Pain
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In 28 Sprague-Dawley rats, unilateral division of the sciatic nerve at the level of the midfemur was performed. Animals were observed for behavioral changes for 1-21 days, and electrophysiological recordings were made from microfilaments dissected from the ipsilateral L5 dorsal rootlets and sciatic nerve from 1 to 14 days postoperatively. Spontaneous discharges of two types were recorded: (1) variable frequency (0-100 Hz) discharges which typically occurred in rhythmic bursts and could be driven by mechanical stimulation of the neuroma; and (2) lower frequency (0.25-14 Hz) irregular activity which persisted after either excision or local anesthesia of the neuroma. ⋯ This study demonstrates that peripheral axotomy of DRG neurons produces spontaneous activity distinct from ongoing neuroma activity in a proportion of fibers which are potentially nociceptive (A delta) as well as abnormal mechanosensitivity of the DRG. Furthermore, electrical stimulation of these fibers produces prolonged inhibition of the discharge. This finding may partially explain the prolonged relief of symptoms patients with chronic pain of peripheral origin may experience following peripheral tetanic electrical stimulation.
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This study examined relationships between chronic pain patients' ratings of pain severity, and other patient ratings about severity of associated impairment, and a series of behavioral measures of health care utilization and activity patterns. Prior to being evaluated, a sample of 150 chronic pain patients completed diary forms on which they recorded severity of pain on a 0-10 scale. Subjects were divided into high-medium-low on mean pain ratings, and were compared on the other measures obtained either from diary forms or at time of evaluation. ⋯ However, these measures showed few relationships to medication consumption, health care utilization, diary recorded activity level, or to patient reported frequency counts of engaging in a set of commonplace activities. The results were interpreted to suggest that, in chronic pain, there may be a questionable relationship between what people say about their pain and what they do. Accordingly, the evaluation of chronic pain should include analyses of patient behavior.
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Children and adolescents with recurrent migraine headaches or musculo-skeletal pain were asked to draw a picture of their pain and another picture of themselves in pain. The drawings were categorized according to content and color. ⋯ Children with recurrent migraine more often drew themselves doing something to relieve their pain, than did children with musculo-skeletal pain. Implications for the use of pain drawings in the treatment of chronic and recurrent pain are discussed.
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The incidence and clinical picture of non-painful and painful phantom limb sensations as well as stump pain was studied in 58 patients 8 days and 6 months after limb amputation. The incidence of non-painful phantom limb, phantom pain and stump pain 8 days after surgery was 84, 72 and 57%, respectively. Six months after amputation the corresponding figures were 90, 67 and 22%, respectively. ⋯ During the follow-up period the localization of phantom pains shifted from a proximal and distal distribution to a more distal localization. While knifelike, sticking phantom pains were most common immediately after surgery, squeezing or burning types of phantom pain were usually reported later in the course. Possible mechanisms for the present findings either in periphery, spinal cord or in the brain are discussed.
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This review emphasizes how little we know about pain induced by a thermal stimulus. The study of the intensity of pain evoked by heat is relatively exhaustive: the influence of various local, stimulus-dependent or general factors upon threshold values has been well studied, as has the relation between pain and stimulus intensities. On the contrary, few studies have used very cold stimuli, since highly efficient stimulators allowing accurate control of the stimulus parameters have been obtainable only recently. ⋯ At supraspinal level, the thermal information reappears in the reticular formation; there it appears to be solely relative to the pain threshold and not to the intensity of a supraliminary stimulus [55]. In the posterior group of nuclei [134] and the ventroposterolateral nucleus of the thalamus [103], on the contrary, the activity of the neurons reflects the intensity of the stimulation. It has been proved that the neurons of the ventroposterolateral nucleus project onto the SI cortex [103].(ABSTRACT TRUNCATED AT 400 WORDS)