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At least 91 records · Page 5Linked to original sources
PubMed2005

Regional differences in pain threshold and tolerance of the transtibial residual limb: including the effects of age and interface material.

OBJECTIVES: To compare the pain threshold (the minimum pressure inducing pain) and pain tolerance (the maximum tolerable pressure) of different regions of the residual limbs of amputees by the indentation method and to evaluate the interface pressure distribution and distortion of the skin surface on indentation by finite element (FE) analysis. DESIGN: Crossover trial. SETTING: Rehabilitation engineering center. PARTICIPANTS: Eight transtibial amputees for indentation test and 1 for FE analysis. INTERVENTIONS: The load applied to the residual limbs using a Pelite or polypropylene indenter attached to a force transducer was increased until subjects could no longer tolerate the load. An FE model was built to simulate the indentation process with the experimentally recorded pain threshold used to load the indenters against the soft tissues. MAIN OUTCOME MEASURES: Pain threshold and tolerance and interface pressure and distortion of soft tissues. RESULTS: The patellar tendon and distal end of the fibula were the best and the worst load-tolerant regions, respectively. Some regions with a thicker layer of soft tissue had lower pain thresholds and tolerance than those with a thinner tissue layer. There was a trend for pain threshold and tolerance to decrease with age. The FE model showed that the peak pressure at the skin surface was very close when both indenters were loaded against the soft tissue at pain threshold limit. CONCLUSIONS: Contrary to common beliefs, regions with a thicker layer of soft tissue did not have a higher load-tolerant ability than thin-skinned regions. Pain threshold and tolerance could be age dependent. The FE model suggests that pain is triggered when peak pressure is applied to the residual limb exceeding a certain limit.

Amputees↗
PubMed1992

Cervicogenic headache, migraine, and tension-type headache. Pressure-pain threshold measurements.

Pressure-pain threshold (PPT) measurements were performed with a pressure algometer, at 22 specified points in the head in patients with cervicogenic headache (n = 32), migraine (with and without aura) (n = 26) and tension-type headache (n = 17). Comparisons were made with a group of healthy controls (n = 20). The average PPT differed significantly between the groups (ANOVA, F = 9.5, P < 0.0005), largely caused by the low threshold in cervicogenic headache patients. There were no significant differences between controls and the 2 other headache groups. In the cervicogenic headache group, the lowest PPT was found in the occipital part of the head on the side with pain predominance. The ratio between the dominant and non-dominant sides (all 11 points on each side) was 0.85 in cervicogenic headache, whereas it was 0.99 in migraine patients with side preponderance of the pain. The present results support the view that the pathogenesis of cervicogenic headache differs from that of migraine and tension-type headache. The results may further support the theory that fibres from the C2 level (innervating the occipital part of the head) may be included in the pathogenetic mechanism in cervicogenic headache.

Adult↗
PubMed1992

[A study of the regularity of pain threshold changes after trauma and the effect of electroacupuncture].

Pain threshold of rats was measured by the latent period of tail flick and limb withdrawal elicited by radiant heat. 52 male SD rats were used and trauma was produced by aseptic amputation just beneath the right ankle joint. The effect of nerve block and electroacupuncture (EA) was studied and non-traumatic groups were arranged as control. The pain threshold was reduced right after trauma and the lowest level appeared on the 3rd day and then recovered gradually up to the 7th day after trauma. Nerve block and EA markedly raised the pain threshold. Particularly, EA elevated pain threshold of traumatic rats more marked and long-lasted than the effect of nerve block. This may be resulted by mobilizing the functions of the endogenous analgesic systems.

Acupuncture Analgesia↗
PubMed2002

The effect of visual stimuli on pain threshold and tolerance.

For many hospital patients, the experience brings pain and anxiety. Unfamiliar surroundings, various diagnostic and therapeutic procedures, and the sight and sounds of medical procedures exacerbate pain and anxiety. To block off the anxiety-inducing sights and sounds of hospital surroundings and create a pleasing environment, the therapeutic potential of visual stimulation as a nursing intervention was investigated. In a randomized, controlled, cross-over study, pain was produced by a modified tourniquet technique in 46 healthy volunteers. Subjects were randomly allocated to two groups (Group V and Group B) with subsequent cross-over. Those in Group V watched a soundless video display of natural scenery during tourniquet inflation, whereas in Group B subjects watched a static blank screen. Pain threshold was defined as the time when subjects reported the first detectable pain, whereas pain tolerance was the time the pain was reported to be intolerable and deflation of the tourniquet was requested. With the use of visual stimuli, there was a significant increase in pain threshold (P < 0.05) and pain tolerance (P < 0.01). Gender and the sequence of visual stimuli did not have any significant effect on pain threshold and pain tolerance. Further studies specifically addressing level of anxiety and physiological data correlated with pain scores and visual stimuli are needed. The findings have implications for nurses and other healthcare professionals to use various visual stimuli as positive adjuncts to other methods of pain relief and for different pain conditions in clinical areas.

