Pain Perception In Men Research Articles

Similar effects of fatigue induced by a repetitive pointing task on local and remote light touch and pain perception in men and women.

Women involved in repetitive, fatiguing, jobs develop more neck and/or shoulder musculoskeletal disorders than men. Sex differences in the pain response to exercise could contribute to the higher prevalence of neck/shoulder musculoskeletal disorders in women. The objective of this study was to assess sex differences in pain sensitivity following a fatiguing upper limb task. Relationships between measures of fatigue and of the sensitivity to nociceptive and to non-nociceptive stimulations were also explored. Thirty healthy adults (15 women) performed a fatiguing repetitive pointing task with their dominant arm. Upper limb electromyography was recorded from the dominant upper trapezius, anterior deltoid and bicep brachii and from the contralateral tibialis anterior. Before and immediately after the repetitive pointing task, pressure pain and light touch sensitivity thresholds were measured over the same muscles. Electromyographic signs of fatigue were observed only in the anterior deltoid and biceps brachii muscles. Pressure pain thresholds over both muscles increased slightly (effect size ≤ 0.34), but no changes occurred over the upper trapezius and the tibialis anterior. Light touch thresholds increased moderately to importantly after the repetitive pointing task over all four muscles (effect sizes = 0.58 to 0.87). No sex differences were observed in any sensory variable. Moreover, no or weak correlations (r = -0.27 to 0.39) were observed between electromyographical signs of fatigue, light touch threshold and pressure pain threshold variables. We observed sex-independent effects of a repetitive upper limb task on the sensitivity to painful and to nonpainful stimuli. Moreover, the hypoalgesia induced by the repetitive pointing task was weak and localized, and did not directly correlate with the induced muscle fatigue. Results suggest that fatigue-related changes in the sensitivity to noxious and innocuous stimuli could not explain women's greater prevalence of neck/shoulder musculoskeletal disorders.

Prior Lubrication of the Urethra Does Not Reduce Pain Perception in Men Undergoing Flexible Cystoscopy

Objective: The study aimed to test the hypothesis that the instillation of lidocaine gel does not reduce the pain related to flexible cystoscopy. Material and Methods: A prospective randomized study was designed to compare the pain perception between intraurethral instillation of lidocaine gel and saline solution in flexible cystoscopy. One hundred consecutive male patients attending for flexible cystoscopy were randomized to receive 10 ml of lidocaine gel or 10 ml of saline solution. Saline solution was also used for the irrigation pressure. Patients recorded their pain on a 10 cm Visual Analog Scale before and after the procedure. Patients also assessed whether the cystoscopy was more painful than the previous one. Statistical comparison was made using the t test for parametrical data and the Mann-Whitney U test for non-parametrical data. Results: Mean pain score in the lidocaine group was 0.67 ± 1.11 cm (range 0-5) compared to 0.55 ± 1.10 cm (range 0-5) in the saline solution group. Pain perception did not differ significantly between the 2 groups (mean difference 0.12 cm, 95% CI -0.32 to 0.55, p = 0.40). Conclusions: Prior lubrication of the urethra does not reduce the pain produced during flexible cystoscopy. The introduction of flexible cystoscopes under direct vision and with an irrigation pressure might guarantee sufficient comfort and the lubricant gel instillation could be avoided.

Prospective Multi-institutional Study Analyzing Pain Perception of Flexible and Rigid Cystoscopy in Men

