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H Kehlet - One of the best experts on this subject based on the ideXlab platform.
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prediction of postoperative pain by preoperative nociceptive responses to Heat stimulation
Anesthesiology, 2004Co-Authors: Mads U. Werner, Preben Duun, H KehletAbstract:Background: Despite major advances in the understanding of the neurobiologic mechanisms of pain, the wide variation in acute pain experience has not been well explained. Therefore, the authors investigated the potential of a preoperatively induced Heat Injury to predict subsequent postoperative pain ratings in patients undergoing knee surgery. Methods: Twenty patients were studied. The burn Injury was induced 6 days before surgery with a contact thermode (12.5 cm(2), 47degreesC for 7 min). The sensory testing, before and 1 h after the Injury, included pain score during induction of the burn, secondary hyperalgesta area, thermal and mechanical pain perception, and pain thresholds. Postoperative analgesia consisted of ibuprofen and acetaminophen. Pain ratings (visual analog scale) at rest and during limb movement were followed for 10 days after surgery. Results: The burn Injury was associated with development of significant hyperalgesia. There was a significant correlation between preoperative pain ratings during the burn Injury and early (0-2 days, area under the curve) and late (3-10 days, area under the curve) postoperative dynamic pain ratings during limb movement. Conclusion: The results of this study suggest that the pain response to a preoperative Heat Injury may be useful in research in predicting the intensity of postoperative pain. These findings may have important implications to identify patients at risk for development of chronic pain and to stratify individuals for investigations of new analgesics. (Less)
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Arthroscopic knee surgery does not modify hyperalgesic responses to Heat Injury.
Anesthesiology, 2003Co-Authors: Mads U. Werner, Preben Duun, Otto Kraemer, Birgit Lassen, H KehletAbstract:Background: Experimental studies suggest that surgical Injury may up- or down-regulate nociceptive function. Therefore, the aim of this clinical study was to evaluate the effect of elective arthroscopically assisted knee surgery on nociceptive responses to a Heat Injury. Methods: Seventeen patients scheduled to undergo repair of the anterior cruciate ligament and 16 healthy controls were studied. The first burn Injury was induced 6 days before surgery, and the second burn was induced 1 day after surgery with a contact thermode (12.5 cm 2 , 47°C for 7 min) placed on the medial aspect of the calf contralateral to the surgical side. Ibuprofen and acetaminophen were given for 2 days before the first burn Injury and again from the time of surgery. In the controls, the two burn injuries were separated by 7 days. Sensory variables included cumulated pain score during induction of the burn (visual analog scale), secondary hyperalgesia area, and mechanical and thermal pain perception and pain thresholds assessed before and 1 h after the burn Injury. Results: The Heat injuries induced significant increases in pain perception (P 0.8), secondary hyperalgesia areas (P > 0.1), mechanical and thermal pain perception (P > 0.1), or mechanical and thermal pain thresholds (P > 0.08) in the burn area before surgery compared to after surgery. Conclusion: Arthroscopic knee surgery did not modify nociceptive responses to a contralaterally applied experimental burn Injury. TISSUE Injury is associated with peripheral and central changes in the nociceptive system leading to primary hyperalgesia in the inflammatory area and secondary hyperalgesia in neighboring noninjured tissue, which may contribute to an increase in pain perception. 1 These pain-sensitizing mechanisms have been well documented in the incisional area after surgery. 2– 6 However,
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Hyperalgesia and temporal summation of pain after Heat Injury in man.
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50 x 25 mm thermode (47 degrees C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P < 0.000001) and secondary (P < 0.00006) mechanical hyperalgesia were evoked by the Heat Injury. The pain threshold to single electrical stimuli was reduced within the Injury (P < 0.03), but not outside. The pain responses to single and repeated electrical stimuli were not significantly altered by the Injury. Temporal summation of pain occurred in 418 stimulus trains out of 576 (73%), but no significant changes in summation developed in skin with primary or secondary mechanical hyperalgesia compared with normal skin (baseline measurements). Temporal summation at high stimulus intensities was more pronounced than at lower intensities (P < 0.0002). We found no correlation between either temporal summation and area of secondary hyperalgesia, or temporal summation and pain intensity during the induction of Heat Injury. We conclude that the development of primary and secondary mechanical hyperalgesia after Heat Injury in man was not associated with changes in temporal summation of painful electrical stimuli.