Adult↗
PubMed2000

Fear and anxiety: divergent effects on human pain thresholds.

Animal studies suggest that fear inhibits pain whereas anxiety enhances it; however it is unclear whether these effects generalize to humans. The present study examined the effects of experimentally induced fear and anxiety on radiant heat pain thresholds. Sixty male and female human subjects were randomly assigned to 1 of 3 emotion induction conditions: (1) fear, induced by exposure to three brief shocks; (2) anxiety, elicited by the threat of shock; (3) neutral, with no intervention. Pain thresholds were tested before and after emotion induction. Results suggest that findings from animal studies extend to humans: fear resulted in decreased pain reactivity, while anxiety led to increased reactivity. Pain rating data indicated that participants used consistent subjective criteria to indicate pain thresholds. Both subjective and physiological indicators (skin conductance level, heart rate) confirmed that the treatment conditions produced the targeted emotional states. These results support the view that emotional states modulate human pain reactivity.

Adult↗
PubMed1992

Hypoalgesic effect of EMLA and lidocaine gel applied on human oral mucosa: quantitative evaluation by sensory and pain thresholds to argon laser stimulation.

Sensory and pain thresholds to argon laser stimulation were used to evaluate the analgesic efficacy and duration of a eutectic mixture of local anesthetics (EMLA) and a 2% lidocaine gel applied topically on the oral mucosa. Application of EMLA for 2 min on the tongue and gingiva increased the pain thresholds by 92.8% and 63.4% respectively. Corresponding values for lidocaine gel were 53.6% and 21.9%. Standardized variation of the EMLA application period (2, 5, and 15 min) produced significantly different analgesic profiles on the tongue but not on the gingiva. Application of EMLA for 5 and 15 min on the tongue and for 2, 5, and 15 min on the gingiva increased the pain thresholds to a predefined analgesic level (2.15 W) for 2 to 25 min. The present experimental model for assessment of oral mucosa pain is suggested to be well-suited for investigations of intraoral analgesia.

Administration, Topical↗
PubMedDate not supplied

Sleep deprivation affects thermal pain thresholds but not somatosensory thresholds in healthy volunteers.

OBJECTIVE: Sleep disturbances have been thought to augment pain. Sleep deprivation has been proven to produce hyperalgesic effects. It is still unclear whether these changes are truly specific to pain and not related to general changes in somatosensory functions. The aim of the present study was to evaluate the effect of total sleep deprivation on thermal pain thresholds (heat, cold) and pain complaints. Thermal detection thresholds (warmth, cold) were included as covariates to determine the contribution of somatosensory functions to changes in pain processing. METHODS: Twenty healthy volunteers were randomly assigned either to two nights of total sleep deprivation or to two nights of undisturbed night sleep. Sleep deprivation nights were separated by two days with normal night sleep. Heat and cold pain thresholds as well as warmth and cold detection thresholds were measured by use of a peltier thermode in the evening before and the morning after each deprivation or control night. Pain complaints were examined by use of a questionnaire in parallel. RESULTS: During treatment nights, sleep deprivation produced a significant overnight decrease in heat pain thresholds. Cold pain thresholds tended to decrease also during sleep deprivation, whereas the warmth and cold detection thresholds remained unaffected. Accordingly, no substantial contributions of the changes in thermal detection thresholds to the changes in thermal pain thresholds were determined by regression analyses. Pain complaints were not induced by sleep deprivation. CONCLUSIONS: The present findings suggest that sleep deprivation produces hyperalgesic changes that cannot be explained by nonspecific alterations in somatosensory functions.

Adult↗
PubMed1979

Pain thresholds in rats during recovery from REM sleep deprivation.

