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Painful Stimuli (painful + stimulus)
Selected AbstractsRandomized Double-blind Placebo Controlled Crossover Study of Acetaminophen, Ibuprofen, Acetaminophen/Hydrocodone, and Placebo for the Relief of Pain From a Standard Painful StimulusACADEMIC EMERGENCY MEDICINE, Issue 9 2009James R. Miner MD Abstract Objectives:, The objective was to compare subjects' change in perceived acute pain from an identical painful stimulus after receiving three separate, commonly used pain medications and placebo. Methods:, This was an institutional review board,approved, randomized, double-blind crossover study of healthy human volunteers. Subjects received 1000 mg of acetaminophen, 800 mg of ibuprofen, the combination of 650 mg of acetaminophen with 10 mg of hydrocodone, or placebo (800 mg of lactose) in a randomized order over four separate occasions each 1 week apart. Prior to receiving the drug on each study day, subjects placed their nondominant hand in a bath of 0°C water for 45 seconds. The bath was divided into two sections; the larger was the reservoir of cooled water monitored at 0°C, and the other half was filled from constant overflow. Water drained from the overflow section into the cooling unit and was then pumped up into the base of the reservoir through a diffusion grid. Subjects completed a 100-mm visual analog scale (VAS) representing perceived pain during the exposure. The cold water exposure and VAS were repeated 1 hour after receiving the study drug, and then subjects were observed for side effects for 4 hours. Data were compared using descriptive statistics, 95% confidence intervals (CIs), and repeated-measures analysis of variance (ANOVA). Results:, Twenty-five subjects were enrolled. The mean VAS preexposure was 56.9 mm (±15.1 mm; range = 5 to 92 mm). The mean decrease in VAS after receiving the study drug for acetaminophen was 10.2% (95% CI = ,1.4 to 20.4), for ibuprofen was ,6.6% (95% CI = ,16.5 to 3.20), for acetaminophen/hydrocodone was 9.5% (95% CI = 1.4 to 20.4), and for placebo was ,6.9% (95% CI = ,15.2 to 1.4). The range in change in pain scores for all agents was ,91.3% to 57.6%. Mild side effects (nausea, dizziness, or somnolence) were reported in 11 subjects (44%) after receiving acetaminophen/hydrocodone; no other side effects were reported. Conclusions:, There was a wide range of changes in pain scores from this identical painful stimulus after receiving the study medications. Acetaminophen and acetaminophen/hydrocodone resulted in a similar decrease in pain (10.2 and 9.5%), while ibuprofen and placebo had a similar lack of effect (,6.6 and ,6.9%). Forty-four percent of subjects receiving acetaminophen/hydrocodone reported mild side effects; no other side effects were seen. In this noninflammatory pain model, the VAS is not able to distinguish differences in pain relief between acetaminophen and acetaminophen/hydrocodone or ibuprofen and placebo. [source] Effects of psychological stress on the cerebral processing of visceral stimuli in healthy womenNEUROGASTROENTEROLOGY & MOTILITY, Issue 7 2009C. Rosenberger Abstract, The aim of the study was to analyse effects of psychological stress on the neural processing of visceral stimuli in healthy women. The brain functional magnetic resonance imaging blood oxygen level-dependent response to non-painful and painful rectal distensions was recorded from 14 healthy women during acute psychological stress and a control condition. Acute stress was induced with a modified public speaking stress paradigm. State anxiety was assessed with the State-Trait-Anxiety Inventory; chronic stress was measured with the Perceived Stress Questionnaire. During non-painful distensions, activation was observed in the right posterior insular cortex (IC) and right S1. Painful stimuli revealed activation of the bilateral anterior IC, right S1, and right pregenual anterior cingulate cortex. Chronic stress score was correlated with activation of the bilateral amygdala, right posterior IC (post-IC), left periaqueductal grey (PAG), and right dorsal posterior cingulate gyrus (dPCC) during non-painful stimulation, and with activation of the right post-IC, right PAG, left thalamus (THA), and right dPCC during painful distensions. During acute stress, state anxiety was significantly higher and the acute stress , control contrast revealed activation of the right dPCC, left THA and right S1 during painful stimulation. This is the first study to demonstrate effects of acute stress on cerebral activation patterns during visceral pain in healthy women. Together with our finding that chronic stress was correlated wit the neural response to visceral stimuli, these results provide a framework for further studies addressing the role of chronic stress and emotional disturbances in the pathophysiology of visceral hyperalgesia. [source] Long-lasting hippocampal potentiation and contextual memory consolidationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2001Benedetto Sacchetti Abstract In order