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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The use of different lasers for stimulation in human experimental pain research has provided a sensitive method for evaluation of thin nerve fiber functions. In this study, sensory and pain thresholds were compared to argon-, copper vapour-, Nd:YAG-, and CO2 laser stimulation on hairy skin and on oral mucosa. The influence on thresholds with respect to laser type, stimulation site, surface colour, and stimulus parameters (laser beam diameter and pulse duration) was investigated. Significant differences in thresholds between the four lasers were found on both surfaces; however, no significant differences existed between thresholds on the skin and on the tongue when the same laser was used. The observations imply that wavelength-dependent optical properties of the stimulated tissue influence on threshold determinations. Furthermore, the results indicate that temporal and spatial summation mechanisms may exist for laser induced warmth and pain perceptions. Laser stimulation may be a new tool for the investigation of origin and genesis of various orofacial pain syndromes.
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PMID:Comparison of four laser types for experimental pain stimulation on oral mucosa and hairy skin. 191 Jan 34

Forty-two patients with congenital spinal deformity were studied by magnetic resonance imaging (MRI). Sixteen patients had intraspinal abnormalities consisting of a tethered cord in 10, diastematomyelia in four, diplomyelia in three, syringomyelia in four, a low lying conus in three, and a teratoma of the sacrum in one patient. In seven patients, intraspinal anomalies were suspected based on routine spinal radiographs and physical findings. We recommend MRI in patients undergoing spinal stabilization procedures and in all patients with lumbosacral kyphosis and those with pain, neurologic findings, or cutaneous hairy patch.
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PMID:Intraspinal abnormalities and congenital spine deformities: a radiographic and MRI study. 198 76

1. Receptive-field properties were investigated in cutaneous C-fiber nociceptive afferents (CMH) responsive to mechanical and heat stimuli. Teased-fiber techniques were used to record from 28 CMHs that innervated the hairy skin of upper or lower limb in anesthetized monkeys. 2. The response to mechanical stimuli was studied with the use of calibrated von Frey probes. The response to heat stimuli was studied with the use of a laser thermal stimulator that provided stepped increases in skin temperature with rise times to the desired temperature near 100 ms. The size of the receptive field (RF) for mechanical stimuli was determined by use of a suprathreshold stimulus that consisted of a 0.5-mm-diam probe that exerted a 200-mN force (10 bar). The size of the heat RF was determined by use of a 49 degrees C stimulus applied to a 7.5-mm-diam area for 1 s. 3. Heat thresholds were determined with an ascending series of stimulus intensities and were found to be stable over many hours: they ranged from 37 to 46 degrees C (mean, 41.1 degrees C). Mechanical thresholds ranged from 1.3 to 7.3 bar (mean, 3.3 bar). There was no correlation between mechanical and heat thresholds. Both thresholds extended well below the corresponding psychophysical pain thresholds in the literature. This suggests that spatial and/or temporal summation of C-fiber input are important for pain induced by either stimulus modality. 4. Mechanical RF diameters ranged from 3.3 to 9.6 mm (mean, 4.7 mm); heat RF diameters ranged from punctate (less than 1 mm) to 9.5 mm (mean, 4.3 mm). There was a significant linear correlation between mechanical and heat RF sizes with a slope of one. The distance between the center of the mechanical RF and the center of the heat RF along one axis ranged from 0 to 1.1 mm (mean, 0.4 mm). These data indicate that the heat RFs coincided with the mechanical RFs. 5. Within the mechanical RF determined with the suprathreshold stimuli, all CMHs had one or more punctate areas of maximal mechanical sensitivity where mechanical threshold was lowest. Heat excitability extended greater than 2 mm beyond these mechanically sensitive spots. Because lateral transmission of the heat stimulus is small, this indicates that heat transduction occurs outside the regions of maximal mechanical sensitivity. 6. Both the threshold to heat and the response magnitude at suprathreshold intensities depended on the percentage of the RF area overlapped by the heat stimulus. This indicates that multiple transducer sites probably contribute to the total evoked response.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Comparison of heat and mechanical receptive fields of cutaneous C-fiber nociceptors in monkey. 228 38