Using 30 Sprague-Dawley female rats, threshold to pain was measured over the course of recovery from REM sleep deprivation. Relative to the untreated controls and to their own pretreatment thresholds, the REM-deprived animals showed significantly reduced pain thresholds which were still evident 96 hours after the termination of the REM deprivation. Possible implications of these data for research with analgesic drugs were noted.

Animals↗
PubMed1986

Effects of vibratory stimulation on muscular pain threshold and blink response in human subjects.

The effects of vibratory stimulation on muscular pain threshold were investigated in 28 healthy subjects. Pain sensation was evaluated by the subjects' verbal reports in response to electrical stimulation of the vastus medialis muscle. Concomitant variations of blink response evoked as a component of the startle reaction were also studied. In all the subjects tested, high frequency vibration (110 Hz) induced a marked and long lasting elevation of the muscular pain threshold but only when vibration was applied to the skin overlying the ipsilateral quadriceps tendon or neighbouring areas and not when applied to remote ipsi- or contralateral regions. This effect was prevented either when tonic vibration reflex (TVR) of the quadriceps muscle was elicited or the skin underlying the vibrator was anaesthetized. Vibratory stimulation at low frequency (30 Hz) failed to produce any consistent effect on muscular pain threshold. Variations in threshold for blink response, as a rule, closely followed those of muscular pain threshold. However, a facilitation of the blink response, not accompanied by changes in pain sensation, was observed during the first period of both high and low frequency vibratory stimulation. The effectiveness of high frequency vibration in raising the muscular pain threshold is coherent with previous results showing that vibration is able to affect pain sensation. Present results suggest a role for rapidly adapting receptors (RA) and/or pacinian corpuscles (PC) in this effect and support the hypothesis of an inhibition of nociceptive messages, possibly at spinal segmental levels, by volleys in large myelinated afferent fibres.

Adult↗
PubMed2000

Pain threshold changes following acupuncture, measured with cutaneous argon laser and electrical tooth pulp stimulation, a comparative study.

1. The present study compared the argon laser technique for pain threshold measurements with the previously often used threshold measurements with electrical tooth pulp (TP) stimulation. 2. Conditioning stimuli with acupuncture was given since it previously has been shown to induce pain threshold changes. Acupuncture needles were inserted in the hands and arms and electrically stimulated. 3. The experiments were performed in a single blind fashion comparing pain threshold effects after either acupuncture or placebo. Pain threshold measurements with a method of limits were used with both electrical TP and the argon laser method. 4. In comparison to placebo the pain thresholds increased after acupuncture, both on the face and on the hand, with the argon laser method, while the TP thresholds were not influenced. No significant pain threshold change was detected with either the argon laser or the TP method following placebo treatment. 5. The results indicate that the argon laser used for sensory testing with a method of limits is a useful method for pain threshold measurements. The difference in pain threshold effects induced by acupuncture measured with the argon laser and the TP stimulation, are discussed and related to mechanisms that may differ between the two types of pain threshold measurements.

Acupuncture Therapy↗
PubMed1993

Muscle tenderness and pressure pain thresholds in headache. A population study.

Tenderness and pain thresholds in pericranial muscles were studied in a random sample of 735 adults aged 25-64 years. This study was a part of a multifaceted, epidemiological study of different headache disorders. Manual palpation and pressure pain threshold were performed by observers blinded to the persons' history of headache. The aim of the study was to evaluate the possible role of pericranial myofascial nociception in headache pathogenesis. Tenderness in migraineurs did not differ from non-migraineurs. Subjects with episodic tension-type headache and females with chronic tension-type headache were more tender than the rest of the population, and males without any experience of headache were less tender than the rest of the male population. A strong positive correlation between tenderness and frequency of tension-type headache was found (males: P < 10(-4); females: P < 10(-5)), while no relation between tenderness and migraine frequency was seen (P = 0.43). In subjects having actual headache at the day of examination tenderness was 32% increased compared to a matched group with identical usual frequency of headache, but without headache during the examination. A significant relation of tenderness to the recency of last episode of headache was detected in both sexes after control for usual frequency and actual headache (males: P < 10(-3); females: P < 10(-4)). Pressure pain thresholds were largely normal indicating normal pain processing and contradicting the idea that tension-type headache mainly is due to generally increased pain sensitivity. This study supports the pathogenetic importance of muscular factors in tension-type headache, while muscular factors are of no primary importance in migraine.