To evaluate pain perception in men undergoing flexible or rigid diagnostic cystoscopy. This is a prospective multi-institutional analysis of men undergoing cystoscopy in 4 European departments of urology. Pain perception was assessed with an 11-point numeric rating scale. Pain categories were as follows: no (0 points), mild (1-3), moderate (4-6), and severe pain (7-10). Assessment of pain was before, during cystoscopy, and at days 1, 4, and 7 of follow-up. A total of 300 cystoscopies were analyzed (150 rigid and 150 flexible). Men undergoing flexible cystoscopy were more frequently free of pain (58.7% vs 24%; P<.0001). Mild pain (54% vs 30.7%; P<.0001) and moderate pain (18.7% vs 9.3%; P= .02) were more common with rigid devices. No significant differences were prevalent in severe pain perception (3.3% vs 1.3%; P=.25). Patients, who had previous experience with cystoscopy reported similar pain levels as patients naïve to cystoscopy, regardless if rigid (P= .92) or flexible (P= .26) devices were used. Pain decreased to the baseline during the 1-week follow-up after both, flexible and rigid cystoscopy. In multivariate regression analyses, rigid cystoscopy was an independent predictor fornot being pain free (odds ratio [OR]= 0.15; confidence interval [CI]= 0.08-0.28; P<.0001), for experiencing mild pain (OR= 2.57; CI= 1.57-4.19; P<.0001), and for moderate pain (OR= 2.39; CI= 1.13-5.07; P= .02). Severe pain was seldom with both devices, and thus, no statistical difference was found. Flexible diagnostic cystoscopy caused less pain than rigid cystoscopy in men. Patient's previous experience with cystoscopy did not influence pain sensation. The type of cystoscope itself was identified as an independent risk factor of pain perception.

Effect of Intraurethral Dwell Time of Local Anesthetic Jelly on Pain Perception in Men Undergoing Outpatient Rigid Cystoscopy: A Randomized Prospective Study

To determine optimum duration of intraurethral 2% lidocaine jelly for pain relief during outpatient rigid cystoscopy. This prospective randomized study was conducted between June 2012 and November 2013. Four hundred consecutive adult males requiring diagnostic rigid cystoscopy were randomized into four groups depending on intraurethral 2% lidocaine jelly dwell time before rigid cystoscopy: jelly was instilled 5, 10, 15, and 20 minutes before start of the procedure in group A, B, C, and D patients, respectively. The patients' age, patient-reported preoperative anxiety score, patient-reported intraoperative pain score, the surgeon-reported patient's pain score, and the duration of rigid cystoscopy were recorded and analyzed. The mean age, patient-reported preoperative anxiety score, and duration of rigid cystoscopy were similar between the four groups with no significant difference noted between them. The least and highest mean patient-reported and surgeon-reported intraoperative pain scores were reported in group C (1.49±0.82 and 1.58±0.67) patients and group A (4.86±1.24 and 4.04±1.11) patients, respectively, while no significant difference was found in these scores between group C and D patients. For male patients undergoing diagnostic rigid cystoscopy, an intraurethral dwell time of 15 minutes (of 20 mL 2% lidocaine jelly) provided optimum pain relief.

Comparison of pain threshold and duration of pain perception in men and women of different ages

Introduction Pain is a sensory and emotional experience that occurs with the presence of tissue injury, actual or potential. Pain is subjective, and its expression is primarily determined by the perceived intensity of the painful sensation, called the pain threshold. Objective To evaluate whether there are differences in pain threshold (LD) and time to pain perception (TPED) between the gender in different age groups and to analyze the correlation between age and pain threshold in each gender. Methods and procedures Participants were 60 volunteers divided into 6 groups (n = 10 each) according to gender and age (18–33, 34–49, and 50–64 years). The evaluation of perception and pain tolerance was performed by immersing the container with one hand in water at a temperature of 0 °C–2 °C; the latency to withdrawal of the hand from ice water was measured in seconds and was considered a measure of LD. The TPED was reported by each participant as the start time of the painful stimulus. Results We found differences between the LD for G1 (men aged between 18 and 33 years) and G2 (women aged 18 to 33 years) with greater LD for G1 (p = 0.0122) and greater LD for women (p = 0.0094); for other comparisons of LD and TPED, there were no differences (p &gt; 0.05 for all comparisons). Low correlation was found between age progression with increased LD and the TPED only in men (p = 0.01 and r = 0.45 and p = 0.05 and r = 0.34, respectively). Conclusion We conclude that women have a higher pain threshold than men especially when these groups are aged between 18 and 33 years, and in men increasing age correlates with increased TPED and LD.