Interferons are new and effective agents in the treatment of various haematological neoplasias. Alpha-interferon (natural or recombinant) has a high efficacy (90% response rate) in hairy cell leukaemia. Complete remissions are, however, rare and definite cure of the disease is unlikely. Alpha-interferon induces haematological remissions in about two thirds of patients with chronic myeloid leukaemia and leads to a reduction in Philadelphia chromosome in about 40% of patients. It is uncertain, however, whether this treatment will actually prolong the life of these patients as compared with conventional treatment. Alpha-interferon has a beneficial effect in some patients with low malignant non-Hodgkin lymphomas (in particular follicular lymphomas). The response rate in myeloma is rather small (20%). Gamma-interferon is not effective in hairy cell leukaemia, non-Hodgkin lymphoma and myeloma. It is, however, of some efficacy in chronic myeloid leukaemia (the response rate in lower than with alpha-interferon) and possibly has some effect in patients with acute myeloid leukaemia and myelodysplastic syndromes. The toxicity of interferons (alpha and gamma) consists of an influenza-like syndrome during the first days of treatment. Low doses of alpha-interferon show virtually no long-term toxicity. However, bone and muscular pain is sometimes dose-limiting with intermediate doses (5 to 15 million units) of alpha-interferon.
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PMID:[Interferon therapy in hematologic neoplasms]. 245 54

1. Seventy-one C polymodal nociceptors supplying glabrous and hairy skin in limbs of awake human volunteers were identified on the basis of cutaneous stimulus-response characteristics recorded intraneurally by microneurography (MNG). The large majority of such units were primarily detected during intraneural microstimulation (INMS) on the basis of subjective quality and cutaneous localization of evoked painful sensation. Electrophysiological studies were supplemented with rigorous psychophysical testing during microstimulation delivered at intraneural C recording sites. 2. The conduction velocity of single C nociceptor units could be shown to become transiently slowed following repetitive INMS at threshold intensity for conscious sensation. Such 'marking' witnessed that particular C units, identified by recording, had been effectively activated during INMS and psychophysical testing. 3. Cognitive attributes of sensations evoked from C recording sites by INMS at threshold intensity for perception were estimated psychophysically for subjective quality, temporal attributes and localized projection. There was remarkable matching of physiological unit type (C polymodal nociceptor) with subjective quality of evoked sensation (dull or burning pain). Further, there was remarkable spatial matching of receptive field of given C nociceptors with projected field of the pain sensation evoked from the C recording site by INMS delivered at threshold intensity for conscious sensation. 4. Dissociated A nerve fibre blocks caused by compression-ischaemia did not abolish the sensation of burning pain projected to hairy skin, evoked by INMS delivered at C recording sites. 5. While the double matching of (a) subjective quality and spatial localization with (b) objective physiological unitary type and receptor location, coupled with the results of A blocks, provide evidence that C nociceptor fibres can be fairly selectively activated during INMS, the results also attest that C polymodal nociceptors from human skin evoke delayed dull or burning pain, accurately projected to a defined locus in skin, even after spatial summation is reduced to a minimum.
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PMID:Sensations evoked by intraneural microstimulation of C nociceptor fibres in human skin nerves. 264 Apr 70

Changes in thermal sensibility for warmth, cold, heat pain and cold pain during nerve compression block of impulse conduction in myelinated fibres were studied in 20 healthy subjects. When mainly unmyelinated fibres were conducting, after 30-36 min of nerve compression, the pain threshold, induced by cold stimulation, was shifted towards higher temperatures (from 19.1 degrees C to 22.8 degrees C, mean values). Furthermore, the sensation of cold pain became more unpleasant and had a hot burning rather than a cold quality. These results indicate that a change in central decoding of the afferent input has occurred, possibly due to lack of inhibition normally exerted by concomitant activation of myelinated fibres. Whereas dramatic changes in the sensation of cold pain were observed during the course of nerve compression, no alteration in heat pain threshold was seen. This implies that heat pain threshold in hairy skin is due to activation of C nociceptor fibres without any significant contribution from myelinated nociceptor fibres. Furthermore, no gating from heat-sensitive myelinated fibre input was evident on heat pain threshold.
Pain 1989 Sep
PMID:Central suppression of cold-induced C fibre pain by myelinated fibre input. 281 42