to ascertain whether there are hippocampal electrophysiological modifications specifically related to memory, exploratory activity and emotional stress, extracellular electrical activity was recorded in hippocampal slices prepared from the brains of male adult rats. Several groups of animals were employed: (i) rats which had freely explored the experimental apparatus (8 min exposure); (ii) rats which had been subjected, in the same apparatus, to a fear conditioning paradigm training entailing the administration of aversive electrical footshocks (8 min exposure); (iii) rats to which the same number of aversive shocks had been administered in the same apparatus, but temporally compressed so as to make difficult the association between painful stimuli and the apparatus (30 s exposure); (iv) naïve rats never placed in the apparatus. Half of the rats from each treatment group were used for retrieval testing and the other half for hippocampal excitability testing. The conditioned freezing response was exhibited for no less than 4 weeks. Hippocampal excitability was measured by means of input,output curves (IOC) and paired-pulse facilitation curves (PPF). Retrieval testing or brain slices preparation were performed at increasing delays after the training sessions: immediately afterwards or after 1, 7 or 28 days. Only the rats subjected to the fear conditioning training exhibited freezing when placed again in the apparatus (retrieval testing). It was found that IOCs, with respect to naïve rats, increased in the conditioned animals up to the 7-day delay. In free exploration animals the IOCs increased only immediately after the training session. In all other rats no modification of the curves was observed. IOC increases do not appear to imply presynaptic transmitter release modifications, because they were not accompanied by PPF modifications. In conclusion, a clear-cut correlation was found between the increase in excitability of the Schaffer collateral,CA1 dendrite synapses and freezing response consolidation. [source] The Fear of Dental Pain questionnaire: construction and validityEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2003Arjen J. Van Wijk Anxiety, fear and pain play an important role in the context of dental treatment and patients' well-being. The Fear of Pain Questionnaire (FPQ)-III is a recently developed self-report questionnaire measuring pain-related fear of a variety of painful stimuli. The present study was undertaken in order to develop a dental equivalent of the FPQ-III, called the Fear of Dental Pain questionnaire (FDP), to determine standard psychometric characteristics and to assess the instruments' validity. Four experienced dentists generated the initial pool of items and two methodologists constructed the initial questionnaire. Two studies were performed. In the study one, a sample of psychology freshmen (n = 309) was taken in order to analyse response patterns. In study two, a sample (n = 176) of patients, dental students and the general population was examined. Results from both studies were used to determine reliability and validity. High internal consistency (0.93) with satisfactory test,retest reliability (0.75) was obtained. Factor analysis revealed a strong one-dimensional factor underlying almost all items. Finally, the proposed FDP version was related to a measure of dental fear and a general measure of fear of pain. All a priori hypotheses were confirmed, thereby providing evidence for the validity of the FDP. The FPD may prove to be a clinically useful tool in the dental setting, and a potentially important covariate in dental pain perception research. [source] Neuronal sensitization for itch in patients with chronic pruritusEXPERIMENTAL DERMATOLOGY, Issue 9 2004A. Ikoma Itch is one of the major symptoms of various skin diseases. Although specific neuronal pathways for itch were identified both peripherally and centrally, they still fail to explain itchy skin observed in patients with chronic pruritus. In this study, sensitivity to itchy and painful stimuli in patients with atopic dermatitis was investigated. Histamine-prick evoked enormous itch in their lesional skin, while less itch in their non-lesional skin than healthy subjects. Flare reaction was not significantly different between their non-lesional and lesional skin, rather smaller than healthy subjects. Mechanical (pin-pricks), electrical, heat and chemical (injection of pH3 solution) stimuli evoked intense itch in their lesional skin and partly also in their non-lesional skin, while only pain in healthy subjects. Itch was also, but not intensely, evoked in healthy subjects by injection of pH3 solution after sufficient histamine stimuli. These results confirm the presence of itchy skin with hyperkinesis (excessive itch by itchy stimuli) and allokinesis (itch by non-itchy stimuli) in patients with atopic dermatitis, which is so intense that painful stimuli cannot suppress but evoke itch, and suggest that neuronal sensitization is involved in their itch not only peripherally