Long-term depression of spinal nociception and pain in man: Influence of varying stimulation parameters

Electrical low-frequency stimulation (LFS) of spinal afferents induces long-term depression (LTD) of nociceptive processing in rodents. LTD and its parameters in man are largely unknown. This study addresses the hypothesis that LTD of spinal nociception and pain in man depends on LFS frequency (0.5, 1, 2 Hz), number of electrical pulses (300, 600, 1200), intensity (relating to pain threshold I P: 1 × I P, 2 × I P, 4 × I P), and on LFS repetition. One hundred and twenty electrophysiological and psychophysical experiments were performed in 29 healthy volunteers. Painful electrical test stimulation (0.125 Hz) and conditioning LFS were applied to right hand dorsum by a concentric electrode. Somatosensory evoked cortical potentials (SEP) were recorded and volunteers rated stimulus intensity. LFS with 0.5, 1, and 2 Hz induced significant reduction of SEP and pain ratings as compared to Control group. Effect on SEP amplitude after 1 Hz LFS preponderated that of 2 Hz stimulation. LTD of SEP and pain perception was induced by noxious LFS with 300–1200 pulses. SEP suppression augmented with increasing number of pulses. LFS with intensities 2 × I P and 4 × I P evoked sustained depression of SEP and pain perception in comparison to Control and 1 × I P LFS. Established LTD after single LFS was amplified by an additional second LFS. Hence this study provides electrophysiological and psychophysical evidence for LTD of spinal nociceptive processing and pain perception in man and indicates appropriate LFS parameters 1 Hz, 1200 pulses and 4 × I P for future studies on human LTD.

Sex Differences and Reductions in Pressure-Induced Pain Following Submaximl Isometric Contractions

PUROSE: To investigate the reliability of pain measurement and perception using a pressure-induced pain device, and to examine the effects of submaximal isometric contractions on pressure pain perception in men and women. METHODS: Pain perception was assessed using a pressure stimulus consisting of a 1 kg weight mounted on a plastic edge and placed on the forefinger for two minutes. Subjects pressed a timing device when they first felt pain (pain threshold) and pain ratings were reported every 20 seconds using a 0–10 scale. At the first session, reliability of pain measurement using the pressure-induced pain device was assessed by measuring pain perception before and after a 30-minute rest period. At the last two sessions, pain perception was measured before and after the performance of a submaximal isometric contraction of the elbow flexor muscles 25 minutes after the first pain assessment. These last two sessions were randomized with subjects performing an isometric contraction at 25% of their maximal voluntary contraction force until task failure or for two minutes. RESULTS: Pain thresholds and pain ratings were similar before and after 30 minutes of rest for men and women (p > 0.05). However, women had lower pain thresholds (p = 0.019) and higher pain ratings (p = 0.04) than men before and after the 30-minute rest. Pain ratings decreased for both men and women following the submaximal fatiguing contraction at task failure (p = 0.001) but not after the 2-minute contraction. Pain threshold increased for both men and women following the submaximal fatiguing contraction at task failure (p = 0.021) and after 2 minutes (p = 0.039). CONCLUSION:1) Pain thresholds and pain ratings were repeatable with the pressure-induced pain device after 30 minutes, 2) Pain perception is more likely to decrease following a low intensity submaximal contraction held to task failure than after 2 minutes, and 3) Women have higher pain ratings and lower pain thresholds than men at rest and after the performance of submaximal voluntary contractions.

Can a sexually dimorphic index of prenatal hormonal exposure be used to examine cold pressor pain perception in men and women?

There is considerable evidence to suggest that important differences exist between men and women in their experience of pain. Research has now turned to determine what the mechanisms of such differences actually are. One potential explanation is the effect of sex hormones, especially those typically found in greater concentration within women, e.g., estrogen, progesterone. However, it is also possible that other hormones, such as testosterone may be important. The current study employed a non-invasive sexually dimorphic index (digit ratio) that is believed to reflect prenatal exposure to testosterone, and related this to the cold pressor pain experiences of 23 men and 27 healthy women. As expected, females had greater symmetry between the second and fourth digits, and also reported lower pain tolerance levels. Although some significant relationships were found between digit ratio/digit length and cold pressor pain reports they were relatively inconsistent. Furthermore, the main finding, that pain thresholds were positively related to digit ratio in women but not men, is somewhat inconsistent with predictions. The results are discussed in light of methods for investigating the effect of prenatal hormonal exposure on pain sensitivity in men and women.