Adult↗
PubMedDate not supplied

[Pain threshold and age in childhood and adolescence]

OBJECTIVE: The few investigations about pressure pain threshold in corporeal surface areas and children age showed no correlation between these parameters in all areas. In this research the existence of correlation between age and pressure pain threshold in seventeen areas of the corporeal surface of children was investigated. METHODS: A descriptive research was made with one hundred children from the Clinical Hospital of the Federal University of Minas Gerais. The selection of patients was made by directed search. There were forty five boys and fifty five girls with ages varying between 5.3 and 15.8 years old, and a mean (-/+ standard deviation) of 9.6 (-/+ 2.7) years old. The seventeen corporeal areas studied were regions of the trapezium, deltoid and supraspinal muscles, nine areas of the abdomen and the median part of the tibias. The pressure of 0.5 kg/cm(2)/s was made using a mechanical algometer. The pressure values that were recorded in the equipment when the children started to complain about the pain, by verbal communication, were considered as pressure pain thresholds. RESULTS: Positive correlations with significant statistic values were found between pressure pain threshold and age in every area investigated: trapezium, r = 0.36; deltoid, r = 0.34; supraspinal, r=0.42; hypochondrium, r=0.41; epigastrium, r=0.41; flank, r = 0.48; periumbilical, r = 0,40; iliac fossa, r = 0.49; hypogastrium, r = 0.45 and tibia, r = 0,29. CONCLUSIONS: Since correlations between age and pressure pain threshold were found in all areas studied, the age of a patient must be taken into consideration during clinical investigations and pain evaluations in children and adolescents. The younger the patient, the lower the pain thresholds.

Journal Article↗
PubMed2000

Low intensity vagal nerve stimulation lowers human thermal pain thresholds.

The effect of vagal nerve stimulation (VNS) on thermal pain sensation was studied in eight subjects who had vagal nerve stimulators surgically implanted for purposes of seizure control. Prior to their involvement in the study, all subjects had the intensity of their VNS (30 Hz, 0.5 ms, 1.0-2.75 mA) adjusted upwards until achieving their desired clinical effect of reduced seizures. Thermal pain thresholds were determined using a Medoc TSA-2001 with a thermode applied to the skin of the forearm. During VNS at settings 100% of those used clinically to control their seizures, subjects showed a statistically significant decrease in their thermal pain threshold of 1.1+/-0.4 degrees C. Acute effects of graded VNS on thermal pain thresholds were determined in seven of the subjects after cessation of chronic VNS. Two thermal threshold measurements were obtained while the subject received sham stimulation (0 mA intensity), during tactile control stimulation and during 30 s of VNS at intensities approximately 33, 66 and 100% of the settings utilized to control their seizures. Tactile control stimulation was provided by electrical stimulation of the skin of the ankle with the intensity adjusted by the patient to match the intensity of any sensations felt in the neck during VNS. Subjects were not aware of the settings employed. Their stimulator was adjusted with each trial and an ascending/descending ordering of intensity was utilized with an inter-trial interval of 2 min. Thermal pain thresholds were significantly decreased in relation to tactile control stimulation at all intensities of VNS tested with the greatest effect occurring at the 66% level. Subjects were also monitored non-invasively and hemodynamic responses to VNS were determined. No significant alterations in hemodynamic variables were observed. The findings of this human study are consistent with experiments in non-human animals which demonstrate a pro-nociceptive effect of low intensity VNS.

Adolescent↗
PubMed2006

Elevated pain thresholds correlate with dissociation and aversive arousal in patients with borderline personality disorder.

In addition to reduced pain perception, patients with borderline personality disorder (BPD) show higher pain thresholds under subjective stress conditions as compared with non-stress conditions. However, the correlation between symptoms of stress and pain thresholds has not been investigated so far. Using a new and convenient methodology, electric stimulation, we expected higher pain and detection thresholds in patients with BPD than in to healthy controls as well as a positive correlation between pain thresholds and symptoms of stress (aversive arousal and dissociation) in BPD patients. Twelve female patients with BPD and twelve healthy controls were included in the study. Electric stimulation was applied on the right index finger, and detection and pain thresholds were assessed by gradually intensifying the stimuli. We found significantly elevated pain thresholds in patients with BPD as compared with healthy controls, but no difference between patients and controls in detection thresholds. In patients, a significant positive correlation was revealed between pain thresholds and dissociation as well as between pain thresholds and aversive arousal. Besides demonstrating a close correlation between pain thresholds and symptoms of stress in patients with BPD, this study replicated earlier findings of reduced pain perception in patients with BPD. Measuring electric pain thresholds is a valid and reasonable method for larger studies.