but also centrally. [source] Effects of Distraction Versus Spatial Discrimination on Laser-Evoked Potentials in MigraineHEADACHE, Issue 3 2008Marina De Tommaso MD Objectives., To evaluate whether migraine patients exhibit less inhibition to painful stimuli when distracted from pain as compared to healthy subjects, testing the spatial discrimination of painful stimuli, the performance during the mental arithmetic task used to contrast the discrimination performance and the behavior of N1 and N2-P2 laser-evoked potentials (LEPs) amplitudes during spatial discrimination and during distraction. Methods., Eight migraine patients and 8 healthy controls were examined. During repetitive series of painful laser stimulation of the hand, they had to (1) perform a spatial discrimination task, contrasted by (2) a mental arithmetic task that served as distraction. Results., Patients made 50% to 100% more mistakes than controls in the spatial discrimination task (P < .001) as well as during mental arithmetic (P < .05). Whereas healthy subjects showed a marked decrease of the LEP vertex potential amplitudes during distraction compared to the discrimination task, no such attenuation of LEPs was seen in migraine patients (group × task interaction, P < .05). N1 amplitude exhibited a left-hemisphere dominance in both groups, significantly smaller amplitude in migraine patients, but no significant task modulation. Conclusion., Migraine patients exhibited reduced inhibition by attentional modulation of pain processing, accompanied by impaired spatial discrimination of painful stimuli. [source] Individual sensitivity to pain expectancy is related to differential activation of the hippocampus and amygdalaHUMAN BRAIN MAPPING, Issue 2 2010Michal Ziv Abstract Anxiety arising during pain expectancy can modulate the subjective experience of pain. However, individuals differ in their sensitivity to pain expectancy. The amygdale and hippocampus were proposed to mediate the behavioral response to aversive stimuli. However, their differential role in mediating anxiety-related individual differences is not clear. Using fMRI, we investigated brain activity during expectancy to cued or uncued thermal pain applied to the wrist. Following each stimulation participants rated the intensity of the painful experience. Activations in the amygdala and hippocampus were examined with respect to individual differences in harm avoidance (HA) personality trait, and individual sensitivity to expectancy, (i.e. response to cued vs. uncued painful stimuli). Only half of the subjects reported on cued pain as being more painful than uncued pain. In addition, we found a different activation profile for the amygdala and hippocampus during pain expectancy and experience. The amygdala was more active during expectancy and this activity was correlated with HA scores. The hippocampal activity was equally increased during both pain expectancy and experience, and correlated with the individual's sensitivity to expectancy. Our findings suggest that the amygdala supports an innate tendency to approach or avoid pain as reflected in HA trait, whereas the hippocampus mediates the effect of context possibly via appraisal of the stimulus value. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source] Using fMRI to dissociate sensory encoding from cognitive evaluation of heat pain intensityHUMAN BRAIN MAPPING, Issue 9 2006Jian Kong Abstract Neuroimaging studies of painful stimuli in humans have identified a network of brain regions that is more extensive than identified previously in electrophysiological and anatomical studies of nociceptive pathways. This extensive network has been described as a pain matrix of brain regions that mediate the many interrelated aspects of conscious processing of nociceptive input such as perception, evaluation, affective response, and emotional memory. We used functional magnetic resonance imaging in healthy human subjects to distinguish brain regions required for pain sensory encoding from those required for cognitive evaluation of pain intensity. The results suggest that conscious cognitive evaluation of pain intensity in the absence of any sensory stimulation activates a network that includes bilateral anterior insular cortex/frontal operculum, dorsal lateral prefrontal cortex, bilateral medial prefrontal cortex/anterior cingulate cortex, right superior parietal cortex, inferior parietal lobule, orbital prefrontal cortex, and left occipital cortex. Increased activity common to both encoding and evaluation was observed in bilateral anterior insula/frontal operculum and medial prefrontal cortex/anterior cingulate cortex. We hypothesize that these two regions play a crucial role in bridging the encoding of pain sensation and the cognitive processing of sensory input. Hum Brain Mapp, 2005. © 2005 Wiley-Liss, Inc. [source] A Psychophysical Investigation of the Facial Action Coding System as an Index of Pain Variability among Older Adults with and without Alzheimer's DiseasePAIN MEDICINE, Issue 8 