Cigarette smoking, stress-induced analgesia and pain perception in men and women

This study examined gender differences in smoking-related analgesia and stress-induced analgesia (SIA), as a function of pain modality. Forty men (20 smokers, 20 nonsmokers) and 37 women (17 smokers) were tested twice for pain sensitivity to tourniquet ischemia, thermal heat, and cold pressor tests; once following mental stress and once following rest control, counterbalancing order. Cardiovascular and neuroendocrine responses to mental stress were also examined. While expected gender differences in pain sensitivity were observed, women smokers had greater threshold and tolerance times to ischemic pain than women nonsmokers ( P<0.05) when pain testing followed rest. Male smokers had greater threshold and tolerance to cold pressor pain than male nonsmokers ( P<0.05) after both rest and stress. Only women showed evidence for SIA, since women nonsmokers demonstrated greater ischemic pain threshold and tolerance following mental stress versus rest ( P<0.05), and all women reported lower thermal heat pain unpleasantness after stress versus rest ( P=0.05). Only nonsmokers showed expected inverse relationships between sympathetic and hypothalamic–pituitary–adrenal (HPA) axis reactivity measures and sensitivity to pain. Smokers showed evidence for blunted HPA-axis function at rest and stress. These results indicate that analgesia related to both being a smoker and stress is influenced by gender and pain modality. The reduced pain perception in smokers and absence of relationships between endogenous pain regulatory mechanisms and pain sensitivity may reflect a maladaptive response to chronic smoking.

Adrenocortical and hemodynamic predictors of pain perception in men and women

Research has demonstrated that women report more pain than men, and clinical observations suggest that attenuated adrenocortical activity is associated with high pain sensitivity. The extent to which cortisol concentrations and hemodynamics contribute to gender differences in pain sensitivity has not been investigated. Thirty-four women and 31 men performed the hand cold pressor test (CPT). Participants rated their pain every 15 s during a 90-s CPT and a 90-s post-CPT recovery period and reported pain using the McGill Pain Questionnaire (MPQ). Salivary cortisol samples and cardiovascular measures were collected prior to, during, and after the CPT. Women reported greater pain than men during and after the CPT and on the MPQ ( Ps<0.01). CPT disrupted the expected diurnal decline in cortisol, as shown by a significant increase in cortisol concentration post-CPT ( P<0.01) in men and women. Regression analyses revealed that pre-CPT cortisol concentrations predicted lower pain reports during and after CPT in men only ( P<0.01). Systolic blood pressure (BP) and stroke volume correlated negatively with pain reports only in women ( Ps<0.05). Controlling for potential confounding variables did not alter these relationships. The negative association between pre-CPT cortisol and pain perception in men and the association between BP and pain in women demonstrate different physiological predictors of pain perception in men and women.

OUTPATIENT FLEXIBLE CYSTOSCOPY IN MEN: A RANDOMIZED STUDY OF PATIENT TOLERANCE

We evaluate the pain of immediate versus delayed outpatient flexible cystoscopy in men after topical local anesthesia application. A total of 100 consecutive men with superficial bladder tumors were randomized to immediate or delayed surveillance flexible cystoscopy after intraurethral instillation of lidocaine gel. Patients recorded the level of pain experienced during cystoscopy on a 4-point pain scale and on a 10-point visual linear analog self-assessment scale. Of the 100 patients 50 underwent immediate and 50 underwent delayed cystoscopy. The mean pain score on a scale of 1-no to 4-severe pain was 1.7 after immediate cystoscopy compared with 1.6 after delayed cystoscopy (p = 0.9). The mean linear analog self-assessment score on a scale of 1-no to 10-most pain was 2.1 after immediate cystoscopy versus 1.8 after delayed cystoscopy (p = 0.7). There was no difference in pain perception in men undergoing immediate or delayed outpatient flexible cystoscopy using the same local anesthetic.

Experimentally Induced Pain Perception in Men and Women in the Morning and Evening

The literature regarding whether or not there are diurnal differences in pain perception in men and women is equivocal. The purpose of this study was to examine the influence of time of day on experimentally induced pain threshold in men and women. A secondary purpose was to measure selected psychological and physiological responses. Pressure (3000 gm force) was applied to the middle digit of the left forefinger for 2-min with the Forgione - Barber pain stimulator. Twenty-nine volunteers (women = 14; men = 15) completed two randomly assigned sessions between 6.00 - 8.00 in the AM and PM. Selected psychological variables (STAI, POMS) and physiological variables (BP, HR, TEMP) were assessed before application of the pressure stimulus. Data were analyzed with a 2 × 2 ANOVA. Results indicated that men had significantly higher (p <. 05) systolic blood pressure and pain thresholds than women however, there was not a significant time of day effect for pain threshold. Significant time of day effects (p <. 05) were found for systolic blood pressure and tympanic temperature. Heart rate, and tympanic temperature were found to be significantly higher (p <. 05) in women in comparison to men. It is concluded that pain threshold did not differ in the AM and PM. Furthermore, men were found to have higher pain thresholds compared to the women.

