Sex differences in pain anchors revisited: further investigation of "most intense" and common pain events.

Recent research suggests that the interpretation of maximal endpoints of pain scales vary between sexes. The purposes of this study were to investigate sex differences in (a) maximal endpoints of pain scales and (b) bias, discrimination, and the "better than average effect" for ratings of common pain events. Study participants described and rated the intensity of events that were the "most intense pain imaginable" for the typical woman, typical man, and one's self. Study participants also described and rated the intensity of the "most painful" events they had experienced. Study participants completed the situational pain questionnaire (SPQ), which measured the amount of pain that the typical woman, typical man, or one's self would be expected to experience during thirty common painful events. One hundred and fifteen undergraduate psychology students completed this study. Men and women differed in the categories of events selected for most intense pain imaginable for one's self. There were no significant sex differences for the intensity of most intense self-imagined pain or most painful event experienced. However, women were more likely to report the intensity of their worst self-imagined pain event as 100/100. In addition, only women demonstrated a significant correlation between the intensity of most painful self-experienced event and intensity of most intense self-imagined event. Analyses of the SPQ discrimination scores revealed no sex or version differences. Analyses of the SPQ bias scores showed that both sexes indicated that the typical woman would rate the intensity of common pain events higher than would the typical man. Women rated the intensity of common pain events for themselves lower than for the typical woman, but higher than the typical man, and men rated also rated themselves as lower than the typical women, but the same as the typical man. Thus, there was inconsistent support for the "better than average effect". Future research is needed to determine the clinical relevance of sex differences in pain anchors and gender-related stereotypes for evaluating other people's pain.     

Acute pain threshold in subjects with chronic pain following spinal cord injury.

Studies of pain perception in patients with chronic pain have yielded contradictory results. While several studies found that acute pain threshold is raised in chronic pain subjects, others showed that these subjects exhibit a decreased pain threshold compared to pain free subjects. The aim of this study was to further examine this topic by studying pain perception in subjects with chronic pain following partial or complete spinal cord injury (SCI). We found a significant elevation of heat-pain threshold (measured above the level of lesion) in complete SCI subjects with chronic pain (CSCIP) as opposed to complete SCI subjects without pain, incomplete SCI subjects with (ISCIP) and without chronic pain and normal controls. This elevation of pain threshold was completely reversed following a complete relief of the chronic pain by DREZ lesion. Moreover, the CSCIP exhibited significantly higher scores in the McGill pain questionnaire compared to ISCIP, indicative of a more intense chronic pain perceived by these subjects. In addition, the chronic pain below the level of spinal lesion, reported by CSCIP originated from a significantly larger body area than that of ISCIP. These results indicate that a critical level of chronic pain must be perceived in order to induce an elevation in acute pain threshold.     

Quantitative testing of pain perception in subjects with PTSD--implications for the mechanism of the coexistence between PTSD and chronic pain

Post-traumatic stress disorder (PTSD) often co-occurs with chronic pain. Neither the underlying mechanism of this comorbidity nor the nature of pain perception among subjects with PTSD is well defined. This study is the first systematic and quantitative evaluation of pain perception and chronic pain in subjects with PTSD. The study group consisted of 32 outpatients with combat- and terror-related PTSD, 29 outpatients with anxiety disorder and 20 healthy controls. Quantitative somatosensory testing included the measurement of warm, cold, light touch and heat-pain thresholds and responses to acute suprathreshold heat and mechanical stimuli. Chronic pain was characterized, and levels of PTSD and anxiety symptomatology were assessed by self-report questionnaires. Subjects with PTSD exhibited higher rates of chronic pain, more intense chronic pain and more painful body regions compared with the other two groups. PTSD severity correlated with chronic pain severity. Thresholds of subjects with PTSD were significantly higher than those of subjects with anxiety and healthy controls, but they perceived suprathreshold stimuli as being much more intense than the other two groups. These results suggest that subjects with PTSD exhibit an intense and widespread chronic pain and a unique sensory profile of hyposensitivity to pain accompanied by hyper-reactivity to suprathreshold noxious stimuli. These features may be attributed to the manner with which PTSD subjects emotionally interpret and respond to painful stimuli. Alternatively, but not mutually exclusive, the findings may reflect altered sensory processing among these subjects.     