2007Amanda C. Lints-Martindale MA ABSTRACT Objective., Reflexive responses to pain such as facial reactions become increasingly important for pain assessment among patients with Alzheimer's disease (AD) because self-report capabilities diminish as cognitive abilities decline. Our goal was to study facial expressions of pain in patients with and without AD. Design., We employed a quasi-experimental design and used the Facial Action Coding System (FACS) to assess reflexive facial responses to noxious stimuli of varied intensity. Two different modalities of stimulation (mechanical and electrical) were employed. Results., The FACS identified differences in facial expression as a function of level of discomforting stimulation. As expected, there were no significant differences based on disease status (AD vs control group). Conclusions., This is the first study to discriminate among FACS measures collected during innocuous and graded levels of precisely measured painful stimuli in seniors with (mild) dementia and in healthy control group participants. We conclude that, as hypothesized, FACS can be used for the assessment of evoked pain, regardless of the presence of AD. [source] Spinal Cord Stimulation as a Novel Approach to the Treatment of Refractory Neuropathic Mediastinal PainPAIN PRACTICE, Issue 4 2009Oren T. Guttman MD Abstract Spinal cord stimulation (SCS) offers new hope for patients with neuropathic pain. SCS "neuromodulates" the transmission and response to "painful" stimuli. The efficacy of SCS has been established in the treatment of a variety of neuropathic pain conditions and more recently in refractory angina pectoris, peripheral vascular disease, and failed back surgery syndrome. Recent publications suggest that visceral pain could be successfully treated with SCS. We report the first successful use of a spinal cord stimulator in the treatment of refractory neuropathic mediastinal, esophageal, and anterior neck pain following esophagogastrectomy. [source] Use of premedication for intubation in tertiary neonatal units in the United KingdomPEDIATRIC ANESTHESIA, Issue 7 2009RAJIV CHAUDHARY MBBS MRCPCH Summary Background:, Endotracheal intubation and laryngoscopy are frequently performed procedures in neonatal intensive care. These procedures represent profoundly painful stimuli and have been associated with laryngospasm, bronchospasm, hemodynamic changes, raised intracranial pressure and an increased risk of intracranial hemorrhage. These adverse changes can cause significant neonatal morbidity but may be attenuated by the use of suitable premedication. Aims:, To evaluate current practices for premedication use prior to elective intubation in UK tertiary neonatal units. Methods:, Telephone questionnaire survey of all 50 tertiary neonatal units in the UK. Results:, Ninety percent of units report the routine use of sedation prior to intubation and 82% of units routinely use a muscle relaxant. Morphine was the most commonly used sedative and suxamethonium was the most commonly used muscle relaxant. Approximately half of the units also used atropine during intubation. Seventy seven percent of units had a written policy for premedication. Ten percent of the units did not routinely use any sedatives or muscle relaxants for elective intubation. Conclusions:, In comparison with data from a 1998 survey, our study demonstrated an increase in the number of units that have adopted a written policy for premedication use, and in the number routinely using premedication drugs for elective intubation. There remains little consensus as to which drugs should be used and in what dose. [source] Distraction produces an increase in pain-evoked anterior cingulate activityPSYCHOPHYSIOLOGY, Issue 4 2004Robert Dowman Abstract This study examined the effects of distraction on pain-evoked activity in the anterior cingulate cortex (ACC). Twenty-eight healthy adults were given painful electrical stimulation of the sural nerve during an attend condition, where they rated the subjective magnitude of each electrical stimulus, and during a distraction condition, where they performed an arithmetic distraction task. The magnitude of the pain-evoked ACC activity was estimated from the dipole source localization analysis of the somatosensory evoked potential. Subjective pain ratings were smaller and pain-evoked ACC activity was larger during the distraction condition than during the attend condition. Recent regional cerebral blood flow studies have also reported a distraction-related increase in pain-evoked ACC activity. Our results confirm these reports, and verify that the distraction effect specifically involves pain-evoked ACC activity. The cognitive demands of the distraction task present the possibility that the pain-evoked ACC activity might be involved, at least in part, in response competition and/or orienting attention toward painful stimuli. [source] Monitoring of sympathetic tone to assess postoperative pain: skin conductance vs surgical stress indexANAESTHESIA, Issue 7 2009T. Ledowski