This paper reviews advances in our knowledge on the physiological properties of human nociceptors and their capacity to signal pain. Conventional microneurography was used in combination with intraneural microstimulation in subjects who estimated the magnitude of pain from nociceptor stimulation. The experimental evidence favours the notion that C polymodal nociceptors can provide a peripheral neuronal basis for determination of heat pain threshold and also an essential peripheral code for suprathreshold magnitude judgments of heat pain. Furthermore, sensitized C polymodal nociceptors can contribute to hyperalgesia after a mild heat injury to hairy skin. Temporal summation is documented for dull, delayed C fibre pain, which is different in quality and less accurately projected than the fast, sharp pain from high-threshold A delta nociceptors. A segmental organization is shown for projected and referred pain from deep structures. Examples are given of central inhibition of pain by a prostaglandin synthetase inhibitor, and by physical manoeuvres such as vibration and cooling. Recent reports on microneurographic findings after nerve injury indicate that the technique may be useful for future studies on pathophysiological pain mechanisms.
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PMID:Nociceptor activation and pain. 285 80

In a closed internal medicine practice for homosexual men in Central Manhattan herpes zoster developed in 112 men between 1980 and mid-1986. In these patients the incidence of acquired immunodeficiency syndrome (AIDS) was high: Kaplan-Meier survival analysis indicated cumulative incidences of AIDS of 22.8% within 2 years after herpes zoster, 45.5% within 4 years, and an estimated 72.8% after 6 years. Severity of zoster (relative risk, RR = 4.6), degree of pain (RR = 3.4), and zoster of the cranial or cervical dermatomes (RR = 2.2) were all associated with a poor outcome. Oral thrush, oral hairy leucoplakia, amoebiasis, and superficial (tinea) fungal infections also indicated an increased risk of AIDS among zoster patients. Oral thrush and oral hairy leucoplakia manifestations were diagnosed an average of 1.2 and 1.1 years, respectively, after the diagnosis of herpes zoster; thus zoster is an early indicator of an impaired immunity. Herpes zoster can be used as a predictor of AIDS and in AIDS risk groups should be regarded as a poor prognostic sign.
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PMID:Risk of AIDS after herpes zoster. 288 39

The effect of physical exercise on dental pain thresholds, the release of pituitary stress hormones and thermal sensitivity of skin was tested in healthy human subjects. Different levels of exercise (100-300 W) at different pedal frequencies were produced by a cycle ergometer. Thermal limen (the interval between warm and cool thresholds) determined from glabrous hand, hairy forearm and leg was used as a parameter of thermal sensitivity. In all subjects the heart rate and blood pressure were increased with increasing work load. Dental pain thresholds were elevated at high work loads with a concomitant activation of pituitary stress hormone (especially growth hormone) release. Thermal limens at all 3 sites were increased work load, too, independent of the pedal frequency. The increase of thermal limen was most marked in the leg and least in the glabrous hand. The results indicate that physical exercise produces a non-segmental, load-dependent decrease of pain and thermal sensitivity with a concomitant activation of pituitary stress mechanisms. The magnitude of modification varies with skin region. Activation of inhibitory mechanisms at spinal levels via muscle and proprioceptive afferents, in a way suggested by the gate control theory of pain mechanisms, seems to have only a minor, if any, contribution to the present findings, since a higher pedal frequency did not produce a more marked decrease of sensitivity.
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PMID:Modification of dental pain and cutaneous thermal sensitivity by physical exercise in man. 300 May 34

Pain and detection thresholds to short CO2 laser pulses were studied in healthy human subjects. Pain thresholds were significantly higher than detection thresholds in both hairy and glabrous skin; in the glabrous skin both thresholds were higher in the hairy skin. The range from detection threshold to pain threshold was larger in the glabrous skin. The minimal energy per surface area needed to produce any sensation (detection) or pain sensation decreased with increasing stimulus surface, and this spatial summation effect was to equal magnitude in the hairy and the glabrous skin. With decreasing stimulus pulse duration (from 45 to 15 msec) the detection and pain thresholds were elevated: this effect was stronger on pain thresholds. With increasing adapting skin temperature, less energy was needed to produce any sensation (detection) or pain sensation. The effect of adapting skin temperature was equal on pain and detection thresholds. The conduction velocity of fibers mediating laser evoked first sensations was in the thin fiber range (less than 10 msec), according to a reaction time study. The results suggest that short CO2 laser pulses produce both non-pain and pain sensations, but that both these sensations are based on the activation of the same primary afferent fiber population of slowly conducting nociceptive fibers. Central summation of primary afferent impulses is needed to elicit a liminal non-painful sensation, and an increased number of impulses in the same fibers produces pain.
Pain 1988 Sep
PMID:Cutaneous pain and detection thresholds to short CO2 laser pulses in humans: evidence on afferent mechanisms and the influence of varying stimulus conditions. 318 73


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