Topology of EEG coherence changes may reflect differential neural network activation in cold and pain perception.

Pain perception in the brain can be analyzed by neuroimaging (PET, fMRI) and electrophysiological parameter mapping (EEG, ERP/MEG, MEF). These studies have generally been focused on the localization of cerebral activation. Whether pain can be conceptualized as localized function or best be understood by distributed function is important to the theory of human pain processing in the brain. Here, we report that cold and pain perception in the brain is characterized by webs of EEG coherence changes which may reflect coupling or de-coupling of different cortical areas during cold and pain processing. EEG was recorded during cold and pain perception (right hand immersion in 15 degrees C cool-water vs. 0.3 degrees C ice-water for 3 min.) with eyes opened. Subjects rated the cold perception at 2.3 (cool to cold, but no pain) and the pain perception at 6.7 (moderate-strong pain) in a 1-10 scale. The obtained EEG spectral parameters were compared with the corresponding parameters of the resting baseline using paired Wilcoxon tests in the sense of statistical filters to depict those differences which differ clearly from changes by chance. The results were presented in probability maps. The EEG results indicated highly differential coherence networks between cold and pain perception. The cold perception was characterized as decreased coherence in the theta band mainly between frontal electrodes and increased interhemispheric coherence in the alpha range mainly between central and frontal positions. During pain perception almost no coherence changes in the theta band were observed, but great coherence increase in the delta band between central, parietal and frontal electrodes. The network of coherence changes in the alpha band showed strong involvement of electrode C3 concerning coherence increases with frontal positions. In the beta-1 band coherence increase within the left hemisphere was much more pronounced during pain than during cold. The differential characteristics of EEG coherence changes based on neural networks and their spatial organization in the neocortex indicate the distributed brain processing between cold and pain perception in man. This study may contribute to our understanding of the large scale neural networks in cognition based on neurophysiological binding hypothesis and network connections of neural ensembles.

Effects of noxious cooling of the skin on pain perception in man

By means of somatosensory evoked brain potentials following painful CO 2 laser stimulation (pain SEPs) and a pain visual analogue scale (VAS), we investigated changes in pain perception caused by noxious cooling of the skin in normal subjects. Pain SEPs were recorded from scalp electrodes following laser stimulation applied to the leg under various conditions as follows: (1) control (without any interference); (2) 46 °C foot (dipping the foot ipsilateral to the stimulated leg in hot water at 46 °C); (3) 0 °C foot (dipping the foot ipsilateral to the stimulated leg in ice water at 0 °C); and (4) 0 °C hand (dipping the hand contralateral to the stimulated leg in ice water at 0 °C). Marked decreases in amplitude of pain SEPs and VAS were observed under all conditions as compared with the control ( P < 0.001); the degree of pain relief was significantly correlated with changes in pain SEPs. These changes were greatest in the ‘0 °C hand’ condition, followed in decreasing order by ‘0 °C foot’ and ‘46 °C foot’, and there was a significant difference between ‘0 °C hand’ and the ‘46 °C foot’ condition. We considered that the decrease in pain is due to the diffuse noxious inhibitory control (DNIC). The reason why the degree of pain relief in ‘0 °C foot’ condition was less than that in ‘0 °C hand’ condition is unclear, but some particular spatial summation of two kinds of nociceptive impulses mediated by the same pathway might take place.