Adult↗
PubMedDate not supplied

Influence of sex and anxiety on pain threshold and tolerance.

The influence of sex and anxiety on experimental pain perception was studied in a homogeneous population of 50 volunteer and healthy dental students. Three threshold (minimum perceptible threshold, pain threshold and pain tolerance threshold) were determined by delivering electrical stimulations, at regular intervals, on the left hand finger pads. At the same time, the students were asked to complete the Cattell's anxiety test, so allowing their degree of anxiety to be quantified. Statistical analysis of the results showed a lower pain tolerance threshold in females than in males and a significant correlation between the anxiety score and the pain tolerance threshold. The fact that females are more anxious than males could explain these results.

Adult↗
PubMedDate not supplied

Reproducibility indices applied to cervical pressure pain threshold measurements in healthy subjects.

OBJECTIVES: To apply various statistical indices for reproducibility analysis of pressure pain threshold measurements and to derive a preferred pressure pain threshold measurement protocol based on these indices. METHODS: The pressure pain threshold of 3 pairs of right and left homologous cervical region sites were measured in 20 healthy subjects (10 women, 10 men) using a hand-held pressure algometer. Measurements took place on 2 occasions (test 1 and test 2) separated by a mean interval of 1 week. On each testing session, the site-related pressure pain thresholds were measured 3 times each according to 2 different protocols. Protocol A consisted of a repetitive order, namely 3 consecutive measurements at each site before proceeding to the next, whereas protocol B consisted of an alternate order in which 3 consecutive rounds of all individually tested sites took place. For test 1, protocol A was followed by protocol B with an hour interval. For test 2, the reverse order took place. RESULTS: The findings revealed no significant differences between the two protocols and indicated a significant rise (P < 0.0001) in the absolute scores from test 1 to test 2 in both protocols. Absolute values (mean +/-SD) derived from the entire sample of pressure pain threshold sites ranged from 140 +/- 60 to 198.7 +/- 95 kPa (1.60 +/- 0.6 to 1.99 +/- 0.95 kg/cm, respectively). No significant gender or side differences were noted. Pearson r as well as the intraclass correlation coefficient revealed good to excellent reproducibility for both protocols and for all sites measured: r = 0.79-0.94 and intraclass correlation coefficient(3,3) = 0.85-0.96, respectively. To define site-specific cutoff values indicating change at the 95% confidence level, 1.96*SEM was calculated, and its values ranged from 31.6 to 58.2 kPa, which correspond to 16.8% to 32.8% of the absolute mean values. In addition, the limits of agreement, which depict the individual test-retest differences relative to their mean, indicated a heteroscedastic trend. DISCUSSION: The two protocols yielded very similar results. However, on the grounds of patient's comfort and compliance as well as facility of application, protocol B stands out as the more preferred between the two.

Abstracting and Indexing↗
PubMed2004

Quantifying pain threshold and quality of life of fibromyalgia patients.

The most typical symptom of fibromyalgia (FM) is diffuse pain, and pain at specific points-tender points-is crucial for its diagnosis. By comparing healthy individuals and FM patients, this study was aimed at assessing pain and quality of life of Brazilian females with FM, while seeking for a correlation between pain threshold and quality of life. A total of 178 women were evaluated: 124 were FM patients and 54 were healthy women. Pain threshold at tender points was quantified by dolorimetry, and diffuse pain by means of the visual analogue scale (VAS); the Fibromyalgia Impact Questionnaire (FIQ) was used to evaluate quality of life. Statistical treatment of the data allowed for proposing two indexes: a pain threshold index (PT) and a quality of life one (QOL). PT is the lowest value among all pain thresholds measured at the 18 tender points; QOL is the mean of responses to the FIQ and VAS. Both indexes were tested and showed significant differences between the test and control groups. By pairing pain threshold values of each tender point in the test and control groups, it was found that the most sensitive points matched between the two groups, that is, the most sensitive anatomic spots in a healthy individual are also likely to be the most sensitive points in a person with FM. This suggests that a stimulus that provokes slight discomfort to a healthy person may produce more pain in FM patients--which may bear implications for FM clinical treatment. In this sample of Brazilian women, FM patients had both lower pain threshold and worse quality of life than healthy women.

Adult↗