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Hyperalgesia and temporal summation of pain after Heat Injury in man
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50×25 mm thermode (47°C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P
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the effect of pre versus postInjury infiltration with lidocaine on thermal and mechanical hyperalgesia after Heat Injury to the skin
Pain, 1993Co-Authors: Jorgen B Dahl, Jannick Brennum, Lars Arendtnielsen, Troels S Jensen, H KehletAbstract:Abstract The aim of the study was to evaluate the effects of pre- and postInjury infiltration with lidocaine on alterations in mechanical and thermal sensitivity after Heat Injury to the skin. In the first part of the study, burn injuries (15 × 25 mm rectangular thermode, 50°C, 7 min) were produced twice in each subject on the medial side of the left and right calves at least 24 h apart in 8 healthy, unmedicated male volunteers, in order to investigate the effects of the Injury on sensitivity in untreated skin. In the second part of the study, burn injuries (15 × 25 mm rectangular thermode, 50°C, 6 min) were produced twice in each subject on the medial side of the left and right calves at least 24 h apart (n = 10). This was preceded by subcutaneous (s.c.) infiltration with 5–6 ml of 1% plain lidocaine (pre-Injury block) on one day, and the same block was performed 35 min after Injury (postInjury block) on the other day. Warm detection thresholds (WDT) and Heat pain detection thresholds (HPDT) were determined within and outside the Injury before and at regular intervals after Injury. Areas of hyperalgesia to pinprick and brush were determined at regular intervals after Injury. In the first part of the study, it was observed that both WDT and HPDT were decreased within but not outside the Injury, and areas of hyperalgesia to pinprick and brush were found in- and outside the Injury in all subjects. These findings were relatively constant throughout the study period and reproducible between the 2 days of examination. In the second part of the study, it was observed that pre-Injury infiltration with lidocaine reduced hyperalgesia to pinprick and brush outside the Injury more effectively than postInjury block, but only for the first 70 min after Injury, while no significant difference was observed 100–190 min after Injury. Likewise, there was no difference in thermal thresholds inside the Injury between pre- and postInjury treatment at the end of the study period. It is concluded, that a shortlasting ‘preemptive’ infiltration with lidocaine may postpone but not prevent the occurrence of hyperalgesia outside a thermal Injury.
Mads U. Werner - One of the best experts on this subject based on the ideXlab platform.
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High-dose naloxone: Effects by late administration on pain and hyperalgesia following a human Heat Injury model. A randomized, double-blind, placebo-controlled, crossover trial with an enriched enrollment design.
PloS one, 2020Co-Authors: Anders Deichmann Springborg, Elisabeth Kjær Jensen, Mads Kreilgaard, Morten Aagaard Petersen, Theodoros Papathanasiou, Trine Meldgaard Lund, Bradley K. Taylor, Mads U. WernerAbstract:Severe chronic postsurgical pain has a prevalence of 4-10% in the surgical population. The underlying nociceptive mechanisms have not been well characterized. Following the late resolution phase of an inflammatory Injury, high-dose μ-opioid-receptor inverse agonists reinstate hypersensitivity to nociceptive stimuli. This unmasking of latent pain sensitization has been a consistent finding in rodents while only observed in a limited number of human volunteers. Latent sensitization could be a potential triggering venue in chronic postsurgical pain. The objective of the present trial was in detail to examine the association between Injury-induced secondary hyperalgesia and naloxone-induced unmasking of latent sensitization. Healthy volunteers (n = 80) received a cutaneous Heat Injury (47°C, 420 s, 12.5 cm2). Baseline secondary hyperalgesia areas were assessed 1 h post-Injury. Utilizing an enriched enrollment design, subjects with a magnitude of secondary hyperalgesia areas in the upper quartile ('high-sensitizers' [n = 20]) and the lower quartile ('low-sensitizers' [n = 20]) were selected for further study. In four consecutive experimental sessions (Sessions 1 to 4), the subjects at two sessions (Sessions 1 and 3) received a cutaneous Heat Injury followed 168 h later (Sessions 2 and 4) by a three-step target-controlled intravenous infusion of naloxone (3.25 mg/kg), or normal saline. Assessments of secondary hyperalgesia areas were made immediately before and stepwise during the infusions. Simple univariate statistics revealed no significant differences in secondary hyperalgesia areas between naloxone and placebo treatments (P = 0.215), or between 'high-sensitizers' and 'low-sensitizers' (P = 0.757). In a mixed-effects model, secondary hyperalgesia areas were significantly larger following naloxone as compared to placebo for 'high-sensitizers' (P < 0.001), but not 'low-sensitizers' (P = 0.651). Although we could not unequivocally demonstrate naloxone-induced reinstatement of Heat Injury-induced hyperalgesia, further studies in clinical postsurgical pain models are warranted.