Sex differences in pain perception and anxiety. A psychophysical study with topical capsaicin

Much evidence indicates that women experience painful stimuli as more intense than men do. Nevertheless, some data suggest that sustained low-level pain may be more disturbing to men than to women. The current experiment evaluated the hypothesis that pain is more disturbing for men than for women by comparing across genders sensory and emotional aspects of pain evoked by capsaicin. Ten men and 10 women (aged 20-46 years) received topical capsaicin for 30 min on the face in one session and on the ankle in another. The subjects rated on visual analog scales pain intensity, unpleasantness and anxiety each minute during capsaicin application and for 30 min after its removal. During capsaicin application, females rated both pain intensity (P = 0.04) and unpleasantness (P = 0.05) higher than did males. Further, subjects rated pain intensity and unpleasantness higher on the face than on the ankle, although the physical stimulus was the same. Despite their lower pain ratings, men reported more pain-related anxiety than women (P = 0.02) Moreover, men showed a significant positive correlation between anxiety and pain intensity and unpleasantness, whereas women did not. After removing the capsaicin, there was no overall effect of sex on either intensity (P = 0.18) or unpleasantness (P = 0.37) of the residual sensation. However, men still showed a positive correlation between anxiety and the intensity and unpleasantness of the sensation. Our data confirm with the topical capsaicin model that women rate pain higher than men, but despite their lower pain ratings, males have more anxiety related to pain.     

Increased taste intensity perception exhibited by patients with chronic back pain

There is overlap between brain regions involved in taste and pain perception, and cortical injuries may lead to increases as well as decreases in sensitivity to taste. Recently it was shown that chronic back pain (CBP) is associated with a specific pattern of brain atrophy. Since CBP is characterized by increased sensitivity to pain, we reasoned that the sense of taste might also be enhanced in CBP. Detection and recognition thresholds were established for a sour taste and ratings of both suprathreshold taste intensity and pleasantness-unpleasantness perception were collected for sweet, sour, salty and bitter stimuli in 11 CBP patients and 11 matched control subjects. As a control, ratings were also collected for visual assessment of degree of grayness. There was no difference between CBP and control subjects for visual grayness rating. On the other hand, CBP patients in comparison to control subjects rated gustatory stimuli as significantly more intense but no more or less pleasant and showed a trend towards a lower detection threshold (i.e. increased sensitivity). The selectivity of the taste disturbance suggests interaction between pain and taste at specific brain sites and provides further evidence that CBP involves specific brain abnormalities.     

Clinical Science (34)

D. Sheffield, P.L. Biles, H. Orom, W. Maixner, D.S. Sh eps : Race and sex differences in cutaneous pain perception. (University of North Carolina at Chapel Hill, Chapel Hill, NC) Psychosomatic Medicine 2000;62:517–523. The purpose of this study was to determine race and sex differences in cutaneous pain perception. Pain perception was measured using a suprathreshold evaluation of pain intensity and pain unpleasantness to a series of thermal stimuli in 27 whites (14 men and 13 women) and 24 African‐Americans (12 men and 12 women). Blood pressure, depressive symptoms, anxiety state levels, and negative mood were assessed before pain testing to examine whether they might account for any sex or race differences in pain perception that emerged. African‐Americans rated the stimuli as more unpleasant and showed a tendency to rate it as more intense than whites. Women showed a tendency to rate the stimuli as more unpleasant and more intense than men. In addition, systolic blood pressure was inversely related to pain intensity. After statistically adjusting for systolic blood pressure, sex differences in pain unpleasantness were reduced and sex differences in pain intensity were abolished; race differences were unaltered. These differences in pain perception may be associated with different pain mechanisms: in the case of sex, differences in opioid activity and baroreceptor‐regulated pain systems; in the case of race, unmeasured psychological characteristics are suggested by the larger differences in ratings of pain unpleasantness than pain intensity. Comment by Mauricio Orbegozo, MD. This is a study where the authors look to elucidate whether there was a difference in cutaneous pain perception determined by race or sex. In general, it is a very well‐designed study where 2 different groups were evaluated, 1 of 27 whites and 1 of 24 African‐Americans with close to half and half distribution of men and women. Pain perception was measured using pain intensity and pain unpleasantness to a series of thermal stimuli. Five different temperatures were used on each subject ranging from 45°C to 49°C. The pain scoring was carried upon a scale from 0 to 150 represented as a line where the evaluated subject had to mark the line at a certain height according to their pain perception. The conclusions reached in the study show that, in general, whites rated the thermal stimuli less painful than African‐Americans. The results show a tendency for men to rate the thermal stimuli as less painful than women did. One of the interesting findings in this study was that the pain differences between men and women were diminished after statically adjusting for systolic blood pressure level. However, the pain intensity and the pain differences after adjusting for systolic blood pressure were unaltered for race differences. In addition, it was also found that pain perception and pain rating was inversely proportional to systolic blood pressure. The hypoalgesia caused by increased systolic blood pressure is a poorly understood mechanism. Several studies have shown that in hypertensive rats there is increased opioid activity in brain tissue. These studies have suggested that at the increase of the pain threshold in subjects who have elevated blood pressure may be related to opioid activity. It is important to mention that in order to establish a definite correlation between systolic blood pressure elevation and the decreased pain perception more studies have to be done. Another important point in this study is the influence of psychological factors on pain perception. In general, it was seen that individuals that were psychologically rated as depressive had a higher rating of the pain compared to individuals that tested as high for anxiety.     