Summary The number of fluctuations in skin conductance per second has been described as a potential tool for monitoring postoperative pain. More recently, the surgical stress index has shown promising correlations with intra-operative painful stimuli. We compared both methods for their ability to assess postoperative pain, in 100 postoperative patients who were also asked to quantify their level of pain at different time points in the recovery room. The number of fluctuations per second and surgical stress index were significantly different between pain scoring , 5/10 and > 5/10 on a numeric rating scale (mean (SE) number of fluctuations per second 0.12 (0.02) vs 0.21 (0.03), respectively; p = 0.017, and surgical stress index 57 (1.4) vs 64 (1.9) points, respectively; p = 0.001). Both number of fluctuations in skin conductance per second and surgical stress index identified timepoints with moderate to severe pain with only moderate sensitivity and specificity. [source] Randomized Double-blind Placebo Controlled Crossover Study of Acetaminophen, Ibuprofen, Acetaminophen/Hydrocodone, and Placebo for the Relief of Pain From a Standard Painful StimulusACADEMIC EMERGENCY MEDICINE, Issue 9 2009James R. Miner MD Abstract Objectives:, The objective was to compare subjects' change in perceived acute pain from an identical painful stimulus after receiving three separate, commonly used pain medications and placebo. Methods:, This was an institutional review board,approved, randomized, double-blind crossover study of healthy human volunteers. Subjects received 1000 mg of acetaminophen, 800 mg of ibuprofen, the combination of 650 mg of acetaminophen with 10 mg of hydrocodone, or placebo (800 mg of lactose) in a randomized order over four separate occasions each 1 week apart. Prior to receiving the drug on each study day, subjects placed their nondominant hand in a bath of 0°C water for 45 seconds. The bath was divided into two sections; the larger was the reservoir of cooled water monitored at 0°C, and the other half was filled from constant overflow. Water drained from the overflow section into the cooling unit and was then pumped up into the base of the reservoir through a diffusion grid. Subjects completed a 100-mm visual analog scale (VAS) representing perceived pain during the exposure. The cold water exposure and VAS were repeated 1 hour after receiving the study drug, and then subjects were observed for side effects for 4 hours. Data were compared using descriptive statistics, 95% confidence intervals (CIs), and repeated-measures analysis of variance (ANOVA). Results:, Twenty-five subjects were enrolled. The mean VAS preexposure was 56.9 mm (±15.1 mm; range = 5 to 92 mm). The mean decrease in VAS after receiving the study drug for acetaminophen was 10.2% (95% CI = ,1.4 to 20.4), for ibuprofen was ,6.6% (95% CI = ,16.5 to 3.20), for acetaminophen/hydrocodone was 9.5% (95% CI = 1.4 to 20.4), and for placebo was ,6.9% (95% CI = ,15.2 to 1.4). The range in change in pain scores for all agents was ,91.3% to 57.6%. Mild side effects (nausea, dizziness, or somnolence) were reported in 11 subjects (44%) after receiving acetaminophen/hydrocodone; no other side effects were reported. Conclusions:, There was a wide range of changes in pain scores from this identical painful stimulus after receiving the study medications. Acetaminophen and acetaminophen/hydrocodone resulted in a similar decrease in pain (10.2 and 9.5%), while ibuprofen and placebo had a similar lack of effect (,6.6 and ,6.9%). Forty-four percent of subjects receiving acetaminophen/hydrocodone reported mild side effects; no other side effects were seen. In this noninflammatory pain model, the VAS is not able to distinguish differences in pain relief between acetaminophen and acetaminophen/hydrocodone or ibuprofen and placebo. [source] Antinociceptive Activity of a New Benzofuranone Derived from a ChalconeBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2009Pâmela Padaratz The aim of this work was the synthesis of a new benzofuranone compound and evaluation of its antinociceptive potential in mice. The new benzofuranone 4 was synthesized from chalcone 3. The antinociceptive activity of 4 was determined by writhing, formalin, capsaicin, and glutamate and hot-plate tests. Compound 4 caused potent and dose-related inhibition against the writhing test with ID50 6.1 (5.1,7.6) ,mol/kg, i.p., being about 15 times more active than the reference drugs, acetyl salicylic acid and acetaminophen. It was also effective in a dose-dependent manner in significantly reducing the painful stimulus in both phases of formalin, in the capsaicin and in the glutamate test with ID50 values of 27.3 (24.5,30.6) and 18.9 (18.5,19.4) ,mol/kg (first and second phase), 12.6 (9.8,16.2) and 24.5 (20.4,29.6) ,mol/kg respectively. The results showed that the studied compound exhibits both central and peripheral antinociceptive activities and might be further used as a model to obtain new and more potent analgesic drugs. [source] | ||||||||||||||||||||||