception, with women reporting more clinical pain and demonstrating lower pain threshold and tolerance levels than men. The present study was designed to assess the notion that sex differences in pain perception may be related to differential activation of supraspinal pain modulation systems. ⋯ Application of forearm ischemia was associated with a significant decrease in nociceptive flexion reflex activity in both men and women, however, the degree of attenuation of nociceptive flexion reflex activity was not significantly different between the sexes. These findings suggest that men and women exhibit similar activation of diffuse noxious inhibitory controls, but they do not exclude the possibility of sex differences in other forms of central pain modulation.
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The analgesic effects of single and repeated applications of a eutectic mixture of local anaesthetics (EMLA) cream on both spontaneous and evoked pains were evaluated in 11 patients with post-herpetic neuralgia (PHN). Detection thresholds, pain thresholds and the responses to suprathreshold mechanical and thermal stimuli were quantitatively determined at baseline, 30 min after the first application and after a series of daily applications over six consecutive days (duration of application: 5 h/day). In the acute situation, EMLA produced an overall anaesthetic effect without significantly reducing spontaneous ongoing pain and mechanical allodynia. ⋯ The effects on spontaneous ongoing pain were more variable. They were inversely correlated to the magnitude of the thermal deficit at baseline, and were significant only in patients with dynamic mechano-allodynia. Pathophysiological implications of these results are discussed.
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The purpose of this study was to determine which specific attributes of painful orofacial symptoms serve as predictors of health care utilization in a population based sample of elderly subjects. Furthermore, we documented patterns of health care utilization selection by type of health care provider. To our knowledge, these specific utilization patterns have never before been reported in the pain literature. ⋯ The overall number of visits was not predicted by pain intensity but by other qualities more associated with time or level of dysfunction caused by the symptom. We also found that elderly adults, typically seek care for toothache from a dentist and from physicians for painful orofacial symptoms not associated with the teeth or mouth. These decisions regarding the selection of a health care professional may, in part, be a function of financial and insurance considerations, anatomical site and perception of the role of dentistry in orofacial care.
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We report findings from clinical examination and cutaneous laser stimulation in a 57-year-old male, who suffered from a right-sided postcentral stroke. In this patient, we were able to demonstrate (i) a dissociation of discriminative and affective components of pain perception and, for the first time in humans, (ii) the dependence of sensory-discriminative pain component and first pain sensation on the integrity of the lateral pain system.