Translation and validation of the Arab version of the fear avoidance beliefs questionnaire

Objective: Determine the reliability and validity of the fear avoidance beliefs questionnaire (FABQ) translated into Arabic. Methods: The FABQ work and physical activity subscales (FABQ-W and FABQ-PA) were translated and culturally adapted into Arabic using the back-translation procedure. Forty-eight subjects with acute low back pain (LBP) and 63 subjects with chronic LBP, whose native language was Arabic, completed a demographic questionnaire, the FABQ, a pain intensity numerical scale, the Modified Oswestry Disability Index (MOSW), and the SF-36 questionnaire. Thirty patients completed the FABQ a second time 3-7 days later. Results: FABQ-W and FABQ-PA showed good internal consistencies (α=0.90 and 0.81 respectively). Test-retest reliability was moderate to high (ICC (1,1) of 0.63 and 0.83 for the FABQ-W and FABQ-PA, respectively). Pain intensity correlated with FABQ-W only for subjects with acute pain (rho 0.41), and with the FABQ-PA only for subjects with chronic pain (rho 0.47). Significant differences between patients with acute and chronic pain were found. Correlations between the FABQ and the MOSW were moderate (rho between 0.40-0.42). Correlations between the FABQ subscales and the SF-36 questionnaire were stronger for subjects with chronic pain. A high ceiling effect was demonstrated for the FABQ-PA, in particular for patients with chronic LBP. Conclusions: The Arabic version of the FABQ has acceptable psychometric properties. However, the results of the physical activity subscale should be interpreted with caution due to a strong ceiling effect.     

Pain in persons with cerebral palsy.

OBJECTIVE: To examine the nature and scope of pain in persons with cerebral palsy (CP). DESIGN: Standardized interviews to assess demographics, pain experiences, and the impact of pain on activities. SUBJECTS: Ninety-three adults with CP recruited from medical clinics at the University of Washington and local residential and community housing for persons with developmental disabilities. MAIN OUTCOME MEASURES: Weekly and 3-month pain intensities, chronic pain grade, interference in daily activities caused by pain, and pain-exacerbating and pain-relieving factors. RESULTS: Sixty-two subjects (67%) reported one or more areas of pain of > or =3 months' duration. Lower extremity pain and back pain were the most common complaints. Fifty-six percent of the subjects reporting pain indicated it occurred daily. Mean average pain intensity, graded on a scale of 0 (no pain) to 10 (pain as bad as could be), was 3.16 (SD = 2.45) in the preceding week and 4.45 (SD = 2.34) in the previous 3 months. Approximately 53% of subjects reporting pain indicated their average pain was of moderate to severe intensity (average pain rated as > or =5). Using Von Korff's Chronic Pain Grade classification system, the majority of subjects who reported pain fell into either grade I (low disability, low pain intensity; 51%) or grade II (low disability, high pain intensity; 39%). Subjects reported many factors that exacerbate pain (eg, stress or weather) or decrease it (eg, exercise or rest). CONCLUSIONS: The data suggest that pain is common in adults with CP. In many subjects, pain levels were moderate to intense.     

Is emotional disturbance a precipitator or a consequence of chronic pain?

The present study examined the relationship between psychological factors and pain in order to assess the contribution of emotional disturbance to the perpetuation of pain. A group of 163 chronic pain suffers in multiple settings was compared with 81 control subjects on measures of personal history antecedent to pain onset, as well as on measures of current emotional disturbance. In addition, these psychological variables were examined for their associations with subjectively rated pain intensity. Overall, pain was found to be related to more current depression and less current life satisfaction, but was not associated with most of the personal history variables examined. These results suggests that emotional disturbance in pain patients is more likely to be a consequence than a cause of chronic pain. The dangers of routinely ascribing intractable pain to psychological causation are discussed in the light of these findings.     