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prediction of postoperative pain by preoperative nociceptive responses to Heat stimulation
Anesthesiology, 2004Co-Authors: Mads U. Werner, Preben Duun, H KehletAbstract:Background: Despite major advances in the understanding of the neurobiologic mechanisms of pain, the wide variation in acute pain experience has not been well explained. Therefore, the authors investigated the potential of a preoperatively induced Heat Injury to predict subsequent postoperative pain ratings in patients undergoing knee surgery. Methods: Twenty patients were studied. The burn Injury was induced 6 days before surgery with a contact thermode (12.5 cm(2), 47degreesC for 7 min). The sensory testing, before and 1 h after the Injury, included pain score during induction of the burn, secondary hyperalgesta area, thermal and mechanical pain perception, and pain thresholds. Postoperative analgesia consisted of ibuprofen and acetaminophen. Pain ratings (visual analog scale) at rest and during limb movement were followed for 10 days after surgery. Results: The burn Injury was associated with development of significant hyperalgesia. There was a significant correlation between preoperative pain ratings during the burn Injury and early (0-2 days, area under the curve) and late (3-10 days, area under the curve) postoperative dynamic pain ratings during limb movement. Conclusion: The results of this study suggest that the pain response to a preoperative Heat Injury may be useful in research in predicting the intensity of postoperative pain. These findings may have important implications to identify patients at risk for development of chronic pain and to stratify individuals for investigations of new analgesics. (Less)
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Arthroscopic knee surgery does not modify hyperalgesic responses to Heat Injury.
Anesthesiology, 2003Co-Authors: Mads U. Werner, Preben Duun, Otto Kraemer, Birgit Lassen, H KehletAbstract:Background: Experimental studies suggest that surgical Injury may up- or down-regulate nociceptive function. Therefore, the aim of this clinical study was to evaluate the effect of elective arthroscopically assisted knee surgery on nociceptive responses to a Heat Injury. Methods: Seventeen patients scheduled to undergo repair of the anterior cruciate ligament and 16 healthy controls were studied. The first burn Injury was induced 6 days before surgery, and the second burn was induced 1 day after surgery with a contact thermode (12.5 cm 2 , 47°C for 7 min) placed on the medial aspect of the calf contralateral to the surgical side. Ibuprofen and acetaminophen were given for 2 days before the first burn Injury and again from the time of surgery. In the controls, the two burn injuries were separated by 7 days. Sensory variables included cumulated pain score during induction of the burn (visual analog scale), secondary hyperalgesia area, and mechanical and thermal pain perception and pain thresholds assessed before and 1 h after the burn Injury. Results: The Heat injuries induced significant increases in pain perception (P 0.8), secondary hyperalgesia areas (P > 0.1), mechanical and thermal pain perception (P > 0.1), or mechanical and thermal pain thresholds (P > 0.08) in the burn area before surgery compared to after surgery. Conclusion: Arthroscopic knee surgery did not modify nociceptive responses to a contralaterally applied experimental burn Injury. TISSUE Injury is associated with peripheral and central changes in the nociceptive system leading to primary hyperalgesia in the inflammatory area and secondary hyperalgesia in neighboring noninjured tissue, which may contribute to an increase in pain perception. 1 These pain-sensitizing mechanisms have been well documented in the incisional area after surgery. 2– 6 However,
L Arendt-nielsen - One of the best experts on this subject based on the ideXlab platform.
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Comparison of hyperalgesia induced by capsaicin injection and controlled Heat Injury: effect on temporal summation.