The Effects of Intraurethral Lidocaine Anesthetic and Patient Anxiety on Pain Perception During Cystoscopy

Despite current practice there is no evidence to demonstrate the efficacy of intraurethral lidocaine gel as an anesthetic for rigid cystoscopy. To evaluate the usefulness of lidocaine in decreasing pain associated with cystoscopy, we performed a prospective, randomized, controlled, double-blind study comparing lidocaine gel with a water based lubricant. The effects of pre-procedure anxiety and prior experience with cystoscopy on pain perception were also evaluated. Physician perception of pain experienced by the patient was compared with the actual pain experienced.We found no decrease in pain perception in men or women following lidocaine gel instillation with a 5 or 10-minute dwell time compared to instillation of the plain lubricant. Increased pre-procedure anxiety correlated with increased pain perception in women. Personal experience with prior cystoscopic procedures significantly decreased the current pain perception in men. Physicians underestimated the patient pain perception in all groups. Overall, we found the use of lidocaine gel to be of no benefit in routine rigid cystoscopy. Lowering pre-procedure anxiety may decrease the amount of pain perceived by women but not by men.

Persistent pain inhibits contralateral somatosensory cortical activity in humans.

To assess cortical activity during pain perception, regional cerebral blood flow (rCBF) studies were done in humans using single photon emission computed tomography (SPECT) with the radiotracer Tc99m-HMPAO and magnetic resonance imaging localization. Normalized SPECT data were analyzed by region of interest and change distribution. Contralateral somatosensory rCBF was decreased when the digits of the hand were immersed in a hot water bath for 3 min which was rated as moderately painful (persistent pain). No decrease was observed when the hand was immersed in tepid water (control). In contrast, cortical rCBF was increased during vibratory and sensorimotor tasks, in the contralateral somatosensory and sensorimotor areas, respectively. These results indicate that pain perception in man is associated with somatosensory cortical inhibition.

Pain, anxiety, and contingent negative variation: A clinical and pharmacological study

Contingent negative variation (CNV) behavior was studied in 16 volunteers who were suffering from spontaneous recurrent pain syndromes (idiopathic trigeminal neuralgia, classic migraine). The subjects were divided into two groups, “more anxious” and “less anxious,” based on psychometric tests (MMPI and STAI X2). The CNV recordings were carried out, respectively, in basal resting state, during an episode of pain, while under anxiolytic treatment, and lastly, during an episode of pain while under anxiolytic therapy. CNV voltage decrease and frequent appearance of postimperative negative variation (PINV) were observed when pain was present during the recording session. These phenomena were more marked when the pain was accompanied by a greater degree of anxiety. Finally, our results suggest that this slow evoked potential is sensitive to various degrees of anxiety and to pain perception in man, making it useful in the investigation of pain as a complex sensation.

Pain perception in man after long term spinal cord stimulation.

Thresholds of non-painful and painful perception for electrical stimuli are not altered significantly during dorsal column stimulation either in the area of induced paresthesia or outside it. After long term stimulation of the dorsal column the thresholds for stimuli are significantly higher within the area of induced paresthesia but not outside it. Median nerve evoked somatosensory cortical potentials are not altered by conditioning or simultaneous DC stimulation. During DCS in three of eight patients only the vibration evoked cortical potentials were attenuated in the early three components of the potential.

Neurophysiological characterization of the anterolateral spinal cord neurons contributing to pain perception in man

These studies have examined threshold, frequency, and refractory period characteristics of a neural population in the anterolateral quadrant (ALQ) of the spinal cord of man, stimulation of which produces pain. Subjects were 18 conscious humans undergoing percutaneous anterolateral cordotomy for relief of intractable pain. Pain could be produced by ALQ stimulation in all subjects. Pain thresholds ranged from 120 to 1000 μA (at 50 pulses/sec; 0.2 msec pulses), but the majority of thresholds were below 300 μA. A linear relationship was found between stimulation frequency and percentage of subjects reporting pain. This relationship ranged from 5 to 25 pulses/sec with 100% reporting pain at 25/sec and 0% at 5/sec. In 2 of 3 subjects, increases in stimulation frequency up to 500/sec did not produce pain when stimulation intensity was below threshold at 50/sec. The neuronal refractory period for pain in these subjects ranged between 1.0 and 2.0 msec, but the majority of relative refractory periods fell between 1.0 and 1.5 msec. The threshold, frequency and refractory period data obtained in this study are similar to those found for wide dynamic range cells in the ventral half of the dorsal horn in the monkey and suggest that activation of these cells is a sufficient condition to produce pain in man.