Spousal congruence on disability, pain, and spouse responses to pain

We examined congruence between chronic pain patients and their spouses on their reports of patient pain severity, patient disability, and spouse responses to pain. Patients reported that they were more physically and psychosocially disabled than their spouses reported them to be. However, spouses reported that the patients' pain was more severe than patients reported. Depressive disorders in the patient and gender interacted with patient-spouse ratings. For physical and psychosocial disability, depressed patient couples reported significantly larger differences in disability ratings than non-depressed patient couples. In addition, female patients' disability was rated as more severe by the female patients than by their husbands. Male patient couples did not report differences on physical disability. Findings relating to other forms of disability and to spouse responses are also described. The results are discussed in the context of an interpersonal perspective of chronic pain and have implications for the assessment of pain and disability.     

Relaxation training as a treatment for chronic pain caused by ulcerative colitis

Relaxation training was found to be highly successful in ameliorating pain in a population that has not been studied before—individuals with ulcerative colitis. Twenty subjects with chronic pain due to ulcerative colitis received 6 weekly training sessions of 75 min duration in the technique of progressive relaxation, and another 20 subjects with the same condition constituted an attention control group. There were no significant differences between experimental and control subjects before treatment but, immediately after treatment and also at the 6-week follow-up, experimental and control subjects differed significantly on 6 of 7 measures. By comparison with control subjects, experimental subjects: (1) used significantly fewer words on the McGill Pain Questionnaire to describe their pain (P < 0.001); (2) rated their pain, on a scale of 1–10, as less intense (P < 0.02); (3) said that their pain was less frequent (P < 0.04); (4) rated their pain relief, on a scale of 1–10, as greater (P < 0.001); (5) reported, on the Zung Pain and Distress Scale, less distress due to pain (P < 0.001). After treatment but not before there were significantly fewer experimental than control subjects taking anti-inflammatory drugs (P < 0.03).     

Physical,lifestyle, psychological,and social determinants of pain intensity,pain disability,and the number of pain locations in depressed older adults

Late-life depression and pain more often co-occur than can be explained by chance. Determinants of pain in late-life depression are unknown, even though knowledge on possible determinants of pain in depression is important for clinical practice. Therefore, the objectives of the present study were 1) to describe pain characteristics of depressed older adults and a nondepressed comparison group, and 2) to explore physical, lifestyle, psychological, and social determinants of acute and chronic pain intensity, disability, and multisite pain in depressed older adults. Data from the Netherlands Study of Depression in Older Persons cohort, consisting of 378 depressed persons, diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria, and 132 nondepressed persons aged 60 years and older, were used in a cross-sectional design. Pain characteristics were measured by the Chronic Graded Pain Scale. Multiple linear regression analyses were performed to explore the contribution of physical, lifestyle, psychological, and social determinants to outcomes pain intensity, disability, and the number of pain locations. Depressed older adults more often reported chronic pain and experienced their pain as more intense and disabling compared to nondepressed older adults. Adjusted for demographic, physical, and lifestyle characteristics, multinomial logistic regression analyses showed increased odds ratios (OR) for depression in acute pain (OR 3.010; P = 0.005) and chronic pain (OR 4.544, P < 0.001). In addition, linear regression analyses showed that acute and chronic pain intensity, disability, and multisite pain were associated with several biopsychosocial determinants, of which anxiety was most pronounced. Further research could focus on the temporal relationship between anxiety, late-life depression, and pain.     

The relationship between somatic and emotional stimuli: a comparison between adolescents with temporomandibular disorders (TMD) and a control group.

The overall purpose of this study was to determine whether adolescents with chronic temporomandibular disorder (TMD) pain are more sensitive to all types of somatic and emotional stimuli compared with a matched healthy control group. Sixty adolescents, 8 boys and 52 girls ranging from 12 to 18 years, participated in the study. Thirty of the subjects exhibited TMD, reporting pain of at least 3 months duration. The age- and gender-matched control group consisted of 30 dental recall patients who reported TMD pain less than once a week. All participants completed a 40-item questionnaire comprising 10 items each of pleasant and aversive qualities crossed with somatic and emotional forms of stimuli. The items, a selection of a broad range of familiar stimuli by a panel of experts, were rated based on intensity of experience (0-10, numerical rating scale). Well-fitting items that formed a valid construct within each of the four domains were selected using Rasch analysis. The results showed that adolescents with TMD pain reported significantly greater sensitivity (p<0.05) to aversive somatic and pleasant somatic stimuli than the controls. The differences between groups for the aversive emotional and pleasant emotional stimuli were non-significant. These findings suggest that chronic TMD pain states in adolescents are accompanied by amplification of bodily, but not purely emotional stimuli and that cognitive systems are implicated, not only an alteration of the nociceptive systems.     