Somatosensory & motor research, 2004Co-Authors: Aysen Yucel, O K Andersen, Akiko Miyazawa, L Arendt-nielsenAbstract:The relationship between induction of central sensitization and facilitation of temporal summation to repetitive stimulation is still unclear. The aim of this study was to investigate temporal summation before and after the induction of secondary hyperalgesia by two different experimental methods: capsaicin injection and controlled Heat Injury. The effect of each Injury model was assessed on a separate day with an interval of at least 5 days. Twelve healthy volunteers participated. Each experiment was performed using electrical, radiant Heat, mechanical impact, and punctuate stimuli consecutively. The pain threshold (PT) to a single stimulus and the summation threshold to five repetitive stimuli for electrical (2 Hz) and radiant Heat (0.83 Hz) were assessed within the secondary hyperalgesic area. The degree of temporal summation for stimulus intensities of 0.8, 1.0, and 1.2 times the baseline pain thresholds were evaluated by the increase in visual analogue scale (VAS) scores from the first to the fifth s...
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The effect of Heat conditioning of the primary area before and after induction of hyperalgesia by topical/intradermal capsaicin or by controlled Heat Injury.
Somatosensory & motor research, 2001Co-Authors: Aysen Yucel, O K Andersen, Akiko Miyazawa, L Arendt-nielsenAbstract:The aim of the present study was to test the effect of Heat conditioning before and after the induction of hyperalgesia. Three different methods were used for induction of hyperalgesia, topical capsaicin, intradermal capsaicin injection, and a controlled Heat Injury. The vascular (blood flow and skin temperature) and sensory changes (area of secondary hyperalgesia and ongoing pain) associated with the cutaneous hyperalgesia were compared. Each experiment consisted of two randomized sessions separated by at least 2 days. In one session, pre-conditioning of the skin by Heat was performed 30 min before the induction of hyperalgesia using a probe at 45°C for 5 min in the center of the expected primary hyperalgesic area. After the induction of hyperalgesia, Heat conditioning was performed twice in the center of the primary hyperalgesic area using a temperature of 2°C above the present individual pain threshold. On the contra-lateral arm, no Heat conditioning was applied while hyperalgesia was induced using the...
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Hyperalgesia and temporal summation of pain after Heat Injury in man.
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50 x 25 mm thermode (47 degrees C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P < 0.000001) and secondary (P < 0.00006) mechanical hyperalgesia were evoked by the Heat Injury. The pain threshold to single electrical stimuli was reduced within the Injury (P < 0.03), but not outside. The pain responses to single and repeated electrical stimuli were not significantly altered by the Injury. Temporal summation of pain occurred in 418 stimulus trains out of 576 (73%), but no significant changes in summation developed in skin with primary or secondary mechanical hyperalgesia compared with normal skin (baseline measurements). Temporal summation at high stimulus intensities was more pronounced than at lower intensities (P < 0.0002). We found no correlation between either temporal summation and area of secondary hyperalgesia, or temporal summation and pain intensity during the induction of Heat Injury. We conclude that the development of primary and secondary mechanical hyperalgesia after Heat Injury in man was not associated with changes in temporal summation of painful electrical stimuli.
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Hyperalgesia and temporal summation of pain after Heat Injury in man
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50×25 mm thermode (47°C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P
O K Andersen - One of the best experts on this subject based on the ideXlab platform.
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Comparison of hyperalgesia induced by capsaicin injection and controlled Heat Injury: effect on temporal summation.
Somatosensory & motor research, 2004Co-Authors: Aysen Yucel, O K Andersen, Akiko Miyazawa, L Arendt-nielsenAbstract:The relationship between induction of central sensitization and facilitation of temporal summation to repetitive stimulation is still unclear. The aim of this study was to investigate temporal summation before and after the induction of secondary hyperalgesia by two different experimental methods: capsaicin injection and controlled Heat Injury. The effect of each Injury model was assessed on a separate day with an interval of at least 5 days. Twelve healthy volunteers participated. Each experiment was performed using electrical, radiant Heat, mechanical impact, and punctuate stimuli consecutively. The pain threshold (PT) to a single stimulus and the summation threshold to five repetitive stimuli for electrical (2 Hz) and radiant Heat (0.83 Hz) were assessed within the secondary hyperalgesic area. The degree of temporal summation for stimulus intensities of 0.8, 1.0, and 1.2 times the baseline pain thresholds were evaluated by the increase in visual analogue scale (VAS) scores from the first to the fifth s...
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The effect of Heat conditioning of the primary area before and after induction of hyperalgesia by topical/intradermal capsaicin or by controlled Heat Injury.