A clinical comparison of two pain scales: correlation, remembering chronic pain, and a measure of compliance

Fifteen chronic pain patients rated their pain intensity on both a visual analogue scale and a verbal scale so that comparisons between the scales could be made for each subject. Compliance to fill in the rating blanks and the remembering of pain intensity were also studied. Subjects first made a pre-baseline estimate of their pain and then they rated their pain throughout a baseline and treatment period averaging 5 weeks. Four to 9 weeks after baseline, subjects were asked to remember how much pain they had had at baseline and to confidentially provide ratings concerning their compliance. Results indicated that two-thirds of the individual subjects had significant correlations between the scales with a mean of 0.68. The one-third of the subjects who did not have significant correlations also had significantly less variability in their ratings than did subjects with significant correlations. This low level of variability may account for the lack of a significant correlation between the scales for these subjects. Discrepancies between actual baseline and remembered pain ratings were observed on both rating scales, but the visual analogue scale produced significantly greater discrepancies than the verbal scale. This was mainly because subjects tended to overestimate their baseline pain on the visual analogue scale, while discrepancies on the verbal scale were in both directions (overestimations, underestimations) when taken as a group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Postoperative pain management: study of patients' level of pain and satisfaction with health care providers' responsiveness to their reports of pain

The present prospective survey was conducted in a 1200-bed hospital to examine postoperative patients' current pain intensity, most intense pain experienced, satisfaction with postoperative pain management, and differences regarding pain and satisfaction levels. All adult patients admitted to a hospital in Hong Kong for surgery, except those receiving local anesthesia, were eligible to enter this study. The patient outcome questionnaire developed by the American Pain Society was used to solicit data about patients' pain and satisfaction with pain relief. The subjects were 294 postoperative patients. Approximately 85% complained about varying degrees of pain during the 24 h prior to the assessment of their pain. When interviewed, most patients complained of mild to moderate pain (median = 2 on a 10-point scale), while the median for 'worst pain intensity' was 5. Approximately 80% of the subjects indicated that both the nurses and physicians reminded them to report pain when it occurred. Only 143 (48.6%) agreed that the nurses and physicians sufficiently emphasized the importance of pain relief. Those who received acute pain services, provided by anesthetists, reported lower levels of current pain intensity. Over 65% of the subjects were satisfied with all levels of health care providers, regarding their postoperative pain management.     

Memory for pain: relation between past and present pain intensity

Memory for the intensity of past physical pain depends critically on the intensity of present pain. When their present pain intensity was high, patients with chronic headaches of myofascial origin rated their maximum, usual, and minimum levels of prior pain as being more severe than their hourly pain diaries indicated. When their present pain intensity was low, the same patients remembered all 3 levels of prior pain as being less severe than they actually had been. The results show that pain produces systematic distortions of memory similar to those associated with alterations of affect or mood, and suggest a resolution to a conspicuous conflict in the current pain literature.     

Risk factors for chronic pain following breast cancer surgery: a prospective study.

Chronic pain following breast cancer surgery is associated with decreased health-related quality of life and is a source of additional psychosocial distress in women who are already confronting the multiple stresses of cancer. Few prospective studies have identified risk factors for chronic pain following breast cancer surgery. Putative demographic, clinical, and psychosocial risk factors for chronic pain were evaluated prospectively in 95 women scheduled for breast cancer surgery. In a multivariate analysis of the presence of chronic pain, only younger age was associated with a significantly increased risk of developing chronic pain 3 months after surgery. In an analysis of the intensity of chronic pain, however, more invasive surgery, radiation therapy after surgery, and clinically meaningful acute postoperative pain each independently predicted more intense chronic pain 3 months after surgery. Preoperative emotional functioning variables did not independently contribute to the prediction of either the presence or the intensity of chronic pain after breast cancer surgery. These findings not only increase understanding of risk factors for chronic pain following breast cancer surgery and the processes that may contribute to its development but also provide a basis for the development of preventive interventions. PERSPECTIVE: Clinical variables and severe acute pain were risk factors for chronic pain following breast cancer surgery, but psychosocial distress was not, which provides a basis for hypothesizing that aggressive management of acute postoperative pain may reduce chronic pain.