Somatosensory & motor research, 2001Co-Authors: Aysen Yucel, O K Andersen, Akiko Miyazawa, L Arendt-nielsenAbstract:The aim of the present study was to test the effect of Heat conditioning before and after the induction of hyperalgesia. Three different methods were used for induction of hyperalgesia, topical capsaicin, intradermal capsaicin injection, and a controlled Heat Injury. The vascular (blood flow and skin temperature) and sensory changes (area of secondary hyperalgesia and ongoing pain) associated with the cutaneous hyperalgesia were compared. Each experiment consisted of two randomized sessions separated by at least 2 days. In one session, pre-conditioning of the skin by Heat was performed 30 min before the induction of hyperalgesia using a probe at 45°C for 5 min in the center of the expected primary hyperalgesic area. After the induction of hyperalgesia, Heat conditioning was performed twice in the center of the primary hyperalgesic area using a temperature of 2°C above the present individual pain threshold. On the contra-lateral arm, no Heat conditioning was applied while hyperalgesia was induced using the...
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Hyperalgesia and temporal summation of pain after Heat Injury in man.
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50 x 25 mm thermode (47 degrees C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P < 0.000001) and secondary (P < 0.00006) mechanical hyperalgesia were evoked by the Heat Injury. The pain threshold to single electrical stimuli was reduced within the Injury (P < 0.03), but not outside. The pain responses to single and repeated electrical stimuli were not significantly altered by the Injury. Temporal summation of pain occurred in 418 stimulus trains out of 576 (73%), but no significant changes in summation developed in skin with primary or secondary mechanical hyperalgesia compared with normal skin (baseline measurements). Temporal summation at high stimulus intensities was more pronounced than at lower intensities (P < 0.0002). We found no correlation between either temporal summation and area of secondary hyperalgesia, or temporal summation and pain intensity during the induction of Heat Injury. We conclude that the development of primary and secondary mechanical hyperalgesia after Heat Injury in man was not associated with changes in temporal summation of painful electrical stimuli.
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Hyperalgesia and temporal summation of pain after Heat Injury in man
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50×25 mm thermode (47°C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P
J L Pedersen - One of the best experts on this subject based on the ideXlab platform.
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Hyperalgesia and temporal summation of pain after Heat Injury in man.
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50 x 25 mm thermode (47 degrees C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P < 0.000001) and secondary (P < 0.00006) mechanical hyperalgesia were evoked by the Heat Injury. The pain threshold to single electrical stimuli was reduced within the Injury (P < 0.03), but not outside. The pain responses to single and repeated electrical stimuli were not significantly altered by the Injury. Temporal summation of pain occurred in 418 stimulus trains out of 576 (73%), but no significant changes in summation developed in skin with primary or secondary mechanical hyperalgesia compared with normal skin (baseline measurements). Temporal summation at high stimulus intensities was more pronounced than at lower intensities (P < 0.0002). We found no correlation between either temporal summation and area of secondary hyperalgesia, or temporal summation and pain intensity during the induction of Heat Injury. We conclude that the development of primary and secondary mechanical hyperalgesia after Heat Injury in man was not associated with changes in temporal summation of painful electrical stimuli.
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Hyperalgesia and temporal summation of pain after Heat Injury in man
Pain, 1998Co-Authors: J L Pedersen, O K Andersen, L Arendt-nielsen, H KehletAbstract:Temporal summation of pain occurs when repeated stimuli become increasingly painful in spite of unchanged stimulus intensity. Summation can be quantified as the difference in pain between the first and the last stimulus in a train of stimuli. The aim of the study was to compare temporal summation of pain in normal skin with summation of pain in skin with primary and secondary hyperalgesia evoked by a Heat Injury. A Heat Injury was produced on the crus of 12 volunteers with a 50×25 mm thermode (47°C, 7 min). Measurements were made before, and 0, 1, 2, and 4 h after the Heat Injury, in three areas: primary and secondary mechanical hyperalgesia induced by the Heat Injury, and in a mirror image of the Injury on the opposite leg. Temporal summation of pain was induced by repeated electrical stimuli (five stimuli at 2 Hz) and assessed by visual analog scale (VAS). Primary hyperalgesia was evaluated by von Frey hairs and electrical stimuli, and the areas of secondary hyperalgesia with a rigid von Frey hair (314 mN). Significant primary (P
